Until recently, it was thought that Homo sapiens and Neanderthals split off from their last common ancestor around 600,000 years ago, but a prehistoric skull from China has just shattered that narrative. Dated to a million years ago, the cranium belongs to an extinct human clade which encompasses the Denisovans, indicating that we had already branched off from our sister lineage prior to this point.

Discovered in Hubei Province in 1990, the so-called Yunxian 2 skull has been at the center of a taxonomic confusion for the past 35 years, largely because the specimen is badly crushed and therefore difficult to study. Due to its age and the shape of its braincase, though, some scholars had assumed that the cranium belonged to Homo erectus.

However, using CT scanning and digital reconstruction techniques, the authors of a new study have managed to correct the skull’s distortions and build a complete model of the specimen. In doing so, they revealed that Yunxian 2 possesses a mosaic of features, some of which are typical of more primitive hominins like H. erectus while others are more aligned with Homo sapiens.

Cross-referencing more than 500 of these morphological traits against 104 other human fossils, the researchers determined that Yunxian 2 belongs to the Homo longi clade, which includes a 145,000-year-old skull that was recently identified as a Denisovan. However, Yunxian 2 itself is not a Denisovan, but probably sits near the base of the lineage that gave rise to this enigmatic species. 

What’s more, while Denisovans and Neanderthals were previously thought to be sister lineages, the team’s analysis indicates that the Homo longi clade is in fact the sister group to the Homo sapiens clade.

“We really have to say we don't know where the common ancestor lived.”
— Professor Chris Stringer

“Because [Yunxian 2] is about a million years old, by definition, the Homo longi clade must be about a million years old at minimum,” said study author Professor Chris Stringer to IFLScience. “And that, in turn, implies that if sapiens and Neanderthals had already branched off, then their groups must be equally or even older in their origin.”

In other words, the Homo sapiens group must have emerged more than a million years ago, which is around 400,000 years earlier than certain genomic models suggest. Overall, the researchers estimate that our clade originated about 1.02 million years ago, while the Homo longi group dates back to 1.2 million years ago.

Ketogenic diets, usually shortened to keto, are promoted as a way of losing weight and improving your general health, but the long-term impacts of following such a diet are still being unraveled. A new study throws some concerning findings into the mix, suggesting that while the diet may be effective for weight loss, it could lead to complications like fatty liver disease. 

Keto diets are designed to get the body into a state of ketosis, where fat stores are used as an energy source rather than carbohydrates. To achieve this, these diet plans recommend strict limits on carbohydrate-rich foods, things like starchy vegetables, grains, and sugars. Instead, there’s a focus on protein- and fat-rich foods like meat, fish, unsweetened dairy, nuts, and seeds. 

For some people, a keto diet is an essential part of medical treatment for a chronic illness. For example, ketogenic diet therapy can help children with drug-resistant epilepsy experience fewer seizures. But as the British Dietetic Association points out, following such a strict diet plan comes with its own risks and should be closely monitored. So, what about people without a medical indication who simply choose to follow this diet for themselves?

Lots of people claim the diet has helped them lose weight and feel better, but the internet also abounds with anecdotes from people who claim it ruined their health. The “long-term effects [of ketogenic diets] on metabolic health remain understudied,” write the authors of a new study.

Shortly before his death in August 2025, A. James Hudspeth and his colleagues at The Rockefeller University’s Laboratory of Sensory Neuroscience accomplished a milestone that had never been reached before. They succeeded in keeping a small section of the cochlea alive and working outside the body, making it possible to study the organ’s function directly for the first time. Using a specially designed device, the team was able to track the cochlea’s extraordinary abilities in real time, including its fine-tuned sensitivity, precise frequency detection, and capacity to process a wide range of sound levels.

“We can now observe the first steps of the hearing process in a controlled way that was previously impossible,” says co-first author Francesco Gianoli, a postdoctoral fellow in the Hudspeth lab.

The achievement, detailed in two recent publications (in PNAS and Hearing Research, respectively), represents the culmination of Hudspeth’s fifty years of pioneering research into the cellular and neural basis of hearing. His work has continually pointed toward new possibilities for preventing and treating hearing loss.

Beyond its immediate applications, the advance also delivers long-sought experimental confirmation of a fundamental biophysical principle that underlies hearing across diverse species, a concept Hudspeth had pursued for more than twenty-five years.

“This study is a masterpiece,” says biophysicist Marcelo Magnasco, head of the Laboratory of Integrative Neuroscience at Rockefeller, who collaborated with Hudspeth on some of his seminal findings. “In the field of biophysics, it’s one of the most impressive experiments of the last five years.”

The mechanics of hearing
Though the cochlea is a marvel of evolutionary engineering, some of its fundamental mechanisms have long remained hidden. The organ’s fragility and inaccessibility—embedded as it is in the densest bone in the body—have made it difficult to study in action.

These challenges have long frustrated hearing researchers, because most hearing loss results from damage to sensory receptors called hair cells that line the cochlea. The organ has some 16,000 of these hair cells, so-called because each one is topped by a few hundred fine “feelers,” or stereocilia, that early microscopists likened to hair. Each bundle is a tuned machine that amplifies and converts sound vibrations into electrical responses that the brain can then interpret.

Sitting in the audience at a stand-up show; watching a comedy at the movies; at the office party when your boss breaks out their best knock-knock joke: these are all places where laughter is both encouraged and expected. During a quiet moment in church? Not so much. But wherever you are, if you hear someone else laughing, it’s likely you’ll get the urge to giggle too – however inappropriate that may be! Should we all just be able to control ourselves better, or is laughter really contagious?
The answer, in short, is yes.

“All emotions are contagious”
“Is laughter contagious? Well, actually, all emotions are contagious,” Dr Sandi Mann, chartered member of the British Psychological Society, told IFLScience. “We are designed to pick up other people’s emotions.”

It’s part of our evolution, and it’s something we share with other mammals. It’s been well established that apes – our closest relatives – laugh in a remarkably humanlike way. If you’re ever close enough to a bonobo to try tickling it (not something we’d necessarily recommend), you’ll find out.

Recent research even found that apes may have a sense of humor and love to tease each other. A 2021 review concluded that 65 different animal species show evidence of “play vocalizations” that mimic humans laughing when we’re having fun, mostly mammals but a few birds as well. 

In fact, laughter is such a fundamental part of what it means to be human that it transcends language and culture – there’s not a single community of people on Earth that we know of who don’t laugh. 

Why laughter is good for us
Part of the reason why a fit of the giggles spreads so easily, Dr Mann told us, is that shared emotions are integral to social bonding. A 2022 paper from University of Oxford Emeritus Professor of Evolutionary Psychology Robin Dunbar explored this further. 

“I suggest that, when hominins needed to increase the size of their groups beyond the limit that could be bonded by grooming, they co-opted laughter […] as a form of chorusing to fill the gap,” Dunbar wrote. 

Grooming – a social behavior we particularly associate with monkeys and apes, but which is seen throughout the animal world – boosts the production of endorphins in the brain. These chemical messengers relieve pain and generally make us feel good. Dunbar detailed some evidence that laughter has a similar effect, with the added benefit of being less intimate and time-consuming than grooming. Hence, humans laugh together all the time, but we’re rarely seen picking lice out of each other’s hair these days. 

A hit of endorphins also helps us de-stress. When a group of people are sharing a tense situation, Dr Mann told IFLScience, humor can help to alleviate that as well as strengthen the bond between them: “Sometimes we just need to smile, laugh, have fun to relieve the stress.”

What drives a person to keep drinking alcohol despite the harm it causes to their health, relationships, and overall well-being? New research from Scripps Research points to a possible answer: a small midline brain region helps shape how animals learn to drink in order to relieve the stress and discomfort of withdrawal.

In a study recently published in Biological Psychiatry: Global Open Science, the Scripps Research team examined brain activity in the paraventricular nucleus of the thalamus (PVT) in rats. They discovered that when rats linked environmental cues with alcohol’s ability to ease withdrawal symptoms, activity in this brain region increased, reinforcing relapse behaviors.

By uncovering this pathway, the study highlights one of addiction’s most persistent aspects—using alcohol not for enjoyment but to avoid suffering—and may pave the way for new therapies for substance use disorders (SUDs) and related conditions such as anxiety.

“What makes addiction so hard to break is that people aren’t simply chasing a high,” says Friedbert Weiss, professor of neuroscience at Scripps Research and senior author of the study. “They’re also trying to get rid of powerful negative states, like the stress and anxiety of withdrawal. This work shows us which brain systems are responsible for locking in that kind of learning, and why it can make relapse so persistent.”

“This brain region just lit up in every rat that had gone through withdrawal-related learning,” says co-senior author Hermina Nedelescu of Scripps Research. “It shows us which circuits are recruited when the brain links alcohol with relief from stress—and that could be a game-changer in how we think about relapse.”

Most people know sloths as slow-moving, bear-like creatures that dangle from trees, take nearly a month to digest a single meal, and defecate only once a week. Their closest relatives are anteaters and armadillos, which may sound like an unusual connection, but evolutionary history explains the link. Today only two sloth species exist, but in the past there were dozens, including one with a bottle-shaped snout specialized for eating ants and another that closely resembled early armadillos.

Many of these ancient sloths were far too large to live in trees. The giants of the group, belonging to the genus Megatherium, grew to the size of Asian bull elephants and weighed around 8,000 pounds [~3629kg].

“They looked like grizzly bears but five times larger,” said Rachel Narducci, collection manager of vertebrate paleontology at the Florida Museum of Natural History.

Narducci co-authored a study published in Science in which researchers examined ancient DNA and analyzed more than 400 fossils from 17 natural history museums to understand how and why some sloths reached such massive proportions.

Ground-dwelling sloths displayed an extraordinary range of body sizes. At one extreme was the enormous Megatherium, capable of stripping leaves from tall trees with its long, flexible tongue, serving as an ecological counterpart to giraffes. At the other was the comparatively smaller Shasta ground sloth, which thrived in the deserts of North America by feeding on cacti.

Tree-dwelling sloths, however, followed a different evolutionary path. Those that lived exclusively in the forest canopy have always been small, averaging about 14 pounds [~6.35kg]. Species that split their time between the ground and the trees were somewhat larger, weighing an average of 174 pounds [~79kg].

You don’t have to be a scientist to puzzle out why trees enforce a strict weight limit. It’s the same reason why modern tree sloths have a strange elastic quality to them: Branches break when put under too much strain, and sloths are not generally known for their ability to swiftly avert sudden disaster. Tree sloths have reportedly survived falls of up to 100 feet [~30m]. However, given that falls from even moderate heights can cause severe damage and some trees in the Amazon Rainforest top out at just under 300 feet [~91m], it makes evolutionary sense to be as small as possible when going out on a limb.

Why Did Ground Sloths Get So Big?
What’s less clear is why some ground sloths grew to such excessive sizes while others seemed content with being merely large. There may have been several reasons, which is why it’s been so hard for scientists to answer the question with confidence.

Larger sizes might have been advantageous for finding food or avoiding predators, for example. Ground sloths had a special fondness for caves, and their size undoubtedly played a role in their ability to find and make shelters. The moderately sized Shasta ground sloth favored small, natural caves bored by wind and water into the cliffsides of the Grand Canyon, like the alveoli of a gigantic, geologic lung. These also doubled as convenient latrines; in 1936, paleontologists discovered a mound of fossilized sloth poop, bat guano, and packrat middens more than 20 feet [~6m] thick in Rampart Cave, near Lake Mead.
Scientists analyzed ancient DNA and compared more than 400 fossils from 17 natural history museums to figure out how and why extinct sloths got so big.

Larger sloths weren’t restricted to pre-existing caves. Using claws that are among the largest of any known mammal, living or extinct, they could carve their own from bare earth and rock. Many of the caves they left behind are still around with claw-mark décor along the interior walls, evidence of their ancient nesting excavations.

This rare case of convergent evolution shows nature arriving at the same mind-altering molecule by two separate paths. The true reason fungi produce psilocybin remains unsolved, but theories range from predator defense to chemical communication. Beyond evolutionary intrigue, the discovery also offers new enzyme tools that could help produce psilocybin more efficiently for future medicines.

Ancient Molecule With a Modern Role
“This concerns the biosynthesis of a molecule that has a very long history with humans,” explains Prof. Dirk Hoffmeister, head of the research group Pharmaceutical Microbiology at Friedrich Schiller University Jena and the Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI).

“We are referring to psilocybin, a substance found in so-called ‘magic mushrooms’, which our body converts into psilocin – a compound that can profoundly alter consciousness. However, psilocybin not only triggers psychedelic experiences, but is also considered a promising active compound in the treatment of therapy-resistant depression,” says Hoffmeister.

Two Evolutionary Paths to Psilocybin
The study, carried out within the Cluster of Excellence ‘Balance of the Microverse’, reveals that fungi developed the ability to produce psilocybin on at least two separate occasions in evolutionary history. Psilocybe mushrooms rely on a familiar set of enzymes to make the molecule, while fiber cap mushrooms use an entirely different biochemical toolkit. Despite these very different methods, both groups arrive at the same compound. Scientists call this convergent evolution, when unrelated species independently evolve the same trait.

Staring at the ceiling while the clock blinks 3am doesn't only sap energy for the next day. A large, long-running US study of older adults has now linked chronic insomnia to changes inside the brain that set the stage for dementia.

The researchers, from the Mayo Clinic in the US, followed 2,750 people aged 50 and over for an average of five and a half years. Every year the volunteers completed detailed memory tests and many also had brain scans that measured two telltale markers of future cognitive trouble: the buildup of amyloid plaques, and tiny spots of damage in the brain's white matter – known as white-matter hyperintensities.

Participants were classed as having chronic insomnia if their medical records contained at least two insomnia diagnoses a month apart – a definition that captured 16 percent of the sample.

Compared with people who slept soundly, those with chronic insomnia experienced a faster slide in memory and thinking and were 40 percent more likely to develop mild cognitive impairment or dementia over the study period.

When the team looked more closely, they saw that insomnia paired with shorter-than-usual sleep was especially harmful. These poor sleepers already performed as if they were four years older at the first assessment and showed higher levels of both amyloid plaques and white-matter damage.

By contrast, insomniacs who said they were sleeping more than usual, perhaps because their sleep problems had eased, had less white-matter damage than average.

Some of the mysterious pinpricks of light at the dawn of the Universe could be a type of object we've never seen before.

According to a new analysis of a "little red dot" (LRD) nicknamed The Cliff, these unexplained objects could be supermassive black holes wrapped in huge, dense clouds of gas, like an atmosphere surrounding a stellar core.

It's a very tidy explanation that solves a problem astronomers are struggling to reconcile: a 'break' in the LRDs' light that makes galaxies in the early Universe seem older than possible.

"We … conclude that the rest-optical and near-infrared continuum of The Cliff cannot originate from a massive, evolved stellar population with an extremely high stellar density," writes a team led by astrophysicist Anna de Graaff of the Max Planck Institute for Astronomy in Germany.

"Instead, we argue that the most plausible model is that of a luminous ionising source reddened by dense, absorbing gas in its close vicinity. Currently, the only model capable of producing both the strength and shape of the observed Balmer break is that of a black hole star."

A Balmer break is a sharp change in the spectrum of an object in space occurring in the ultraviolet part of the spectrum, where shorter-wavelength light on one side of the line is much lower in intensity than the higher-wavelength light on the other side of the line. This feature is created by the absorption of shorter-wavelength light by hydrogen atoms.

A strong Balmer break is associated with galaxies that have a dominant population of A-type stars, which are just the right temperature to absorb light at the requisite wavelength.

Here's the kicker: to display that strong Balmer break, those galaxies have to be old enough for the earliest dominant population of O and B stars to have largely died off, leaving the A-type stars responsible for most of the galaxy's light, with little to no new star formation.

Many LRDs exhibit a strong Balmer break, at an epoch starting just 600 million years after the Big Bang, 13.8 billion years ago. Scientists believe this is too early in the lifespan of the Universe for a galaxy to have reached the stage of a dominant type-A population.

In turn, this has led to some investigation into what these small red lights at the dawn of spacetime might be – from primordial black holes to the seeds of supermassive stars.

For the first time, scientists in the Femtosecond Spectroscopy Unit at the Okinawa Institute of Science and Technology (OIST) have directly tracked how dark excitons evolve in atomically thin materials. This achievement paves the way for advances in both classical and quantum information technologies. The study was published in Nature Communications.

Professor Keshav Dani, who leads the unit, emphasized the importance of the work: “Dark excitons have great potential as information carriers, because they are inherently less likely to interact with light, and hence less prone to degradation of their quantum properties. However, this invisibility also makes them very challenging to study and manipulate. Building on a previous breakthrough at OIST in 2020, we have opened a route to the creation, observation, and manipulation of dark excitons.”

“In the general field of electronics, one manipulates electron charge to process information,” explains Xing Zhu, co-first author and PhD student in the unit. “In the field of spintronics, we exploit the spin of electrons to carry information. Going further, in valleytronics, the crystal structure of unique materials enables us to encode information into distinct momentum states of the electrons, known as valleys.”

The ability to use the valley dimension of dark excitons to carry information positions them as promising candidates for quantum technologies. Dark excitons are by nature more resistant to environmental factors like thermal background than the current generation of qubits, potentially requiring less extreme cooling and making them less prone to decoherence, where the unique quantum state breaks down.

A new study has attempted to pin down the properties of interstellar comet 3I/Atlas, finding it is "anomalously massive" at around 33 billion tons. 

On July 1, 2025, astronomers spotted an object moving through the Solar System at nearly twice the velocity of previous interstellar visitors ‘Oumuamua and Comet Borisov. The object, which was confirmed to be an interstellar comet with its own dusty coma, and suspected to be far larger than the previous two, with a then-estimated nucleus (the rocky part of the comet, excluding its coma) of around 5.6 kilometers (3.5 miles).

Sizing comets is a tricky business, primarily because to do so, you need to distinguish the comet from its coma. As comets approach the Sun in their orbit and heat up, they outgas, losing gas and later (when they are even closer to the Sun) dust, which forms their distinctive trail or coma. This outgassing acts like a thruster, slightly altering the trajectory, rotation, and speed of the comet.

That can complicate measurements, but it can also provide key clues. In a new paper, which has not yet been peer reviewed, from Harvard's Richard Cloete, Avi Loeb, and Peter Vereš, the team looked at data compiled by the Minor Planet Center between May 15 and September 23, 2025, from 227 observatories around the world, and compared the object's trajectory to what we would expect from gravitational acceleration alone (i.e. acceleration caused by the Sun's mass as it approaches closer).

The team's paper found that the non-gravitational acceleration was pretty small, at below 15 meters per day squared. That's pretty tiny, considering that we have already seen significant outgassing by the comet, including using the JWST, with a mass loss rate of around 150 kilograms (330 pounds) per second. To this team crunching the numbers, that suggests that the object's nucleus is massive, resisting change to acceleration as the Sun-facing side outgasses. 

The team estimates that the object weighs over 33 billion tons – or 33 trillion kilograms – with a nucleus diameter of 5 kilometers (3.1 miles). This is large for a comet, yes, but at 500 trillion tons, or 5×1017 kilograms (500 quadrillion kilograms), C/2014 UN271 (Bernardinelli-Bernstein) still has it beat. But then again, it has the largest comet nucleus ever seen at 128 kilometers (80 miles) across.

So, where is the anomaly? According to Loeb, the mystery is why we haven't spotted many more interstellar objects before we spotted one of this size.

"3I/ATLAS is more massive than the other two interstellar objects, 1I/Oumuamua and 2I/Borisov by 3–5 orders of magnitude, constituting a major anomaly," Loeb said in a blog post. "Given the limited reservoir of heavy elements, we should have discovered on the order of a hundred thousand interstellar objects on the 0.1-kilometer scale of 1I/Oumuamua before finding 3I/ATLAS, yet we only detected two interstellar objects previously."

DMT, short for dimethyltryptamine, is a naturally occurring psychoactive compound that exists in a variety of plants and animals.

A recent study published in Science Advances by researchers at the HUN-REN BRC Institute of Biophysics and the Semmelweis University Heart and Vascular Centre reports that DMT can lessen the damaging impact of stroke in both laboratory cell cultures and animal models.

A solution from nature in the spotlight
This compound is also produced in the human brain, where it is now being investigated in clinical trials as a potential aid for restoring brain function following stroke. Until recently, the way DMT worked in this context remained unclear. “It is amazing how we can always turn to nature to find ingenious solutions for health problems,” says co-lead author Mária Deli from the HUN-REN BRC.

The blood-brain barrier as a therapeutic target
“We found that DMT significantly reduced infarct volume and edema formation in a rat stroke model,” explains co-first author Marcell László. In both animal experiments and cell culture models, the authors showed that DMT treatment restored the structure and function of the damaged blood-brain barrier and improved the function of astroglial cells.

This psychoactive compound also inhibited the production of inflammatory cytokines in brain endothelial cells and peripheral immune cells, while reducing the activation of brain microglia cells through Sigma-1 receptors.

DMT could serve as therapeutic adjuvant to existing stroke treatments
“The therapeutic options currently available for stroke are very limited. The dual action of DMT, protecting the blood-brain barrier while reducing brain inflammation, offers a novel, complex approach that could complement existing treatments,” says Judit Vigh, co-first author of the work.

Since current stroke therapies do not always result in full recovery, a DMT-based treatment may represent a promising new alternative, mainly in combination with existing methods. The recent findings from researchers in Szeged and Budapest, Hungary, support the development of a therapy that goes beyond the limitations of conventional stroke treatment. Clinical trials on the use of DMT and investigations on its long-term effects are currently ongoing.

Around 30,000 years ago, a hunter-gatherer left behind what may be a "personal toolkit" in what is now the Czech Republic, a new study finds.

Researchers uncovered the extraordinary cluster of artifacts in 2021 during an excavation at the Paleolithic site of Milovice IV. The "kit" contains 29 stone blades and bladelets that were found clumped together. The nature of the find indicates that the tools were bundled when deposited, likely in a container or case made from a perishable material, according to the study, which was published Aug. 13 in the Journal of Paleolithic Archaeology.

The find provides a remarkable glimpse into the life of a hunter-gatherer from the Paleolithic, which spans roughly 3.3 million years ago to just over 10,000 years ago.

The artifacts likely highlight an episode in the life of one person — which is "very rare" for the Paleolithic, study first author Dominik Chlachula, a researcher at the Institute of Archaeology of the Czech Academy of Sciences, told Live Science in an email.

Moreover, the discovery may shed light on the behavior of prehistoric people during migrations or hunting trips, which did not tend to leave behind many traces in the landscape and are therefore practically invisible to archaeologists, he said.

In a groundbreaking first, a gene therapy in clinical trials has slowed the progression of Huntington's disease, a rare genetic disorder in which toxic bits of protein cause brain cells to malfunction and die.

To date, approved treatments for Huntington's disease aim to manage its symptoms, which most often emerge in a person's 30s or 40s. The progressive condition injures and kills key neurons involved in controlling mood, cognition and motor control. Various drugs can help to offset the depression, hallucinations and poorly coordinated movements that arise from that destruction.

Now, in trial results shared Wednesday (Sept. 24), scientists announced that a new gene therapy called AMT-130 appears to slow the disease's progression — marking a first for the field.

"These groundbreaking data are the most convincing evidence in the field to date and underscore the disease-modifying effect in Huntington's disease, where an urgent need persists," Dr. Sarah Tabrizi, the lead scientific advisor on the trial and the director of the University College London (UCL) Huntington's Disease Centre, said in a statement. "For patients, AMT-130 has the potential to preserve daily function, keep them in work longer, and meaningfully slow disease progression."

Don't rule out the grasshopper mouse. These rodents are equipped with special venom-blocking proteins that are especially useful when battling a potentially paralyzing foe—like the giant hairy scorpion.

A team of MIT geochemists has unearthed new evidence in very old rocks suggesting that some of the first animals on Earth were likely ancestors of the modern sea sponge.

In a study appearing in the Proceedings of the National Academy of Sciences, the researchers report that they have identified "chemical fossils" that may have been left by ancient sponges in rocks that are more than 541 million years old. A chemical fossil is a remnant of a biomolecule that originated from a living organism that has since been buried, transformed, and preserved in sediment, sometimes for hundreds of millions of years.

The newly identified chemical fossils are special types of steranes, which are the geologically stable form of sterols, such as cholesterol, that are found in the cell membranes of complex organisms. The researchers traced these special steranes to a class of sea sponges known as demosponges. Today, demosponges come in a huge variety of sizes and colors, and live throughout the oceans as soft and squishy filter feeders. Their ancient counterparts may have shared similar characteristics.

"We don't know exactly what these organisms would have looked like back then, but they absolutely would have lived in the ocean, they would have been soft-bodied, and we presume they didn't have a silica skeleton," says Roger Summons, the Schlumberger Professor of Geobiology Emeritus in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

The group's discovery of sponge-specific chemical fossils offers strong evidence that the ancestors of demosponges were among the first animals to evolve, and that they likely did so much earlier than the rest of Earth's major animal groups.

It may look like these comets are racing, but they are not. Comets C/2025 K1 ATLAS (left) and C/2025 R2 SWAN (right) appeared near each other by chance last week in the featured image taken from France's Reunion Island in the southern Indian Ocean.

Fainter Comet ATLAS is approaching our Sun and will reach its closest approach in early October when it is also expected to be its brightest -- although still only likely visible with long exposures on a camera. The brighter comet, nicknamed SWAN25B, is now headed away from our Sun, although its closest approach to Earth is expected in mid-October, when optimistic estimates have it becoming bright enough to see with the unaided eye. Each comet has a greenish coma of expelled gas and an ion tail pointing away from the Sun.

Image Credit & Copyright: Luc Perrot (TWAN)

Whenever you see the ISS from Earth, WE aboard the ISS cannot see you!

When ISS is exposed in sunlight, our window reflectivity blinds us! We can only see you when you cannot see us!

Same effect as how you cannot see through your kitchen window at night when the lights are on!