AI algorithm unblurs the cosmos

The cosmos would look a lot better if Earth's atmosphere wasn't photo bombing it all the time.

Even images obtained by the world's best ground-based telescopes are blurry due to the atmosphere's shifting pockets of air. While seemingly harmless, this blur obscures the shapes of objects in astronomical images, sometimes leading to error-filled physical measurements that are essential for understanding the nature of our universe.

Now researchers at Northwestern University and Tsinghua University in Beijing have unveiled a new strategy to fix this issue. The team adapted a well-known computer-vision algorithm used for sharpening photos and, for the first time, applied it to astronomical images from ground-based telescopes. The researchers also trained the artificial intelligence (AI) algorithm on data simulated to match the Vera C. Rubin Observatory's imaging parameters, so, when the observatory opens next year, the tool will be instantly compatible.

While astrophysicists already use technologies to remove blur, the adapted AI-driven algorithm works faster and produces more realistic images than current technologies. The resulting images are blur-free and truer to life. They also are beautiful -- although that's not the technology's purpose.

"Photography's goal is often to get a pretty, nice-looking image," said Northwestern's Emma Alexander, the study's senior author. "But astronomical images are used for science. By cleaning up images in the right way, we can get more accurate data. The algorithm removes the atmosphere computationally, enabling physicists to obtain better scientific measurements. At the end of the day, the images do look better as well."

The research will be published March 30 in the Monthly Notices of the Royal Astronomical Society.

Alexander is an assistant professor of computer science at Northwestern's McCormick School of Engineering, where she runs the Bio Inspired Vision Lab. She co-led the new study with Tianao Li, an undergraduate in electrical engineering at Tsinghua University and a research intern in Alexander's lab.

When light emanates from distant stars, planets and galaxies, it travels through Earth's atmosphere before it hits our eyes. Not only does our atmosphere block out certain wavelengths of light, it also distorts the light that reaches Earth. Even clear night skies still contain moving air that affects light passing through it. That's why stars twinkle and why the best ground-based telescopes are located at high altitudes where the atmosphere is thinnest.

"It's a bit like looking up from the bottom of a swimming pool," Alexander said. "The water pushes light around and distorts it. The atmosphere is, of course, much less dense, but it's a similar concept."

The blur becomes an issue when astrophysicists analyze images to extract cosmological data. By studying the apparent shapes of galaxies, scientists can detect the gravitational effects of large-scale cosmological structures, which bend light on its way to our planet. This can cause an elliptical galaxy to appear rounder or more stretched than it really is. But atmospheric blur smears the image in a way that warps the galaxy shape. Removing the blur enables scientists to collect accurate shape data.

"Slight differences in shape can tell us about gravity in the universe," Alexander said. "These differences are already difficult to detect. If you look at an image from a ground-based telescope, a shape might be warped. It's hard to know if that's because of a gravitational effect or the atmosphere."

To tackle this challenge, Alexander and Li combined an optimization algorithm with a deep-learning network trained on astronomical images. Among the training images, the team included simulated data that matches the Rubin Observatory's expected imaging parameters. The resulting tool produced images with 38.6% less error compared to classic methods for removing blur and 7.4% less error compared to modern methods.

When the Rubin Observatory officially opens next year, its telescopes will begin a decade-long deep survey across an enormous portion of the night sky. Because the researchers trained the new tool on data specifically designed to simulate Rubin's upcoming images, it will be able to help analyze the survey's highly anticipated data.

For astronomers interested in using the tool, the open-source, user-friendly code and accompanying tutorials are available online.

"Now we pass off this tool, putting it into the hands of astronomy experts," Alexander said. "We think this could be a valuable resource for sky surveys to obtain the most realistic data possible."

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Generating power with blood sugar

In type 1 diabetes, the body does not produce insulin. This means that patients have to obtain the hormone externally to regulate their blood sugar levels. Nowadays, this is mostly done via insulin pumps that are attached directly to the body. These devices, as well as other medical applications such as pacemakers, require a reliable energy supply, which at present is met primarily by power from either single-use or rechargeable batteries.

Now, a team of researchers led by Martin Fussenegger from the Department of Biosystems Science and Engineering at ETH Zurich in Basel have put a seemingly futuristic idea into practice. They have developed an implantable fuel cell that uses excess blood sugar (glucose) from tissue to generate electrical energy. The researchers have combined the fuel cell with artificial beta cells developed by their group several years ago. These produce insulin at the touch of a button and effectively lower blood glucose levels much like their natural role models in the pancreas.

"Many people, especially in the Western industrialised nations, consume more carbohydrates than they need in everyday life," Fussenegger explains. This, he adds, leads to obesity, diabetes and cardiovascular disease. "This gave us the idea of using this excess metabolic energy to produce electricity to power biomedical devices," he says.

Fuel cell in tea bag format

At the heart of the fuel cell is an anode (electrode) made of copper-based nanoparticles, which Fussenegger's team created specifically for this application. It consists of copper-based nanoparticles and splits glucose into gluconic acid and a proton to generate electricity, which sets an electric circuit in motion.

Wrapped in a nonwoven fabric and coated with alginate, an algae product approved for medical use, the fuel cell resembles a small tea bag that can be implanted under the skin. The alginate soaks up body fluid and allows glucose to pass from the tissue into the fuel cell within.

A diabetes network with its own power supply

In a second step, the researchers coupled the fuel cell with a capsule containing artificial beta cells. These can be stimulated to produce and secrete insulin using electric current or blue LED light. Fussenegger and his colleagues already tested such designer cells some time ago (see ETH News, 8 December 2016).

The system combines sustained power generation and controlled insulin delivery. As soon as the fuel cell registers excess glucose, it starts to generate power. This electrical energy is then used to stimulate the cells to produce and release insulin into the blood. As a result, blood sugar dips to a normal level. Once it falls below a certain threshold value, the production of electricity and insulin stops.

The electrical energy provided by the fuel cell is sufficient not only to stimulate the designer cells but also to enable the implanted system to communicate with external devices such as a smartphone. This allows potential users to adjust the system via a corresponding app. A doctor could also access it remotely and make adjustments. "The new system autonomously regulates insulin and blood glucose levels and could be used to treat diabetes in the future," Fussenegger says.

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'Taffy galaxies' collide, leave behind bridge of star-forming material

Galaxy collisions are transformative events, largely responsible for driving the evolution of the Universe. The mixing and mingling of stellar material is an incredibly dynamic process that can lead to the formation of molecular clouds populated with newly forming stars. But, a head-on collision between the two galaxies UGC 12914 (left) and UGC 12915 (right) 25-30 million years ago appears to have resulted in a different kind of structure -- a bridge of highly turbulent material spanning the two galaxies. Though this intergalactic bridge is teeming with star-forming material, its turbulent nature is suppressing star formation.

This pair of galaxies, nicknamed the Taffy Galaxies, is located about 180 million light-years away in the direction of the constellation Pegasus.

This new image, captured with Gemini North, one half of the International Gemini Observatory, operated by NSF's NOIRLab, showcases the fascinating feature that gave them their name. A tenuous bridge composed of narrow molecular filaments, shown in brown, and clumps of hydrogen gas, shown in red, can be seen between the two galaxies. Its complex web structure resembles taffy being stretched as the pair slowly separates.

Galaxy collisions can happen out of a variety of different scenarios, often involving a larger galaxy and a smaller satellite galaxy. As they drift near one another, the satellite galaxy can attract one of the larger galaxy's primary spiral arms, pulling it out of its orbit. Or the satellite galaxy can actually intersect with the larger galaxy, causing significant distortions to its own structure. In other cases, a collision can lead to a merger if neither member has enough momentum to continue on after colliding. In all these scenarios, stellar material from both galaxies mixes through a gradual combining and redistribution of gas, like two puddles of liquid that are slowly bleeding into each other. The resulting collecting and compression of the gas can then trigger star formation.

A head-on collision, however, would be more like pouring liquid from two separate cups into a shared bowl. When the Taffy Galaxies' collided, their galactic disks and gaseous components smashed right into each other. This resulted in a massive injection of energy into the gas, causing it to become highly turbulent. As the pair emerged from their collision, high-velocity gas was pulled from each galaxy, creating a massive gas bridge between them. The turbulence of the stellar material throughout the bridge is now prohibiting the collection and compression of gas that are required to form new stars.

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A reconstruction of prehistoric temperatures for some of the oldest archaeological sites in North America

Scientists often look to the past for clues about how Earth's landscapes might shift under a changing climate, and for insight into the migrations of human communities through time. A new study offers both by providing, for the first time, a reconstruction of prehistoric temperatures for some of the first known North American settlements.

The study, published in Quaternary Science Reviews, uses new techniques to examine the past climate of Alaska's Tanana Valley. With a temperature record that reaches back 14,000 years, researchers now have a glimpse into the environment that supported humans living at some of the continent's oldest archaeological sites, where mammoth bones are preserved alongside evidence of human occupation. Reconstructing the past environment can help scientists understand the importance of the region for human migration into the Americas.

"When you think about what was happening in the Last Glacial Maximum, all these regions on Earth were super cold, with massive ice sheets, but this area was never fully glaciated," says Jennifer Kielhofer, Ph.D., a paleoclimatologist at DRI and lead author of the study. "We're hypothesizing that if this area was comparatively warm, maybe that would have been an attractive reason to come there and settle."

Kielhofer conducted the research during her doctoral studies at the University of Arizona, and was attracted to the Alaska location because of the wealth of research expertise being focused on the area. She also saw an opportunity to contribute to scientific understanding of a part of the world that is particularly sensitive to global climate change.

"We have to look to the past to try to better constrain how these areas have responded previously," she said, "and how they might respond in the future under climate scenarios that we predict."

Earlier research had relied on coarse temperature records by examining changes in vegetation and pollen. However, this information can only provide a general sense of whether a region was warming or cooling over time. To obtain a more precise history of temperatures, Kielhofer examined soil samples from the archeological sites. Using a technique known as brGDGT paleothermometry, she examined temperature records stored in bacteria to obtain a record of mean annual air temperature above freezing with a precision within about 2.8 degrees Celsius.

"Bacteria are everywhere," she said. "That's great because in areas where you might not have other means of recording or assessing past temperature, you have bacteria. They can preserve for millions of years, so it's a great opportunity to look at pretty much anywhere on Earth."

The results were surprising, she said, because many scientists had previously believed that the region experienced large swings in temperature, which may have contributed to the movement of early humans. But Kielhofer's data showed that temperatures in the Tanana Valley remained fairly stable over time.

"The region wasn't really responding to these global scale climate changes as we might expect," she said. "Because temperatures are really stable through this record, we can't necessarily use temperature as a way to explain changes in human occupation or adaptation through time, as scientists have previously tried to do."

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New, exhaustive study probes hidden history of horses in the American West

A team of international researchers has dug into archaeological records, DNA evidence and Indigenous oral traditions to paint what might be the most exhaustive history of early horses in North America to date. The group's findings show that these beasts of burden may have spread throughout the American West much faster and earlier than many European accounts have suggested.

The researchers, including several scientists from the University of Colorado Boulder, published their findings today in the journal Science.

To tell the stories of horses in the West, the team closely examined about two dozen sets of animal remains found at sites ranging from New Mexico to Kansas and Idaho. The researchers come from 15 countries and multiple Native American groups, including the Lakota, Comanche and Pawnee nations.

"What unites everyone is the shared vision of telling a different kind of story about horses," said William Taylor, a corresponding author of the study and curator of archaeology at the CU Museum of Natural History. "Focusing only on the historical record has underestimated the antiquity and the complexity of Indigenous relationships with horses across a huge swath of the American West."

For many of the scientists involved, the research holds deep personal significance, added Taylor, who grew up in Montana where his grandfather was a rancher.

"We're looking at parts of the country that are extraordinarily important to the people on this project," he said.

The researchers drew on archaeozoology, radiocarbon dating, DNA sequencing and other tools to unearth how and when horses first arrived in various regions of today's United States. Based on the team's calculations, Indigenous communities were likely riding and raising horses as far north as Idaho and Wyoming by at least the first half of the 17th Century -- as much as a century before records from Europeans had suggested.

Groups like the Comanche, in other words, may have begun to form deep bonds with horses mere decades after the animals arrived in the Americas on Spanish boats.

The results line up with a wide range of Indigenous oral histories.

"All this information has come together to tell a bigger, broader, deeper story, a story that natives have always been aware of but has never been acknowledged," said Jimmy Arterberry, co-author of the new study and tribal historian of the Comanche Nation in Oklahoma.

Study co-author Carlton Shield Chief Gover agreed, noting that the love of horses may be one thing that extends across societies and borders.

"People are fascinated by horses. They've grown up with horses," said Shield Chief Gover, a citizen of the Pawnee Nation of Oklahoma and curator for public anthropology at the Indiana University Museum of Archaeology and Anthropology. "We can talk to one another through our shared love of an animal."

Mud Pony

For many Native American communities that shared love goes a long way back.

The Pawnee, for example, tell the story of "Mud Pony," a boy who began seeing visions of strange creatures in his sleep.

"He makes these little mud figurines of these animals he sees in his dreams, and, overnight, they become alive," Shield Chief Gover said. "That's how you get horses."

European historical records from the colonial period, however, have tended to favor a more recent origin story for horses in the West. Many scholars have suggested that Native American communities didn't begin caring for horses until after the Pueblo Revolt of 1680. During this event, Pueblo people in what is today New Mexico temporarily overthrew Spanish rule, releasing European livestock in the process.

Taylor, also an assistant professor of anthropology at CU Boulder, and his colleagues didn't think it fit as an origin story for the relationships between humans and horses in the West: "We thought: There's something fishy about this story."

Clues in bone

With funding from the U.S. National Science Foundation (NSF), they formed an equine dream team that includes archaeologists from the University of Oklahoma and University of New Mexico. Geneticist Ludovic Orlando and Lakota scholar Yvette Running Horse Collin took part from the University of Toulouse.

"This research demonstrates how multiple different types of data can be integrated to address the fascinating historical question of how and when horses spread across the West," said NSF Archaeology program director John Yellen.

The researchers began collecting as much data as they could on horses remains from the West. DNA evidence, for example, suggests that most Indigenous horses had descended from Spanish and Iberian horses, with British horses becoming more common in the 18th and 19th Centuries.

"Our analyses show it was born and raised locally," Taylor said. "It was cared for, and when that animal passed, there was extraordinary significance to that event."

The remains of this horse, along with several others from the study, also seemed to date back to around the turn of the 17th Century, decades before the start of the Pueblo Revolt.

How animals like it arrived in Wyoming isn't clear, but it's likely that Europeans weren't involved in their initial transport.

Shield Chief Gover explained that few Indigenous people will be surprised by the results of the study. But the team's findings may help to illustrate for academic scientists just how important these animals were to the history of Indigenous peoples. The Pawnee, who lived in Nebraska, for example, rode horses on twice-a-year buffalo hunts, traveling farther and faster into the "sea of grass" of the Great Plains. Comanche also galloped on horseback to hunt buffalo, while owning a lot of horses was a sign of wealth.

"I don't want to diminish the reverence and the respect we have for horses," Arterberry said. "We see them as gifts the Creator gave us, and, because of that, we survived and thrived and became who we are today."

Respecting horses

Study co-author Chance Ward, a master's student in Museum and Field Studies at CU Boulder, would like to see the archaeology community begin to treat those relationships with more respect. He was born and raised on the Cheyenne River Reservation in South Dakota, which is home to four bands of the Lakota Nation. Ward grew up listening to his mother's childhood stories about riding ponies in the Bear Creek community. His father's parents started a ranch on the reservation where members of the family practice rodeo today.

He explained that many researchers don't handle animal remains with the same care they reserve for cultural objects and human remains.

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Earth prefers to serve life in XXS and XXL sizes

Life comes in all shapes in sizes, but some sizes are more popular than others, new research from the University of British Columbia has found.

In the first study of its kind published today in PLOS ONE, Dr. Eden Tekwa, who conducted the study as a postdoctoral fellow at UBC's department of zoology, surveyed the body sizes of all Earth's living organisms, and uncovered an unexpected pattern. Contrary to what current theories can explain, our planet's biomass -- the material that makes up all living organisms -- is concentrated in organisms at either end of the size spectrum.

"The smallest and largest organisms significantly outweigh all other organisms," said Dr. Tekwa, lead author of "The size of life," and now a research associate with McGill University's department of biology. "This seems like a new and emerging pattern that needs to be explained, and we don't have theories for how to explain it right now. Current theories predict that biomass would be spread evenly across all body sizes."

In addition to challenging our understanding of how life is distributed, these results have important implications for predicting the effects and impacts of climate change. "Body size governs a lot of global processes as well as local processes, including the rate at which carbon gets sequestered, and how the function and stability of ecosystems might be affected by the composition of living things," said Dr. Tekwa. "We need to think about how body size biomass distribution will change under environmental pressures."

"Life constantly amazes us, including the incredible range of sizes that it comes in," says senior author Dr. Malin Pinsky, associate professor in the department of ecology, evolution, and natural resources at Rutgers University. "If the tiniest microbe was the size of the period at the end of this sentence, the largest living organism, a sequoia tree, would be the size of the Panama Canal."

To obtain their results, Dr. Tekwa spent five years compiling and analyzing data about the size and biomass of every type of living organism on the planet -- from tiny one-celled organisms like soil archaea and bacteria to large organisms like blue whales and sequoia trees. They found that the pattern favouring large and small organisms held across all types of species, and was more pronounced in land-based organisms than in marine environments. Interestingly, maximum body size seemed to reach the same upper limits across multiple species and environments.

"The largest body sizes appear across multiple species groups, and their maximum body sizes are all within a relatively narrow range," Dr. Tekwa noted. "Trees, grasses, underground fungi, mangroves, corals, fish and marine mammals all have similar maximum body sizes. This might suggest that there is a universal upper size limit due to ecological, evolutionary or biophysical limitations."

Dr. Tekwa was also able to uncover some intriguing details about the distribution of life in various ecosystems. "Even though corals occur in only a small fraction of the ocean, it turns out that they have about the same biomass as all the fish in the ocean," said Dr. Tekwa. "This illustrates how important the balance of biomass is in the oceans. Corals support a lot of fish diversity, so it's really interesting that those two organisms have almost the same biomass."

As for humans, we already know we comprise a relatively small biomass, but our size among all living things reveals our place in the global biome. "We belong to the size range that comprises the highest biomass, which is a relatively large body size," said Dr. Tekwa.

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Astronomers witness the birth of a very distant cluster of galaxies from the early Universe

Using the Atacama Large Millimeter/submillimeter Array (ALMA), of which ESO is a partner, astronomers have discovered a large reservoir of hot gas in the still-forming galaxy cluster around the Spiderweb galaxy -- the most distant detection of such hot gas yet. Galaxy clusters are some of the largest objects known in the Universe and this result, published today in Nature, further reveals just how early these structures begin to form.

Galaxy clusters, as the name suggests, host a large number of galaxies -- sometimes even thousands. They also contain a vast "intracluster medium" (ICM) of gas that permeates the space between the galaxies in the cluster. This gas in fact considerably outweighs the galaxies themselves. Much of the physics of galaxy clusters is well understood; however, observations of the earliest phases of formation of the ICM remain scarce.

Previously, the ICM had only been studied in fully-formed nearby galaxy clusters. Detecting the ICM in distant protoclusters -- that is, still-forming galaxy clusters -- would allow astronomers to catch these clusters in the early stages of formation. A team led by Luca Di Mascolo, first author of the study and researcher at the University of Trieste, Italy, were keen to detect the ICM in a protocluster from the early stages of the Universe.

Galaxy clusters are so massive that they can bring together gas that heats up as it falls towards the cluster. "Cosmological simulations have predicted the presence of hot gas in protoclusters for over a decade, but observational confirmations has been missing," explains Elena Rasia, researcher at the Italian National Institute for Astrophysics (INAF) in Trieste, Italy, and co-author of the study. "Pursuing such key observational confirmation led us to carefully select one of the most promising candidate protoclusters." That was the Spiderweb protocluster, located at an epoch when the Universe was only 3 billion years old. Despite being the most intensively studied protocluster, the presence of the ICM has remained elusive. Finding a large reservoir of hot gas in the Spiderweb protocluster would indicate that the system is on its way to becoming a proper, long-lasting galaxy cluster rather than dispersing.

Di Mascolo's team detected the ICM of the Spiderweb protocluster through what's known as the thermal Sunyaev-Zeldovich (SZ) effect. This effect happens when light from the cosmic microwave background -- the relic radiation from the Big Bang -- passes through the ICM. When this light interacts with the fast-moving electrons in the hot gas it gains a bit of energy and its colour, or wavelength, changes slightly. "At the right wavelengths, the SZ effect thus appears as a shadowing effect of a galaxy cluster on the cosmic microwave background," explains Di Mascolo.

By measuring these shadows on the cosmic microwave background, astronomers can therefore infer the existence of the hot gas, estimate its mass and map its shape. "Thanks to its unparalleled resolution and sensitivity, ALMA is the only facility currently capable of performing such a measurement for the distant progenitors of massive clusters," says Di Mascolo.

They determined that the Spiderweb protocluster contains a vast reservoir of hot gas at a temperature of a few tens of millions of degrees Celsius. Previously, cold gas had been detected in this protocluster, but the mass of the hot gas found in this new study outweighs it by thousands of times. This finding shows that the Spiderweb protocluster is indeed expected to turn into a massive galaxy cluster in around 10 billion years, growing its mass by at least a factor of ten.

Tony Mroczkowski, co-author of the paper and researcher at ESO, explains that "this system exhibits huge contrasts. The hot thermal component will destroy much of the cold component as the system evolves, and we are witnessing a delicate transition." He concludes that "it provides observational confirmation of long-standing theoretical predictions about the formation of the largest gravitationally bound objects in the Universe."

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How dogs are used impacts how they are treated

Research into the unique cognitive abilities of dogs often leads to surprises, including dogs' ability to form mental representations of things they smell, or that they know when their owners do something by accident. However, dog cognition research suffers from the same biases as general psychology: in both fields, studies are usually done in WEIRD (Western, educated, industrialized, rich, and democratic) societies.

Although nearly everything we know about dog-human bonds, dog behavior, and dog cognition comes from WEIRD societies, the majority of dogs in the world live outside of these conditions. To address this bias and form a better understanding of dog-human relationships in societies around the world, a team of researchers from the MPI of Geoanthropology and the MPI for Evolutionary Anthropology assessed data on the functions and treatment of dogs in 124 globally distributed societies.

The researchers found that, across all societies, dogs' functions are a good predictor of how they are treated by their owners. Analysis showed that the more functions dogs have in a society, such as guarding, herding, or hunting, the closer the dog-human relationship is likely to be.

To conduct the study, the researchers investigated ethnographic data from the eHRAF cross-cultural database and identified societies in which dogs serve any of five main functions: hunting, defense, guarding herds, herding, and carrying or transporting supplies. They then collected data on how dogs are treated in those societies and coded it into three dimensions: positive care (e.g. dogs are allowed indoors, dogs receive healthcare, puppies are raised), negative treatment (e.g. dogs are not fed, dogs are physically abused, dogs are regularly culled), and personhood (e.g. dogs are named, dogs are buried and/or mourned, dogs are perceived as family members).

By analyzing the relationship between dog functions and treatment, the researchers showed that the number of functions is positively associated with positive care and personhood and negatively associated with negative treatment. However, they also found that not all of a dog's jobs influence treatment equally. For example, herding is particularly likely to increase positive care, whereas hunting has no impact on positive care or negative treatment, but does increase the odds of personhood. Thus, in societies where dogs are kept for hunting, humans are more likely to name their dogs and perceive them as family members.

Additionally, the study showed that negative treatment and positive care are not mutually exclusive. In fact, of the 77 societies with data for all three dimensions of dog treatment, 32 showed the presence of both positive care and negative treatment. This suggests that the dog-human relationship is not as simple or straightforward as "man's best friend," but involves a complex balance between offering care and minimizing costs.

"Our study adds a systematic test for explaining the cultural drivers that shape the variety of dog-human bonds around the world," says Juliane Bräuer of the Max Planck Institute of Geoanthropology. "This represents a first step into understanding whether the cognitive and social skills associated with dogs are universal or are influenced by the cultural environment the dogs live in."

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New research shows how cultural transmission shapes the evolution of music

New research has found that constraints in the way our brains work can shape the way people interact when creating music, influencing its evolution. The results are published this week [22 March] in the journal Current Biology.

The research team made up of scientistic from the University of Oxford, the University of Cambridge, and the Max Planck Institute for Empirical Aesthetics, used singing experiments to perform the largest ever cultural transmission study on the evolution of music.

Dr Manuel Anglada-Tort, Lecturer at the University of Oxford said: 'Singing is a universal mode of musical communication, practiced by all cultures and ages, even in infants. For most of our history, oral transmission was the main mechanism by which songs were passed down human generations.

'We believe that cross-cultural commonalities and diversities in human song emerged from this transmission process, but thus far it has been difficult to test how oral transmission shapes music evolution.'

The research team developed a novel method to simulate the evolution of music with singing experiments, where sung melodies are passed from one singer to the next. Over time, participants make errors in their efforts to replicate the melodies that they hear, gradually shaping the evolution of music in systematic ways. This approach allowed the researchers to study music evolution in unprecedented detail, quantifying the evolution of 3,424 melodies transmitted across 1,797 participants in the USA and India.

'This work demonstrates the benefits of combining large-scale online data collection with innovative psychological paradigms to explore cultural transmission processes in unprecedented detail.' Dr Anglada-Tort continues.

They found that oral transmission has profound effects on music evolution, revealing the emergence of musical structures that are consistent with widespread musical features observed across world cultures. In several controlled experiments, the researchers found that this happens because as humans, we are limited by our capacity to produce and process music. For example, musical elements that are difficult to sing such as large pitch intervals or to remember such as unfamiliar melodies, are consistently less likely to survive the transmission process.

Despite the infinite patterns in which music could be combined, the researchers found in practice, 'human transmission biases' shape vocal music towards those structures that are easier to learn and transmit. They found individual participant biases, including biological and cognitive factors, are an important bottleneck for evolution by oral transmission.

Dr Nori Jacoby, Research Group Leader at the Max Planck Institute for Empirical Aesthetics who supervised the study said: 'This work demonstrates the benefits of combining large-scale online data collection with innovative psychological paradigms to explore cultural transmission processes in unprecedented detail.

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Deep ocean currents around Antarctica headed for collapse

The deep ocean circulation that forms around Antarctica could be headed for collapse, say scientists.

Such decline of this ocean circulation will stagnate the bottom of the oceans and generate further impacts affecting climate and marine ecosystems for centuries to come.

The results are detailed in a new study coordinated by Scientia Professor Matthew England, Deputy Director of the ARC Centre for Excellence in Antarctic Science (ACEAS) at UNSW Sydney. The work, published today in Nature, includes lead author Dr. Qian Li -- formerly from UNSW and now at the Massachusetts Institute of Technology (MIT) -- as well as co-authors from the Australian National University (ANU) and CSIRO.

Cold water that sinks near Antarctica drives the deepest flow of the overturning circulation -- a network of currents that spans the world's oceans. The overturning carries heat, carbon, oxygen and nutrients around the globe. This influences climate, sea level and the productivity of marine ecosystems.

"Our modelling shows that if global carbon emissions continue at the current rate, then the Antarctic overturning will slow by more than 40 per cent in the next 30 years -- and on a trajectory that looks headed towards collapse," says Prof England.

Modelling the deep ocean

About 250 trillion tonnes of cold, salty, oxygen-rich water sinks near Antarctica each year. This water then spreads northwards and carries oxygen into the deep Indian, Pacific and Atlantic Oceans.

"If the oceans had lungs, this would be one of them," Prof England says.

The international team of scientists modelled the amount of Antarctic deep water produced under the IPCC 'high emissions scenario', until 2050.

The model captures detail of the ocean processes that previous models haven't been able to, including how predictions for meltwater from ice might influence the circulation.

This deep ocean current has remained in a relatively stable state for thousands of years, but with increasing greenhouse gas emissions, Antarctic overturning is predicted to slow down significantly over the next few decades.

Impacts of reduced Antarctic overturning

With a collapse of this deep ocean current, the oceans below 4000 metres would stagnate.

"This would trap nutrients in the deep ocean, reducing the nutrients available to support marine life near the ocean surface," says Prof England.

Co-author Dr Steve Rintoul of CSIRO and the Australian Antarctic Program Partnership says the model simulations show a slowing of the overturning, which then leads to rapid warming of the deep ocean.

"Direct measurements confirm that warming of the deep ocean is indeed already underway," says Dr Rintoul. The study found melting ice around Antarctica makes the nearby ocean waters less dense, which slows the Antarctic overturning circulation. The melt of the Antarctic and Greenland ice sheets is expected to continue to accelerate as the planet warms.

"Our study shows that the melting of the ice sheets has a dramatic impact on the overturning circulation that regulates Earth's climate," says Dr Adele Morrison, also from ACEAS and the ANU Research School of Earth Sciences.

"We are talking about the possible long-term extinction of an iconic water mass," says Prof England.

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