Sometimes, it takes a great struggle to build towering peaks. And what more thunderous event is there than the clashing of continental plates?

Geological pileups have birthed some of the largest and tallest mountains on the planet, including Mount Everest and its Himalayan neighbors. But has there ever been a peak taller than Mount Everest, which stands 29,032 feet (8,849 meters) above sea level?

The answer is still a mystery, but there are some geological clues about where the tallest peaks would have been in the ancient past, experts told Live Science.

Earth's lost mountains

Geologists don't have the level of detail required to pinpoint an exact highest peak hundreds of millions of years ago. "We're never going to get that granularity, unfortunately," Alan Collins, a professor of geology at Adelaide University in Australia, told Live Science.

However, clues in residual sediments lodged inside Earth's crust hint at the lost grandeur of primordial snowcaps and summits. Scientists study these crusts to understand how deep they went, which can reveal how tall ancient mountains might have been.

Mountains are really just parts of the continental crust that have been thrust upward as tectonic plates slowly crash together. This crust is very heavy, and there is much more to it than what you see on the surface; even the most spectacularly tall peaks, like Everest, are anchored in deep crust. Just as crust gets thrust up to form mountain peaks, it also gets pushed deep under the surface. Both Collins and Ziyi Zhu, a geochemist at Curtin University in Australia, compared mountains to icebergs, in the sense that only a bit pokes above the surface.

"We can argue or speculate that [the biggest mountain] was in a place where there were deep roots in the crust," Zhu told Live Science.

Geologists estimate that the Himalayas, for example, have a crustal column that goes down as far as 50 miles (80 kilometers). Compare that to Everest's elevation of about 29,000 feet (9,000 m), and the world's tallest mountain at most represents only 14% of the rock slab it's part of. That means there's a limit to how tall mountains can get before they collapse under their own weight.

The Himalayas began forming between 50 million and 40 million years ago from the collision between the Indian Eurasian continental plates. As far as mountains go, they are relatively young. And that's partly why they are still so tall. Tall, jagged mountains erode quickly over time, though the Himalayas are still growing as the two plates continue to collide.

Such continental collisions have happened countless times before, though. For example, the Transgondwanan Supermountain, an ancient range in what is now East Africa, began emerging some 650 million years ago when Africa and South America crashed into Arabia, India, Australia and Antarctica to form the supercontinent Gondwana.

Gondwana split up again, but evidence of these mountains in places like southern India, Sri Lanka, Tanzania and Kenya point to them being three times the length of the Himalayas. "If you walk around there now, you can see rocks that were at the bottom of this mountain belt," Collins told Live Science. On average, the crust is deeper than the crust of the Himalayas. "We think this is at least the scale of the Himalayas if not more," Collins said.

The crusts found in these areas also hint at how tall the mountains were, with sections that descend up to 18 miles (30 km) deep, despite half a billion years of erosion. "At some point, they were likely halfway down a crustal column that was 60 kilometers [37 miles deep]," Collins said. This means that the mountains above this base could have been as tall as Everest.

In the Himalayas, the tallest mountains sit around the rim of the Tibetan Plateau, which has the highest elevation on the planet, at about 3.7 miles (6 km) above sea level, on average. The Transgondwanan range may have had a similar plateau around southern Madagascar, meaning its rim would have been in eastern Madagascar, southern India and eastern Antarctica, Collins said.

Another candidate for the tallest mountains was the Grenville orogeny, which popped up with the formation of the supercontinent Rodinia starting about 1.3 billion years ago. Its remains can be seen around southeastern Ontario and northwestern Vermont. But less is known about this extinct range, Collins said, with some scholars arguing that it wouldn't have been as tall as the Transgondwanan range or the Himalayas.

Further back, some 2 billion years ago, the formation of the supercontinent Nuna (also called Columbia) also left evidence of truly giant mountains. Zhu's paper found evidence of this supermountain by examining the composition of zircon crystals left in the crust underneath this vanished range.

Look any further back, however, and the picture gets murkier. When Earth was hotter, mountains likely couldn't get as high because warmer crusts can support less weight, Collins said. Stable continental plates and rocks didn't start to form until about 4 billion years ago, and it took hundreds of millions of additional years for large continents to form.

For Zhu, the Nuna, Transgondwana and Himalaya ranges are currently the best candidates for holding the tallest mountains that ever existed. But it's likely impossible to pinpoint the highest specific peak, at least with current scientific methods. "It's an open question," Zhu said.

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The year is 2050, and as the sun sets, the night's first constellations emerge in perfect rows. But these amber-glowing arrays aren't stars at all; they're satellite clusters, harvesting the day's last rays before beaming their power back to Earth.

If it reads like science fiction, that's because it started that way. Called space-based solar power (SBSP), the concept featured prominently in the techno-utopian imaginations of 20th-century visionaries and writers. But for decades, it was dismissed — a pie in the sky proposal.

Now, as a new space race heats up, governments and private companies in China, the U.S., the U.K. and Japan are developing several projects to reassess the idea's feasibility. These include China's ZhuRi ("Chase the Sun") program, Japan's OHISAMA project, the U.K.'s Space Solar, and power-beaming experiments by Caltech and the Air Force Research Laboratory in the U.S., all of which are targeting test launches in the next five years.

Proponents say the technology has the potential to meet Earth's energy needs many times over while causing minimal harm to the environment. But first it needs to get off the ground: In the eyes of critics, space-based solar power is exorbitantly expensive, riddled with untested assumptions, and far too complex to be deployed in time for an urgent green-energy transition.

The challenges include getting the massive solar-panel-covered satellites into space; assembling them; getting those solar panels to constantly face our star; and then finding ways to convert, concentrate and transmit their collected power back to Earth.

Despite these hurdles, researchers keep returning to the idea. Perhaps because the most crucial step — generating energy in the first place — is already being done by the sun. Every second, our star fuses hydrogen atoms to expel the same energy as nine trillion atomic bombs. All that's left to do is catch it.

"We're not a competitor to fusion. We are fusion," Peter Garretson, the U.S. Air Force's former chief of future technology and an SBSP expert, told Live Science.

From science fiction to NASA proposal

The first glimmers of SBSP as a concept came from the Russian rocket scientist and astronautics pioneer Konstantin Tsiolkovsky, who, in 1923, suggested deploying space-based mirrors that could concentrate sunlight to Earth with enough intensity to boil 10 cups of coffee.

Tsiolkovsky's fanciful proposal soon entered science fiction, appearing in the British writer Olaf Stapledon's 1937 novel "Star Maker" as a "gauze of light traps" that an advanced alien civilization used to focus "the escaping solar energy for intelligent use" — an idea later formalized by theoretical physicist Freeman Dyson as a Dyson sphere.

Then, in 1941, Isaac Asimov made the clearest, most famous early sketch of SBSP in his short story "Reason," in which a robot colony toils aboard a power station that collects solar energy and fires it back to Earth in the form of microwaves. Asimov provided few details on the fictional station's engineering, instead focusing on the robots' religious worship of the vessel.

But the transformation from science fiction to a concrete proposal didn't take long. In 1968, aerospace engineer Peter Glaser, a consultant and project manager for the Apollo 11 mission's distance-measuring laser reflectors, drew up an engineering design for a "solar power satellite" consisting of three key elements: a ray-collecting device, a converter and a transmitter.

Glaser's collector was a disk of photovoltaic panels that would be lifted some 22,400 miles (36,000 kilometers) off the ground. Locked in a geostationary orbit above Earth and bathed in near-constant sunlight, the satellite would harvest solar rays before converting them into microwaves to be beamed, largely unimpeded through the atmosphere, to receiving antennae on the ground. Once there, the microwaves would be converted into electricity and distributed across the grid.

NASA awarded Glaser a contract to study the concept further, with both domestic and international energy crises (such as the 1973 oil crisis and the 1979 Three-Mile Island nuclear accident) adding wind to his solar sails.

But Glaser's design hit technical and financial roadblocks, the most forbidding being the project's sheer size. By 1981, when the U.S. Department of Energy's four-year study of space-based solar power was released, it estimated that a "meaningful" contribution of 300 gigawatts (sufficient to power hundreds of millions of homes) would require 60 satellites, each spanning 21 square miles (55 square kilometers) and weighing 50,000 tons (45,000 metric tons). The plan was deemed unaffordable.

Later reassessments, such as a 1997 report by NASA physicist John Mankins, pointed to advances such as improved solar cells that made the concept more realistic. Yet the overall consensus remained hostile. A 2015 report released by the Strategic Studies Institute (SSI) of the U.S. Army War College stated that while SBSP systems are "technically feasible," there was "no compelling evidence that such systems will be economically competitive" with terrestrial power systems. It concluded that "the reality is that such systems always seem to be seen as just 10 years away by their advocates."

Aiming high

But a lot can change in a decade, including the cost of firing rockets. Since the SSI report, SpaceX's reusable Falcon 9 rocket has sent launch costs plummeting to around 30 times less than those of NASA's Space Shuttle, with satellites also getting cheaper due to mass production and advances to the clean rooms where they're made. And SpaceX's even bigger Starship rocket promises to more than quintuple Falcon's payload capacity, lowering prices further.

"What you have is a cadre of people in the space community that have grown up before Starlink and SpaceX," Garretson said. "They literally could not believe that, as your launch rate goes up and you amortize your costs, [the launch cost] approaches the cost of fuel." Some took notice. A 2021 assessment commissioned by the U.K. government estimated that a 2-gigawatt, mile-wide space-based solar power array would cost 17.3 billion British pounds ($23.4 billion) and generate energy at 50 British pounds ($68) per megawatt hour over its century lifetime.

That's the equivalent output of a large power station in the U.K., with the initial costs being 39% to 49% cheaper than biomass, nuclear or the most efficient gas energy sources, according to the assessment. And while it's still 14% to 52% more expensive than current terrestrial wind and solar energy, the technology could be beamed anywhere, even to remote locations.

Based on these findings, in 2023, the U.K. government awarded 4.3 million British pounds ($5.8 million) in seed funding to a handful of companies and universities to develop SBSP further.

The U.K. report chose one satellite design as its reference architecture: CASSIOPeiA. Belonging to the U.K. SBSP company Space Solar, the satellite's design is an attempt to crack a significant challenge faced by early solar satellite blueprints: how to keep solar panels constantly aligned with the sun to maximize radiation collection.

Unlike other satellite designs, such as China's Multi-Rotary Joint Solar Power Satellite or Mankins' SPS-ALPHA, which rotate the panels or use a system of mirrors to constantly redirect sunlight onto them, CASSIOPeiA is shaped like a gigantic DNA strand.

This design, alongside a sun-synchronous orbit and a slow spin, enables CASSIOPeiA to constantly receive and transmit solar energy without any heavy or failure-prone moving parts. Space Solar claims that a single CASSIOPeiA satellite, which would be about 1 mile (1.6 km) in diameter, could microwave-beam as much as 2 gigawatts of constant power to a fixed point on the ground — enough to supply a city of 2 million people.

Space Solar says that once the satellite is in space, it will be far more efficient and economical than gathering sunlight on the ground could ever be. That's because the light hitting the space-based power station isn't deflected or attenuated by the atmosphere.

"You use a lot less materials compared with terrestrial solar, and you utilize them more," Sam Adlen, co-founder and co-CEO of Space Solar, one of the funding recipients, told Live Science. "So it's 100% utilized in space rather than 10% if you're on the ground — and you've got 13 times more instant energy, so you're getting much more out of the materials."

Beaming down

However, the next step — beaming gigawatts of energy down and across tens of miles of atmosphere and through potential cloud cover — remains a major technical hurdle.

Proposed power-beaming methods are currently split between two types: lasers and microwaves. California-based startup Aetherflux, which has plans to beam power from satellites in low Earth orbit, has developed an infrared laser transmission system that it will test using a demonstration satellite launched on October 1. The microwave energy will be transmitted at around one kilowatt (enough to supply the basic electrical demands of a household).

Meanwhile, Caltech and Overview Energy, another U.S. startup, have both demonstrated respective microwave and laser-power beaming from orbit and from a plane, respectively, albeit in negligible amounts ( less than a kilowatt).

Despite their efficiency and proven ability to travel vast distances, optical beams in the infrared and near-infrared ranges are easily scattered by water droplets in the atmosphere, preventing power from being transferred on cloudy days. Persisting efficiency issues with optical power transmission also worsen at gigawatt power levels, meaning lasers are less feasible for use at the utility scale.

Microwaves, on the other hand, can be beamed at frequencies with much higher power and suffer relatively little atmospheric attenuation. That's why Space Solar, Japan's OHISAMA project and China's ZhuRi program all plan to use microwave-beaming systems. Nonetheless, microwaves have comparatively longer wavelengths, so their beams diffract more widely across longer distances. This means that even if beams are sent by transmitters hundreds of meters wide, they would need Earth-based receivers spanning dozens of square miles.

These limitations mean that "it's going to take many years" before gigawatt-scale power beaming is achieved, Remo Proietti Zaccaria, head of the DELTA Lab at the Italian Institute of Technology, told Live Science.

Improvements in power-beaming efficiency will bring their own challenges. Even battery-powered laser pointers can blind or burn, so prototypes by laser-beaming SBSP companies like Aetherflux must be designed with that possibility in mind. They promise safety mechanisms that switch off their lasers if anything flies between the transmitter and the receiver.

"Definitely for the weapon side, this technology now can be used efficiently," Proietti Zaccaria said.

If you're imagining an orbital weapon devised by a Bond villain, you may be disappointed — even fully developed power-beaming lasers and microwaves would take a while to cook an egg, or boil Tsiolkovsky's coffees. But beaming technology could still have potent military use: Scrambling communications systems on Earth to create havoc with relatively little effort.

"If you throw even that amount of intensity of power to our antennas, you're going to freeze the electronics; that's for sure," Proietti Zaccaria said. "It's not necessary to destroy them. As long as you freeze the electronics, you've done the job."

The challenges associated with power beaming have pushed some engineers to simpler concepts. One (going full circle back to Tsiolkovsky's original proposal) envisions the deployment of space-based mirrors that reflect sunlight back to Earth after sunset, with a single reflector extending the daylight delivered onto solar panels by around 20 minutes.

This may not seem like much on its own, "but then you can increase this with multiple reflectors," Onur Celik, a researcher in space technology at the University of Glasgow, told Live Science. "If you have 10 or more of them, you can arrange them in space in such a way that you can extend this to up to two hours or so at that altitude."

"The sunlight that you deliver, if it all turns into electricity, could power thousands of homes," he concluded.

The light of day

The trillion-dollar question is whether that power will be cheaper and more efficient than that generated on the ground. The median cost of the electricity generated by SBSP as estimated by the U.K. government is 50 British pounds per megawatt hour ($68), putting it roughly in line with the costs of offshore wind and terrestrial solar power.

However, this estimate is orders of magnitude too sunny for the 2024 NASA cost report, with its projections suggesting SBSP's baseline electricity costs fall between $610 and $1,590 per megawatt hour, depending on the array design. NASA concluded that the U.K.'s median estimate was achievable only after drastic future reductions in launch and manufacturing costs.

Independent studies are also divided over feasibility. One assessment suggests that SBSP could reduce Europe's need for land-based renewable energy by up to 80%, while another counters that the costs could be 12 to 80 times more expensive than those for terrestrial alternatives. This variability exists within the studies themselves, with research published in the journal Acta Astronautica estimating that SBSP could contribute to meeting anywhere from 3% to 31% of global electricity demand, depending on possible constraints in how many satellites can safely fit into an orbit, the receiver size, and where power is beamed to.

"For the numbers we found, I don't believe that this technology could actually be employed to generate energy for Earth," said Proietti Zaccaria, a co-author of the Acta Astronautica study. If humanity had used up all available space for solar panels on Earth, "then I will tell you it would make sense, because at that point, 3%, 5%, 10% could make a difference."

Proietti Zaccaria does see use cases for SBSP schemes for future moon or Mars missions, but otherwise, "the cost for building technology of this kind is really very, very high," he said. "Vice versa, the cost nowadays of buying and installing a solar panel on the roof of any building has become extremely cheap."

Among the challenges would be ferrying the raw materials for the systems into space and then assembling them. Such a feat would make the construction of the International Space Station — currently the most complex structure built in orbit — seem like child's play. Maintaining arrays and preventing them from crashing into other satellites in Earth's increasingly crowded orbits would also take significant international coordination.

Then there are the unweighed environmental costs. All modern rockets use methane, a potent greenhouse gas, to propel them into space, and they release much of it into Earth's upper atmosphere, where its effects are the strongest.

"And so clearly, there is a question there on how launching 100,000 of these superheavy vehicles into the atmosphere will actually impact the atmosphere itself, as opposed to the benefit that we get in the next 20 years or so from having solar power from space," Matteo Ceriotti, a senior lecturer in space systems engineering at the University of Glasgow, told Live Science. "It's not entirely clear."

Ceriotti said the likeliest route for overcoming all of these difficulties come from smaller companies running, and then streamlining, proof-of-concept tests in space.

"Obviously, it's not something that we have ever done," he said. "So clearly, we need to start somewhere, and we need to start small."

The hopes of SBSP proponents remain unclouded by gloomy estimates. They cite several technologies, from personal computers to reusable rockets, that were once thought to be impossibly expensive, even fictitious, that are now ubiquitous and cheap. Their eyes remain fixed on demonstration missions to be launched over the next four years by the likes of Space Solar, Reflect Orbital, Aetherflux and Virtus Solis. If these missions succeed, another once-impossible idea could appear much brighter.

"The private sector is good at this, because it has to be," Sanjay Vijendran, an SBSP consultant who led the European Space Agency's now-shuttered SOLARIS project to test the feasibility of SBSP, told Live Science. "It can break the problem down to quite a small level and start to do things with today's technology and today's way of doing things, and start to show that this can be valuable."

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Fish meal is a commercial, protein-rich product created from raw fish and their byproducts, such as the heads and bones. It tends to be made from smaller fish species, including anchovies, sardines and herring. The fish are cooked, dried and ground into a powder, and then used to feed livestock, farmed fish and pets. But it is not a straightforward market.

In this excerpt from "Every Last Fish: A Deep Dive into the World of Fishes and Fishing" (Granta Books, 2025), journalist and author Rose George looks at how vast quantities of staple fish are taken from the sea off West Africa and turned into fishmeal for farming in Europe and China, instead of ending up on the plates of people in Africa.

"Every Last Fish" was short-listed for the 2026 Royal Society Trivedi Science Book Prize.

Rose George interview: 'If you do want to be a criminal, there is no better place to do it': Diving into the dark depths of the fishing industry

Take a fish. Eat its flesh if you want, but don't scorn the rest. It can always be used, one way or another, whether you want fishmeal or face cream.

Products derived from fish turn up everywhere. Guanine, an ingredient produced from fish scales, is found in bath foam, perfume, nail products, shampoo, skincare products, and lipstick. Fishes can become gelatine, glue, and squalene. They can be in your dietary supplements or your glass of wine: isinglass, derived from dried fish air bladders, is used in wine-making.

Futuristic piscigrafts are irrelevant to most people in Senegal, but they still have to deal with the fish by-products industry, because they have to watch as fish they could eat are transformed into the most common and lucrative fish by-products and sent abroad.

Fishmeal is a sandy grubby powder that is worth billions. Minks eat it. Pigs eat it. Cattle eat it. Fishes eat it. It is also an ingredient in fertilizer and pet food. Fishmeal is part of a huge silent industry of fish by-products that used to be known as FMFO (fishmeal and fish oil) and has now been rebranded by the industry association as 'marine ingredients,' a vague term that covers a broad range of fish-derived products, most of which are never noticed.

The Food and Agriculture Organization defines fishmeal as 'the clean, ground, dried tissue of undecomposed whole fish or fish cuttings, either or both, without the extraction of part of the oil.'

American pets may also find themselves eating fish liver and glandular meal, made from dried complete fish viscera; more general fish by-products, which are 'non-rendered, clean, undecomposed portions of fish (such as, although not limited to, heads, fins, tails, ends, skin, bone and viscera)'; or condensed fish protein digest, the 'condensed enzymatic digest of clean undecomposed whole fish or fish cuttings using the enzyme hydrolysis process'.

'Undecomposed' is doing a lot of work here, a strange term because unless a fish is caught by a vessel with freezer capacity — which no artisanal fisher has — it will be decomposing for days. In theory, fishmeal is impeccably sustainable. It should be a product made from parts of fishes that would otherwise be discarded. It is because of fishmeal that the term 'reduction fisheries' was coined.

Take the meat and the prized flesh, and the rest can be reduced or diverted to other uses. That is the theory. It is not what happens in West Africa.

Each year, half a million tonnes of wild fish are caught in African waters and sent to Europe to feed animals, when they could have fed 33 million Africans instead. That number of people is more than the combined populations of Senegal, Mauritania, and The Gambia. Globally a fifth of wild fishes become fishmeal or fish oil, but 90 per cent of fishmeal fishes are suitable for human consumption.

China uses nearly half of all FMFO, but then China uses most of everything. Europe also takes and takes. Spain imports the most fish oil from Senegal, and France takes 70 per cent of Mauritania's.

In 2019, Changing Markets Foundation produced a detailed investigative report into the fishmeal industry in India, Vietnam, and The Gambia. In each country, the pattern was similar: first the foreign factories come, then they take the fish, then they pollute the environment, then the fishermen say there are no fish left.

Although noting 'a surprising lack of traceability and transparency regarding the origin and supply chain of farmed seafood products,' the foundation linked plenty of reputable European retailers to FMFO supply chains that may use West African fish. For example: Sainsbury's, ALDI, Lidl, and Marks & Spencer in the UK; Auchan, Groupe Casino, Monoprix, and Système U in France (that is a full house of big French supermarkets); all the German ALDIs; and Mercadona in Spain. Sainsbury's, Marks & Spencer, and Mercadona have said they don't use West African FMFO in their seafood products, but how will they know?

The European Union's IUU [Illegal, Unreported and Unregulated fishing] regulations, which require a catch certificate or similar to show the fish was legally caught, do not cover fishmeal. In Mauritania, some Chinese-owned fishmeal factories have their own trawler fleets. The fish bypasses human mouths and goes straight to the factory. That is one tactic. The other is to outbid.

The fish processors tell me that they cannot compete with the prices that fish factories will pay for sardinella. Fish processors get no subsidies from the government, unlike Chinese fishing companies. In The Gambia, one fishmeal factory used 40 per cent of the country's entire fish catch in one year. Black and white. White stealing from Black. The villain/victim template seems neat and unassailable.

It is true — Europeans are using fish that West Africans could eat — and yet it is not all the truth. In Senegal, The Gambia, Mauritania, local fishermen supply fishmeal factories because the factories pay better. In Senegal, a fisheries union official tells me that there are too many pirogues. They are chasing smaller and smaller fish to sell to the factories. It is unsustainable.

The website of the IFFO, which used to stand for International Fishmeal and Fish Oil Organization and now somehow is short for the Marine Ingredients Organisation, is plain. Marine ingredients 'play an essential role in global food security'.

Rubbish, said Francisco Marí of Bread for the World at the CAOPA [African Confederation of Professional Organisations of Artisanal Fisheries] workshop. 'It's just for prawns and salmon — they are not necessary foods; it's a luxury. It's not enough for us to have 10—15 per cent of fish to feed salmon and prawns. Indirectly, we are eating your fish. It's not essential for the alimentation of the US or Japan. We are taking your fish to feed a luxury product that we don't need.'

Every Last Fish: A Deep Dive into the World of Fishes and Fishing by Rose George is published by Granta

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The patient: A 16-year-old girl in California

The symptoms: The teenager was referred to an emergency department because she was having hallucinations, including seeing a flying green dinosaur and hearing voices telling her to hurt others. She also had a sense that she was being followed.

In the emergency room, she was trembling and sweating and had a racing pulse and shallow, fast breathing. She did not have a fever, although she did have one at the hospital that had referred her.

During her conversations with ER clinicians, the teen reacted to the vision of the dinosaur as though the creature were present in the room. She reported that she had experienced these hallucinations since seventh grade,‬ so for about four years.

While her parents countered that she hadn’t exhibited psychotic symptoms until 48 hours before they arrived in the ER, they noted that her interest in school and extracurriculars had waned over the past month.

What happened next: Because of the patient's abnormal vital signs, the ER doctors suspected that her hallucinations might be secondary to some physical ailment, such as trauma to the brain, they wrote in a case report. However, a CT scan showed no signs of swelling or hemorrhage in her head. The doctors attempted a lumbar puncture (also called a spinal tap) but failed to collect any cerebrospinal fluid that they could test for irregularities.

The doctors judged the girl to be too medically unstable to be referred to the hospital's psychiatric ward, so she was admitted to the general pediatric department. Pediatric neurologists suggested an electroencephalogram (EEG), a test that measures electric signaling in the brain, but this revealed no further clues.

On her second day in the hospital, the girl entered a complete catatonic state. Her specific symptoms were not described in the report, but in general, catatonia disrupts how a person processes and reacts to the world around them. Catatonic patients often stop moving and speaking. Doctors treated the patient with lorazepam, which slows down nervous-system signaling, and her catatonia subsided in days.

Meanwhile, interventional radiologists performed a successful second lumbar puncture, but the girl's cerebrospinal fluid appeared normal in the initial panels they ran.

After the patient had spent eight days in the hospital, psychiatrists recommended that the girl be transferred to their ward. However, this was not possible because she developed problems with feeding herself. Her continued psychotic symptoms were treated with the antipsychotic drug olanzapine.

The diagnosis: While initial tests of the girl's cerebrospinal fluid did not show signs of meningitis or other abnormalities, a later test came back positive for autoantibodies — immune proteins that target healthy tissues instead of foreign invaders. These antibodies targeted neuronal intermediate filament (NIF), a protein that helps give nerve cells structural support.

Based on this finding, the patient was diagnosed with autoimmune encephalitis, a condition in which the body produces antibodies that attack nervous tissue, leading to harmful inflammation that can cause psychiatric symptoms.

Autoimmune encephalitis is often triggered by a tumor; proteins produced by the growth can resemble proteins within nervous tissue, and the immune system develops a harmful response against the latter while attempting to fight the tumor. The doctors performed MRIs and a PET scan to look for tumors, but they did not find any.

The treatment: The girl received intravenous infusions of a steroid to reduce inflammation, as well as immunoglobulin — antibodies from healthy donors that are often used to calm autoimmune reactions. She also got an infusion of rituximab, a drug that kills B lymphocytes, a type of white blood cell that makes antibodies like the ones attacking the girl's neurons.

In addition to these infusions, the girl underwent five sessions of plasmapheresis over the next month. In that procedure, blood is drawn from the body, a machine separates plasma (the liquid portion of blood) from blood cells, and the extracted plasma is substituted with a replacement fluid before that blood is returned to the patient. This treatment can help rid the body of autoantibodies.

The girl was discharged after having spent almost two months in the hospital. She was treated with ongoing prescriptions of olanzapine and lorazepam, as well as prednisone and monthly immunoglobulin treatments. As her symptoms improved over the following year, she stopped taking the psychiatric drugs but continued her immunotherapy.

What makes the case unique: Autoimmune encephalitis is rare. One study conducted in the U.K. suggests it affects only 5 to 8 out of every 100,000 people. Additionally, most data about the condition in pediatric patients comes from cases caused by autoantibodies that target NMDA receptors, which detect a key chemical messenger in the brain, rather than NIF.

The case report did not name a specific trigger for the girl's condition, but the authors noted that anti-NIF autoimmune encephalitis has been documented in adults following infections, including certain tick-borne bacterial infections, HIV and COVID-19. Cases associated with these infections are rarer than those linked to tumors.

The doctors did not attribute the teen's case to a specific infection, but her family did report that she'd had a cough three weeks before going to the emergency room. The family had visited the Philippines, and the girl and multiple relatives came down with the same illness.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

Can you guess the diagnosis in these strange medical cases? Find out with our diagnostic dilemma quiz!

This recent satellite snap shows off a multicolored "mosaic" of tightly packed mini farms covering part of Taiwan in the western Pacific Ocean. The sea of fields and shade nets demonstrates the scale of the agricultural challenges facing the densely populated island.

Taiwan is 14,000 square miles (36,000 square kilometers) — about the same size as Maryland — but has a population around four times as large, with approximately 23 million people living there, according to NASA's Earth Observatory. This places a heavy burden on the island's agricultural industry to provide enough food for everyone on the island, especially as large parts of the landmass are covered by mountains and rainforest.

Researchers estimate that there is only around 3,200 square feet (300 square meters) of Taiwanese farmland per citizen, which is around two-thirds the size of a basketball court, according to the Earth Observatory. This is around 10 times less than the equivalent for U.S. citizens.

The majority of the island's food is produced within Yunlin County, which is situated around halfway along the Chianan Plain, a lengthy strip of flat terrain that hugs Taiwan's west coast. Just under half of the county is visible in the satellite image, which spans roughly 15 miles (24 kilometers) across.

The flat ground in Yunlin County, as well as access to water from the island's largest river, the Zhuoshui (visible across the top of the image), makes it an ideal place to grow a variety of different crops, including "rice, sweet potatoes, peanuts, corn, sugarcane, garlic, scallions, coffee, fruit, and leafy greens," Earth Observatory representatives wrote.

The average size of a farm in Yunlin County is under 100,000 square feet (10,000 square m), which is around 90 times smaller than the average U.S. farm. As a result, the region looks like a giant patchwork of tens of thousands of irregular cuboids when viewed from above.

The sizes of Taiwanese farms are restricted by longstanding legislation that limits the amount of land any individual can own, according to the Earth Observatory. Most of the farms are passed down from generation to generation.

While Yunlin County's agricultural mosaic is fairly consistent across this image, two main areas stand out from the rest (see below).

The first outlying region is a swarm of blue and turquoise rectangles surrounding the town of Xiluo in the upper right of the image (just below the river). These farms are covered with plastic shade nets, which shelter them from harsh sunlight in the summer and monsoon-like rains in the wet season

The second and perhaps most noticeable anomaly is a cluster of much larger, lightly colored farms near the town of Baozhong (bottom left of the photo). These are sugarcane fields, left over from when Japan controlled Taiwan between 1895 and 1945.

A large portion of the Chianan Plain was used to grow sugarcane by the Japanese, who also constructed railway lines to move the crop across the island. However, most of these fields have since been repurposed, and all but one of the railway lines have fallen out of use.

In addition to growing crops, these small farms are used to rear livestock, including chickens, cattle and "millions of pigs," according to the Earth Observatory.

See more Earth from space

Slavery has existed for thousands of years, permeating ancient and modern societies across the world. The Vikings were no different. Enslaved people were valuable commodities, being captured and then traded across the Vikings' vast networks. Legal texts and written sources show how enslaved people were sold at trading centers in the same vein as cattle.

In this excerpt from "The Sea-King and the Sorceress: Life and Death in the Viking Age" (Basic Books, 2026), author and archaeologist Neil Price looks at the horrific lives of the "thralls" — the Viking term for the enslaved. In it, he highlights the inhumane treatment of enslaved people, from the raids to kidnap people into the slave trade to a woman who appears to have been killed as a tribute to a high-status man.

Neil Price interview: 'It gives us a glimpse of a different kind of Viking life': Archaeologist Neil Price on the sea-kings, sorcerers and Sámi who lived during the Viking Age

The vast majority of the Norse population were farmers, but there is another group of people who were almost as numerous, though very hard to find in the archaeological record: the enslaved. They have only recently begun to be properly acknowledged in our histories, partly because of the long-standing neglect of the marginalized and vulnerable in many cultures, but in the Viking world also due to a particular coincidence of terminology. For the Norse, the unfree were þrælar, translated into English as "thralls," which is too mild a word to convey its true meaning.

Today, we can be enthralled by a work of art or even a person, but we do not say that we're enslaved by them. Norse thraldom took many forms, some less severe or permanent than others, but all involved the loss of liberty and rights, and the subjugation of one person to another through servitude. A chapter here, even with tangential references in a few others, is nowhere near enough to do justice to this side of the Norse experience (or rather, often the non-Norse experience, since many of them were kidnapped abroad during raids and other campaigns). Archaeological recognition can at least restore some measure of individual dignity, though more comforting to us than to them.

Slavery, as both a practice and an integrated economic system, was an indivisible part of Viking-Age Norse society and had probably already become established in Scandinavia centuries or even millennia earlier. People could be born into slavery, or be forced into it through kidnap or war, and then find themselves sold on, sometimes through many hands and over great distances. Some free people might even temporarily sell themselves in a form of indenture, as a means of paying off debts or other obligations.

Thralls on Norse settlements were ranked in a hierarchical and quite specific nomenclature of service categories and forced to undertake all the tasks of the farm and household. In a few, rare cases, thralls could take on senior responsibilities of estate management, with a special title — bryti — to match. One such man ran the royal estate at Hovgården opposite the island town of Birka, and was allowed to raise a runestone to himself and his wife, though one wonders who paid for it. Nonetheless, the vast majority of thralls endured lives of drudgery.

The grim reality is summarized with derogatory terminology in the poem Rígsþula, the "List of Rígr" (another name for the god Heimdall, or perhaps for Odin): "They fixed fences, dunged fields, worked at the pigs, watched over the goats, dug the peat." Even their names are shaming, mocking their appearance or hygiene: they translate as Badbreath, Stumpy, Fatty, Bedmate, Craneshanks, Dumpy, and many more. Thralls were extremely vulnerable to sexual exploitation. The textual records of viking raids, coming from every culture that was attacked, emphasize that women were particularly targeted for kidnapping and enslavement.

In the ninth century, as the viking attacks escalated both in Western Europe and on the rivers of the east, the taking of captives came to be one of their prime objectives, feeding the lethal trinity of raiding, trading and slaving. In the words of Ibn Miskawayh, a Persian official who described a viking attack on the city of Bardha'a in what is now Azerbaijan in 943: "They kept the women and boys, whom they raped and enslaved [ . . . ] They dragged the women, boys and girls they wanted with them."

The repetition drives home the point, and little imagination is required to sense the undiluted horror. Some of these raids were informed by advance intelligence gathering and directed against high-profile targets for whom ransom could be demanded, but many were destined for sex trafficking, especially to the Arab world. Enslaved humans, particularly from the Baltic region, were among the main commodities exchanged eastwards along the Silk Roads.

In late ninth-century Scandinavia, the logistical needs of the escalating raids brought new demands on the workforce at an ever-larger scale, especially in all the many industries connected with shipbuilding (including textile production, timber management, tar manufacture, ironworking, and much more). This in turn drove the need for unfree labor to still greater levels.

As economic expansion enlarged the capacity for ship-borne aggression and released the agricultural workforce to crew these expeditions, the increased flow of human victims enabled its continuance in a vicious circle. Enslavement was one of the primary characteristics of the Viking Age: the raids were a key component of it and of the Norse diaspora that resulted.

To what degree these people are visible in the funerary record is hard to know. There were probably no diagnostic items that were used exclusively by thralls, so we cannot perceive them through specific objects in the graves. It also seems unlikely that those without rights and with few possessions, indeed with hardly any legal identity as individuals rather than chattel, would be accorded conventional burials. Ibn Faḍlān says that thralls who died while traveling were simply discarded, but this is unlikely to have been the case in settlements. When we do encounter them, it is often because they were killed as part of funerary rituals and their bodies deposited in burials. One example that we can explore here comes from an excavation at the site of Ballateare, in Jurby parish on the northwestern coast of the Isle of Man — the best preserved of all the Viking-Age graves on the island.

At Ballateare, it is instructive to see just how normal the initial funeral, and its circumstances, appear to have been, albeit for a high-status individual. By Viking-Age standards he was in his prime when he died in the early tenth century, somewhere between eighteen and thirty years old. He may have been among the early Norse settlers on Man. We have no reason to believe that the clothes he was buried in, and the things laid in the grave, are not reflections of his life and the international milieu he came from.

He had been interred in a wooden coffin, dug down quite deep into the ground. A sheathed knife was suspended on a lanyard round his neck and he wore a cloak held by an Irish ringed pin. Inside the coffin was a sword — probably from Norway, but with a belt from the British Isles — that had been cut into pieces before being sheathed in the scabbard; the hilt lay broken off beside it. A spearhead also lay in the coffin by the man's feet, snapped off because there was no room for the shaft. A shield, also deliberately damaged with two heavy blows to the boss, had been slid vertically down the outer side of the coffin; the shield board itself may have been smashed too. This was not battle damage; all his weapons were made unusable for reasons we can only guess. Fragments of the shield also revealed traces of paint: it had been decorated with white gesso, banded with black, with rows of red dots along the stripes. Two more spears had been laid across the top of the coffin.

The burial pit was then filled with fine white sand, and a mound was built on top — about 3 metres [10 feet] high and 22 metres [72 feet] in diameter. It was made of thick-cut turfs, which had been brought to the mound from a wide area rather than simply dug up in the vicinity. The earth of the mound seems to be an offering of the land itself, a territorial tribute to the dead man.

I do not wish to relate what happened next in terms of dramatized reconstruction; archaeological description must suffice. On top of the mound lay the body of a woman aged between twenty and thirty, who had been deliberately killed: the back of her head had been removed by a single blow from a sharp blade, probably a sword. Rigor mortis had set in, and some twelve to seventy-two hours had elapsed between her death and the time when her body was covered. She had either lain exposed on the mound for some time after her death, or been killed elsewhere (perhaps more likely, as the missing part of her skull was not present with the body). The woman seems to have died while kneeling, and had fallen forwards with her hands raised. A post was raised on top of the mound beside her body, presumably a grave marker.

A paragraph is not enough to convey what actually occurred, let alone to extrapolate the life that the woman had led before her death — possibly decades of servitude and enslavement, with all that this implies. Her corpse was covered by a very thick layer of cremated animal bone, including considerable numbers of oxen, horses, sheep and dogs. (Somewhere nearby must have been a truly massive cremation pyre.) The mound was finally sealed with turf, covering her body and the ashes of the animals.

Excerpted from The Sea-King and the Sorceress: Life and Death in the Viking Age by Neil Price. © 2026 by Neil Price. Available from Basic Books, an imprint of Hachette Book Group, Inc.

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This wooden figurine was discovered in 1977 in an early house built by the ancestors of the Inuit on Baffin Island in northern Canada. The unique carving represents a person wearing European clothing and a cross on their chest. Dated to 1350, the figurine is the earliest Indigenous representation of a European anywhere in the Western Hemisphere and probably depicts a Norseman.

The tiny driftwood carving, which is currently on display at the Canadian Museum of History, measures just 2.1 inches (5.4 centimeters) tall. According to the museum, the featureless face and stumpy arms are common in 14th-century Inuit carvings, but the depiction of a non-Inuit is unique.

The mysterious figure wears a long robe or tunic with a cross on the front ‪—‬ a garment that is similar to those worn in the 11th to 13th centuries by Norse Christians from Greenland. The Norse sagas mention a place called "Helluland," which Leif Eriksson (also spelled Erikson) visited in the early 11th century and is most likely Baffin Island.

Around A.D. 1000, Norse explorers landed in what is now Newfoundland and set up camp at a site archaeologists call l'Anse aux Meadows. Wood buildings and remains from iron production are all that is left of the earliest European settlement in the Americas.

The Norse likely made multiple trips from Greenland to Canada over the centuries in order to trade metal and cloth with the Inuit's ancestors, known as the Thule, and procure walrus ivory in return, as European-origin artifacts have been found in early Inuit houses on Baffin Island. But the Norse eventually abandoned their westward trade routes, possibly due to the resistance of the Indigenous people and the long distance.

This wooden figurine may commemorate a meeting between the Inuit and the Norse and is especially important because it was crafted long before sustained contact in the late 15th century, according to the museum. It is also the earliest evidence of the Indigenous perspective of visitors from the east, revealing which characteristics of the Norse the artisan observed and felt were important to depict.

For more stunning archaeological discoveries, check out our Astonishing Artifacts archives.

Can you put together last week's Astonishing Artifact?

When Christopher Columbus made landfall in the Americas on Oct. 12, 1492, he encountered Indigenous Lucayans living on the Bahamian island now called San Salvador. Columbus wrote in his diary about "great multitudes of men" who greeted him that day, bartered with him and told him about other groups who lived on nearby islands.

But within a few decades after Columbus' arrival, the Indigenous people of the Americas were decimated by what anthropologist Eric Wolf called the "Great Dying" — a combination of epidemic disease, warfare and enslavement that led to a rapid decline in the Native population.

For centuries, researchers have been trying to figure out how many Indigenous people lived in the Americas just prior to the fateful arrival of European colonizers.

The answer to that question has been surprisingly elusive, and estimates based on historical censuses, archaeological sites and land carrying capacity in the Western Hemisphere have varied wildly.

Recent research into Native American demography has revealed that the population peaked several centuries before Europeans showed up on the shores of North America — and that if Europeans had arrived at that peak, the entire history of the continent may have been different.

Early estimates of the Indigenous population

People have lived in the Americas for at least 14,000 years, having entered the continents via the region around the Bering Strait. Archaeological evidence shows these first Americans dispersed throughout the newly encountered lands fairly quickly. But what happened to the population between that dispersal and the arrival of Columbus is a huge unknown; estimates of the number of Indigenous people living in the Western Hemisphere in 1492 have ranged from 1 million to 112 million people.

"We don't have good quantitative estimates," George Milner, an anthropologist at Penn State, told Live Science. "The numbers are all over the place."

One of the first modern researchers who attempted to quantify the Indigenous population prior to Columbus was anthropologist Henry Dobyns. In a 1983 book, Dobyns used estimates of how many people each type of landscape could support as well as historical records of 16th-century disease epidemics to arrive at an Indigenous population estimate of around 112 million people — more than 100 times larger than some previous experts had believed.

"In essence, Dobyns filled up the landscape to its maximum carrying capacity, so that all environmentally similar places were occupied by the same number of people," Milner said. "He also made the assumption that epidemic disease spread widely and universally, which would make sense if the landscape was filled up."

But a burst of archaeological research in the 1970s and 1980s revealed that the Americas were not uniformly settled, Milner said. Dobyns' estimates were therefore much too high.

Researchers then began to focus on creating population estimates for specific regions of the hemisphere, using techniques such as the relative density of pottery sherds at a site, the number of stone tools and flakes, the number and size of houses, and mortality trends from human skeletons.

In a 2019 study, geographers compiled 129 population estimates from 82 published studies to model the hemisphere-wide distribution of the Indigenous population in 1492. The researchers split the hemisphere into seven regions — the Caribbean, Mexico, Central America, Inca territory, Amazonia, North America and the rest of the Americas — and reached a combined estimate of 60.5 million. Their estimate for North America (modern-day Canada and the U.S.) was about 3 million to 6 million, less than one-third of Dobyns' estimate of 18 million.

A regional perspective – North America

The 2019 study found that the most populous groups in the Western Hemisphere in 1492 were the Aztecs, largely in modern-day Mexico; and the Inca, who lived along the west coast of South America.

But the people we know the most about from an archaeological standpoint are Indigenous groups in the U.S. and Canada.

In a 2010 study, Milner and geographer George Chaplin zoomed in on the data from eastern North America, compiling historic group sizes and sizes of archaeological occupation areas to estimate the location and size of "population aggregates." Using this method, their overall estimate for the eastern U.S. and southeastern Canada was about 1.6 million people.

"Our mean estimates," Milner and Chaplin wrote, "indicate that North America held roughly 2.8 to 5.7 million people" or a "best estimate" of 3.8 million people in the early 16th century, before European diseases dramatically decreased the size of the Indigenous population.

"If you want to start estimating specific populations, you should use measures that work across regions," Robert Kelly, an archaeologist at the University of Wyoming, told Live Science. "People produce things that can be carbon-dated everywhere, because everyone had to build fires for heat and for cooking."

Charcoal from hearths is one of the main human-made things that archaeologists use to radiocarbon-date a site. The radiocarbon data provides a range of dates showing when the firewood was likeliest to have been used.

In North America, many of those carbon-14 dates from charcoal, as well as from animal bones and plant remains from archaeological sites, have been entered into the Canadian Archaeological Radiocarbon Database (CARD).

In a 2009 study, Matthew Peros, a geographer at Bishop's University in Quebec, and co-authors mathematically combined the radiocarbon date ranges in CARD to generate a single curve that revealed how common C-14 dates were over time. At the time, CARD had about 25,000 records.

Because time periods with more people most likely produced more material that could be carbon-dated, the shape of the radiocarbon date curve gave the team an idea of when the population of North America increased and decreased.

They found that the population of North America increased rapidly around 50 B.C. and peaked around A.D. 1150. From that time until European contact, the Indigenous population may have been declining, possibly because of increased mortality from diseases like tuberculosis as people aggregated into denser settlements.

"The 1150 date was an interesting finding that also surprised us," Peros told Live Science. "I had assumed it would be more like 1500 just following the arrival of the Europeans."

In a 2025 study, Kelly and co-authors found a similar temporal peak. By that time, CARD's dataset had ballooned to over 100,000 dates, making the estimate more robust.

"Although devastated by European contact, the Indigenous population did not simply increase to a peak at 1500 CE and then decline," the researchers wrote in the study. In fact, they found evidence for a slight recovery in population numbers just prior to 1500.

But how large was that population? By combining the radiocarbon date curve with a starting population and factoring in average annual population growth, researchers can estimate the number of people living in North America around 1492, Peros said.

In their study, Peros and co-authors assumed that a handful of extended families — around 1,000 people — entered North America about 15,000 years ago as the founder population. With those inputs, the researchers estimated that the maximum population of North America was about 2.5 million in 1150 and had declined to about 1.8 million in 1492. But if people arrived significantly earlier than 15,000 years ago — which might be the case, given evidence from sites like White Sands in New Mexico, which dates to 23,000 years ago — or arrived in greater numbers, those population figures would be even higher.

"Had Europeans tried settling the continent at A.D. 1000, they would have run into a much, much larger Indigenous population," Kelly said. At that time, the city of Cahokia, near modern-day St. Louis, encompassed 6 square miles (16 square kilometers) and had a population of nearly 20,000 people.

"They could have fielded thousands of warriors, and it would have been a very different experience for the Europeans," Kelly said. "It could have been a very different history."

Why does this matter?

Experts told Live Science that the pre-1492 population of what is now the U.S. and Canada was between 2 million and 4 million. The archaeological deep dive in this region sets up the possibility that a full Western Hemisphere population estimate may be made someday.

Milner is optimistic they'll eventually get there. "Will it be done in my lifetime? Probably not," he said. "It's time-consuming, laborious and not especially flashy work to do."

Nonetheless, demography is important work, he said, because it can help us make estimates to prepare for the future.

"The world's population has more than doubled in my lifetime; that's unheard of in human existence," Milner said. "Environmental scientists are really trying to look at what's happened over long periods of time to give us a range of variation of what might happen in the future. We have to make some informed decisions about how to manage our landscape and accommodate these changes."

Understanding the number of Indigenous inhabitants in the Western Hemisphere in 1492 is also key to understanding the history of North America.

"North America was not an empty continent when the Europeans arrived," Peros said. "There were people and civilizations pretty much everywhere in the Americas for a long period of time. It is important for people to understand that when we talk about questions of reconciliation and when we do land acknowledgements."

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Since the discovery of their remains in the 19th century, Neanderthals have fascinated scientists and the general public alike. Although our understanding of these ancient hominins has been transformed tremendously since then, how we have viewed this other human lineage became deeply entrenched in how we see our own species, with geopolitical events shaping the rhetoric around our ancient relatives.

In his new book, "Neanderthals Among Us: The Making of a Prehistoric Human" (Oneworld Publications, 2026), historian and author Peter Sahlins examines our complicated view of Neanderthals, with this lost human lineage being viewed through the lens of cultural and political ideologies. In this excerpt, he looks at our theories for why they went extinct and the philosophical reckoning we've placed up on them.

Between violent extermination and peaceful absorption — with cultural exchange — prehistorians and others propose a wide range of theories to account for Neanderthals' extinction. Just as we've projected our concerns and anxieties about race and gender onto Neanderthals, so too do contemporary challenges shape how we imagine their extinction.

Sometimes it's the newspapers that translate a more neutral science into easily relatable headlines. "Immigrants Halt Neanderthal Era," announced the Glasgow Herald (29 July 2011), claiming that "Europe's earliest residents may have been crowded out by uncontrolled immigration 40,000 years ago." Glossing a highly technical study by Cambridge archaeologist Paul Mellars about the notable increase in population size during the Upper Palaeolithic, the news reports tweaked the science to speak to contemporary anxieties.

But often the science itself is framed or informed by current events. The pathogen thesis gained credence during and after the COVID-19 epidemic. A 2024 study of a 50,000-year-old case of herpes in a sequenced viral genome confirmed widespread speculation that Sapiens-borne pathogens were passed to a Neanderthal population without immunities. Jonathan Kennedy's popular world history "Pathogenesis" (Crown, 2023) argued that Homo sapiens would have been less vulnerable to Neanderthal diseases because they arrived in much larger numbers and had more evolved immune systems from their tropical environment.

Of growing importance over the last twenty years is the thesis that climate change, our own existential challenge of the Anthropocene, was the principal cause of Neanderthal extinction. The idea takes many shapes, beginning with an update of French geologist Georges Cuvier's "catastrophism," where species died off in cataclysmic geological events like earthquakes and volcanic eruptions. Since 2007, researchers point to the Campanian Ignimbrite eruption near Naples (Italy), now dated to around 39,280 BP [before present] (+/- 110 years), fictionalised in the 2013 animated film The Croods.

Scientists argue that arriving Homo sapiens were not as affected, perhaps because there were fewer directly touched by the 120 cubic miles [500 cubic kilometers] of magma released, or perhaps because almost everyone died out — but waves of Sapiens arrived later. After all, while most of us share small parts of the Neanderthal genome, the lineages from which we 'directly' descend settled much later in Europe — long after the Ice Age. By far, the greatest portion of our genome comes from our Neolithic, not Palaeolithic, ancestors.

But perhaps "Climate Change Killed the Neanderthals," that is, the extreme climatic fluctuations during the Upper Pleistocene that National Geographic (9 February 2004) announced, following the work of an international team of thirty scientists who laboured for more than seven years on the study. The team identified a general climatic instability during the Middle Palaeolithic marked by a severe cooling event around 41,000 years ago, lasting six centuries — interstadials GIS 13 to 7 of the Greenland ice-core records, to be precise.

For the last twenty years, scientists have sought to specify the timing, magnitude and ecological impact of a "mini-Ice Age" — the prehistorical obverse of global warming — that reduced vegetation and herbivore food sources, forcing Neanderthals towards warmer climates, including southern Spain. Clive Finlayson, trained as a zoologist, was an early contributor to sophisticated ecological modeling of Neanderthal extinction. At Gibraltar, he argued, "the last Neanderthal" could be found as late as 29,000 years ago, but there's competition for the title: elsewhere in the southern climatic refugium, Zafarraya (Granada) yielded a skeleton dated to 30,000 BP, but there are skeptics, while other candidates come from the Mezmaiskaya Caves in the Caucasus.

The trope, we've seen, is a frequent one in Neanderthal fiction, including Claire Cameron's "The Last Neanderthal" (Little Brown & Co., 2017), a moving, feminist revision of "Neanderthal Woman." It's also been widely used in popular nonfiction, including in Ludovic Slimak's 2023 account of twenty-five years of research in the Mandrin Cave .

Some of the science blaming climate change for the demise of Neanderthals marks a retreat from the recent archaeological rehabilitation of Neanderthals as a type of human equal to Homo sapiens, as these theories need to account for Sapiens' survival in the same severe conditions. Some experts rewrite basic wisdom, arguing that Neanderthals were not a cold-adapted species, since their origins lay during a warm interglacial stage (MIS 11); or that they lacked the technologies for making complex (and warm) clothing; or perhaps that their preexisting biological cold adaptations delayed the development of such technologies — a story about their technological inertia and deep conservatism.

That Neanderthals died out because of their conservatism, while humans alone mastered innovation, and with it, conquered the world, is the principal claim in Philip Lieberman's "The Unpredictable Species: What Makes Humans Unique" (Princeton University Press, 2013), and it's a widely shared belief.

Aside from the fact that the high value placed on "innovation" corresponds to the ideological superstructure of contemporary neoliberalism and late-stage capitalism, it seems fitting that Neanderthals died out because, in this view, they were, well, truly Neanderthal. The rhetorical figure returns to haunt the science: Neanderthals were conservative, backward, clinging mindlessly to the past in a changing world.

Neanderthal conservatism — not rhetorically, but as an original character trait — has origins in nineteenth-century anthropological judgements about "primitive" peoples. Augustus Pitt Rivers, an early innovator in British archaeology, underscored "the form of a persistent conservatism" of indigenous peoples, and quoted approvingly his colleague E. B. Tylor's "Primitive Culture" (1871): "The savage is firmly, obstinately conservative. No man appeals with more unhesitating confidence to the great precedent-makers of the past; the wisdom of his ancestors can control against the most obvious evidence of his own opinions and actions."

Just as "savages" were once seen as descendants of Neanderthals, so too is their conservatism a cultural legacy, even when anthropologists, transcending an outdated comparative method, no longer deem them ancestral, or even savage.

NEANDERTHALS AMONG US: The Making of a Prehistoric Human by Peter Sahlins is published by Oneworld, hardback £28.

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What color is the moon? Ask an Earthling, and you'll get a predictably monochromatic answer: white or gray.

But ask the four crewmembers of NASA's Artemis II mission — who spent nearly seven hours circling the moon from just 4,000 miles (6,400 kilometers) from the lunar surface this April — and you'll wonder if they're talking about the same dusty satellite we can see from Earth.

Yellow, brown, green, blue and tan features fan across vast volcanic plains and lurk at the edges of ominous craters, according to the crew's in-the-moment observations, which were shared this week in NASA's Artemis II Preliminary Lunar Science Report. The 130-page document catalogs everything crewmembers Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen saw during their historic close flyby of the moon on April 6, drawing from 814 gigabytes of photo, video and audio recordings taken from the Orion crew capsule.

This rainbow of lunar color represents distinct geological features that could inform future missions on where to land and where to explore as the world's space agencies race to set up a permanent presence on the moon.

One spot that particularly enthralled the astronauts (and is featured in the image above) is the Aristarchus Plateau — a broad, elevated region on the northwestern edge of the moon's nearside. The region hosts one of the moon's densest collections of ancient volcanic features, including swaths of dark lava deposits and colorful volcanic glasses.

Koch, mission specialist for Artemis II, was shocked to see distinct yellow shades in the region; she likened the plateau to "a yellow snow-capped mountain," with sunlight-reflecting craters providing the bright "snow." She went on to call the region "a jaundiced cheek of the Moon."

"There are so many colors now," Glover, Artemis II's pilot, added while photographing the area. "There's also a green. I see brown, especially Aristarchus and north toward the north pole. … It kind of flows down from the north in brown streaks."

According to the report authors, these colorful hues "could be associated with orange (titanium-rich) and green (magnesium-rich) glass beads respectively," similar to volcanic glass beads collected by the Apollo 15 and 17 missions on separate parts of the moon.

"Chaos across the entire area"

Another colorful patch of the lunar surface that caught the crew's attention was Orientale Basin — a huge, young and multiringed impact crater that's about three times as wide as Massachusetts, according to NASA. Straddling the moon's near and far sides, this massive bull's-eye is rarely visible from Earth, but it dominated the crewmembers' field of view as they orbited around the side of the moon.

"It has just created chaos across that entire area," Wiseman, commander for the mission, said at the time.

When flying over this sprawling basin, the crew noted gray, brown, tan and green below. The largest, outermost ring in the basin contained "almost swamp-like colors," Koch reported, while Glover spotted what looked like "dusted peaks" and "white on the very edges of [the mountains], the spines, the ridgebacks." Chains of craters parading away from the impact site looked "like bubbles rising from a team of scuba divers below," Koch added.

While these may sound like off-the-cuff observations, the Artemis II crew spent more than two years training to study and describe the moon's geology. Their regimen included visiting craters on Earth, taking lessons individually and in classrooms, conducting simulated flybys and, according to the report, bringing "self-selected reference materials" into the Orion capsule to read on the way to the moon.

Thanks to this training, the crew's observations provided a wealth of scientific information that no autonomous camera or orbiter could, the report said.

"The Artemis II mission demonstrated the exceptional value of human observation and cognition as scientific assets in planetary exploration," the report authors concluded. "Unlike cameras, which capture isolated moments and often narrow subsets of a scene, human observers continuously interpret their surroundings, integrating realtime visual perception with contextual understanding."

Or, to put that in Glover's more relatable words to mission control, "It's quite a wicked view."

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Aqueducts are some of the ancient Romans' most prominent surviving archaeological remains. These aqueducts relied on gravity to bring down the water to cities gradually. But some, such as the aqueduct at Aspendos in Turkey, had sections where they had to go uphill. So how did the Romans get water to flow upward?

The Romans used a few methods, including siphons and various water-lifting devices, experts told Live Science.

Inverted siphons

One strategy was a system called an inverted siphon (sometimes simply called a siphon).

At Aspendos, in southern Turkey, there is a second-century-A.D. Roman aqueduct with inverted siphons that scholars have reconstructed with a virtual modeling simulation. To get water through a valley, the Romans built a "header tank" on one end of the valley and a slightly lower "receiving tank" (or "outlet tank") on the other side. In the valley, they constructed two towers between the tanks, Paul Kessener, a researcher in the Department of Language and Culture Studies at Radboud University in the Netherlands, noted in an article published in 2000 in the Journal of Roman Archaeology.

As water dropped down a steep hill, the resulting pressure pushed it up the first tower before dropping it steeply down the other side, with the force allowing it to climb the second tower. The water eventually reached the receiving tank on the other side of the valley and continued toward the city of Aspendos.

It was important to prevent air pockets from forming as the water went through the inverted siphons. The header and receiving tanks were relatively large, allowing air bubbles to escape, Giovanni De Feo, a professor of industrial engineering at the University of Salerno in Italy, noted in an email.

"As the flow entered a relatively large chamber, its velocity decreased, allowing air bubbles to rise naturally to the water surface and escape through the open top of the structure," De Feo explained. This reduced the risk of air pockets forming.

The Romans tried to avoid using inverted siphons, said Charles Ortloff, a research associate in the Department of Anthropology at the University of Chicago who has a background in both engineering and history. When "Roman engineers encounter a valley, rather than construct a siphon, they [preferred] to build a bridge with a top channel to cross a valley," Ortloff said in an email. One example of this is at the Segovia aqueduct in Spain, which has a stunning bridge that still survives today.

Roman water-lifting devices

While the Romans used inverted siphons to move water upward in an aqueduct, they employed other devices to push water out.

Perhaps the best known of these devices is the Archimedes screw, which was sometimes used to help lift water from rivers to fields. (It was allegedly designed by Archimedes, a Greek inventor who lived during the third century B.C. However, it might have actually been invented at an earlier time, noted historians Stephanie Dalley and John Peter Oleson in a 2003 paper.) When "turned by use of animal power, [it] can effectively raise water from lower river heights to higher land area heights," Ortloff said.

The Archimedes screw "consisted of a wooden shaft that had [curves] of thin and flexible willow or wicker branches one stuck on top of the other, so that an endless screw was created," the Kotsanas Museum of Ancient Greek Technology's website notes. This screw was placed within a wooden pipe, and the "device was placed in the water with an inclination of 30 degrees," the museum representatives wrote. As the screw was rotated, it lifted the water.

Water wheels were also used to lift water, including in Roman mines. "The water wheel is a device that raises water and that is made up of several buckets that are fastened to a big wheel," scientists wrote in a 2024 paper. This "kind of wheel resembles a carriage wheel but it is larger and features buckets to catch water in addition to its larger size," they explained.

Another device, sometimes known as Ctesibius' pump, "was hand-moved, operating a wooden lever with a swinging motion," the scientists wrote. It had two cylinders connected to a central chamber through pistons, and the driven water exited through a nozzle connected to the central chamber.

Whatever method was used, the Romans would not let an uphill climb stop them from bringing water where they wanted it to go.

From Augustus to Nero, see how much you know about ancient Rome's famous leaders with our Roman emperor quiz!

The written word is one of humanity's most important information technologies. Without it, mathematical and scientific discoveries would be lost to history. But it can also lock ideas in place long after they've stopped making sense.

So does writing speed up cultural change or slow it down?

Russell Gray, a professor in the Department of Linguistic and Cultural Evolution at the Max Planck Institute for Evolutionary Anthropology in Germany, heads a research project investigating how writing affects the way languages change. His team uses methods borrowed from evolutionary biology to trace languages through family trees — similar to the way biologists trace species.

Language is one element of culture that researchers can measure to determine whether writing speeds up or slows down cultural change.

"The obvious answer," Gray said, is that writing slows culture down because writing "is all codified and specified and people get trained in it." Gray doesn’t think the obvious answer is necessarily the right one. But other researchers agree that writing can lock in ways of thinking.

"Writing can lead to what learning psychologists sometimes call 'canalization,'" Charles Perreault, an associate professor in the School of Human Evolution and Social Change at Arizona State University, told Live Science in an email. "It can narrow the range of ways people think about a problem. When a rule, method, or story is written down, people may come to see it as the correct version … and may not even consider that a better or different way could exist."

Religious texts and legal codes are good examples. In both cases, the interpretation of rules written hundreds ‪—‬ or even thousands ‪—‬ of years ago shapes the way things are done, long after the circumstances that produced them have changed.

This idea shows up in artistic expression, too: A 2017 analysis by ethnomusicologist Patrick Savage looked at more than 4,000 British-American ballads from the 16th through 20th centuries and found that written melodies changed less than those shared through oral tradition.

But there are also ways that writing may speed up cultural change.

"Before writing, much cultural knowledge had to be stored in people's brains," Perreault said. "That has obvious limits."

People forget things they don't study routinely, and when people die, their knowledge often dies with them. Because writing moves information storage beyond the human brain, it can reduce those losses, Perreault said.

"If writing prevents knowledge from being lost, and if it also helps information spread through a society, as with the printing press, then it could accelerate the ratchet effect of cumulative cultural evolution," Perreault said. "But this remains, to some extent, a hypothesis."

By the book

One reason the question of whether written language speeds or slows cultural evolution is that writing is hard to separate from everything that comes with it.

Writing has been separately invented only around four times in human history — although "some people argue there's a fifth in India," Gray said — which means nearly every writing system on Earth descends from that handful. Those systems spread through contact; trade, war, religion and the other ways humans intermingle had their own effects on cultural change that are hard to untangle from the effects of writing.

Also, "mass literacy is quite recent," Gray said. "If you've got these written varieties that are just used by, often, religious elites, that's potentially going to have much less impact."

So which force wins? Both experts think writing speeds up cultural change, though neither can prove it yet.

"I would say that writing probably speeds up cultural change overall," Perreault said. Gray agreed, though he acknowledged that most people would guess the opposite.

Still, Perreault cautioned, "these are empirical questions that have yet to be answered empirically."

Imagine you're road-tripping across the country 10 years from now. You spend a few minutes charging your electric vehicle and then set off — and your car's solar paint keeps it charged as you drive.

Your eyes are on the stunning scenery, taking in the vistas along Route 66 or the grandeur of the Rocky Mountains, or you're catching up on messages. Your hands barely touch the wheel, and your foot doesn't push a pedal. Your car communicates with others on the road, so there's no need to brake suddenly or swerve. That's because it knows a vehicle five cars up from you has done so, and all those in between are slowing at exactly the right pace to avoid dramatic changes in trajectory.

And when you park for the night, your car makes you money, selling the excess energy it's harvested from its paint back to the grid. Or maybe you don't feel like being in the driver's seat at all, so you hail a self-driving car and take a nap in the back seat in between adventures.

Some of that scenario may become a reality in the next 10 years, at least for those who are using the most cutting-edge cars on the market. Although there's some heavy speculation involved in that futuristic vision, vehicle manufacturers are already incorporating increasingly sophisticated automated driving technology into high-end personal vehicles, and self-driving taxis are coming to dozens of U.S. cities.

What's more, dramatic changes in range, cost and charging speed for electric vehicles (EVs) are arriving at a rapid pace. While some of these technologies may not wind up in personal cars, others are already taking to the roads.

An ecosystem of connected vehicles

Some car models within the next decade may interact with their surroundings in new ways, including by communicating with other cars to avoid collisions, drawing energy from natural sources, or letting drivers get paid for sending their cars' unused energy back to the grid.

If you're driving an EV, you might avoid the hassle of finding a charger when you're at work or running errands. In 2024, EV company Aptera unveiled a prototype car equipped with solar panels. Those panels — on the car's hood, roof, dashboard and hatch — allow the vehicle to travel about 40 miles (64 kilometers) per day on solar power. That's more than the average American drives per day. Aptera's vehicle can also travel up to 400 miles (640 km) on a standard electrical charge.

Some sunlight-powered cars might ditch the solar panels altogether in favor of a more integrated design. In 2024, Mercedes-Benz revealed it was researching a photovoltaic paint that could convert sunlight into energy for electric cars. In sunny cities such as Los Angeles, the company calculated, the paint could draw in enough energy to power the car for nearly 7,500 miles (12,000 km) per year. The tiny particles in the paint convert about 20% of the energy from sunlight into electricity, which is comparable to the efficiency of existing solar panels.

You might even be able to sell some of the energy stored in your car's battery back to the grid. EV owners could charge during the day or late at night, when the demand for electricity is lower and pay lower rates for electricity. Then, in the evenings when the electrical grid is under more strain and the price of electricity is higher, they could sell that stored energy back at a profit.

Standardized software programs that throttle EV charging speeds during peak hours already exist. Drivers can use them if, for example, they want to keep charging costs down by primarily charging their cars during off-peak hours when electricity costs are lower, or if they want to use electricity only from solar power to charge, said Rajit Gadh, a researcher who studies EV charging and scalability at UCLA. But the process for sending energy back to the grid is a different story. Individual manufacturers haven't yet landed on a standard way to tell cars when and how much energy to discharge, Gadh said.

"What is needed is really [for] every EV charging vendor ‪—‬ and every EV manufacturer, actually ‪—‬ to have this protocol built in, adhere to it in its full specification, and make it available," Gadh told Live Science.

With the right protocols, though, cars of the future will be able to do more than interface with the electrical grid. "Vehicle-to-everything" technologies could enable cars to communicate with infrastructure and other vehicles to avoid traffic and collisions.

Some cars today are already equipped with vehicle-to-vehicle (V2V) communications. These systems use short-range radio signals to alert other V2V-equipped vehicles of the car's speed, direction of travel and braking patterns. The radio signals can travel about 1,000 feet (300 meters), allowing the vehicle to receive data from cars that are not in the driver's line of sight.

V2V systems could help reduce traffic collisions by warning drivers about oncoming cars they can't see yet — for example, by alerting a driver to another car speeding toward an intersection or coming around a bend as the driver is passing another vehicle on a twisty, two-lane highway. Not all cars have the technology, though, so its practical utility is limited for now.

Hands off the wheel; eyes off the road

Some driver assistance technologies, such as lane departure warnings and cruise control, have been on the market in personal cars for decades. These technologies and more recent assistive features require the driver to be in control of the vehicle, but theoretically, they make driving easier. For example, Tesla's Full Self-Driving (Supervised) mode handles most steering and braking tasks, but safe operation requires the driver to keep their eyes on the road and be ready to take over at a moment’s notice. In the next several years, drivers will likely see new features that automate driving in more contexts.

Some of these features will allow drivers to take their attention off the road entirely and enjoy some in-car entertainment, as long as they're alert and able to retake control of the vehicle within a few seconds if conditions change. Technologies that fully automate driving in many circumstances within certain service areas will likely be in about 4% of cars on the market by 2035, according to a white paper from the World Economic Forum.

In cars equipped with these features, "you're still going to have driver controls, but under certain circumstances, it will be effectively an automated vehicle," Luke Neurauter, who leads the Division of Vehicle, Driver and System Safety at the Virginia Tech Transportation Institute, told Live Science.

Mercedes-Benz introduced its Drive Pilot system for two consumer car lines in 2022. On the entire German Autobahn network and on certain freeways between and around Los Angeles, San Francisco and Las Vegas, during heavy traffic, the system lets the driver turn their attention toward other activities, such as reading a book or eating lunch, while the car handles steering and keeping pace with other nearby vehicles.

But as the artificial intelligence (AI) models that control autonomous driving improve and become better able to handle unusual scenarios — often called "edge" or "corner" cases — on the road, drivers will be able to hand over control to their cars in more situations, said Rahul Jain, an electrical and computer engineer at the University of Southern California.

Future AI systems might "have some reasoning ability, and then because of that, it can handle these corner cases much better than current systems are able to do," Jain told Live Science. For example, a car might be able to better respond to an indecisive pedestrian who suddenly enters a crossing, assess whether to enter potentially hazardous conditions such as flooded roads, or safely navigate around unusual circumstances, such as construction work, on a highway.

While some systems will enable drivers to make fewer decisions, others that may roll out in the next several years will track a driver's attention and alert them with sounds, an indicator light or haptic feedback when their focus falters. These systems use cameras and software to track head position, eye movement and steering-wheel input to ensure drivers are focused on the road even when they're using assistive features such as lane centering, Neurauter said.

In addition to looking for distracted driving, the technology might expand to monitor drivers for fatigue and alcohol impairment, he added. That information could then affect "whether or not other features become active, or change how they act, based on the driver state at that moment in time," Neurauter said. Proposed legislation could make this technology a requirement in new vehicles as early as 2027, but technological hurdles and concerns over privacy and false positives could stall its implementation.

The technology could also assist drivers who become unable to safely operate the vehicle — for example, if the driver falls asleep or experiences a medical emergency. If a car detects that the driver is not holding the steering wheel or actively controlling the vehicle, it could send a series of visible, audible, or tactile alerts. If the driver doesn’t respond to those cues, a car might turn on its hazard lights and come to a stop. Some vehicle manufacturers are already rolling out such technology; for example, Volkswagen has made it available in all new vehicles from model year 2025.

Fully autonomous vehicles

While personal cars may not offer full automation, highly automated car services will become much more common as rideshare vehicles in major metro areas. In some cities, like San Francisco, commuters already rely heavily on autonomous vehicles from Waymo. The company has rolled out its cars in nearly a dozen cities —‬ including Dallas, Houston, Atlanta and Los Angeles —‬ and has announced plans to expand service to more than 20 additional locales. Other companies ‪—‬ such as Nuro and Volkswagen’s MOIA ‪—‬ are testing their vehicles with human drivers on board before rolling out full public service.

Currently, autonomous vehicles navigate by combining information from preloaded, high-resolution maps and real-time radar, lidar and visual data collected by cameras and sensors attached to the car. An onboard computer uses that information to build a 3D map of its surroundings. Right now, the cost of these sensors makes them impractical for consumer vehicles, Jain said, but they’re becoming cheaper as manufacturers scale up production. The cars also use an AI model trained on both common and unusual driving situations to anticipate how other vehicles and pedestrians will behave and plot a safe path forward, Jain added.

Developing those high-resolution maps takes time, which is one of the main reasons autonomous rideshares aren’t available everywhere yet. Mapping usually involves decking out a car with high-end visual sensors and lasers and driving it throughout the region. Although cities like San Francisco have been mapped with this level of precision, much of the U.S. has not.

"It's very difficult to do overnight," said John Dolan, an autonomous-driving researcher at the Carnegie Mellon University Robotics Institute.

Complexities also tend to arise in city environments, where unexpected stops are more common and there are many pedestrians who behave unpredictably or jaywalk. But interstate highway driving doesn't face as many of those obstacles, and that could enable autonomous long-haul drives.

"[Autonomous] trucking, I would expect, would be the first thing that's going to happen" in terms of autonomous travel outside of major cities, Jain said. A few driverless trucks are already on the road: Pittsburgh-based company Aurora deployed the technology on I-45 in Texas, between Dallas and Houston, in 2025, with plans to expand across the southern U.S.

Longer range and faster charging

While there's speculation involved in predicting the range of self-driving capabilities available in a decade, the picture for EVs is a little clearer.

Right now, lithium-ion batteries dominate the EV market. Each cell in a lithium-ion battery has two electrodes, commonly a layered graphite electrode and a metal oxide or phosphate electrode, separated by a liquid electrolyte solution. Lithium ions migrate back and forth between these two electrodes when a person charges and discharges the battery.

Many electric cars with lithium-ion batteries can already travel more than 300 miles (480 km) on a charge. But that's not ideal for a long-range car trip, because charging stations are few and far between in the country's vast interior and charging takes longer than filling up a gas tank.

Solid-state batteries, which replace the liquid electrolyte with a solid electrolyte made of ceramic, polymer or sulfide materials, could make that cross-country trip in an EV a practical option, allowing an electric car to travel more than 750 miles (1,200 km) on a single charge. Some prototype battery packs can already achieve this range under controlled conditions. If a solid electrolyte were paired with an anode made of pure lithium, rather than graphite or hard carbon, it would allow the battery to store more energy than a lithium-ion cell of similar mass can.

Solid-state batteries may also enable faster charging. In current batteries that use liquid electrolytes, charging and discharging the battery too quickly can cause dendrites, thin branches of lithium that stretch across the cell and short-circuit the battery. A solid electrolyte could, in theory, block those dendrites, which would enable cars to charge fully in just 10 to 15 minutes. The higher energy density from a lithium metal anode also translates to a greater range than that from a similarly sized lithium-ion battery, Eric Wachsman, director of the Maryland Energy Innovation Institute at the University of Maryland, told Live Science.

Cheap EVs

Many of the raw materials that go into existing lithium-ion batteries are concentrated in a handful of geographic areas. In 2023, Australia, China and Chile mined about 85% of that year's lithium supply; China mined the majority of graphite used that year as well. And battery materials still make up a significant portion of an electric vehicle's cost.

Sodium-ion batteries could be cheaper and easier to source. Sodium is plentiful in Earth's crust, which means mining could be done throughout the U.S., potentially with a comparatively low environmental impact.

Such batteries also rely on a more widely available electrode material. Sodium ions are larger than lithium ions, so they don't fit in between layers of graphite like lithium ions do. Instead, sodium-ion batteries use hard carbon electrodes.

"When you cook at home and your soup boils over and you get this black ring around your pot, this is hard carbon," Maximilian Fichtner, a solid-state chemist at the Helmholtz Institute Ulm for Electrochemical Energy Storage in Germany, told Live Science. "You can produce this from sucrose or from biomass, from whatever. You can do that everywhere."

The downside is that hard carbon holds less sodium than graphite holds lithium, said Eric McCalla, a battery materials chemist at McGill University in Canada. That means sodium-ion batteries can't store as much energy relative to their mass, and they don't last quite as long as their lithium counterparts.

"The range won't be as large," McCalla told Live Science. "It'll be a fantastic commuter car, but you're not going to go on a family trip from Montreal to California so easily."

Manufacturers are already bringing sodium-ion technology to market. For instance, the Chinese company CATL began mass-producing the batteries in February and claims that their battery packs enable EV ranges over 250 miles (400 km).

But new technologies are being developed rapidly. For example, some scientists are making sodium-ion batteries that use solid electrolytes, combining the higher energy density of solid-state lithium batteries with the cost savings of sodium batteries.

This hybrid battery chemistry is still in the early stages of development, experts told Live Science. "I would be surprised to see them in cars in the next decade," McCalla told Live Science in an email. "I've been surprised before, though."

Bumps in the road

The future we're describing is the utopian scenario. But the biggest obstacles are likely not technological but rather regulatory, economic, political or cultural, experts said.

"We're going to try to guess at a timeline of when some of these things are going to come in, and odds are, we're going to be wrong," McCalla told Live Science. "Odds are, we're going to be slower than we think."

Solar panels may not wind up being the most economic or practical way to increase EVs' range, while scaling up manufacturing capacity for next-generation batteries is expensive and could slow EV adoption in the U.S. The utility of vehicle-to-vehicle communications, meanwhile, could be limited by a slow rollout and adoption of V2V-equipped cars among drivers.

Whether EVs will be ubiquitous will likely come down to their affordability relative to gas-powered vehicles, which is affected not just by manufacturing and technological advances but also domestic policy choices, such as whether to subsidize EVs or their charging networks.

One challenge for manufacturers is that the automated features drivers prefer may not always be safer. A recent review of automated systems found that those focused on driver safety, such as automatic safety or lane centering, tend to reduce crashes, while those focused on comfort, such as adaptive cruise control, can increase accidents. The authors proposed that such systems make it easier for people to disengage or become distracted while driving and possibly overestimate the capabilities of the system.

And there are other kinks to work out for autonomous rideshare vehicles. In December 2025, a horde of Waymos stalled during a power outage, clogging San Francisco intersections. The cars are programmed to treat dark traffic signals as four-way stops, according to a statement from Waymo, but they occasionally ping human operators for confirmation. During the outage, the number of confirmation requests spiked, leading to delayed responses — and lengthy traffic jams. The company says it has since released software updates that allow its vehicles to act more decisively at dark signals. But questions remain about how the fleet will respond in natural disasters, and some have expressed frustration that autonomous rideshare vehicles already slow down ambulances, fire trucks and police cars responding to emergencies.

One of the biggest roadblocks to automated driving is the regulatory environment, Neurauter said. Regulations on self-driving vehicles vary by state, and some, such as New York, effectively prohibit driverless vehicles entirely. Where they are legal, they often must carry higher insurance and pass testing, which could limit their rollout.

"When we get into automated driving, the driving behavior is being governed by software that's installed on a computer that's in the vehicle," Steven Shladover, a research engineer at the University of California, Berkeley, told Live Science. "That gets us into a messy gray area where both the federal and the state roles kind of overlap, and that's politically very complicated." For example, different states could end up with different rules for establishing who's legally responsible for an accident involving automated driving.

In 10 years, you'll almost certainly be able to drive from Los Angeles to Las Vegas in an autonomous vehicle. But if you want to drive to New York City, you might have to stop in New Jersey — and take a train into the city.

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The patient: A 65-year-old woman in Michigan

The symptoms: The woman arrived at the emergency room via ambulance and asked to see a psychiatrist for her visual hallucinations. "I'm seeing dead people," she told clinicians, adding that she'd even fired a gun at her hallucinations in one instance, according to a report of her case. (The report does not describe what the hallucinations looked like.)

Despite this reaction to her hallucinations, she was calm and alert during her physical exam, with normal vital signs other than high blood pressure. She reported a history of high blood pressure, diabetes, heart failure and chronic back pain but no prior psychiatric history.

What happened next: Since the woman had no past psychiatric history, doctors opted for a medical assessment before consulting a psychiatrist. A blood test revealed mild metabolic acidosis, meaning her blood was too acidic. A toxicology screen detected high levels of salicylates, a class of compound that includes acetylsalicylic acid, better known as aspirin.

The diagnosis: When questioned, the woman acknowledged that she had been taking over 15 aspirin pills a day for multiple weeks. Each of these pills, marketed for back and body pain, contained 500 milligrams of aspirin.

Upon further questioning, the woman confirmed that she had tinnitus (ringing in her ears), which is a classic symptom of salicylate toxicity. In other words, she'd overdosed on aspirin.

The treatment: Doctors consulted experts at Michigan's poison control center, who recommended intravenous (IV) treatment with sodium bicarbonate (the chemical name for baking soda). This treatment alkalinizes blood and urine, meaning it makes them less acidic. This enables more salicylate to be excreted through the kidneys, allowing the drug to be eliminated through the urine.

After 11 hours of the IV treatment, the woman's blood salicylate levels dropped from 28.8 milligrams per deciliter (mg/dL) to 18.3 mg/dL. Her hallucinations ceased and the tinnitus improved within 48 hours of her arrival at the hospital. She was discharged without having seen a psychiatrist.

What makes the case unique: Aspirin is generally safe when used in doses indicated on the bottle or advised by a person's doctors. However, taking too much aspirin can irritate the gastrointestinal tract, as well as disrupt the activity of parts of the nervous system.

At high enough doses, salicylates can stimulate part of the brain called the medulla, which regulates breathing. This results in hyperventilation that causes the body to lose too much carbon dioxide, and at first, the blood becomes more alkaline. This process is known as respiratory alkalinosis.

However, salicylates also disrupt metabolism, leading to metabolic acidosis from a buildup of lactic acid in the body, as the woman experienced. When metabolic acidosis overwhelms the respiratory alkalinosis and causes the blood to acidify, organ damage can occur. These metabolic effects may also explain the tinnitus, as it drives increases in arachidonic acid that stimulate receptors in the inner ear.

The woman's daily intake of roughly 75 milligrams of aspirin per kilogram of body weight was about half the typical dose associated with acute salicylate poisoning. However, it was still a large amount to take every day for weeks, and older age is also a risk factor for severe outcomes of acute salicylate toxicity.

The authors of the case report noted that although she had tinnitus, she lacked many other hallmark symptoms of salicylate overdose, such as nausea and fever.

To the clinicians, the woman's case served as a reminder that long-term aspirin toxicity may result in different symptoms than acute poisoning does. In past case reports, other patients with chronic salicylate toxicity have also reported visual hallucinations. But that potential symptom is not as well understood as more common symptoms like tinnitus.

The case report authors added that longer-term exposure to aspirin may be associated with more neurological symptoms because chronic exposure increases the odds of the drug crossing the blood-brain barrier — a gatekeeper that allows only certain substances from the blood into the brain. They added that doctors should consider poisoning, including salicylate toxicity, for patients with psychotic symptoms with no clear cause.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

Can you guess the diagnosis in these strange medical cases? Find out with our diagnostic dilemma quiz!

This eye-catching astronaut photo mosaic shows a rare "sunglint" transforming a snaking reservoir into a giant silver river.

The winding waterway at the heart of this image is a section of Lake Powell in southern Utah. The artifical reservoir starts around 70 miles (110 kilometers) southwest of the town of Moab and ends roughly 60 miles (100 km) northeast of the Grand Canyon in Arizona. When full, Lake Powell holds up to 1.2 billion cubic feet (33.3 million cubic meters) of water, making it the second-largest reservoir in the U.S. — close behind the nearby Lake Mead, which stretches across the Arizona-Nevada border.

Lake Powell is located on the Colorado River, inside a steep ravine known as Glen Canyon. The reservoir emerged in the 1960s, following the construction of the Glen Canyon Dam, which caused water levels to rise by around 200 feet (60 meters) over the next two decades. In addition to generating hydroelectric power, the artificial lake has become a popular tourist destination. (Lake Mead is also located along the Colorado River and was created by the construction of the Hoover Dam.)

This image mosaic, which stitches together several astronaut photos into a single image, was captured during a sunglint, according to NASA's Earth Observatory. This phenomenon occurs when sunlight bounces off a reflective surface directly into the line of sight of an observer in orbit, such as a satellite or an astronaut, giving the object a metallic, mirror-like gleam.

Normally, this effect would be visible only across a small section of the lake. But by combining photos taken as the sunglint moved along the reservoir's length, the entire body of water was illuminated.

The reservoir is named after John Wesley Powell, an explorer and former director of the U.S. Geological Survey, who mapped out Glen Canyon and other parts of the Colorado River in the late 1860s. Powell was particularly captivated by Glen Canyon, which contained a "labyrinth of overhanging cliffs, hanging gardens, sweeping river bends, and natural arches set amidst a backdrop of colorful buttes and mesas," Earth Observatory representatives wrote.

Powell later described his recollections of the canyon. "Past these towering monuments, past these mounded billows of orange sandstone, past these oak-set glens, past these fern-decked alcoves, past these mural curves, we glide hour after hour, stopping now and then, as our attention is arrested by some new wonder," Powell wrote in his 1875 book "Canyons of the Colorado."

Some of the sights that Powell marveled over still exist, including many smaller canyons that branch off the reservoir and are cast in deep shadow. A similar effect is seen in sections of Utah's Green River, a tributary of the Colorado River that has long perplexed geologists due to its ability to flow "uphill."

From above, one of the canyon's most striking geological features ‪—‬ a large, doughnut-shaped depression known as The Rincon ‪—‬ is visible as a dark ring surrounding a bend along one of the widest sections of the lake. This rusty doughnut, which is up to 3 miles (5 km) across, is a former section of the Colorado River that dried out thousands of years ago when part of the canyon collapsed, enabling water to bypass the rocky loop.

However, many of the other wonders that Powell described have been lost beneath the reservoir's elevated water level. These include a side canyon dubbed the Music Temple, which was shaped in a way that gave it remarkable acoustic properties, according to the Earth Observatory.

During periods of drought, when the reservoir's water levels temporarily drop, other lost geological treasures can be exposed. For example, in 2023, researchers found rare fossils from a mammal-like Jurassic creature lurking beneath the lake's high-water line.

In recent years, some environmental groups have petitioned to drain Lake Powell and return Glen Canyon to its former glory as the "heart of the Colorado River," according to Newsweek. Such a change may help to alleviate pressure on the rest of the river, which has lost a significant amount of water in recent decades. But experts told Newsweek that this is unlikely to happen.

See more Earth from space

This colorful ceramic urn depicts a person wearing a jaguar costume and surrounded by human skulls, about to be received into the Maya underworld. The urn once held the bones of an ancestor for their descendants to venerate.

The urn was anonymously gifted to The Walters Art Museum in Baltimore in 2008. According to the museum, the urn is about 17.5 inches (44.5 centimeters) tall and was likely produced in Guatemala by the K'iche' Maya people more than a millennium ago. Originally, the urn probably had an elaborate lid that was tied on with string through the loops near the lip of the vessel, but it is now missing.

The decoration on the urn is striking. A person wearing a jaguar costume splashed with blood — claws and teeth bared — looks out at the viewer from the center of the urn. This individual may be a deceased ruler who is entering the world of the dead, which is symbolized by two pairs of human skulls and the dark figures of two Maya gods of the underworld. Behind the underworld gods are raised spikes representing thorns of the tropical kapok tree (Ceiba pentandra).

The Maya believed that the kapok tree, which was also called the Maya "world tree" or the Yaxche, had roots in the aquatic underworld, so its depiction on this funerary urn may reflect how it is a conduit between realms, according to The Walters Art Museum. Jaguars also held important spiritual meaning to the Maya; they were thought to move fluidly between the three realms — sky, Earth and underworld. Therefore, the depiction of the deceased ruler wearing a jaguar costume to enter the underworld may have suggested that they could also mediate between the world of the living and the Maya gods.

This colorful and symbol-laden urn shows that death was not an ending for the Maya, according to The Walters Art Museum, and that the urn "serves as a graphic reminder of how the dissolution of the body could be a positive change, transforming a beloved ancestor into an honored spirit who would continue to guide the living for eternity."

For more stunning archaeological discoveries, check out our Astonishing Artifacts archives.

Can you put together last week's Astonishing Artifact?

The debut images from a new Earth-observing satellite have just given us a view of the impossible: giant auroras rippling over the North Pole in broad daylight.

Earth's auroras are one of our planet's signature wonders — a sight worth advertising in interstellar travel guides, alongside our perfect total solar eclipses, bright shooting stars and majestic blobfish. They are the beautiful result of electrical storms in the atmosphere, appearing when charged solar particles skate along Earth's magnetic-field lines and collide with light-emitting molecules near the poles. (Auroras do exist on other planets, but they are usually not in bright visible colors like ours.)

To human eyes, auroras come out only at night and rarely stray from the poles. That's what makes these first observations from the joint European-Chinese Smile mission, which officially began science operations this week, so special.

Captured in ultraviolet light, the stunning images show a huge, serpent-like ring of charged particles coiling around the North Pole in July 2026. In the foreground, Earth appears ghostly and featureless, glowing like a half moon. The aurora writhes around our planet's sunlit side, covering about a third of it, while Earth's dark nightside bleeds into the background sky. Far behind, bright stars fall like raindrops as Smile shifts subtly in its orbit.

The view alone is worth smiling about, but the new images also promise exciting science to come. Taken just two weeks after scientists first turned Smile's Ultraviolet Aurora Imager on, the observations show that the satellite's instruments are working as they should and that the joint European Space Agency (ESA) and Chinese Academy of Sciences mission can officially begin.

Launched on May 19, Smile will spend the next three years watching Earth from a highly elliptical orbit that takes it about 75,000 miles (121,000 kilometers) over the North Pole — about a third of the way to the moon. From there, Smile can observe the North Pole for a record-breaking 45 hours at a time, offering an unprecedented view of solar activity there.

In addition to the Ultraviolet Aurora Imager, Smile carries three more science instruments to detect X-rays, magnetic fields and light ions over Earth.

This week, scientists also tested the spacecraft's soft X-ray imager by pointing it at the distant supernova remnant Cassiopeia A, located about 11,000 light-years from Earth (image above). Although the camera is working fine, the detector is still picking up a bit too much light when aimed at Earth, so it will require a bit more calibration from scientists on the ground.

In 2023, an African gray parrot named Jack went viral for mimicking the coughs and wheezes of her owner's father, who often struggled to breathe from severe chronic obstructive pulmonary disease.

But it wasn't just the imitation that made Jack famous; it was also that she seemed to relish the suffering of a man she purportedly hated. In the video, Jack's owner even claimed that she had a favorite cough.

The parrot appeared to be experiencing a complex emotion that in humans is known as schadenfreude, or pleasure at seeing another's pain. Literally translated from German as "harm joy," it's a feeling that might emerge when a rival coworker gets fired, or when a rude neighbor has their package stolen.

When a cat seems a little too happy watching a human stub their toe, or a horse seems to grin at a person stepping in poop, their owners might also interpret their behavior as schadenfreude.

But can any animals really experience such a complicated emotion? Or is this a classic case of anthropomorphization?

A complex emotion

Animals probably do not experience schadenfreude, according to researchers who study animal behavior and intelligence. However, the question hasn't received much attention in formal research. That's partly due to limitations of animal behavior methodology, but also because the question is bound up with how we define and communicate emotion in the first place.

"The study of complex emotions is incredibly difficult when you're talking about an animal that cannot communicate their emotions linguistically," Zachary Silver, an assistant professor of psychology who leads the canine intelligence lab at Occidental College in Los Angeles, told Live Science. "We don't have the ability to be as precise as we like to be in the scientific community."

Silver explained that researchers can look at behavior, neurological signals or hormonal activity to make an educated guess about what an animal might be feeling. A dog that has its ears back and tail tucked, for instance, is probably experiencing a negative emotion, while one wagging its tail is feeling a positive one.

But "aside from positive and negative, without words to describe the emotion, it becomes very difficult to disentangle," Silver said. The dog could be happy, but it could also just be interested in something new. "It's just so hard for us to say with any definitive nature that we really can know exactly what emotion is going on there," Silver said.

Animal behavior researchers try to avoid anthropomorphizing animals ‪(attributing human qualities to them) without evidence. When a cat or dog comforts a grieving human, for example, it could just be that the behavior was previously reinforced by rewarding the animal with treats or pets, rather than a genuine outpouring of sympathy. Similarly, Jack the parrot could have been mimicking coughs just for attention.

To truly experience a complicated emotion like schadenfreude, an animal needs to understand the emotional states of both itself and others — a concept called theory of mind.

"Dogs may have some ability to attribute mental states like emotions, thoughts, beliefs, intentions to other individuals, but this really only occurs in very select contexts and in really kind of a rudimentary way," Silver said. Because of this, "it's exceedingly unlikely that dogs would be able to experience schadenfreude in the way that we as humans do."

David Stahlman, an animal behavior researcher at the University of Mary Washington, agreed that such emotional capacity in animals is unlikely. He said that animals do not seem to have the ability to recognize their own emotional states, though he noted that not all animal behavior researchers agree.

"There's a difference between the affect, the emotional behavior, and then the recognition of the emotional behavior in oneself," Stahlman said. If nonhuman animals were to have this capability, he suspected it would probably be found in highly social great apes, like chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). Schadenfreude, in particular, would require animals to live in close social groups, since it requires knowledge of the individual experiencing the harm and whether it's deserved.

In hierarchical groups, it's possible that the suffering of one animal might benefit another and lead to something resembling happiness, Stahlman said, but he doubts this would ever qualify as true schadenfreude.

"The kind of Machiavellian stuff is a very human thing," he said.

Nevertheless, “there is a lot of data pointing in the direction that animals do have really deep capacities for emotional intelligence,” said Kaeli Swift, an animal behavior researcher at the University of Washington and author of the Corvid Research blog.

Swift noted that studies of some corvid species have found evidence of emotional recognition, fairness and "some of the strongest evidence across the animal world" for theory of mind. However, when it comes to studying an emotion as complex and subjective as schadenfreude, she said that researchers "haven’t quite crossed that threshold."

In the study of animal emotions, she said "we have barely started to scratch the surface."

Mammals first appeared on Earth over 200 million years ago, scuttling around alongside the dinosaurs as little mouse-sized creatures. But after the asteroid hit 66 million years ago, it was their time to shine ‪—‬ and the Age of Mammals began.

But the path to understanding our own branch of the animal kingdom hasn't been straightforward. In this excerpt from "The Story of the Mammals in 25 Discoveries" (Columbia University Press, 2026), author Donald R. Prothero looks at a time when philosophers and early naturalists believed giants roamed the Earth and explores the idea that extinction was heresy.

Many cultures around the world have a mythology that includes legends about gigantic races of humans that lived on Earth in the dark mysterious past. They may have fought against the gods, or they may have been destroyed by floods. These stories were reinforced by the discovery of gigantic bones, much larger than those of any living human, all over the Mediterranean and Europe.

The Greek philosopher Empedocles (492-432 BCE) reported gigantic bones from Sicily, supposedly remnants of a race of giants. The Roman historian Pliny the Elder (23-79 CE) mentioned fossil ivory in the ground, and according to the Roman historian Suetonius (69- 122 CE), Emperor Augustus owned a collection of large bones that had been found on the island of Capri, near Pompeii. The skulls of elephants, with their huge central opening in front (for the trunk), were thought to be the skulls of the one-eyed cyclops.

In the Middle Ages, these huge bones were again attributed to gigantic humans or other monsters (Genesis 6:4) that were drowned in Noah's flood. Giant tusks from Siberia were thought to be the horns of the mythical unicorn or the tusks of dragons. In some places gigantic teeth or vertebrae of mammoths were revered as relicts of saints. Nearly every possibility was suggested except that they were the bones of extinct elephants.

In the early seventeenth century, some giant bones dug up in a sand pit near Langon in southeastern France were exhibited around France as the remains of the giant Teutons, Germanic tribes that once roamed Gaul and were defeated by the Romans in 101 BCE.

But in 1613 the famous anatomist Riolan attacked the prevailing interpretation, suggesting that they were the bones of an elephant. This generated a raging controversy between physicians and anatomists and the barber-surgeons who called them gigantic human bones. Others thought they were hoaxes or generated by mysterious "plastic forces" (vis plastica in Latin) that percolated through Earth. Still others attacked the anatomists for questioning the biblical account of giants on Earth. The controversies died down in 1618 without being resolved, and for the next two centuries most people continued to interpret new finds as gigantic humans.

The giant bones that kept turning up in the New World were also a source of much mystery and consternation. The Native American tribes usually attributed them to giant monsters fought by their ancestors and incorporated them into their folklore. When these bones were first seen by European settlers, they were thought to be the bones of gigantic humans that roamed the earth in biblical times. Others thought that the giant tasks so revered by the Native Americans were the works of Satan, placed there to tempt the believer.

In 1519, the Spanish explorer and conquistador Hernan Cortez received a bone of a "giant," a gift from the friendly Tlascalan tribe of Mexico during the conquest of the Aztecs. He sent it back to the King of Spain as proof that giants at once lived in the New World. In 1706, the Reverend Cotton Mather of the Massachusetts Bay Colony pronounced them to be "the remains of godless giants drowned in Noah's Flood." He sent some bones to the Royal Society in London to have them certified as evidence of this "wicked giant" because biblical scholars were calculating Adam's height at 123 ft. 9 in.

The Royal Society never pronounced an opinion on these bones, although by that time many members were becoming skeptical of the literal interpretations of Genesis. The stifling effect of religious dogma about giants and Noah's flood was complicated by another idea: the notion of Divine Providence. An omnipotent, benevolent God would never allow any of his creatures to become extinct. As the poet Alexander Pope wrote in An Essay on Man (1734), "who sees with equal eye, as God of all, a hero perish, or a sparrow fall."

The prevailing concept was that of a "great chain of being" that linked the animals to man to the angels to God. Breaking any link in that chain implied the destruction of the whole chain. In the same poem, Pope also wrote: "Where, one step broken, the great scale's destroy'd; From Nature's chain whatever link you strike, Ten or ten thousandth, breaks the chain alike."

By the late 1700s, however, it was becoming more and more apparent that many of the recently discovered fossils had no living counterparts. Remote corners of the world were being explored, and although many new and surprising beasts were discovered, clearly the gigantic beasts were not hiding in South America or Africa or the East Indies. Many strange fossils, such as the bones of hippopotami in Paris and London, were clearly related to tropical animals, but it was assumed that these bones had been washed from the tropics during the Great Flood.

The notion of extinction was still blasphemous. The New World soon provided unequivocal evidence that these large bones were not simply gigantic humans. In 1739, Charles le Moyne, the second Baron de Longueil, left Montreal with French and Indian troops to fight the Chickasaw Indians along the Ohio River. Somewhere along the Ohio he found the remains of what appeared to be three elephants. When the war ended in 1740, le Moyne collected the bones and shipped them to New Orleans and ultimately to Paris, where they came to the attention of French naturalists.

In the 1740s and 1750s, English settlers in the region sent more of these bones from Big Bone Lick, Kentucky, off to England and also to Benjamin Franklin in America. Most of the bones (especially the tusks) were clearly like those of elephants and mammoths, but the teeth were puzzling. They were clearly unlike any living elephant, yet they were part of an animal of elephantine size. (We now know that these were specimens of the American mastodon, Mammut americanum.) Franklin speculated that the teeth were reminiscent of a carnivorous animal, although he and others later decided it was a vegetarian.

In 1769, the famous British anatomist William Hunter took the carnivory suggestion seriously and suggested this was not a true elephant but a "pseudelephant" or "American incognitum" (Latin for "unknown") that had independently developed ivory tusks:

"This monster, with the agility and ferocity of a tiger . . . cruel as the bloody panther, swift as the descending eagle, terrible as the angel of night. . . . And if this animal was indeed carnivorous, which I believe cannot be doubted, though we may as philosophers regret it, as men we cannot but thank Heaven that its whole generation is probably extinct."

This very precocious suggestion was still not accepted by naturalists of the time. Nevertheless, remains of the "incognitum" and also of the Siberian mammoth (including frozen carcasses with hair and skin) were turning up again and again. Georges Louis Leclerc, the Comte de Buffon (1707-1788), concluded in his Théorie de la terre in 1749 that although most of the supposedly extinct animals were hiding somewhere in an unknown region, it was likely that the large terrestrial mammals such as the mammoth and "incognitum" had actually perished.

By 1778, Buffon was relating their disappearance to his ideas of violent cataclysms in Earth's early history. During this time the climate was warmer and polar regions had once been tropical, so "elephants" (meaning mammoths) could live in Siberia. This implied a nonbiblical Earth of much greater antiquity. Buffon suggested it was as much as 75,000 to 3,000,000 years old, rather than the 6,000 years demanded by most literalist biblical scholars.

Naturally, such revolutionary ideas were not popular with the theologians in the Sorbonne. Buffon was protected by the king, however, so he was not persecuted for his heresy, although his ideas were not widely accepted either. The fact of extinction was finally proved by one of the greatest scientists of all time, the Baron Georges Cuvier (1769-1832).

Jean Leopold Frederic Georges Cuvier was an impressive man. Tall of stature, he had a "massive" head crowned by a large mane of hair. One admirer wrote that his head "gave to his entire person an undeniable cachet of majesty and to his face an expression of profound meditation." After his death, scientists weighed his brain and found that it was a massive 1830 grams [4 pounds], more than 400 grams [14 ounces] above average, and 200 grams [7 ounces] heavier than any brain ever measured at that time.

More important, he was one of the most brilliant men of his time, with a command of many subjects, some of which he invented all by himself. Before Cuvier, natural history was a field that resembled stamp collecting, with many amateur naturalists compiling long lists and descriptions of new species without analyzing the similarities in their anatomy. Cuvier almost single-handedly revolutionized natural history by dissecting many different animals and discovering their underlying similarities and differences.

This became the foundation of comparative anatomy, a subject that has been fundamental to biology ever since. Naturalists and explorers sent him their fossil bones, and he was the first to correctly describe many types of extinct animals. Cuvier solved the mystery of the puzzling fossil teeth called the "Great Incognitum" and recognized them as the teeth of the elephant-like mastodons. He also correctly deciphered the huge marine lizards we now know as mosasaurs.

For this reason, he is also considered to be the founder of vertebrate paleontology. Cuvier is most famous for his "law of correlation of parts," wherein he discovered that certain types of anatomical features tend to be associated. If you are a flesh eater, you will have sharp teeth and claws; if you are a plant eater, you will have flat grinding teeth and hooves; and so on. Using this law, paleontologists have been able to reconstruct whole animals from just a few key bones because the other parts of the anatomy are so predictable.

Excerpted from The Story of the Mammals in 25 Discoveries: Amazing Fossils and the People Who Found Them by Donald R. Prothero. Copyright (c) 2026 Donald R. Prothero. Used by arrangement with the Publisher. All rights reserved.

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Among the many risks astronauts face during long-haul spaceflight, an extended stay in microgravity is one of the most consequential for long-term health, with effects on vision, bones, muscles and many other aspects of the body.

One solution might be artificial gravity —‬ some way to create forces similar to Earth's gravity on a spaceship, akin to the giant rotating ring from Stanley Kubrick's 1968 film "2001: A Space Odyssey."

But is that technology ever coming, or will it remain science fiction?

"There's really no reason it couldn't happen," Torin Clark, an associate professor of aerospace engineering at the University of Colorado Boulder, told Live Science. "From a technical perspective, this is something that could happen in the very near future."

In fact, artificial gravity has almost made its way to space before. The Centrifuge Accommodation Module was a planned 8.2-foot-wide (2.5 meters) centrifuge for the International Space Station (ISS), but the project was canceled in 2005 for budgetary reasons.

"[Artificial gravity] is one of those things ‪—‬ like all of a sudden, it's super popular, and then all of the scientists at NASA and everybody … have a lot of funding to understand how to actually implement this, and then it just dies," Ana Diaz Artiles, an associate professor of aerospace engineering at Texas A&M University, told Live Science. "And then it comes back, and dies, and comes back. I've been going through a couple of these cycles in the time that I've been doing this."

Besides budgetary concerns, there are questions about how such a solution would be implemented.

"Everybody agrees it's a good thing to do. The problem is that we don't know how to implement it," Diaz Artiles said. "How much gravity do you need? How big does [the device] have to be? How long do you need it to be? And how long do you have to use this? Should we use continuous gravity or a short-radius centrifuge, something where you go in and out?"

Researchers have three main approaches for creating artificial gravity. One is the classic sci-fi idea: a giant ring that rotates passengers' entire living quarters so they live and work under forces similar to Earth's gravity.

"You have a relatively long radius, which means you don't have to spin very fast to create gravity," Diaz Artiles said. "But this is massive. You can't get all the parts up there in the same spacecraft — you need multiple spacecraft and to assemble everything. So, of course, you can see what a big endeavor this is."

A short-radius centrifuge is a more feasible option. It's essentially a tube with a radius of 6 to 10 feet (1.8 to 3 m) that spins to simulate gravity. A passenger sits or stands inside, with their head closest to the center of rotation, so the spin generates the strongest pull down toward their feet.

Instead of allowing passengers to live in artificial gravity, this smaller device would be used in short daily sessions. "It's kind of like an exercise device," Diaz Artiles said. "In the ISS, you have a treadmill, you have this resistive exercise machine, so you go there for 30 minutes to do your exercise, and then you get out."

The final option is for spacecraft to create gravity via linear acceleration. This works in the same way that an accelerating car pushes passengers back into their seats, except the spacecraft would be oriented to push an astronaut's feet into the floor. To slow down, the spacecraft would turn around, firing its thrusters in the opposite direction to decelerate smoothly while maintaining a roughly similar gravity for its occupants.

"But then you need something like an engine that is able to accelerate all the time," Diaz Artiles said. "And propulsion-wise, I think we're not there yet."

Although a short-radius centrifuge is the most feasible approach in terms of both cost and engineering, it does have some drawbacks. For one, its fast spin can induce the Coriolis cross-coupled illusion ‪—‬ a sensation of tilting or tumbling that happens when you tilt your head off-axis while rotating.

This is the effect that causes motion sickness, Clark said.

However, Clark and his team have found that people can build a tolerance to the sensation with training, simply by being in a slowly spinning centrifuge and gradually increasing the speed when they no longer feel the sensation.

"If you very slowly, incrementally increase the spin rate … and do that not just over one session but over multiple sessions across multiple days, as far as we could tell, anyone can be made to incrementally acclimate to the rotating environment [of] up to 20 to 30 rotations per minute," Clark said.

Would artificial gravity prevent harmful effects on the body?

But researchers still don't know how fast the centrifuge would need to rotate, or how long someone needs to spend inside it, to benefit. Long periods in microgravity can lead to bone and muscle loss, loss of aerobic fitness, blood clots, and visual issues from fluid shifts in the eyes. The hope is that artificial gravity could prevent those effects, but exactly how much gravity is necessary remains an open question.

Studies of people on head-down tilt bed rest ‪—‬ the standard research method for simulating spaceflight deconditioning ‪—‬ have found that 30 minutes a day in a centrifuge did prevent some loss of muscle function.

"Thirty minutes a day … maybe is not enough," Clark said. "Maybe an hour or even two hours a day, and maybe at higher G levels, would be beneficial."

But these studies are expensive and time-consuming. "It's very difficult," Diaz Artiles said. "I think people are interested in this concept, but we just don't have a good answer."

In the end, it's not a technological challenge that's keeping artificial gravity from being used in space; it's knowing the best way to employ it and securing the budget for it.

"We know how to do this. As humans, we have done more difficult things," Diaz Artiles said. "We need the money, but we also need to better understand the need."

See how much you know about human exploration into space with our spaceflight quiz!

Meriah DeJoseph grew up below the poverty line, so she was intrigued in college when she started reading what researchers had to say about people from low-income backgrounds. But there was something eating away at her. Although well-intentioned, the early research mainly focused on the risks of growing up in poverty.

As she progressed through her education, studying how poverty affects children, she'd go home and describe research in the field to her mom and her friends. The looks on their faces seemed to be saying "Is that really everything? Is that all it says? Is that what you think?"

She realized the research was missing the strengths people she grew up with exhibited, such as creative problem-solving skills and abilities to navigate social hierarchies and read people.

This helped motivate DeJoseph, who is now a developmental psychologist at University of Denver, to try to tell the other side of the story. "I felt like there was more to say about children and family strengths in those contexts that just wasn't being told yet."

Now, along with a handful of other researchers, DeJoseph aims to understand the full spectrum of changes that come with growing up in dangerous, deprived or unpredictable environments.

That is not to say that growing up in poverty is all flowers and roses, DeJoseph stressed. "Growing up in poverty is very hard and does cause a lot of challenges and does increase risk for things that we don't want," she said. But "the other side of it was missing." It's about capturing the full picture, not romanticizing hardship, she added.

Indeed, this balanced perspective does not deny that growing up in adversity — a catchall term that encompasses, for example, neglect, exposure to household or community violence, and household instability — can be damaging or even traumatizing. Rather, the approach acknowledges that individuals raised in such environments may also develop specialized skills that have previously been overlooked or discounted by researchers.

They hope that an understanding of these skills can eventually lead to changes in the educational system that will help narrow achievement gaps between those who grew up facing adversity and those who didn't.

An impoverished view of childhood adversity

Research has repeatedly shown extensive mental health disparities between individuals who faced adversity in childhood and those who do not. For example, children who experience multiple forms of adversity ‪—‬ such as lacking access to basic necessities or enduring aggression or neglect ‪—‬ in early childhood are more likely to be anxious and depressed at age 15. This affects a significant fraction of the population: 16.3% of U.S. children live in poverty, according to a 2022 report by the U.S. Census Bureau, and around 15% experienced neglect or abuse, according to a 2015 estimate.

However, under the prevailing "deficit model" of childhood adversity, experiencing multiple stressors as a young child does nothing but harm brain development. The fact that children from disadvantaged backgrounds score lower, on average, on standardized tests of various cognitive abilities has been used to support this view.

The deficit model is "really stigmatizing and really disrespectful" to people from disadvantaged backgrounds, Bruce Ellis, a professor of psychology and anthropology, heads the Developmental Adaptation, Stress, and Health (DASH) Lab at the University of Utah, told Live Science.

What's more, it "doesn't make any sense from an evolutionary perspective," he said. "Stress should not so much impair development as direct or regulate it towards strategies that are adaptive under stressful conditions."

Even the slightly more hopeful "resilience model," which looks at why some people can overcome adversity to become healthy and successful, focuses on why some people flourish despite experiencing early hardships.

Instead, Ellis and his colleagues have developed what they call an evolutionary developmental perspective. Unlike the resilience or deficit models, both of which frame adversity as solely negative, their framework looks at adversity as a selective pressure that pushes people to develop specialized abilities so they are better equipped to thrive in the environments they grew up in.

"Instead of doing well despite adversity, it's showing a potentially adaptive outcome because of adversity," DeJoseph said.

Humans evolved to be adaptable

From birth, an infant's biology, psychology and behavior are fine-tuned to suit the environment in which they are raised. This adaptability is partly due to genes being switched on differently depending on the environment the individual grows up in during sensitive periods of development, like in early childhood. As a result, people become specialized to their particular setting.

Stress, violence, chaos, hunger and scarcity have been a part of the human experience at many points throughout evolutionary history, so the ability to adapt and thrive when faced with such challenges has likely played a huge role in what it means to be human across time.

In principle, that means that individuals who face adversity early in life are "stress-adapted," meaning they've developed skills and traits that allow them to survive in their harsh and unpredictable settings, such as facing housing instability or living with an abusive caregiver.

In this view, social and cognitive skills that improve the individual's chances of surviving in harsh and unpredictable environments are likely to be more common in people who come from such environments.

The strengths-based approach

But what are these skills? Research has shown a handful of abilities that seem to be enhanced in people who were raised in stressful or chaotic environments. Psychologists initially called these "hidden talents."

Researchers hypothesize that these skills, such as heightened memory for faces and the ability to shift attention quickly, are useful in such environments.

For example, the ability to shift attention quickly may be important when you don't know when or where the next danger could be. "The assumption is, when you're in an unpredictable world where, again, threat can come without warning, where things can change unpredictably, that it's really important to be able to kind of fluidly unstick your attention from one thing and shift to something else, as opposed to being really good at sustaining attention," Ellis said.

In contrast, the ability to focus one's attention on a single task for long periods may be adaptive for someone who can rely on feeling safe; they have learned that they can tune out the outside world without worrying about something bad happening.

Suppressing impulses and resisting temptations based on the promise of future benefits might not be helpful in changeable environments, where rewards are fleeting and may not come around often, DeJoseph said.

Nowadays, to avoid the implication that people who faced childhood adversity have no need of support, researchers tend to call these "stress-adapted skills" rather than "hidden talents," DeJoseph said.

In fact, many of these adaptations that enable children to survive or thrive in stressful or unpredictable settings may still have downsides. For instance, being very attuned to threats may increase your chance of surviving in dangerous environments, but hypervigilance can lead to heightened anxiety in safe environments.

"It might help a child function in one context but create a challenge in another," DeJoseph said.

Uncovering stress-adapted skills

This budding field is "still very broad," and researchers are still mapping out the repertoire of skills that emerge from adversity, DeJoseph said. But a flurry of research has begun to home in on some of those skills.

For example, memory for who has more power in a given situation may be enhanced because understanding who sits where in the social pecking order, including who is more likely to win in a physical fight, is critical for surviving in harsh or dangerous environments. And being quicker to identify patterns in the environment could mean individuals are able to anticipate and spot threats or opportunities in changeable circumstances.

However, it is now clear that some stress-adapted skills require a bit of coaxing to reveal themselves. That's because these skills are specific to the contexts in which they developed, Ellis said, meaning they are more likely to appear in threatening or uncertain situations.

For example, the capacity to update information you are holding in your mind — known as "working memory updating" — is key for tracking incoming information and ensuring it is up-to-date. In a study involving 372 adults, individuals were randomly assigned to read a fake news article that either highlighted economic uncertainty or discussed computer technology. After reading these news clips, the participants completed working-memory-updating tasks.

Participants who reported having more unpredictable childhoods and read about economic uncertainty tended to be better at updating their working memory than children with more stable upbringings. But the results flipped for those who had unpredictable childhoods and read about computer technology. This suggests the ability to detect and quickly process information in a changeable environment can shine in situations that may call for it, the researchers suggested.

Context is key, but so is the content of the testing. For instance, almost all early studies used standardized tests that relied heavily on abstract questions, which may have missed some of the nuances of stress-adapted skills, Tochukwu Nweze, a developmental cognitive psychologist and co-director of the DASH Lab at the University of Utah, told Live Science. Now, some studies are using familiar, real-life stimuli rather than abstract stimuli, like numbers, shapes or colors, he said.

A 2022 study found that teenagers who had been exposed to high levels of violence and poverty in the past scored lower when generic shapes, like squares and triangles, were used, but almost caught up to peers who experienced relatively lower adversity when more relevant shapes, like buses, dollar bills and faces were used.

In fact, a recently published study found that children in the Scampia neighborhood of Naples, Italy — which faces high crime rates, toxic waste pollution, economic marginalization and institutional neglect — showed enhanced working memory and short-term memory compared with kids from a relatively higher socioeconomic neighborhood, but only when the tasks involved remembering faces.

Mixed results and known unknowns

Because this is a young field, mixed results are cropping up everywhere. For example, research on 800 Dutch adults found inconsistent links between current adverse environments and performance on working-memory tasks. Other research from the same team also revealed that exposure to threats in childhood and adulthood was associated with slower information processing across a range of tasks but was not linked with the ability to suppress impulsive actions or quickly shift attention.

These mixed findings highlight the essential need to replicate some of the core findings of the field. No studies in this area have been conducted on older adults, so researchers have no idea how stable these skills are throughout someone's life, Ellis said.

Moreover, as with a lot of other psychological research, the studies into stress-adapted skills have been conducted predominantly in "WEIRD" populations — that is, with people from Western, educated, industrialized, rich and democratic societies. People from non-WEIRD populations have been "grossly understudied," Nweze said, and there must be a concerted effort to correct this imbalance. "There is a need to understand whether there is cultural generalizability of these findings," he said.

In an attempt to do so, Nweze has investigated some of these ideas in his home country of Nigeria. For example, in a 2020 study, he and his colleagues compared 53 children in orphanages or foster homes with 51 children being raised by their biological parents. The team used standard psychological tests to assess these children's abilities to hold information in their mind and suppress impulses.

The children living in orphanages or foster homes performed either just as well as or better than the children living with their biological parents. These results were surprising because they bucked the trend of prior studies finding that institutionalized children were worse at inhibiting their impulses, Nweze said.

Similar results have recently been found in Mozambique, with children from a high-stress community outperforming kids from a relatively lower-stress town on social memory tasks.

What's not clear is how a dangerous, deprived or highly changeable childhood mediates these changes in the brain.

Early life adversity shapes brain development

One researcher who is trying to map out those brain differences is Christopher Monk, a professor of psychology, psychiatry and neuroscience at the University of Michigan.

Monk and his team have found that 15-year-olds who had been exposed to relatively high levels of adversity throughout childhood had different neural connectivity than teens with comparatively low or medium exposure. Adversity in this context included experiences such as exposure to emotional and physical abuse, and to neighborhood and parental violence.

MRI brain scans revealed that kids who had been exposed to cumulatively higher levels of adversity had denser connectivity in the default mode network, which is most active when the brain is not focused on external stimuli, such as during daydreaming. They also had denser connectivity in the frontoparietal network, which is involved in problem-solving and planning.

The salience network ‪—‬ which includes the amygdala, the region involved in processing danger and emotions‪ —‬ was less densely connected.

Although the environment "truly does sculpt the brain," these brain changes are not necessarily good or bad, Monk told Live Science. "They just are what they are. The brain is just always adapting to the environment."

Because it is impossible — and unethical — to randomly allocate children to high- and low-adversity settings, these studies can't show that adversity causes these brain differences. "We're not able to talk about causation," Monk said. "We're talking about one point in time correlating with another point in time."

Also, it's still not clear how differences seen in brain scans translate to stress-adapted skills and abilities. Partly, that's because most neuroscience research has not been focused on these hidden strengths. Instead, it has focused on how childhood adversity harms brain structure and function, often with the goal of explaining the higher incidence of depression, anxiety, impulsiveness and aggression in those who had stressful childhoods.

"New studies could incorporate appropriate measures to specifically test for the neural bases of hidden talents and their development," Ellis and his colleagues wrote in a book on hidden talents.

The $64,000 question

Although some of these stress-adapted skills may emerge when kids navigate changeable, stressful environments, many of these children will wind up leaving those environments later in life. So how can society leverage the skills of stress-adapted people to help them thrive in an environment that may be very different from the one they grew up in?

Although the research is intriguing, experts acknowledged that it isn't robust enough yet to show exactly which skills stress brings out — let alone to inform policy or educational recommendations. "I feel like we need to get the science a bit more solid before it makes sense to put those in real-world settings," DeJoseph said.

But experts agreed that schools are the easiest places to start based on what is already known. The hope is for researchers to work with school curriculum development staff and teaching experts to replace abstract concepts with more meaningful materials. "That's where one policy could potentially have manifestable impacts," Nweze said.

Ellis said the discovery that some skills can be equalized or enhanced when the right materials or contexts are employed could be the answer to "the $64,000 question, or more like the $64 billion question: how do you address the disparity in educational success and career success among people from rich versus poor backgrounds?"

Still, simply moving away from assumptions that individuals from lower socioeconomic backgrounds are "broken" could have a positive impact.

When researchers ran a series of sessions for educators at two U.S. universities in which they described the strengths of kids who had faced economic hardship, they found that educators had more positive beliefs about their more marginalized undergraduate students.

"Perhaps most strikingly, economically marginalized students earned grades that were more than a quarter of a grade point higher, on average, in courses taught by educators who participated in the strength-based learning group compared to those in the control group," the study authors wrote in the paper. This translated to a difference between a C+ and a B-, which was achieved not by changing curriculum but simply helping teachers better understand their students' identities and strengths.

"This perspective change seems so simple," DeJoseph said, "but it seems to have a real impact."

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The patient: A 50-year-old woman in New York

The symptoms: The woman went to the hospital because she could not bend her legs, walk or sit up. She also had chronic lower-back pain, recurring episodes of fever and chills, and unexplained weight loss of more than 30 pounds (14 kilograms).

What happened next: The patient told doctors that, one month earlier, she had visited another hospital due to persistent back pain, stiffness in her knees, fever and significant weight loss. However, she noted that she'd actually begun feeling discomfort in her knees and back about five years before that.

Over time, increased rigidity in her right leg began affecting her balance and caused frequent falls. Doctors prescribed her ibuprofen and physical therapy, but the stiffness and pain continued.

During the patient's first hospital visit, blood tests had revealed that her white blood cell count was normal, suggesting that she was not fighting an infection. She was not producing antibodies that might have suggested she had rheumatoid arthritis, an autoimmune disease that causes joint stiffness. Nor did she have antibodies associated with other several conditions that can cause pain, numbness or stiffness in the extremities, such as HIV, Lyme disease or the autoimmune condition Sjögren's disease.

Nevertheless, over the next month, her symptoms steadily worsened until she couldn't get out of bed; she was also unable to sit up or turn to either side.

At her second hospital visit, the patient's arm had normal movement during an exam, but her leg stiffness prevented doctors from testing the range of motion in her lower extremities. When the doctors tried to flex the woman's knee, it caused contraction in her quadriceps — the large muscle in the front of the thigh — and "was painful for the patient," the doctors wrote in a report of the case.

The diagnosis: Based on her earlier test results and her past and current symptoms, the doctors suspected that the woman had developed an extremely rare autoimmune neurological disorder: stiff person syndrome (SPS).

Autoimmune disorders are characterized by the immune system attacking healthy tissues in the body. In the case of SPS, this rogue immune response targets nerve cells that control muscle contraction. Destruction of these cells disrupts signals to the muscles, causing painful muscle spasms and contractions that affect a person's balance and restrict their movement.

A clue from the woman's blood tests hinted at this condition. Doctors found high levels of antibodies that block the enzyme glutamic acid decarboxylase (GAD). Elevated levels of these antibodies are seen in up to 80% of people with SPS. The anti-GAD antibodies prevent the enzyme from producing a chemical messenger called GABA, which acts like a brake on nerve cell activity. Without enough GABA, the nerve cells that control how muscles move can go into overdrive, which can cause spasms and prevent muscles from relaxing as they normally would.

The treatment: There is no cure for SPS, but medication can help slow the disease's progression and manage symptoms. This patient received intravenous immune globulin, an antibody treatment that regulates the immune system and is often used to treat autoimmune disorders. She also received rituximab, another type of antibody that targets specific immune cells to pare down their activity.

In addition, her doctors prescribed the steroid prednisone, the anticonvulsant gabapentin and the sedative diazepam, along with a regimen of physical therapy to help relax the woman's spasming muscles.

Within a few days, the woman's condition had significantly improved. "Prior to discharge, the patient could turn in her bed unassisted, could flex her left hip and knee fully, could flex [her] right hip fully and right knee with assistance to 110 degrees, and could stand with assistance," the report authors noted.

At a three-month checkup after being discharged, the patient could stand unassisted and walk using a rolling walker. The doctors started reducing her steroid dose, but she continued taking diazepam and gabapentin as prescribed, along with a monthly dose of immune globulin and a maintenance dose of rituximab every six months.

What makes the case unique: Just 1 to 2 in 1 million people are thought to be affected by SPS each year, although by some recent estimates, that number is higher. Its rarity and the slow development of symptoms make the condition challenging for health professionals to recognize and treat. What's more, the mechanisms and progression of the disease are "incompletely understood," the case report authors noted.

Often, SPS is misidentified as other conditions, including psychiatric disorders, Parkinson's disease, multiple sclerosis, or a neurological disorder called dystonia, which causes muscle spasms.

On average, the diagnosis of SPS takes about seven years from the start of symptoms, according to the Stiff Person Syndrome Research Foundation. It is most commonly diagnosed in people ages 40 to 50, but SPS can also appear in older adults and in children. It affects about twice as many women as it does men, according to the National Institute of Neurological Disorders and Stroke.

One well-known person with SPS is singer Celine Dion. She publicly shared her diagnosis in 2022, after her illness led her to cancel multiple shows in 2021. Dion told People magazine that she was experiencing "severe and persistent muscle spasms" and that the pain caused by her condition eventually became so intense that she was sometimes unable to walk.

This article is for informational purposes only and is not meant to offer medical advice.

Can you guess the diagnosis in these strange medical cases? Find out with our diagnostic dilemma quiz!

This striking satellite snap shows a giant, "sponge-like" dome towering over central Brazil. The dark monolith and the rare biome that covers it are key to the region's famed hot springs.

The imposing oval structure, which is around 12 miles (20 kilometers) long and 7 miles (12 km) across, is known as the Caldas Novas dome, or Serra de Caldas, according to NASA's Earth Observatory. It is located in southeast Goiás state and towers up to 1,000 feet (300 meters) above the surrounding landscape, although an optical illusion known as relief inversion may cause some viewers to see the raised land as a bowl-like depression.

The monolithic feature, which one 2004 study predicted could be at least 600 million years old, gets its name from the town of Caldas Novas, which is visible in the satellite image, sandwiched between the dark-green dome and Lake Corumbá, an artificial reservoir created by a nearby hydroelectric dam. The town is home to around 100,000 people but receives hundreds of thousands of visitors a year, many of whom travel there to bathe in its famous hot springs.

The dome is blanketed by savanna known as the Cerrado, which covers around a quarter of Brazil and is the second-most-abundant biome in South America, behind rainforests like the Amazon.

This biome is a tropical savanna. It is much more ecologically diverse than most savannas and is often described as a mix of woodland, grassland and wetland.

The Cerrado readily soaks up rainwater, making the dome act like a giant sponge. The collected liquid percolates through the monolith's inner structure, refilling submerged groundwater reservoirs that help feed the nearby hot springs with a regular supply of warm water, even throughout the region's dry season, according to the Earth Observatory.

The Cerrado is often called the "cradle of waters" in Brazil because of its role in recharging groundwater and feeding major rivers across the country. It also helps to feed several waterfalls around the dome's edges (see below).

Unlike most thermal baths, the hot springs surrounding Caldas Novas are not heated by volcanic activity. Instead, water within deep fractures in the rock is "heated by Earth's naturally higher temperatures at depth before it circulates back to the surface," Earth Observatory representatives wrote.

Many experts previously thought the monolith was formed by an ancient "magmatic intrusion," in which molten rock burst through the planet's crust. However, a 2021 study largely disproved this theory, suggesting instead that the structure was most likely created by other geological processes, instead.

The dome and its surroundings are protected as part of Caldas Novas State Park, which was established in 1970. It is home to several unique species, including the red-legged seriema (Cariama cristata) birds, the pequi tree (Caryocar brasiliense), and the wolf's plant (Solanum lycocarpum), according to the Earth Observatory.

But the park's main purpose is to protect the Cerrado covering the dome. In recent decades, large swaths of the biome have been cleared across South America to make way for more agricultural land, similar to the deforestation that plagues the Amazon rainforest.

You can see this issue in the satellite photo. The region surrounding the dome was likely once covered with the Cerrado, but it is now a patchwork of farms and fields.

See more Earth from space

This masterpiece of ancient Celtic weaponry was discovered by a laborer who was working on a bridge over the River Thames in 1857. Named the Battersea Shield after the London neighborhood near where it was found, the bronze artifact shows no signs of use, leaving archaeologists wondering how it ended up at the bottom of the river.

According to the British Museum, which acquired the shield directly from the construction worker who found it nearly 170 years ago, the weapon is made of several pieces of sheet bronze fastened together with rivets. The shield is about 30.6 inches (77.7 centimeters) long and 14 inches (35.7 cm) wide, and it weighs roughly 7.5 pounds (3.4 kilograms). Originally, the thin bronze shield facing would have been affixed to a wooden or leather base to create a substantial shield, but no trace of the underlying material has survived.

Experts think the Battersea Shield dates to the Iron Age because of the Celtic-style decorations that have been hammered into the shield from the back. The circular shield boss in the middle — which served to protect the wearer's fist — is a specifically British form of decoration, according to the British Museum, suggesting the object was made in Britain and not imported from another Celtic culture.

Palmettes and interlocking S-shaped motifs adorn the shield, and there are 27 circular decorations filled with red glass enamel and bronze in the shape of swastikas, which were symbols of good luck in ancient Celtic culture. These ornaments could also represent eyes staring back at an enemy, archaeologist Sophia Adams, a curator at the British Museum, has suggested.

The shield likely predates the invasion of Rome; Julius Caesar and his forces invaded Britain in 55 and 54 B.C., but they left soon after. The Romans didn't return until the Roman emperor Claudius launched another invasion in A.D. 43, long after the shield was created sometime between 350 and 50 B.C.

Because there's no evidence of damage to the shield, it was probably never used in battle, according to Adams. Rather, the shield could have been thrown into the Thames as a ritual sacrifice to the river or to an important ancestor.

"There's something of a watery element to these shapes, the swirls and eddies," Adams said in a London Museum video. "So I wonder if there's almost an intention that this was meant to end up in the water."

The Battersea Shield is the "most famous object ever to be found in the Thames," archaeologist Kate Sumnall, a curator at the London Museum, said in the video. As such, it has become a potent symbol of ancient Britain and has been featured on items as diverse as postage stamps, cigarette boxes and CD cases.

Can you put together last week's Astonishing Artifact?

Behold: one of the largest panoramas from the James Webb Space Telescope (JWST) released to date. This busy and breathtaking image offers a remarkably detailed view of IC 348, a nearby stellar nursery where astronomers are investigating some of the smallest objects produced by star formation.

IC 348 is one of the closest stellar nurseries to Earth and appears in this near-infrared image as an intricate landscape of stars, glowing material and sweeping clouds of gas and dust.

Across the scene, young stars punctuate the dark and luminous clouds. The concentration is greatest around the center, where bright stars show JWST's distinctive diffraction spikes — a result of the telescope's optical structure. In the upper-right of the image, still-forming protostars launch streams of material.

And lurking all around this colorful nursery are strange objects that challenge the very definition of a star.

Stars come in all shapes and sizes, from massive stars that explode as supernovas after only a few million years to the smallest and most common stars, red dwarfs, which last for many billions of years. However, there is also a class of substellar objects called brown dwarfs — objects halfway between giant gas planets, like Jupiter, and stars.

In the hunt for tiny brown dwarfs in IC 348, researchers used Webb’s NIRCam instrument in 2024 to survey part of IC 348 and found 39 brown dwarf candidates. The following year, Webb’s NIRSpec instrument studied the light of 15 of them. Nine were identified as new substellar members of the cluster, with the faintest estimated to have masses of around two Jupiters — the least massive brown dwarfs ever found.

How small the smallest brown dwarf can be is an open question in astrophysics. They form as molecular clouds of dust and gas collapse under their own gravity, much like regular stars do. However, unlike stars, brown dwarf cores never become hot enough to fuse hydrogen into helium. The brown dwarfs — or "failed stars," as they're sometimes called — in this JWST image will help researchers constrain the limits of how tiny these strange objects can get.

The upper-right portion of the panorama provides a dramatic look at another stage of star formation. Protostars hidden within the dusty environment fire jets into nearby gas and dust, producing luminous, eye-catching jets and streams known as Herbig-Haro objects. These gargantuan jets can stretch trillions of miles into space; just one tiny detail in one of JWST's biggest images yet.

But if that tremendous view still isn't enough for you, IC 348 was also recently snapped by NASA's Chandra Observatory, which captured the stellar nursery and other cosmic objects shining purple in brilliant X-ray light.

When you think of objects close to the sun, Mercury, the solar system's innermost planet, probably comes to mind. But has any other object — natural or artificial — gotten closer to our star? And what's the closest an object has gotten to the sun while still escaping?

Many objects have reached much closer than Mercury, including asteroids, comets and spacecraft, experts told Live Science.

At its closest point to the sun, called perihelion, Mercury comes within 29 million miles (47 million kilometers) of our star, according to NASA.

But several known asteroids come even closer. Scott Sheppard, an astronomer at Carnegie Science, an independent research institute in Washington, D.C., said such asteroids, with orbits that cross Mercury's, are called Mercury-crossers. They have highly eccentric orbits, meaning "they did not form in this location but were likely scattered from the main asteroid belt towards the Sun," he told Live Science in an email. A search through NASA's Small-Body Database for such asteroids shows 2024 YL3 is the current record holder. This 463-foot-long (141 meters), skyscraper-size rock has a perihelion of 6.4 million miles (10.3 million km).

Another group of celestial objects, though, may beat 2024 YL3. These are proposed asteroids that are thought to have circular orbits within Mercury's path. Dubbed Vulcanoids, their name comes from Vulcan, a theoretical planet once hypothesized to exist in this region.

Martin Beech, a professor emeritus of physics at the University of Regina in Canada, told Live Science in an email that numerical models show such asteroids would have stable orbits between 5.58 million and 23.23 million miles (8.98 million to 37.39 million km) from the sun's center. This means some Vulcanoids may whiz even nearer the sun than Mercury-crossers do. There's just one glitch: Like their namesake planet, Vulcanoids haven't been shown to exist, and a 2013 study found no trace of them.

But some spacecraft have come much, much closer. For instance, NASA's Parker Solar Probe, which launched in 2018, studied the sun's outer atmosphere, or corona. For the primary mission's final three orbits, the probe took an eccentric path with a perihelion of merely 4.5 million miles (7.3 million km) from the sun's center. At this distance, illustrated graphically on the mission's official webpage, the spacecraft flew through the corona, where a carbon foam shield protected the probe from the extreme heat.

"Sungrazers" and "sun-diving" comets

Another class of natural objects — dubbed sungrazing comets — reach closer still. A 2018 study described such comets as coming closer than 1.49 million miles (2.39 million km) of the sun's center, although any of these comets' precise solar proximity would depend on their orbital parameters.

Man-To Hui, a researcher at the Shanghai Astronomical Observatory, told Live Science that small sungrazers — some of which are just 30 feet (10 m) wide —break up as they rotate because they get nonuniformly heated, while the sun's powerful gravity pulls apart larger ones. Nonetheless, several escape unscathed; one of the closest observed so far was the Great Southern Comet of 1887, which came within an incredible 446,187 miles (718,070 km) from the sun.

But the real "winners" are "sundiving," or "sunstriking," comets. Such comets likely abounded in the early solar system, although they're thought to be rare nowadays. These comets would cross the sun's visible surface, or photosphere, plunging into the sun. Although no one has detected such a sundiver yet, the 2018 study noted that a comet would need a perihelion less than the sun's radius, or 432,244 miles (695,630 km) from the sun's center. There are no second passes, though ‪—‬ all sundiving comets are destroyed within the sun.

So, the detected object that got closest to the sun was the Great Southern Comet of 1887. If a sundiver is ever spotted, however, it would become the new record-holder, edging out the Great Southern Comet by 13,943 miles (22,439 km).

See how much you know about the sun with our sun quiz!

History is rife with lost treasures, from Aztec gold hidden during the Spanish conquest to the Ark of the Covenant, which vanished during the destruction of Jerusalem over 2,500 years ago. In his book, "The Museum of Lost Things: True Tales of Fabled Treasures, Legendary Cities, and Mythical Creatures That Vanished From History" (National Geographic Books, 2026), writer Sam Kean examines all things lost to time.

In this excerpt from the book, he looks at how the tomb of Genghis Khan, arguably the most successful ruler in history, has remained hidden for nearly 800 years and counting.

If archaeologists could vote on which lost grave they'd most like to find, Genghis Khan's would likely appear near the top of the list — in part to fact-check the gruesome legends surrounding his burial.

He was born in Mongolia around 1162, and supposedly emerged from the womb clutching a clot of blood in his fist. By all rights, the boy — whose original name was Temüjin — should have died young. His father, a nobleman in their tribe, was poisoned by a rival tribe when Temüjin was nine, and greedy schemers within his own clan banished the boy's family to the empty steppes, expecting them to starve. Historical accounts describe Temüjin as overly sensitive, terrified of dogs and prone to crying.

But he grew up fast. Even before adolescence, he'd already been enslaved (he engineered his own escape) and killed his older half brother. As a young man he discovered that soldiering suited him, and he ruthlessly eliminated all potential rivals among other nomadic tribes, until he was crowned Genghis Khan — universal ruler — in 1206. His other nickname was the Disturber of the Universe. His warriors were bold and battle-tested, and when they stopped murdering each other and turned their attention outward, they proved unstoppable.

They favored blitzkrieg tactics, sweeping in on horses and bombarding the enemy with arrows. But they could be surprisingly patient, too, and perfected the art of siege warfare. One notorious siege involved the city of Merv, in what's now Turkmenistan. Merv was the Alexandria of its day: a desert oasis teeming with gardens and libraries, famous for its silks and refreshing melons.

The Mongols couldn't resist it, and when the terrified artists and merchants inside surrendered after just six days of siege, a massacre ensued. "It was a memorable day for shrieking and weeping," lamented one chronicle. After burning Merv for good measure, Genghis Khan ordered his troops to count the corpses. There were 700,000. Yet however crazy it sounds, life under Genghis Khan had its benefits. He allowed the conquered to worship whatever gods they liked, a rare example of religious tolerance. He introduced the idea of diplomatic immunity to facilitate negotiations, and outlawed torture during interrogations. He promoted free trade, and founded history's first international mail system.

Over time, his empire also spread key technologies like the compass, abacus, printing press, and paper currency, as well as key social programs like universal education for children. No one was more ruthless when conquering (ask Merv). But if the vanquished people picked up the pieces and swore fealty afterward, life generally improved under Mongol rule. Genghis Khan's realm stretched from Korea to the Caspian Sea, an area twice the size of the Roman Empire. (Under his successors, it grew to the size of Africa.) And he accomplished all this with an army of just 100,000 warriors — fewer people than some modern stadiums hold.

Historian Jack Weatherford summed up his achievements thus: "[Imagine] if the United States ... had been founded by one of its illiterate slaves, who, by the sheer force of personality, charisma, and determination, liberated America from foreign rule, united the people, created an alphabet, wrote the constitution, established universal religious freedom, invented a new system of warfare, [and] marched an army from Canada to Brazil." Alexander, Julius Caesar, Napoleon — they weren't fit to carry Genghis Khan's saddle. If anyone in history deserved a grand mausoleum, it was him.

Genghis Khan wanted the opposite. Despite all the blood they shed, the Mongols were oddly squeamish about discussing d-e-a-t-h, so beyond the year 1227, contemporary sources say little about how Genghis Khan died. As a result, rumors multiplied. One story claims he died after tumbling off a horse. Others have him struck down by lightning or an arrow to the knee during battle (at age 65, no less). One source swears he was trying to ravish a conquered queen who, anticipating the crime, concealed a blade inside her vagina that sliced lil' Genghis wide open.

Regardless of the truth, his longtime wife Yesui dressed his body in a white robe, wrapped it in white felt with sticks of fragrant sandalwood, and clasped the shroud shut with golden straps. What happened next is impossible to say for certain. But according to lore, Genghis Khan received probably the most outrageous funeral in history.

After his wife bound him in white, a thousand soldiers took off on horseback to bury him atop a mountain. This cortege quickly turned into a rampage. To conceal their destination, the troops reportedly slaughtered every person they encountered on the 40-day journey, often with the cry "Go to the other world to serve our lord!" In some accounts, the soldiers killed every animal, too. Based on other Mongol burials, they likely interred him 20 yards deep, with the body oriented north-south and the head facing east. They probably tossed some treasures in — gilded saddles, gold rings, pearls wrapped in silk — along with slaves, concubines, and horses. (One tale has the soldiers burying a live baby camel with him, either so its bleating would serve as a funeral dirge, or so the grieving mother could lead them back to the site if necessary.)

After filling the grave, Genghis's soldiers either diverted a river to conceal it or trampled the ground with a thousand horses to obliterate all trace. Then they resumed the merry rampage on the return trip, butchering every unlucky hunter or merchant who wandered across their path. To their surprise, the thousand soldiers were themselves slaughtered when they reached home, as a further guarantee of secrecy — and then those slaughterers were also slaughtered, to make doubly sure.

Genghis Khan took privacy seriously. We have no idea how much of that is true. But it hasn't deterred the hunt for the grave. To the contrary: The elaborate concealment has made the pursuit all the more enticing. Four nations — Mongolia, China, Kazakhstan, and Russia — have claimed that Genghis Khan's bones lie within their borders. The strongest claim points to Burkhan Khaldun (God Mountain) in northeast Mongolia. Genghis Khan was born nearby, hunted there regularly, and worshipped the sky god Tengri there. He also once took refuge there while fleeing his enemies, and miraculously escaped. The mountain seemed charmed to him, and he'd mused during his life that it would make an ideal final resting place.

Strengthening the case for Burkhan Khaldun is the fact that later Mongol rulers proclaimed the land around the peak a forbidden zone and stationed a clan of ferocious guards there — the Darkhad, who murdered anyone who dared approach. (In exchange, the Darkhad paid no taxes and avoided compulsory military service.) Incredibly, the Darkhad kept this watch for 700 years, until the founding of the communist Mongolian People's Republic in 1924. The republic was a puppet state of the U.S.S.R., and Soviet leaders had a schizoid attitude toward the Disturber of the Universe. On the one hand, they admired his ruthlessness and gazed longingly at all the territory he'd gobbled up. On the other, they feared his memory would stir up nationalist sentiments in Mongolia and spur a revolt against the hated communists.

To forestall this, the Mongolian government banned the very mention of Genghis Khan's name. And to prevent Burkhan Khaldun from becoming a rallying point, officials fenced off a "highly restricted area" around the peak of 3,900 square miles (twice the size of Delaware), and parked a tank base at the site's entrance. The ban thawed somewhat after Joseph Stalin died in 1953, and one Mongolian official decided to celebrate the Disturber's 800th birthday in 1962 by putting him on a stamp. He overreached. Moscow ordered the man arrested, and he was chopped to bits with an axe. After the republic collapsed in 1992, the restricted area devolved into a nature reserve with some public access. But the land near Burkhan Khaldun remains daunting to explore. It's one of the most desolate places on Earth, with few roads and a population density down there with Greenland's.

Centuries of vegetation growth have choked off many areas, and the clear parts are prone to flash floods. Temperatures can swing from 100 degrees [Fahrenheit, or 38 degrees Celsius] in the summer to 50 below [minus 46 C] in the winter, so cold that even yaks drop dead. None of this has stopped Genghis Khan obsessives from searching out his grave. They've suffered snakebites and frostbite and been left stranded when their vehicles tumbled off cliffs. One man spent 40 years crossing and crisscrossing and re-crisscrossing the slopes and died without finding a thing.

In 2010, a few archaeologists tried a new approach. They posted satellite images of the Burkhan Khaldun region online and recruited volunteers to scour them for bumps, depressions, and other features that might indicate graves. Ten thousand people spent approximately 30,000 hours (3.4 collective years) poring over 2,300 square miles [5,950 square kilometers]. They flagged over a hundred spots worth checking out. While several proved inaccessible due to challenging terrain, 55 legitimate archaeological sites turned up among the rest, including megaliths, Bronze Age burial mounds, and an ancient city.

But there was zero trace of Genghis Khan. One archaeologist lamented that it was like looking for a needle in a haystack, except you don't know what the needle looks like. Call it Genghis Khan's final victory. The diverted river and trampling horses and the slaughter of all potential witnesses have succeeded in hiding him for most of a millennium now. His victims lay scattered across Eurasia, their skeletons long since ground to dust. But the bones of history's greatest warrior remain at peace.

Excerpted from The Museum of Lost Things by Sam Kean, published by National Geographic Partners, LLC. Copyright © 2026. All rights reserved.

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In modern times we tend to think of lithium as powering smartphones and cars, yet its historical fame comes from its role as a mood stabilizer.

Lithium was first used as a treatment for bipolar disorder in 1949. Yet despite decades of research and drug development, this simple medication remains the gold standard for treating one of the most complex psychiatric conditions. But why?

According to Becci Strawbridge, a senior lecturer in psychological medicine at King's College London, lithium's simplicity could be what helps it cut through the complexity of bipolar disorder, a lifelong disorder that affects about 36 million people worldwide.

Clinically, bipolar disorder is defined as a mood disorder characterized by specific, lasting changes to a person's mood and energy levels. Depending on the type of bipolar disorder, individuals can experience manic, hypomanic and depressive episodes — either individually, or in sequence.

However, "experiencing mania itself is sufficient to have a diagnosis of bipolar [disorder]," said Dr. David Cousins, a clinical senior lecturer and honorary consultant psychiatrist at Newcastle University in the U.K. "It's probably easiest to think of that as the opposite of depression — people become elevated in mood, extremely energized, driven, motivated, and engage in hedonistic behavior with lots of risk taking," he said. "It's a highly detrimental, highly damaging, highly disruptive state."

Treating an illness that operates at such extremes is a difficult balance to strike, with any intervention to treat one emotional state needing to factor in how it could impact the other. "For example, if you gave somebody antidepressants without an antimanic drug, you might either trigger mania or destabilize the illness," Cousins explained.

A combination of antidepressants, antipsychotics, and mood-stabilizing anticonvulsants are often prescribed in combination to juggle these highly variable symptoms. "There are really very few medications that have an overall effect against both poles," Strawbridge said. Once stabilized, the challenge then becomes preventing relapse back into this destructive cycle.

Lithium, by contrast, does not suffer from these limitations, Strawbridge added.

"It's often considered the gold standard for bipolar disorder; it's helpful for the depression and for the mania, but its main benefit overall is in preventing relapse, so stopping either of those two types of episodes from coming back."

Psychiatrists usually prescribe lithium as either lithium carbonate tablets or a lithium citrate liquid, both of which dissociate inside the body into lithium ions and their corresponding counterion (either carbonate or citrate). This simple active form is part of what gives lithium its powerful, broad-ranging mood-stabilizing effect, Strawbridge said.

"Because lithium is quite a simple ion, it's able to disguise itself as sodium, and that means it can slip inside of brain cells, whereas most medications act on the surface of cells," she explained.

Lithium's simple form enables it to spread throughout the brain and rest of the body. Once inside, it interacts with many cellular processes, but doctors still don't really understand the underlying mechanism behind its beneficial effects.

"We know that the monoamine system and the neurotransmitters in the brain that are involved in reward emotions and cognition are disrupted," Victoria Wing, a National Institute for Health and Care Research clinical lecturer at Newcastle University and CNTW NHS Foundation Trust, told Live Science. Included in this disruption is the regulation of crucial mood molecules, such as dopamine and serotonin, which may be underactive or overactive depending on the nature of the bipolar episode.

The same small lithium ion also blocks an enzyme called glycogen synthase kinase 3. This enzyme has wide-ranging downstream effects, such as controlling gene activity, regulating the body's circadian rhythms and managing inflammation and cell survival.

"Lithium can also help with autophagy, which is the clearance of debris and toxins in cells, and it has antioxidant effects and boosts mitochondrial function, which are important for cell energy processes," Wing said.

However, despite its manifold therapeutic benefits, lithium does have some drawbacks. While around one-third of people experience profound benefits from the drug, another close third only experience intermediate effects, and the final rough third don't respond at all.

This means it's vital to identify which patients respond well to the drug as early as possible, especially because the cyclic nature of the condition means it can take years to ascertain whether lithium is effective in preventing relapses in the long-term, said Cousins. The drug also has a narrow therapeutic window, which means it has a small margin of safety between doses that are high enough to be effective and those that are toxic to the kidneys and thyroid. Some patients who undergo lithium treatment also report having to urinate more frequently or experiencing slight tremors.

As with any medication, some side effects are unavoidable. The alternatives to lithium also carry their own risks. But if carefully and correctly managed, lithium medications can have a transformative impact for patients.

"I've met a lot of patients through patient involvement groups that have told me how effective and lifesaving lithium has been for them," Wing said. "We know it works, but can we fine-tune the use even better so more people can benefit from it?"

This article is for informational purposes only and is not meant to offer medical advice.

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Fusion-powered space travel has long held the promise of rapid trips across the solar system: Mars in weeks, Saturn in months, Pluto in years.

For decades, such possibilities have remained theoretical, like something plucked out of a science fiction novel. But several companies are now working to build practical nuclear fusion propulsion engines, with significant milestones being hit.

Pulsar Fusion, a U.K.-based startup, hopes to launch a demonstration mission to space in 2027, while Princeton University and Helicity Space in the U.S. are continuing their own work on fusion drives.

If any of these efforts prove successful, missions across the solar system for robots and humans could be unlocked like never before, turning us into a true spacefaring species.

"If we continue on the current trajectory, everything we know about space travel is going to change within a decade," Stephane Lintner, CEO and co-founder of Helicity Space, told Live Science.

But is it too good to be true? Can the dream of nuclear fusion propulsion ever be fully realized, or will it remain a sketchbook fantasy? After decades of dreaming, we might be on the cusp of finding out.

Fusion power

Nuclear fusion is a process whereby two atoms combine, or fuse, to form a heavier one, releasing excess energy in the form of light and heat. The best-known type of fusion is the process that occurs inside the sun at up to 27 million degrees Fahrenheit (15 million degrees Celsius), where atoms of hydrogen fuse to form helium.

If this process could be replicated on Earth, it would provide us with huge amounts of energy. "The holy grail is free energy for everyone," Lintner said. Entire cities and countries would be transformed, bringing about a new age of clean and abundant power.

Many experiments and tests have been performed, and large fusion experiments, like the International Thermonuclear Experimental Reactor (ITER) in France, are under construction. However, commercially viable fusion reactors have yet to be built. One of the main problems is keeping the turbulent, superhot plasma required for fusion confined and at the right temperature. The record is currently 22 minutes.

If you take the same concept and put it in space, you suddenly have a means to power a spacecraft. What's more, the same problems with sustaining the plasma don't arise. Instead, the plasma can be fired out of the spacecraft, providing a steady thrust that can be used to accelerate a spacecraft to enormous speeds in the frictionless vacuum of space.

"Fusion propulsion in some ways is harder, and in some ways is easier, than terrestrial energy production," Bhuvana Srinivasan, a professor of aeronautics and astronautics at the University of Washington, told Live Science.

A fusion-powered spacecraft could be accelerated to hundreds ‪—‬ or even thousands ‪—‬ of miles per second through this method, multiple times faster than any spacecraft in history. In the most optimistic scenario, such a spacecraft could reach significant fractions of light speed, making interstellar travel a possibility.

There are tremendous challenges, of course. A space-based fusion reactor must be small enough to fit inside a spacecraft on a rocket. That's no easy feat, considering fusion reactors like ITER are the size of houses. You also need a way to create the immense heat required for fusion to occur, a source of fuel and propellant, and powerful magnets to keep the plasma from burning through the engine's walls.

Producing meaningful thrust requires staggering numbers of fusion reactions every second. A quintillion reactions would provide about 10 newtons of thrust ‪—‬ equivalent to the weight of a 1-liter bottle of water in your hand. But a fusion-powered engine would provide this thrust for months, rather than minutes for typical chemical propulsion, allowing large speeds to be reached eventually.

At first glance, this might sound nearly impossible, but some recent tests have shown it could be plausible

First plasma

In March, Pulsar Fusion demonstrated "first plasma" inside a nuclear fusion engine for the first time. In the test, which took place at the company's facility in Bletchley, one of Pulsar's Sunbird engines briefly transformed krypton gas into a plasma, demonstrating how the company might confine plasma within its exhaust system.

The demonstration showed "the plasma will sit in the system where you want it to sit," confined by an electromagnetic field, Richard Dinan, the company's CEO and founder, told Live Science. "The difficult work now is to be able to heat the plasma to temperatures nearer to fusion."

Dinan founded Pulsar Fusion in 2011 with the goal of building a fusion-powered propulsion system. The company's plan is to fuse helium-3 and deuterium, a lighter form of helium and a heavier form of hydrogen, and use the energy produced to heat helium-4 and expel it as propellant to produce thrust. The amount of thrust that can be produced depends on "how good you are at diverting those particles out the back of the spacecraft," Dinan said. "And right now, nobody knows how efficient we can be."

Just a few hundred grams of deuterium and helium-3 fuel would be needed to sustain the fusion process on a trip to Mars, Dinan said, but he claims their rocket would need 10 to 20 metric tons (11 to 22 U.S. tons) of deuterium propellant to provide the thrust to reach the speeds they're hoping for.

If they can make it work, their plans are ambitious. The company imagines fleets of its Sunbird vehicles traversing the solar system, taking people and cargo to and from destinations at speeds of up to 329,000 mph (529,000 km/h) ‪—‬ about 10 times faster than the Voyager 1 spacecraft currently traveling outside the solar system.

At those speeds ‪—‬ which aren't reached instantly, as the spacecraft need months to accelerate and decelerate ‪—‬ travel time to Mars could be halved from the nine months it takes with conventional chemical propulsion. Weight could be freed up for equipment because fusion is more efficient and needs less fuel. Quicker missions to farther destinations, such as to Saturn's moon Titan or the metal-rich asteroid Psyche, would also be in reach.

"I think we will see fusion as a propulsion system pretty soon," Dinan said. "The demand is certainly there."

A billion degrees

Pulsar Fusion's method of propulsion is known as dual direct fusion, where the plasma from the process is directly used to provide thrust. Samuel Cohen, a physics professor at Princeton University, is working on a similar concept, the Direct Fusion Drive, as part of a project called Starfire.

Cohen and his team have been investigating this concept for more than 20 years. Their idea is to fuse deuterium and helium-3, which is rare on Earth but abundant on the moon. His team has built a prototype fusion thruster at Princeton with plasma that reaches 18 million F (10 million C).

"It's a start, but you've got to get to a billion degrees" Celsius for deuterium and helium-3 fusion to occur, Cohen told Live Science. There are a few promising approaches to reaching those temperatures, including squishing the plasma or heating it up with radio or neutron beams.

Using their current plasma, Cohen claims the team has demonstrated a small amount of thrust ‪—‬ a few milligrams, or a few hundred-thousandths of a newton. Now, they hope to get more funding to take their concept further. "We need a few million dollars to start things off," Cohen said.

With enough support, Cohen said, they could have a working fusion propulsion system in 10 to 20 years. Meanwhile, Pulsar Fusion, which has received support from the European Space Agency and the U.K. Atomic Energy Authority, hopes to perform a demonstration of its thrusters in orbit by 2027.

Helicity Space is targeting a launch of its fusion propulsion system in the 2030s. The company, which raised $5 million in 2023, is developing the Helicity Drive, which relies on pulses of plasma, rather than continuous fusion, to provide thrust.

"If you get a reaction every few seconds, that's an amazing science experiment on Earth, but you can't do anything with it," Lintner said. "In space, you have the most advanced electric propulsion drive ever built. You change the game for propulsion."

Lintner said the company is aiming "for fusion temperatures very, very soon," and is then "planning on flying a first prototype within three years." By the 2030s, Lintner hopes to reach net gain in its fusion engines ‪—‬ producing more energy than is put in ‪—‬ to have a true fusion drive ready for use in space.

Going interstellar

But not everyone is convinced that fusion drives will propel us through the solar system. John Slough, who is working on his own fusion rocket design called the Fusion Driven Rocket (FDR), said he is wary of "false promises" in the field. He noted that much of the underlying physics around fusion propulsion remains extremely difficult.

"It still relies on scientific discovery for us to push it," Srinivasan said. "We need to figure out, how do we keep this fuel stable? Have we sorted a lot of the engineering and scientific challenges? It's not going to happen next year."

Remaining challenges include not only keeping the plasma stable, but also developing walls that can sufficiently contain the plasma, and shrinking the fusion system to fit inside a spacecraft, she added.

Other forms of nuclear propulsion might be more promising. NASA is developing SR-1 Freedom, a spacecraft powered by nuclear fission, not fusion. The goal for the spacecraft, announced in March, is to launch to Mars by December 2028, where three small robotic helicopters would be sent to explore the surface. The fission reactor would split uranium-235 to generate thrust.

"SR-1 Freedom will pave the way for space nuclear hardware," Steven Sinacore, the Space Reactor-1 Freedom Program Director at NASA, told Live Science in response to questions via email. "To sustain a presence on the Moon, send crews to Mars, and explore the outer solar system, the nation needs power that works everywhere, independent of the sun, and fission is that power."

However, fission-based propulsion, while extremely useful, cannot match the speeds promised by fusion propulsion. That's because fusion systems magnetically confine the plasma, meaning much higher temperatures can be reached. Fission temperatures, by contrast, are limited by the materials of the reactor where the fission reactions take place.

If any of the proposed fusion concepts were to become a reality, however, the possibilities would be enormous. Last year, Elena Ancona, a flight dynamics engineer at the Polytechnic University of Bari in Italy, and her colleagues described how a direct fusion drive could enable a mission to Sedna, a remote icy dwarf planet far beyond Neptune. For that mission, time is of the essence.

The dwarf planet will reach its closest point to the sun in 2075, and it will not be that close again for another 11,000 years. "If we want to make this mission, it's either now or in 11,000 years," Ancona said. With a traditional chemical spacecraft, a mission would need to be launched 30 years in advance. But with fusion propulsion, it could get to Sedna in just 10 years.

Many more destinations would be within reach if fusion propulsion were to become a reality. Perhaps even interstellar travel would be possible much further down the line. "People have known that fusion is the answer to deep-space travel since the 1960s," Lintner said. "It's only in the last decade that, commercially, people started to spend a lot of time on cracking the fusion code."

But there's a long way to go. "It's not for the faint of heart," Lintner said. But if fusion propulsion is ever going to happen, the next few years look as good a bet as any.

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The patient: A 16-year-old boy in India

The symptoms: The teen developed swelling on his left upper eyelid that persisted for a few months but was painless. However, he later noticed two sharp, white projections poking out from the skin above his eye.

About a month after these projections appeared, he went to a hospital.

What happened next: Doctors examined the teen's eyelid, noting that the spikes had a "fairly smooth surface and were hard on palpation," said Dr. Meghana Tanwar, a medical consultant at the Aravind Eye Hospital in India who co-authored a report of the case. The texture and color of the projections suggested they might be teeth, she told Live Science in an email.

Initially, the doctors thought the points also might have been related to a teratoma, a rare type of tumor that can include different types of tissue, including bone and tooth tissue. They also wondered if the projections might be a foreign body in the eyelid. They conducted a CT scan to take a closer look.

The diagnosis: The scan revealed that the projections were indeed part of a tooth.

"The structure of a lone tooth in the superior orbit was quite obvious," Tanwar said. "Superior orbit" refers to the upper eye socket, and the tooth had poked out in the small space between the boy's eyelid and eyebrow.

Teeth that develop and erupt in abnormal locations are known as ectopic teeth. This umbrella term includes teeth that are in the mouth but erupt outside their typical positions; for instance, in about 2% to 6% of people, their first permanent molars grow "out of place" in the expected line-up of teeth.

In this case, though, the patient had an ectopic tooth that appeared completely outside the dental arch, which is far rarer.

The treatment: The doctors surgically removed the ectopic tooth from the patient's eyelid and found that it was a mature canine tooth. It didn't have any features that suggested it was part of a teratoma.

"Since the imaging done did not show the presence of any other ectopic teeth, the likelihood of him having another one are unlikely," Tanwar noted.

What makes the case unique: This is not the first ectopic tooth in the medical literature, but it was in a very notable location.

"To the best of our knowledge this is the first and only ectopic tooth reported in the superior orbit," Tanwar said. Previously, they've been reported in the nasal cavity and the bottom of the orbit, under the eye, she noted. According to MedPage Today, they've also been found in the nostrils, chin and maxillary sinus, which is located inside the cheekbone.

"This was a first not just for us but the world over," Tanwar said of the case. "We were very surprised by it."

Prior to the case, Tanwar had personally seen a tooth in the bottom of the eye socket of a different patient, but it was part of a rare type of mass called an odontogenic choristoma.

In this teen's case, the underlying cause of the ectopic tooth was unknown. Hypotheses suggest that, in general, ectopic teeth may grow out of place due to developmental disorders, physical trauma, infection or genetic factors.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

This intriguing astronaut photo shows a bright-white, salty surprise lurking at the summit of a giant volcano in the Sahara. The ancient, lava-covered peak also holds hidden, shadowy waterways, despite its extremely arid environment.

Emi Koussi (also known as Emi Koussou) is a pyroclastic shield volcano in northern Chad. It's located within the Tibesti Massif, a volcanic mountain range that straddles the border between Chad and Libya. The volcano's dome-shaped cone is up to 43 miles (69 kilometers) across and reaches a maximum elevation of 11,204 feet (3,415 meters) above sea level, making it the tallest peak in the Sahara, according to NASA's Earth Observatory.

Emi Koussi is classified as extinct, and there are no historical records of it erupting, according to the Smithsonian Institution's Global Volcanism Program. However, scientists know that it was once highly active because its gradual slopes are covered with ancient lava. Some experts think this once-molten rock is around 2 million years old and likely flowed with low viscosity, "more like motor oil than toothpaste," Earth Observatory representatives previously wrote.

At the volcano's summit lies a complex caldera system that spans up to 9 miles (15 km) across and is covered with various volcanic vents and cones (see photos below). A second, smaller crater, dubbed Era Kohor, lies at the caldera's southern end.

Nestled within Era Kohor, a thick crust of brilliant-white salt covers the lowest part of the caldera's floor. This crystal layer, which reaches up to 3,300 feet (1,000 m) across, reflects light in such a way that astronauts commonly confuse it for snow, which rarely falls in the area.

The salty compound, known as natron, is a mix of sodium carbonate decahydrate, sodium bicarbonate, sodium chloride and sodium sulfate. It was left behind by an ancient salty lake that once filled Era Kohor but has long since evaporated.

This is not the only notable natron deposit in the Tibesti Massif. Around 150 miles (240 km) northwest of Emi Koussi (also in northern Chad) lies a volcanic caldera known as Trou au Natron (or Doon Orei), which contains a layer of the salty substance that is arranged with a pair of cones in a way that makes it look like a giant skull when viewed from above. This unusual deposit lies next to another hefty volcano, dubbed Toussidé, which is also covered with tendrils of ancient lava.

While Emi Koussi's ancient activity was mostly centered at its summit, a pair of volcanic cones can be seen on the mountain's northern flank. The lava that quickly flowed from these openings likely helped to create a series of ravines between the mountain and a volcanic plateau, dubbed Tarso Ahon, which is partly visible in the top left of the photo.

These ravines are very narrow and deep, meaning they are near-permanently cast in shadow and much cooler than their surroundings. As a result, they can often hold liquid water, despite the Tibesti Massif receiving as little as 0.8 inches (20 millimeters) of rain a year. Two of the largest canyons — which are 2,000 feet (600 m) and 700 feet (250 m) deep, respectively — contain permanent waterways that flow east and west of the volcano, according to the Earth Observatory.

Emi Koussi's slopes are covered with dry "stream channels," which were carved out by millennia of rain flowing down its flanks. Current rainfall patterns would struggle to create such structures. However, thousands of years ago, during the mid-Holocene, the average rainfall was at least 10 times greater, according to a 2025 study that compared the ancient lakes of Era Kohor and Trou au Natron. (The Holocene is the current geological epoch, which began about 11,700 years ago, at the end of the last ice age.)

This is not the first time that astronauts have gazed down upon Emi Koussi. In fact, the volcano was one of the first geological formations photographed from space, when the crew of NASA's Apollo 7 mission snapped the imposing peak in October 1968.

See more Earth from space

This gold mask was made on the Indonesian island of Java around two millennia ago and was likely used to cover the face of a corpse, possibly with the aim of "confusing" the deceased's spirit so that it did not torment the living.

According to the Yale University Art Gallery, which has the prehistoric artifact in its collection, the mask measures roughly 8.9 by 6.7 inches (22.6 by 17 centimeters) and weighs about 2.1 ounces (60.9 grams). The mask has openings at the mouth, eyes and nostrils, along with slits and slashes representing eyebrows, eyelashes and teeth. A series of holes punched around the edge of the mask suggests that it was once attached to a corpse or funeral statue, archaeologist John Miksic wrote in a book titled "Old Javanese Gold" (Yale University Press, 2011).

To create the mask, an ancient artisan would have procured high-purity gold from the nearby islands of Sumatra or Borneo, hammered the metal into a thin sheet roughly the size and shape of a human face, and then cut the incisions with a chisel, Miksic wrote. Because of the simple technique used to create the mask, Miksic dated the artifact to Java's Preclassic period (500 B.C. to A.D. 200). During this era, prehistoric Javanese people inhumed their dead, before they switched to cremation in the following period. Gold face coverings were therefore most likely part of a prehistoric burial tradition, Miksic noted.

The custom of using gold to cover part or all of the deceased's face has been found in prehistoric India, China and other parts of Southeast Asia, according to Miksic, coinciding with inhumation burials made just before the advent of cremation. But it is unclear whether one culture learned the practice from another or if it was invented independently. Other gold death masks predate the Asian examples, including the famous 3,500-year-old Mask of Agamemnon from Bronze Age Greece.

Scholars have argued about whether Javanese gold death masks were meant to be realistic or idealized versions of the deceased. In a 1990 book on Indonesian traditional masks, archaeologist Wahyono Martowikrido noted that the Javanese mask was unusually naturalistic and was likely created to resemble the deceased.

It is unclear why the ancient Javanese created and used death masks, Miksic wrote, but experts have three main ideas. The ancient Javanese had high regard for the spirits of their ancestors, so they may have used precious gold as the most suitable material for honoring those departed ancestors. Another possibility is that only high-status people merited gold masks, which would have separated the elite from the commoners in the next world.

Miksic also learned from ethnographic accounts of people who lived on eastern Indonesian islands that spirits of the dead could be hostile. To prevent these malevolent spirits from attacking the living, people would turn the corpse around during the funeral procession and even place the corpse's head in a pot to confuse the spirit and make it unable to find its way back. This sort of belief may have led to the use of gold face covers, Miksic wrote.

The gold burial mask is one of the oldest artifacts in a collection of nearly 500 gold objects from Java donated to the Yale University Art Gallery by collectors Hunter and Valerie Thompson in 2007.

For more stunning archaeological discoveries, check out our Astonishing Artifacts archives.

Can you put together last week's Astonishing Artifact?

Imagine opening your eyes for the first time and seeing that the sky is full of green doughnuts.

This was the view that greeted NASA's Nancy Grace Roman Space Telescope, which just activated its powerful, 300-megapixel infrared camera for the first time.

The telescope, which launched to space on Aug. 30, is partway through a months-long commissioning process, with NASA scientists testing and tuning each of the spacecraft's instruments as it undertakes a million-mile (1.6 million kilometers) journey to Lagrange point L2 — an orbital "parking spot" where the competing gravity of Earth and the sun will hold Roman in place, alongside the James Webb Space Telescope (JWST) and other scientific spacecraft.

Roman's camera system, known as the Wide Field Instrument (WFI), hasn't been fully focused yet, so the stars look like lime-colored loops in this debut test image. But so far, all systems are working as they should, according to a NASA statement.

By the time Roman is ready to beam home its first full science images in early 2027, it will be capturing cosmic snapshots as crisp and detailed as those from the Hubble Space Telescope ‪—‬ but each of Roman's images will cover an area 100 times larger than Hubble's.

"After years of effort to build and test the instrument on the ground, we now have confirmation that it is operational in space. This is a huge milestone," Josh Schlieder, chief WFI scientist at NASA's Goddard Space Flight Center in Maryland, said in the statement. "There is much to do, but we are on our way to groundbreaking science."

The wavy rows of squares in the new image are key to Roman's photo-taking power. Each square represents one of Roman's 18 detectors, which translate photons from distant light sources into electrical signals that encode enormous images of the universe. Scientists are preparing for the telescope to beam roughly 1.4 terabytes of data — about five to 10 times the storage capacity of an average smartphone — back to Earth every day.

With all that data, NASA scientists expect Roman to push the frontiers of some of the biggest mysteries in astronomy. Planned long-term surveys of distant galaxies will help scientists discover new objects and calculate the expansion of the universe, potentially shedding new light on the phenomenon of dark energy.

The telescope will also contribute to the search for alien life. By selectively blocking out starlight with Roman's built-in coronagraph — another instrument that NASA successfully tested this week — the telescope will be able to zoom in on exoplanets with unprecedented precision, free from stellar glare. These observations could increase the number of known alien worlds from the current count of over 6,000 to more than 100,000 by the end of Roman's planned 10-year mission.

But in a final piece of good news, that 10-year mission now looks likely to double. According to NASA, a successful thruster burn (combined with bonus fuel loaded onto the spacecraft at launch) means that Roman may be looking at 22 years worth of power rather than 10. Like Hubble, which has continued operating far beyond its initial mission parameters, Roman may be an orbital gift that keeps giving for decades.

Are you a UFO fanatic? Find out with our extraterrestrials quiz!

In movies and TV shows, it's a popular motif: A dead Viking is placed on a boat, and it drifts slowly out to sea; from land, an archer shoots a fiery arrow that falls onto the boat and engulfs it in flames.

It's been seen in the 1958 movie "The Vikings," the History Channel show "Vikings" and fantasy series such as "Game of Thrones." But did the Vikings actually do this?

To find out, we asked experts whether there is any archaeological or historical evidence to support the idea.

Archaeological evidence

Our sources noted that a burial like this would leave little archaeological evidence. Such "practices would leave little trace, and they are unverified by archaeological sources," Howard Williams, an archaeology professor at the University of Chester in the U.K., said in an email.

Erin McGuire, an anthropology professor at the University of Victoria in Canada, also noted this limitation. From "an archaeological standpoint, we have no evidence for this very common motif," McGuire told Live Science in an email, adding that it would be hard to differentiate a fire set by a fire arrow from a regular fire. Additionally, shipwrecks "with human remains are very, very rare globally," McGuire added. "It takes particular kinds of environmental conditions for them to be preserved and I know of none from the Viking Age."

However, the Vikings were master seafarers and frequently cremated their dead. And there is evidence that Vikings burned ships, McGuire noted. We "do have archaeological examples of ships and parts of ships that were burnt during funerary practices while still on land and were buried after being burned," McGuire said. These include the ninth-century Myklebust ship, a burnt Viking ship that was found in a burial mound in Norway and was built for a rich person, possibly a king.

Historical evidence and legends

Perhaps the closest historical evidence for the fire-arrow ritual comes from Ahmad ibn Fadlan, a 10th-century Arab traveler who went to the Volga River in what is now Russia and spent time with Viking groups there. In ibn Fadlan's written account, a Viking chieftain is placed on a boat, which is set ablaze.

However, there are some key differences between this account and the scene depicted in popular culture. First, there's no flaming arrow; rather, the boat was lit on fire by a person described as a chief mourner. Additionally, the boat and its dead chieftain were on land, not on the water.

Although not strictly historical, there are some legendary and mythical accounts of burials at sea that were possibly inspired by real events. "From medieval literature we have rare references to boats/ships involved in funerals over water," Williams said.

In the epic poem "Beowulf," the funeral of the Danish king Scyld Scefing sees the dead king placed on a ship that drifts off to sea. In the 13th-century Scandinavian book "Heimskringla," by Snorri Sturluson of Iceland, the "sea-king Haki [was] set adrift and set alight so that his body burned with those of his slain retinue," Williams said, and in another story by Sturluson, "the god Baldr is set adrift and his ship set alight by his brother Thor."

The funeral of Baldr has been particularly notable, McGuire said, noting that it inspired J.R.R. Tolkien to include a similar scene in his "Lord of the Rings" books.

Practical problems

Experts noted that this kind of fire-arrow burial might not have even been possible.

"Personally, I consider cremation at sea using a ship set alight from the shore with flaming arrows to be rather unrealistic," Matthias Toplak, head of the archaeology department at the Viking Museum Haithabu in Germany, told Live Science in an email. "My own experiments show that it is not at all easy to set something alight with flaming arrows."

He noted that fire must burn at a high temperature for several hours for cremation to be effective. "At sea, the ship would probably sink before the body had been sufficiently cremated," Toplak said. "Apart from that, there is of course also the danger that a ship ablaze and adrift would be driven by currents or the wind into other ships or harbour facilities."

McGuire also noted that there are practical problems with the idea. "if you send a burning boat out onto the water, how do you stop it from drifting ashore with rather grisly contents?"

Overall, the scholars we spoke with doubted that the Vikings used fire arrows to burn funeral boats set adrift at sea. "However romantic the idea of such a funeral scene may be, I unfortunately consider it highly unlikely," Toplak said.

Instead, Williams suspects 20th-century Hollywood movies played a major role in the creation of this idea. "I strongly suspect this specific trope owes its origin to the 1958 film The Vikings and the concluding scene of Einar's funeral," Williams said.

It "says little about how 'Vikings' treated their dead," Williams added, "but tells us a lot about our valorised ideals of fate, honour and death linked to both fantasy and historical 'Vikings.'"

See how much you know about ancient norsemen with our Viking quiz!

If your blond preteen seems to be turning into a brunette, you're not imagining things. For some children, hair that starts out platinum blond gradually becomes darker and may end up dark brown, or even black, as they grow.

So what causes this change?

The short answer is that hair color is controlled by a complex interplay of genes, pigment-producing cells and, later in childhood, hormones. Scientists understand many of the genes involved in hair color, but they are still trying to find out why some blond children's hair darkens while others' locks remain blond for life.

"It depends on their genetic inheritance," Desmond Tobin, a professor of dermatological science at University College Dublin, told Live Science in an email.

Hair gets its color from a pigment called melanin, which is produced by specialized cells called melanocytes in hair follicles. There are two main types of melanin: eumelanin, which produces brown and black shades, and pheomelanin, which contributes yellow and red tones to hair. The amount and type of melanin produced by a follicle largely determine the color of the hair that grows from it.

In general, more eumelanin means darker hair. For example, during pregnancy, high levels of estrogen and progesterone can encourage hair darkening as more eumelanin is produced.

The activity of hair follicles isn't necessarily fixed throughout childhood. As children grow, the biological signals controlling pigment production can change, too.

From blond to brown

For many blond children, the most noticeable darkening happens around puberty, typically between about 10 and 13 years old, Tobin said.

It is likely the hormonal changes during puberty, such as estrogens and androgens that stimulate an increased production of eumelanin, that gradually turn blond hair darker over time, he said. "Those that remain blond typically have a genetically determined reduction in eumelanin pigment formation," Tobin added.

Exactly how hormones might cause this change, however, is still something of a mystery.

One clue comes from a group of hormones called melanocortins. One of these, alpha-melanocyte-stimulating hormone (alpha-MSH), is involved in telling pigment-producing cells to make more melanin. In our skin, alpha-MSH is triggered by ultraviolet (UV) light. UV light can damage DNA in skin cells that, via a cellular signaling pathway, encourages the release of alpha-MSH to make the skin tan.

But in hair, things get, well, hairy. Scientists haven't shown that a rise in alpha-MSH, testosterone, estrogen or any particular hormone is what makes blond hair darken.

The melanocortin system shows that hormones can tell pigment-producing cells to make more eumelanin. What remains unclear is whether changes in this system are actually responsible for blond hair darkening during puberty.

"We haven't yet identified the genes that control this process," Wojciech Branicki, a researcher who studies the genetics of human pigmentation at Jagiellonian University in Poland, told Live Science in an email.

One possibility Branicki suggested is that hormones may affect children's hair follicles differently depending on their genetic background. For now, researchers don't know which genes are involved or how they interact with hormonal changes during puberty, as more research is needed.

Branicki posits that in some children, the hormones could induce the production of melanin or the transport of pigment within the hair follicle. In other words, two children could start out with similarly blond hair but respond differently to the hormonal changes as their bodies develop. One might continue producing relatively little eumelanin and stay blond, while the other's follicles might gradually ramp up pigment production, causing new batches of hair to grow darker.

"Research on human genome variation is quite advanced, but not all aspects have been explained yet," Branicki said.

In the summer of 2008, New York City lowered the threshold for activating its emergency heat plan.

The city had historically relied on the National Weather Service threshold of a heat index of 105 F (40.6 C), but they noticed that people were getting heat stroke at lower temperatures.

As part of a wider effort, they changed the alert threshold: it would trigger if the temperature reached 100 F (37.8 C) for a day, or 95 F (35 C) for two days in a row. When the threshold was reached, city officials conducted targeted outreach, including to vulnerable groups, like homeless people; alerted residents on their phones; launched measures to protect the power and water supply; and opened cooling centers.

Lowering this threshold correlated with a more than 50% reduction in hospitalizations for heat stroke and related illnesses on hot days.

New York's case study offers one of the clearest examples of an intervention that worked to protect people from deadly heat.

As the planet warms, we will need to find more of these solutions. The consensus among scientists is that the most effective way to avoid the worst health outcomes of climate change is to slow warming by reducing carbon emissions. Limiting warming to 1.5 degrees Celsius (2.2 degrees Fahrenheit), for instance, would mean 11,600 fewer deaths due to wildfire smoke exposure in the U.S. annually, compared with warming of 5.4 F (3 C).

But even if we rapidly reduce emissions, climate change will have wide-ranging effects on our health

So what measures actually work to protect people's health? Live Science reviewed dozens of studies and talked with 19 climate and health experts at universities and health and climate associations, to identify the most promising solutions to two of the biggest climate-related threats: extreme heat and wildfire smoke.

Some interventions have demonstrated a reduction in deaths or disease at the population level, while others have used modeling to predict health impacts or rely on proxy measures.

"The strongest evidence is where these approaches reduce illness, hospital visits or death," said Charles Leonard, an associate professor of epidemiology at the University of Pennsylvania, told Live Science, "not just heat exposure, pollution levels or other intermediate markers."

Most solutions do not offer the level of clarity of the New York example, however. Many reduce temperatures or alter human physiology in ways that are likely to decrease the number of heat-related deaths or cases of illness. But a deeper examination reveals limited evidence that many seemingly intuitive interventions, such as cooling centers, are effective on a societal level.

For both heat and wildfire smoke exposure, we analyzed the evidence to see which interventions have actually worked.

Extreme heat

Air conditioning and heat pumps

Evidence grade: Strong

One of the most common interventions for managing indoor temperatures is the use of mechanical systems with refrigerants, such as air conditioning or heat pumps.

Air conditioning has been tied to reduced hospital admissions in California and reduced heat-related deaths at Texas prisons. During a heat wave in Portugal, patients admitted to an AC-supported hospital had a 40% lower risk of dying than those in wards without AC. It is a clear way to impact health outcomes.

But AC can't be the whole solution.

"One of the most important lessons emerging from heat adaptation research is that no single intervention is sufficient on its own," said Shweta Arya, senior project manager for smart surfaces at the American Public Health Association's Center for Climate, Health and Equity, which leads the association's work on health and climate action.

While 90% of U.S. households used AC in 2020, the latest year for which energy survey data is available, it's not a cure-all. It is vulnerable to power outages, and it contributes to outdoor warming via added electricity demand and heat expelled from vents.

Additionally, just because people have AC doesn't mean they can afford to use it. This is known as the "heat or eat" dilemma: analysis of US household data have consistently shown families limit food purchases and take on debt to pay AC-linked energy bills.

"In many cases, the primary barrier to stay[ing] cool indoors is not access to cooling equipment but the ability to pay monthly energy bills," Pilar Botana Martinez, a research scientist at Boston University's Department of Environmental Health, told Live Science.

Shade, rest and hydration outdoors

Evidence grade: Strong

Staying indoors to avoid the heat is one way to reduce the health impacts of climate change, "but this is not a practical solution for everyone, especially those doing demanding jobs in very hot warehouses, on construction sites, in agricultural fields," Barrak Alahmad, director of the Occupational Health and Climate Change Program at Harvard University, told Live Science.

Nearly one-third of U.S. employees — mostly men — have regular outdoor exposure as part of their job.

Some of the strongest evidence for strategies for keeping them safe on the job comes from studies of sugarcane workers in Central America, Alahmad said. A nongovernmental organization called La Isla Network has rolled out a strategy in which workplaces incorporate mandated rest, shade, hydration and sanitation breaks.

In data collected over six years, La Isla Network has shown that this strategy improves health by reducing negative outcomes such as heat-related kidney failure. Similar reductions in heat-related illnesses have been seen in California; Texas; and Guangzhou, China, when such measures have been implemented. And although these interventions have some training and supply costs, they increase productivity, the data shows, which makes them an easier sell for companies.

"The aim is to build systems that reduce risk and harm, increase productivity and provide a return on investment so that these efforts just become business as usual," Jason Glaser, CEO of La Isla Network, told Live Science.

Passive cooling

Evidence grade: Intermediate

Passive cooling reduces indoor temperatures without mechanical devices like AC. These strategies include modern technologies, such as reflective surfaces and roofs that reflect more sunlight and thus keep buildings cooler; shade structures and urban greenery; and traditional techniques, like courtyards, shades and ventilation.

"These are often low-cost material choices that can make a big difference in the safety and comfort inside a building and have a proven track record of performance [in lowering temperature]," said Kurt Shickman, senior fellow at the WRI Ross Center for Sustainable Cities.

These passive technologies also make AC more efficient, thus reducing costs and lowering demand for electricity on peak power days, Shickman said.

The evidence suggests cool roofs work at scale. A 2019 California modeling study predicted that state-wide adoption of this technology would halve the number of people exposed to heat wave conditions by 2050, while a 2024 study in London that modeled cool-roof deployment predicted that the technology could reduce heat-related deaths by up to 32% during heat waves.

Green spaces can also reduce heat exposure. In dense cities in Southeast Asia, the introduction of green infrastructure, such as trees lining streets and additional bodies of water, has been shown to reduce air temperatures by up to 4.7 F (2.6 C) and surface temperatures by 19.8 F (11 C).

Those interventions won't work everywhere, though, in part because strategies that reduce deaths from heat could worsen those from cold, and cold-related deaths are four times more common globally, a 2025 study found. So places that have both cold snaps and heat waves will need to think about those trade-offs before implementing such strategies.

City-wide heat warning systems

Evidence grade: Strong

Heat warning systems have been proposed to reduce heat exposure. There is evidence that some existing systems, such as New York City's, work to reduce death or hospitalization. But whether these systems are effective depends on how they're implemented.

"Effective systems do far more than issue a temperature alert" based on forecast high-heat events, Arya told Live Science ‪—‬ an idea other experts echoed. Instead, they trigger coordinated actions, such as reaching out to vulnerable populations, extending utility protections, and coordinating with healthcare systems for surges in the number of patients.

It's difficult to test such plans in controlled experiments, but researchers try by comparing a city before and after an intervention, or by finding comparable cities or regions that did or didn't implement a heat plan and assessing the plan's effectiveness. These "natural experiments" offer a comparison without having an alternative universe as a control group. Academics using such methods concluded in 2025 that heat exposure prevention plans led to a 25% reduction in deaths attributable to extreme heat across Europe.

Personalized alerts

Evidence grade: Strong

While most warning systems trigger when temperatures cross a threshold that's considered dangerous for an average person, Shickman said, "[i]n reality, people experiencing the same air temperature will have very different responses to it."

One solution could be to individualize attention. Shickman pointed to a pilot program by insurance company Emblem Health in New York, in which a trained artificial intelligence (AI) agent supported 17,000 people with personalized advice targeted to those with complex health or social issues. The intervention halved hospital admissions compared with a control group that didn't take part.

"We can go a step further and use technology to shift from generic, passive warnings to proactive ones that address individuals' needs," he explained.

Cooling centers

Evidence grade: Weak

A common strategy implemented during heat waves is the use of cooling centers — dedicated public spaces like libraries, schools, religious buildings or commercial locations where cooler air (often via air conditioning) offers respite.

Despite extensive adoption across the U.S. and internationally, there is very limited evidence that cooling centers reduce deaths or hospitalizations from heat exposure — likely because they're not visited much.

For example, a 2024 study into Virginia's cooling centers questioned the state's existing strategy because communities that had cooling centers also had higher numbers of heat-related illnesses. Surveying the field, a 2025 review from the National Bureau of Economic Research questioned "whether those who can most benefit from reduced heat exposure can or are willing to access cooling centers, and whether travel to centers can actually increase heat exposure relative to staying at home."

Wildfire smoke

Wildfire smoke is full of fine particulate matter known as PM_2.5. These particles are 30 times smaller than the diameter of an average human hair and can penetrate deep into the lungs and the bloodstream, thereby increasing the risk of ailments such as heart attacks, asthma attacks and adverse pregnancy outcomes.

PM_2.5 pollution contributes to tens of thousands of excess deaths every year in the U.S. And research suggests that wildfire smoke emissions could increase by 262% to 482% by 2055, depending on the level of carbon emissions.

Here's what has been shown to work against this threat.

Commercial air filtration

Evidence grade: Intermediate

Data repeatedly shows that air filtration — whether through commercial HVAC systems or even a fan with a filter taped to it — reduces indoor PM_2.5 exposure.

"For wildfire smoke, an important adaptation is cleaner indoor air, as simple as that may sound," Leonard said.

Staying indoors protects individuals from the worst PM_2.5 exposure. But a 2021 California study that used 1,400 air quality sensors showed that on days with nearby wildfires, smoke found its way into households, tripling PM_2.5 compared with days without fires.

Putting newer-grade filters (MERV 16 or higher) on commercial systems, however, can reduce PM_2.5 indoors by 81%, studies found. Similarly, portable air filters have been shown to reduce PM2.5 exposure in Montana offices, Seattle homes and Singapore apartments.

However, what's still unclear is the extent to which air filtration will reduce deaths or hospitalizations related to wildfire smoke. This is because we don't know whether interventions that make air cleaner in perfect conditions scale up; people may not replace their air filters, or they may use the portable ones only some of the time, for example.

Modeling of some air filtration measures, however, suggests that they could prevent 11% to 63% of the hospital admissions and 7% to 39% of wildfire-linked deaths.

Masks for outdoor smoke exposure

Evidence grade: Intermediate

Many people, including those who work in construction and other outdoor jobs, must venture outside during smoky days, and they need information and tools to protect themselves, said Gillian Capper, program manager at the American Public Health Association's Center for Climate, Health and Equity.

For example, these measures include "distributing N95 respirators and requiring smoke protection plans for outdoor workers," she said.

Modeling studies show that N95 respirators can reduce exposure to wildfire smoke by 90%, and a modeling exercise that used data from 2012 wildfires in Washington state showed that these masks decrease smoke-linked hospitalizations by up to 30%, compared with a group that did not use masks.

Land management

Evidence grade: Intermediate

The evidence to support a reduction in wildfires through land management is mixed. The idea is that by thinning forests, harvesting trees, clearing underbrush and doing prescribed burns to prevent unplanned conflagrations, we can reduce the risk of massive, uncontrolled wildfires.

"Reducing fuels today may help avoid larger, more severe fires and associated smoke impacts in the future," Micah Hahn, an associate professor of environmental health at the University of Alaska Anchorage, told Live Science. "But relatively little research has directly measured those downstream health benefits."

A 2022 modeling exercise led by U.S. Forest Service scientists compared four forest management scenarios ‪—‬ including actions such as forest thinning and prescribed burning — in the Lake Tahoe basin over the next century. It found that these measures reduced PM_2.5 particle levels as well as smoke-related illness and death, compared with fire suppression on its own. It also modeled the health impacts for one year (2039) and found reduced health costs tied to such management.

But the benefits plateaued with more land burns. Research from the southeastern U.S. shows that management can become a large source of PM_2.5.

Still, prescribed burns have an advantage over a spontaneously erupting wildfire, experts said. "With prescribed burning, one distinct difference is the ability to plan for smoke," Heidi Huber-Stearns, director of the Center for Wildfire Smoke Research and Practice at the University of Oregon, told Live Science, and to "know when and where it will likely affect communities as compared to the unpredictability of wildfires."

Smoke alerts

In theory, fire alerts, which use high-resolution air-quality data, could reduce smoke exposure, Laura Kate Bender, vice president of nationwide advocacy and public policy at the American Lung Association, told Live Science. Alerts would be paired with tailored guidance to notify people of dangerous smoke levels and to tell them when to take action.

Because these alerts are a fairly new idea, however, there's little data showing that such programs would reduce smoke exposure or related hospitalizations and deaths. That said, there’s evidence from other fields: a 2012 World Bank modeling exercise calculated that weather data and early warnings saved nearly 800 lives per year in Europe, and could save a further 23,000 in the Global South if systems were upgraded.

"The hurricane warnings are good examples to follow, as people do act on these early warnings", Kai Chen, faculty director at the Yale Center on Climate Change and Health, told Live Science.

Ultimately, the researchers we spoke with agreed that we need more data, which requires funding for further studies into which interventions are effective and can be scaled.

"We've put a lot of effort into understanding the impacts of climate change and related exposures," Alahmad said. "But there comes a point where we need to move from studying the impacts to looking at interventions and solutions and see what actually works out there."

How we evaluated studies

We categorized evidence as strong, intermediate, or weak. Here's the criteria we used to assess them.

Strong: Data shows a reduction in disease, hospitalization or death at a population level. Data comes from either randomized trials or quasi-experimental protocols. Sample sizes are robust enough to show a clinically meaningful effect.

Intermediate: Data shows an improvement in an intermediate proxy measure, such as temperature or particulate matter concentrations, which has been tied to negative health outcomes, and/or data relies on modeling to show improved health outcomes at the population-level.

Weak: Limited data exists, or the data that does exist does not show a strong protective effect.

Burning up — How can we adapt to a warming world?

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Time keeps getting away from us. It has a fraught relationship with our subjective experience — sometimes slowing down or dragging on; and at other times speeding up, with years seeming to fly by as we get older. Our brain cells are even known to distort our sense of time when we're tired.

In physics, time gets even more complicated, incorporated into theories of relativity — the experience of the clock's ticking being relative to the observer and their place in space — and entropy, which gives time its unidirectional flow. Meanwhile quantum mechanics indicates time can move both forwards and backwards, at least inside quantum systems.

In this excerpt from "On Time: The Physics That Makes the Universe Tick" (Princeton University Press, 2026), author and theoretical physicist Jim Al-Khalili looks at the possibility that time did not begin with the Big Bang — but if this outburst was just another moment, what was there before?

There is an alternative cosmological theory to the one that says the Big Bang marked the beginning of time itself, which was then followed by a brief period of rapid inflation of space. The alternative is known as eternal inflation. In this scenario, our universe was born as a small bubble in an infinite space that has been undergoing inflation forever.

So, rather than time beginning with our Big Bang, we should regard the Big Bang as an event that took place at some moment in time, in which our region of this infinite space suddenly stopped inflating and began instead to expand at a more sedate pace.

So instead of a brief period of inflation happening just after the Big Bang, in the eternal inflation theory it is the other way around, with the Big Bang marking the end of inflation in our part of space, creating our bubble universe outside of which inflation continues. The theory predicts there will be other big bangs happening elsewhere that give rise to other universes — possibly an infinite number of them — all forever separated from each other, and all being driven apart by the ever-expanding, rapidly inflating space outside of them. The totality of this infinite space is referred to as the multiverse, to distinguish it from the individual bubble universes.

Some physicists argue that such an idea falls outside of proper science, since we do not have a way of testing it. There are two other ideas worth mentioning on the matter of whether the Big Bang marked the beginning of time or not, both of which are alternatives to inflation theory. The first is that our universe is part of a repeating process called conformal cyclic cosmology'.

This idea, proposed by Roger Penrose, suggests that our universe is going through an infinite series of lives, or epochs, each of which starts with a big bang and ends with a universe in thermal equilibrium, filled only with evenly spread-out thermal radiation. The idea here is not, as you might expect, that the universe reaches some maximum expansion before collapsing down to a 'Big Crunch' that then marks the Big Bang of the next epoch, but rather because of a subtle geometrical idea called 'conformal mapping' that connects up the very dif­ferent end of one universe (cold and spread-out) with the birth of the next (hot and dense).

I will not say any more about this theory, in particular since it has been argued that it suffers from several flaws, such as the problem of conservation of information (similar to the so-called black hole information paradox) and the difficulty of reconciling the high entropy at the end of the old epoch with the low entropy of the new epoch.

A related hypothesis, which I admit I find aesthetically rather appealing, is known as the ekpyrotic universe model. The name is based on the Greek word ekpyrosis (ἐκπύρωσι), meaning 'conflagration', which refers to a cosmological model proposed by the Stoic philosophers of ancient Greece in which the universe cycles endlessly through fiery birth, expansion, and cooling, followed by contraction, reheating, and rebirth.

The name 'ekpyrotic universe' was devised by one of the modern theory's originators, Paul Steinhardt. The idea comes out of the highly mathematical world of string theory. Basically, the whole of our three-dimensional space (which as we know is really a part of 4D spacetime) forms what is called a 3D brane (a higher-dimensional generalisation of a 2D membrane, or sheet). This 3D brane of ours is floating in a higher-dimensional (4D) space, and the Big Bang is when it collided with a neighbouring brane (in a sense this would be another universe). This collision creates tremendous heat and radiation (the Big Bang) and sets off the expansion of our space.

At the same time, it is drifting away from the other brane that it collided with, but will eventually reach maximum separation from it before they are pulled back together, colliding again in a new Big Bang. Here I simply wish to stress that if this theory is right then there may not have been a beginning of time, and certainly not at the Big Bang.

Another cosmological model, which also does away with the need for inflation, as well as suggesting that the Big Bang was not the beginning of time, has been proposed by another of the originators of the ekpyrotic universe idea, Neil Turok. But this idea, known as the 'mirror universe' theory, is rather dif­ferent. It's a nice idea, and it certainly solves Loschmidt's paradox regarding the conflict between time symmetry and the second law of thermodynamics. Due to the time-symmetric underlying fundamental equations of physics, starting a system off at any arbitrary moment means that its entropy should increase equally into the past as it does into the future.

But this just doesn't make sense. If the system at all times before our chosen arbitrary moment has higher entropy, then starting from any of those earlier times should see the system decrease in entropy in order to reach its state at the original arbitrary moment. Therefore, it cannot be arbitrary; the system had to have been in a specially prepared state at that moment, the moment of the Big Bang. There would be no increase in entropy going backwards in time if that is when time started.

But what if there were a mirror universe on the other temporal side of the Big Bang, evolving in a direction we would consider to be towards the past? This is precisely what Turok is suggesting. What is neat (or convenient, depending on how much you like this theory) is that both sides of the Big Bang are completely separated from each other, with each seeing time pointing in the direction of increasing entropy. If such a mirror universe exists and contains intelligent life that has also hit upon the mirror universe idea, then they would think that our side was the one before the Big Bang in the same way we think that theirs is. As well as doing away with inflation, this idea also conveniently explains why there is more matter than antimatter in our universe because, guess what, the mirror universe would have it the other way round: What they call normal matter is our antimatter.

How seriously should we take these cosmological theories? Are they even proper science? Their proponents know they require some sort of empirical evidence to support their hypotheses, such as some imprint of a reality before the Big Bang frozen in our cosmic microwave background. For without observational evidence, these ideas will remain just theoretical curiosities.

Excerpted from On Time: The Physics That Makes the Universe Tick © 2026 by Jim Al-Khalili. Reprinted by permission of Princeton University Press.

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The patient: A 61-year-old man in India

The symptoms: The man went to an emergency department after fainting. He had felt nauseous just before the episode, which lasted about three minutes and was followed by a second fainting episode lasting about two minutes. He also had swelling around one eye.

His family told doctors that he hadn't shown any jerking movements, loss of bladder control or subsequent grogginess, which would have been telltale signs of a seizure.

What happened next: Because the man had fainted twice and had a history of heart disease, doctors first looked for problems affecting his brain and heart. An MRI of his brain, used to look for structural abnormalities that could explain the fainting, and an electroencephalogram (EEG), which records the brain's electrical activity, did not reveal a cause.

The man had persistently low blood pressure, the doctors observed, and this led them to move him to the intensive care unit. There, doctors carried out tests for infections and heart attack, but all came back negative.

Meanwhile, the swelling around one of his eyes spread to both eyes and then across his face, while his blood pressure continued to fall despite treatment with intravenous fluids.

The doctors probed further into the man's medical history and activities before the fainting episodes. They learned that he had applied an artificial hair dye two days before he became ill. Soon afterward, he developed itching on his scalp, neck and face. He self-treated with the allergy medicine cetirizine, an antihistamine, for two days. He also reported spending two to three hours outdoors in the sun each day after he'd applied the hair dye.

The diagnosis: Based on the man's recent use of hair dye, the itching that followed, his rapidly worsening facial swelling and his persistently low blood pressure, doctors concluded that he was experiencing anaphylaxis, a severe allergic reaction that can affect the whole body. The reaction can be life-threatening if left untreated.

The treatment: Doctors treated the man with epinephrine (also called adrenaline), a hormonal medication that rapidly reverses the effects of anaphylaxis. They also gave him antihistamines and steroids to help bring the allergic reaction under control, along with intravenous fluids to raise his blood pressure.

However, the patient's blood pressure remained dangerously low, so doctors continued giving him epinephrine through an intravenous drip for about 16 hours. Over the next three days of treatment, his blood pressure stabilized and the swelling in his face gradually subsided.

He was transferred to a general ward and treated there for another five days before being discharged. He was advised that he could have a similar reaction in the future and referred to a dermatologist.

What makes the case unique: Most allergic reactions to hair dye remain limited to the skin, causing itching, redness and swelling where the dye has touched it. Severe reactions affecting the whole body are uncommon, the man's doctors wrote in a report of the case.

The itching the man noticed shortly after applying the dye was likely an early, mild allergic reaction, his doctors wrote. That reaction later progressed to a much more severe one, they suggested, raising the possibility of a "biphasic" allergic reaction, an uncommon pattern seen in about 5% of patients with anaphylaxis. However, this remains only a possible explanation.

The doctors also noted that the man's prolonged sun exposure after he applied the dye may have intensified the reaction; they cited previous research that ultraviolet light can enhance the allergy-triggering effects of para-phenylenediamine, a common ingredient in hair dyes. In the report, the doctors did not identify the exact hair dye ingredient that triggered the reaction in this instance.

The case highlights the importance of asking about recent use of products such as hair dye when doctors evaluate patients with otherwise unexplained fainting, facial swelling or shock, the medical team concluded.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

Can you guess the diagnosis in these strange medical cases? Find out with our diagnostic dilemma quiz!

This eye-catching astronaut photo shows the point where an ancient Patagonian lake has been split by a peculiar land bridge, creating two contrastingly colored bodies of water.

Lake Pueyrredón (on the left in the photo) is the Argentine half of a roughly 40-mile-long (65 kilometers) glacial lake, which stretches across the country's border with Chile in Patagonia — a region in South America that is well known for its diverse range of geographic features, including mountains, fjords, deserts and rainforests. The Chilean half of the lake is known as Lake Cochrane (not shown in this image). Both halves hold crystal-clear water that is up to 1,600 feet (500 meters) deep, giving Pueyrredón a deep blue hue when viewed from above.

Thousands of years ago, a thick sediment barrier formed across the southern section of Lake Pueyrredón, creating a new body of water known as Lake Posadas. This smaller body, which is roughly 5 miles (8 km) long, has a lighter, teal color due to its shallow water and a large influx of sediment from a nearby river, according to NASA's Earth Observatory.

Other rivers from nearby hills have previously dumped large quantities of sediment along the western shore of Lake Pueyrredón (bottom of the photo), creating a trio of fan-shaped landforms, known as deltas, that increase in size from north to south (left to right in the photo).

Wind-driven currents and waves have pushed some of this sediment from the outer edges of the two smaller deltas, creating long, thin strips of land, known as sandspits, pointing down-current.

The strip of land separating Pueyrredón and Posadas looks similar to the sandspits. However, it is most likely a moraine — a barrier of sediment and larger rocks that formed along the edge of a hefty iceberg or long-lost glacier, according to the Earth Observatory.

Eagle-eyed viewers may be able to spot a narrow airstrip on the smallest delta (running almost parallel with its sandspit). While the area is largely uninhabited, it is popular with tourists, who travel to the lakes to camp, hike, fish and kayak, according to a local travel site.

Lake Posadas is also home to a unique island with a massive rocky arch (see below) that is also popular with tourists.

The two lakes in the astronaut photo sit within a large valley, which was carved by a massive ice sheet that once covered the area. The last remnants of this ice sheet are located in northern Patagonia, around 20 miles (30 km) west of Lake Cochrane, and have also been snapped from space by astronauts.