Most massive touching stars ever found will eventually collide as black holes

Two massive touching stars in a neighbouring galaxy are on course to become black holes that will eventually crash together, generating waves in the fabric of space-time, according to a new study by researchers at UCL (University College London) and the University of Potsdam.

The study, accepted for publication in the journal Astronomy & Astrophysics, looked at a known binary star (two stars orbiting around a mutual centre of gravity), analysing starlight obtained from a range of ground- and space-based telescopes.

The researchers found that the stars, located in a neighbouring dwarf galaxy called the Small Magellanic Cloud, are in partial contact and swapping material with each other, with one star currently "feeding" off the other. They orbit each other every three days and are the most massive touching stars (known as contact binaries) yet observed.

Comparing the results of their observations with theoretical models of binary stars' evolution, they found that, in the best-fit model, the star that is currently being fed on will become a black hole and will feed on its companion star. The surviving star will become a black hole shortly after.

These black holes will form in only a couple of million years, but will then orbit each other for billions of years before colliding with such force that they will generate gravitational waves -- ripples in the fabric of space-time -- that could theoretically be detected with instruments on Earth.

PhD student Matthew Rickard (UCL Physics & Astronomy), lead author of the study, said: "Thanks to gravitational wave detectors Virgo and LIGO, dozens of black hole mergers have been detected in the last few years. But so far we have yet to observe stars that are predicted to collapse into black holes of this size and merge in a time scale shorter than or even broadly comparable to the age of the universe.

"Our best-fit model suggests these stars will merge as black holes in 18 billion years. Finding stars on this evolutionary pathway so close to our Milky Way galaxy presents us with an excellent opportunity learn even more about how these black hole binaries form."

Co-author Daniel Pauli, a PhD student at the University of Potsdam, said: "This binary star is the most massive contact binary observed so far. The smaller, brighter, hotter star, 32 times the mass of the Sun, is currently losing mass to its bigger companion, which has 55 times our Sun's mass."

The black holes that astronomers see merge today formed billions of years ago, when the universe had lower levels of iron and other heavier elements. The proportion of these heavy elements has increased as the universe has aged and this makes black hole mergers less likely. This is because stars with a higher proportion of heavier elements have stronger winds and they blow themselves apart sooner.

The well-studied Small Magellanic Cloud, about 210,000 light years from Earth, has by a quirk of nature about a seventh of the iron and other heavy metal abundances of our own Milky Way galaxy. In this respect it mimics conditions in the universe's distant past. But unlike older, more distant galaxies, it is close enough for astronomers to measure the properties of individual and binary stars.

In their study, the researchers measured different bands of light coming from the binary star (spectroscopic analysis), using data obtained over multiple periods of time by instruments on NASA's Hubble Space Telescope (HST) and the Multi Unit Spectroscopic Explorer (MUSE) on ESO's Very Large Telescope in Chile, among other telescopes, in wavelengths ranging from ultraviolet to optical to near infrared.

With this data, the team were able to calculate the radial velocity of the stars -- that is, the movement they made towards or away from us -- as well as their masses, brightness, temperature and orbits. They then matched these parameters with the best-fit evolutionary model.

Their spectroscopic analysis indicated that much of the outer envelope of the smaller star had been stripped away by its larger companion. They also observed the radius of both stars exceeded their Roche lobe -- that is, the region around a star where material is gravitationally bound to that star -- confirming that some of the smaller star's material is overflowing and transferring to the companion star.

Talking through the future evolution of the stars, Rickard explained: "The smaller star will become a black hole first, in as little as 700,000 years, either through a spectacular explosion called a supernova or it may be so massive as to collapse into a black hole with no outward explosion.

"They will be uneasy neighbours for around three million years before the first black hole starts accreting mass from its companion, taking revenge on its companion."

Pauli, who conducted the modelling work, added: "After only 200,000 years, an instant in astronomical terms, the companion star will collapse into a black hole as well. These two massive stars will continue to orbit each other, going round and round every few days for billions of years.

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A healthy but depleted herd: Predators decrease prey disease levels but also population size

Nature documentaries will tell you that lions, cheetahs, wolves and other top predators target the weakest or slowest animals and that this culling benefits prey herds, whether it's antelope in Africa or elk in Wyoming.

This idea has been widely accepted by biologists for many years and was formalized in 2003 as the healthy herds hypothesis. It proposes that predators can help prey populations by picking off the sick and injured and leaving healthy, strong animals to reproduce.

The healthy herds hypothesis has even been used to suggest that manipulating predator numbers to protect prey might be a useful conservation strategy. Even so, hard evidence supporting the hypothesis is scarce, and in recent years many of its assumptions and predictions have been questioned.

In a study published online April 26 in the journal Ecology, a University of Michigan-led research team used a pint-sized predator-prey-parasite system inside 20-gallon water tanks to test the healthy herds hypothesis.

Their study system consisted of predatory fly larvae that feed on the water flea Daphnia dentifera, which hosts a virulent fungal parasite.

The researchers found that while high predation levels reduced parasitism in Daphnia -- providing partial support for the healthy herds hypothesis -- populations of those poppy seed-sized crustaceans were often dramatically reduced, as well. In some cases, Daphnia populations were nearly wiped out by predation.

The findings may have implications for conservation efforts involving much larger animals, according to the study authors. Specifically, the results suggest that caution is warranted when wildlife managers manipulate predator numbers in the hopes of promoting healthy herds of prey.

"The appeal of the healthy herds hypothesis lies in the alignment of multiple conservation goals -- simultaneous conservation of predators, reduction of parasitism, and protection of vulnerable populations -- as well as the potential to reduce spillover risk to other populations, including humans," said U-M aquatic and disease ecologist Meghan Duffy.

"But even when predators reduce disease in their prey populations, that does not necessarily lead to increased prey population size, as our study shows," said Duffy, senior author of the new study and a professor in the U-M Department of Ecology and Evolutionary Biology.

One well-known example of "healthy herds" gone wrong involves the culling of badgers in the United Kingdom in an effort to reduce bovine tuberculosis in livestock. In that case, the culling can be viewed as a particularly efficient form of predation by humans.

The assumption behind those campaigns was that higher predation of badgers, which are a wildlife reservoir of bovine tuberculosis, would drive healthy livestock herds. Instead, the campaigns increased bovine tuberculosis in cattle. In another example, the culling of bats to reduce the spread of rabies has not been effective at reducing rabies in domestic dogs or wildlife.

Findings of the new study, and others like it, could help explain why some attempts to control disease by manipulating predators fail, according to the authors.

"Unless we develop a more comprehensive understanding of when and how predators influence disease, management strategies that propose to reintroduce or augment predator populations could backfire," said study lead author Laura Lopez, a former postdoctoral researcher in Duffy's lab who now works for the National Centre for Immunisation Research and Surveillance in Australia.

Duffy has used Daphnia as a model organism to investigate the causes and consequences of infectious disease outbreaks for nearly 20 years -- work that has included several studies of the healthy herds hypothesis.

For the latest study, the researchers experimentally manipulated the density of a predator in their three-organism study system, then monitored Daphnia population sizes and infection levels.

The predators were larvae of the phantom midge, which commonly prey on Daphnia in North American temperate lakes. The parasite was the virulent fungus Metschnikowia bicuspidata.

The predator-prey-parasite interactions occurred inside 48 experimental water tanks called mesocosms, which also contained nutrients and green algae.

At the highest levels, predation completely eliminated the fungal pathogen. However, the highest predation levels often dramatically reduced Daphnia population sizes, as well -- an outcome that does not support the healthy herds hypothesis.

"If your primary concern is the overall population size of a vulnerable animal species, then adding high levels of predation that eliminate disease could be detrimental," Duffy said.

"Interestingly, intermediate predation levels reduced parasitism in our study without incurring a cost in terms of overall prey density. Any management decisions would need to weigh the potential costs and benefits associated with increasing predation."

The authors of the Ecology study warned that achieving and maintaining a predation level that reduces parasitism without harming prey population size "might be equivalent to threading the proverbial needle."

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Abundance of urban honeybees adversely impacts wild bee populations

Who hasn't received a pot of homegrown honey from a friend or relative who decided to take up urban beekeeping? The sentiment behind the gift is sweet, but their newfound interest in urban agriculture may be adversely affecting local biodiversity.

In a new paper in the journal PeerJ, a team led by Concordia researchers argue that the rapid growth in urban honeybee-keeping over the past decade may be negatively impacting nearby wild bee populations. Small bees with limited foraging ranges may be especially at risk, they write.

The researchers compared bee population data collected from sites around the island of Montreal in 2013 to data they collected at the same sites in the summer of 2020.

"We found that the sites with the largest increase in honeybee populations across sites and years also had the fewest wild bee species," says Gail MacInnis, a former Concordia postdoctoral researcher and the study's lead author. Etienne Normandin from the Université de Montréal and Carly Ziter, an assistant professor in the Department of Biology, are co-authors.

According to Quebec's Ministère de l'Agriculture, des Pêcheries et de l'Alimentation (Ministry of Agriculture, Fisheries and Food), the number of honeybee colonies on the island of Montreal has increased over twelvefold. In 2013, there were under 250 colonies. That number has ballooned to almost 3,000 in 2020.

Honeybees are not native to the region, the researchers note. This type of bee is therefore in competition with almost 180 other species for resources like pollen and nectar, as identified in the 2013 study.

Invasive and hungry

The researchers visited 15 sites across the island of Montreal that were known to attract pollinators. Sites included community gardens, cemeteries and large urban parks. The researchers used a standardized system of pan trap triplets -- multicoloured bowls designed to attract bees -- and nets to collect their samples. Each site was sampled five times between late June and early September 2020, with a total sample size of 6,200 bees. The researchers also measured other important factors that influence wild bee populations, like habitat and floral resource availability.

Nearly 4,000 samples turned out to be wild bees belonging to 120 species. Roughly 2,200 were honeybees. By contrast, in 2013, approximately 5,200 bees were collected at similar locations. Nearly all of these samples were wild bees belonging to 163 species.

Statistical analyses were performed across sites in 2020 on wild bee diversity; bee traits and honeybee abundance; wild bee community composition; and pollen depletion. Similar analyses compared the bee communities of 2013 and 2020.

The study found that wild bee species richness declined significantly. Honeybee abundance increased but remained similar to 2013 levels in areas where the honeybee population was comparatively lower. Honeybee abundance was also associated with pollen depletion in white clover flowers.

Not a risk-free hobby

MacInnis points out that a lack of registry or regulations makes studying bee populations difficult. Understanding honeybee colony density is crucial, she says, as just one honeybee colony can support up to 50,000 individuals.

"We need to provide food if we want to support large bee populations. But we also need to be careful about population density, especially for commercially managed bees, because they are prone to many diseases," she says. "This issue can become especially bad when there are many new beekeepers in the area. They may not be as knowledgeable about controlling for things like mites, viruses and other pathogens."

"Beekeeping provides an agricultural product that is valuable to people in the form of honey. My concern is that urban beekeeping is often falsely marketed as a solution to biodiversity loss," Ziter adds. "Just as we wouldn't advocate keeping backyard chickens to save the birds, we shouldn't look to beekeeping to save the bees. It's important that our actions match our goals or motivations."

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Humidity may increase heat risk in urban climates

As temperatures across the globe reach record-level highs, urban areas are facing increased heat stress. Cities are generally warmer and dryer than adjacent rural land. But in the Global South, there is an additional complicating factor -- urban humid heat.

A new study, led by Yale School of the Environment scientists and published in Nature, investigated the combined effect of temperature and humidity on urban heat stress using observational data and an urban climate model calculation. Researchers found that the heat stress burden is dependent on local climate and a humidifying effect can erase the cooling benefits that would come from trees and vegetation.

"A widely held view is that urban residents suffer more heat burden than the general population owing to the urban heat island phenomenon. This view is incomplete because it omits another ubiquitous urban microclimate phenomenon called the urban dry island -- that urban land tends to be less humid than the surrounding rural land," says Xuhui Lee, Sara Shallenberger Brown Professor of Meteorology, who directed the study. "In dry, temperate, and boreal climates, urban residents are actually less heat-stressed than rural residents. But in the humid Global South, the urban heat island is dominant over the urban dry island, resulting in two to six extra dangerous heat stress days per summer."

Lee and YSE doctoral student Keer Zhang, lead author of the study, say they were motivated to investigate the issue for several reasons: a large percentage of the global population lives in urban areas; many people in informal urban settlements do not have access to air conditioning; and the problem is going to get worse as temperatures rise and more people move to cities. About 4.3 billion people, or 55% of the world's population, live in urban settings, and the number is expected to rise to 80% by 2050, according to the World Economic Forum.

The researchers developed a theoretical framework on how urban land modifies both air temperature and air humidity and showed that these two effects have equal weight in heat stress as measured by the wet-bulb temperature, in contrary to other heat indexes, which weigh temperature more heavily than humidity. Wet-bulb temperature combines dry air temperature with humidity to measure humid heat. The results of the study, the authors note, raise important questions.

"Green vegetation can lower air temperature via water evaporation, but it can also increase heat burden because of air humidity. The question then is to what extent this humidifying effect erases the cooling benefit arising from temperature reduction. We hope to answer this question in a follow-up study, where we are comparing observations of the wet-bulb temperature in urban greenspaces (with dense tree cover) and those in built-up neighborhoods," Lee says.

Zhang says she hopes the study can lead to further research on how cities can mitigate heat stress.

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Astronomers solve the 60-year mystery of quasars -- the most powerful objects in the Universe

Scientists have unlocked one of the biggest mysteries of quasars -- the brightest, most powerful objects in the Universe -- by discovering that they are ignited by galaxies colliding.

First discovered 60 years ago, quasars can shine as brightly as a trillion stars packed into a volume the size of our Solar System. In the decades since they were first observed, it has remained a mystery what could trigger such powerful activity. New work led by scientists at the Universities of Sheffield and Hertfordshire has now revealed that it is a consequence of galaxies crashing together.

The collisions were discovered when researchers, using deep imaging observations from the Isaac Newton Telescope in La Palma, observed the presence of distorted structures in the outer regions of the galaxies that are home to quasars.

Most galaxies have supermassive black holes at their centres. They also contain substantial amounts of gas -- but most of the time this gas is orbiting at large distances from the galaxy centres, out of reach of the black holes. Collisions between galaxies drive the gas towards the black hole at the galaxy centre; just before the gas is consumed by the black hole, it releases extraordinary amounts of energy in the form of radiation, resulting in the characteristic quasar brilliance.

The ignition of a quasar can have dramatic consequences for entire galaxies -- it can drive the rest of the gas out of the galaxy, which prevents it from forming new stars for billions of years into the future.

This is the first time that a sample of quasars of this size has been imaged with this level of sensitivity. By comparing observations of 48 quasars and their host galaxies with images of over 100 non-quasar galaxies, researchers concluded that galaxies hosting quasars are approximately three times as likely to be interacting or colliding with other galaxies.

The study has provided a significant step forward in our understanding of how these powerful objects are triggered and fuelled.

Professor Clive Tadhunter, from the University of Sheffield's Department of Physics and Astronomy, said: "Quasars are one of the most extreme phenomena in the Universe, and what we see is likely to represent the future of our own Milky Way galaxy when it collides with the Andromeda galaxy in about five billion years.

"It's exciting to observe these events and finally understand why they occur -- but thankfully Earth won't be anywhere near one of these apocalyptic episodes for quite some time."

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Massive iceberg discharges during the last ice age had no impact on nearby Greenland, raising new questions about climate dynamics

During the last ice age, massive icebergs periodically broke off from an ice sheet covering a large swath of North America and discharged rapidly melting ice into the North Atlantic Ocean around Greenland, triggering abrupt climate change impacts across the globe.

These sudden episodes, called Heinrich Events, occurred between 16,000 and 60,000 years ago. They altered the circulation of the world's oceans, spurring cooling in the North Atlantic and impacting monsoon rainfall around the world.

But little was known about the events' effect on nearby Greenland, which is thought to be very sensitive to events in the North Atlantic. A new study from Oregon State University researchers, just published in the journal Nature, provides a definitive answer.

"It turns out, nothing happened in Greenland. The temperature just stayed the same," said the study's lead author, Kaden Martin, a fourth-year doctoral candidate in OSU's College of Earth, Ocean, and Atmospheric Sciences. "They had front-row seats to this action but didn't see the show."

Instead, the researchers found that these Heinrich events caused rapid warming in Antarctica, at the other end of the globe.

The researchers anticipated Greenland, in close proximity to the ice sheet, would have experienced some kind of cooling. To find that these Heinrich Events had no discernible impact on temperatures in Greenland is surprising and could have repercussions for scientists' understanding of past climate dynamics, said study co-author Christo Buizert, an assistant professor in the College of Earth, Ocean, and Atmospheric Sciences.

"If anything, our findings raise more questions than answers," said Buizert, a climate change specialist who uses ice cores from Greenland and Antarctica to reconstruct and understand the Earth's climate history. "This really changes how we look at these massive events in the North Atlantic. It's puzzling that far-flung Antarctica responds more strongly than nearby Greenland."

Scientists drill and preserve ice cores to study past climate history through analysis of the dust and tiny air bubbles that have been trapped in the ice over time. Ice cores from Greenland and Antarctica provide important records of Earth's atmospheric changes over hundreds of thousands of years.

Records from ice cores from those regions have served as pillars for scientists' understanding of past climate events, with ice collected from both locations often telling similar stories, Martin said.

The impact of Heinrich Events on Greenland and Antarctica was not well understood, spurring Martin and Buizert to try to find out more about what was happening in those parts of the world.

The core used for the latest study was collected in 1992 from the highest point of Greenland, where the ice sheet is around 2 miles thick. Since then, the core has been in storage in the National Science Foundation Ice Core Facility in Denver.

Advancement in scientific tools and measurements over the last few decades gave Martin, Buizert and their colleagues the opportunity to re-examine the core using new methods.

The analysis shows that no changes in temperatures occurred in Greenland during Heinrich Events. But it also provides a very clear connection between Heinrich Events and the Antarctic response.

"When these big iceberg discharges happen in the Arctic, we now know that Antarctica responds right away," Buizert said. "What happens in one part of the world has an effect on the rest of the world. This inter-hemispheric connection is likely caused by change in global wind patterns."

The finding challenges the current understanding of global climate dynamics during these massive events and raises new questions for researchers, Buizert said. The researchers' next step is to take the new information and run it through climate models to see if the models can replicate what occurred.

"There has to be a story that fits all of the evidence, something that connects all the dots," he said. "Our discovery adds two new dots; it's not the full story, and it may not be the main story. It is possible that the Pacific Ocean plays an important role that we haven't figured out yet."

The ultimate goal is to better understand how the climate system is connected and how the components all interact, the researchers said.

"While Heinrich Events are not going to happen in the future, abrupt changes in the globally interconnected climate system will happen again," Martin said. "Understanding the global dynamics of the climate system can help us better project future impacts and inform how we respond and adapt."

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Mysterious underwater acoustic world of British ponds revealed in new study

The previously hidden and diverse underwater acoustic world in British ponds has been uncovered by a team of researchers at the University of Bristol.

Ponds are magnets for life and a lot of that life is very noisy. Water beetles, bugs, fish, frogs, and even aquatic plants all produce sound creating a diverse underwater orchestra that scientists are only just starting to understand.

Acoustic monitoring has been shown to effectively survey birds and monkeys in rainforests, and marine mammals in the oceans. However, freshwater environments have remained largely unexplored despite their diverse soundscapes.

"Ponds are packed full of bizarre and mysterious sounds made by scratching aquatic insects, booming fish, and popping plants. It's like an underwater disco!" explained lead author Dr Jack Greenhalgh from Bristol's School of Biological Sciences.

To better understand these mysterious soundscapes, the team collected 840 hours of underwater sound recordings from five ponds in the southwest of England using an underwater microphone (a hydrophone).

And in findings published in the journal Freshwater Biology, analysis of the audio files revealed clear daily acoustic activity cycles in each pond.

Typically, a nocturnal chorus is made by aquatic insects that compete to attract mates by producing strange scratching sounds as they rub their genitals against their abdomens. During the daytime, however, aquatic plants dominate the underwater orchestra with rhythmic whining and ticking sounds produced as tiny oxygen bubbles are released by plants respiring in the hot sun.

Prof. Gareth Jones said: "Recording animal sounds has provided great advances for monitoring and surveying terrestrial animals remotely. Given the rich diversity of underwater sounds that is only now being revealed, the potential for assessing the health of freshwater ecosystems is great, especially with low-cost monitoring devices now becoming available."

Using this acoustic method, the presence of species, and a determination of ecological health, can be inferred simply by listening to the natural world without disturbing the environment or harming the plants and animals within it. This research is the first to provide a detailed description of pond soundscapes in the UK and will help inform the acoustic monitoring of freshwater ecosystems to help prevent irreversible species loss due to climate change and habitat loss.

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Mixing theory, observation to envision warmer world

Climate changes are conjuring a whirlwind ride that seems to present some creatures opportunities to thrive. Scientists scripting supercharged scenarios caution the difference between seasonal coping and long-term adaption is vast -- and tricky to predict.

Michigan State University biologists have studied damselflies -- which resemble dragonflies and are abundant as both predator and prey in wetlands -- to understand what happens throughout their lifecycle from nymph to winged insect, along with what they eat when summers grow warmer and longer.

Their work in this week's Proceedings of the Royal Society B has a twist -- combining seasons of observational and experimental work in the field and lab with input from a theoretical ecologist, a mathematician by training with supersized modeling creds.

The results: A more realistic look at what a hot summer can bring to a nearby pond, and new respect for the blinding speed global warming is bringing.

"We are seeing the pace of climate change is much more rapid than organisms have endured in their evolutionary experience," said co-author Phoebe Zarnetske, an associate professor of integrative biology

PI of the Spatial and Community Ecology (SpaCE) Lab and director, IBEEM. "That rapid pace is going to be even more of an issue with the increase in extreme events like heat waves."

The work in "Life-history responses to temperature and seasonality mediate ectotherm consumer-resource dynamics under climate warming" finds that inserting the right level of data gleaned from field experiences, specifically the effects of seasonal changes in temperature on consumer lifecycles, creates a more robust predator-prey simulation model. The work differs from the findings of similar models with less biological realism that predicted warming trends would doom predators. They see Michigan damselflies surviving climate warming by shifting into a lifecycle similar to their southern relatives -- squeaking out two lifecycles in a season rather than one.

The work developed from first author Laura Twardochleb's work as a PhD student in Zarnetske's lab. She had spent time observing damselflies' one-year lifecycle in Michigan. They emerge as adults from ponds in the spring. They mate, reproduce and the juveniles grow over a year in the pond by eating zooplankton. They make good study subjects, she said, because they thrive both outside and in the laboratory.

Twardochleb, now with the California State Water Resources Control Board, was part of MSU's Ecology, Evolution, and Behavior Program and as a part of that took a class by Chris Klausmeier, MSU Foundation Professor of Plant Biology and Integrative Biology.

She saw that early models projecting how warming climates would affect ectothermic predators were significantly simpler than the nature she was observing. For one thing, the models didn't allow for the north's change of seasons. The models also weren't keeping track of a predator's size and growth rate and changes in their lifecycle with warming.

Meanwhile, Klausmeier, a theoretical ecologist, was recognizing the special sauce an experimentalist brings when creating mathematical models that take assumptions about how organisms behave, grow, birth, die.

"I can make up any model I want unconstrained by reality," Klausmeier said. "But that's a little dangerous because of course you want something related to the real world. When you join with an experimentalist you can bring not just the experimental results and parameters, but also bring the deep natural history and knowledge to the system to know the key variables and constraints."

The work, factoring in a warmer, but still seasonal climate shows how the damselflies can grow and breed more quickly. Creating a model that only allowed the virtual damselflies to live a one-year lifecycle in a warmer world, they burned out and died. Extinction was on the horizon.

But allow the bugs the option of bringing two generations into a season, and thriving was a possibility. "A lot of models said [predators] were going to starve," Twardochleb said. "That's what's exciting -- that we can make models more realistic."

Twardochleb said the work is good groundwork to understand how other species will respond to a warmer world, particularly species like mosquitoes which are both nuisances and potentially carry diseases.

Zarnetske added that the continual challenge will be beyond the idea that different species will be adapting to a new world. Climate change is outpacing that kind of evolution in an unprecedented way. And the weather extremes -- heat waves, droughts, floods -- are a whole variable.

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Medium-sized black holes eat stars like messy toddlers

If they exist, intermediate-mass black holes likely devour wayward stars like a messy toddler -- taking a few bites and then flinging the remains across the galaxy -- a new Northwestern University-led study has found.

In new 3D computer simulations, astrophysicists modeled black holes of varying masses and then hurled stars (about the size of our sun) past them to see what might happen.

When a star approaches an intermediate-mass black hole, it initially gets caught in the black hole's orbit, the researchers discovered. After that, the black hole begins its lengthy and violent meal. Every time the star makes a lap, the black hole takes a bite -- further cannibalizing the star with each passage. Eventually, nothing is left but the star's misshapen and incredibly dense core.

At that point, the black hole ejects the remains. The star's remnant flies to safety across the galaxy.

Not only do these new simulations hint at the unknown behaviors of intermediate-mass black holes, they also provide astronomers with new clues to help finally pinpoint these hidden giants within our night sky.

"We obviously cannot observe black holes directly because they don't emit light," said Northwestern's Fulya Kıroğlu, who led the study. "So, instead, we have to look at the interactions between black holes and their environments. We found that stars undergo multiple passages before being ejected. After each passage, they lose more mass, causing a flair of light as its ripped apart. Each flare is brighter than the last, creating a signature that might help astronomers find them."

Kıroğlu will present this research during the virtual portion of the American Physical Society's (APS) April meeting. "Tidal disruption events of stars by intermediate-mass black holes" will take place on April 25, as a part of the session "Medium: Cosmic Rays, AGN & Galaxies." . The Astrophysical Journal has accepted the study for publication.

Kıroğlu is an astrophysics graduate student at Northwestern's Weinberg College of Arts and Sciences and member of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). She is advised by paper co-author Frederic Rasio, the Joseph Cummings Professor of Physics and Astronomy at Weinberg and member of CIERA.

While astrophysicists have proven the existence of lower- and higher-mass block holes, intermediate-mass black holes have remained elusive. Created when supernovae collapse, stellar remnant black holes are about 3 to 10 times the mass of our sun. On the other end of the spectrum, supermassive black holes, which lurk in the centers of galaxies, are millions to billions times the mass of our sun.

Should they exist, intermediate-mass black holes would fit somewhere in the middle -- 10 to 10,000 times more massive than stellar remnant black holes but not nearly as massive as supermassive black holes. Although these intermediate-mass black holes theoretically should exist, astrophysicists have yet to find indisputable observational evidence.

"Their presence is still debated," Kıroğlu said. "Astrophysicists have uncovered evidence that they exist, but that evidence can often be explained by other mechanisms. For example, what appears to be an intermediate-mass black hole might actually be the accumulation of stellar-mass black holes."

To explore the behavior of these evasive objects, Kıroğlu and her team developed new hydrodynamic simulations. First, they created a model of a star, consisting of many particles. Then, they sent the star toward the black hole and calculated the gravitational force acting on the particles during the star's approach.

"We can calculate specifically which particle is bound to the star and which particle is disrupted (or no longer bound to the star)," Kıroğlu said.

Through these simulations, Kıroğlu and her team discovered that stars could orbit an intermediate-mass black hole as many as five times before finally being ejected. With each pass around the black hole, the star loses more and more of its mass as its ripped apart. Then, the black hole kicks the leftovers -- moving at searing speeds -- back out into the galaxy. The repeating pattern would create a stunning light show that should help astronomers recognize -- and prove the existence of -- intermediate-mass black holes.

"It's amazing that the star isn't fully ripped apart," Kıroğlu said. "Some stars might get lucky and survive the event. The ejection speed is so high that these stars could be identified as hyper-velocity stars, which have been observed at the centers of galaxies."

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For birds, blending in may result in more diversity

The saying "Birds of a feather flock together" is being given new meaning by a study published in the Philosophical Transactions of the Royal Society b. Flocking birds often travel in groups made up of a single species, in which individuals are nearly indistinguishable from one another, as noted by the proverbial adage. But something strange happens in flocks of two or more species from Southeast Asia. Even when flock species are distantly related, they still seem to converge on the same appearance, as if trying to fit in.

"They all share haphazard traits, like crests or yellow bellies, which makes them almost identical. You can't really tell them apart without looking at their markings," said study co-author Scott Robinson, Ordway eminent scholar at the Florida Museum of Natural History.

According to Robinson, this similarity in plumage is likely a type of mimicry, which by itself isn't uncommon in birds. Alfred Russel Wallace, the co-discoverer of natural selection, was the first to suggest that some bird species engage in mimicry when noting the similarities between orioles and friarbirds in Australia. Birds can mimic one another to reduce aggression from a dominant species; to resemble a more formidable adversary to predators; and, in at least one case, to make themselves appear toxic.

But resemblance in multispecies flocks is something different, said lead author Rebecca Kimball, professor of biology at the University of Florida.

"In mimicry, you often want to look like something because there's an advantage to being that other thing. You want species to think you're toxic or low-profitable prey," she said. "In flocking birds, one idea is that this has more to do with a predator's ability to isolate a target. When there are a bunch of birds moving around, it may be easier for predators to identify an individual that has a distinct color pattern."

This idea that unrelated birds find safety in collective obscurity was first proposed in the 1960s for flocks along the Andes Mountains. But follow-up studies failed to show conclusive evidence of mimicry in Andean multispecies flocks, and the theory was largely abandoned.

"The idea sat fallow for a long time," Robinson said. But in 2010, Robinson began working with a Chinese colleague in Yunnan province and observed what appeared to be the same phenomenon that had been described decades earlier.

Robinson and his colleagues spent the next several years documenting similarities in China's multispecies flocks, uncovering the same pattern again and again. While some of the similarities between species are subtle, the authors points to several visually conspicuous examples.

In western Asia, Himalayan cutias (Cutia nipalensis) look like they're dressed in mismatched layers, with a mask of black feathers, chestnut wings, and white chests with zebra stripes. This pattern might seem impervious to emulation, yet the rufous-backed sibias (Leioptila annectens) they flock with do a remarkably good impression. Both species have similar behavior, foraging patterns and markings, with the exception of stripes, which the sibias lack.

Some birds also seem capable of mimicking more than one species as they mature. Juvenile white-hooded babblers (Gampsorhynchus rufulus) have rusty head feathers, brown wings and creamy underbellies, similar to the parrotbills they flock with. Adults look like an entirely different species, with white heads and dark brown wings that resemble white-crested laughingthrushes (Garrulax leucolophus), all of which are part of the same flock.

Somewhat counterintuitively, this conformity within multispecies flocks may be contributing to diversity in the region. Not only can birds mimic more than one species at different stages of development, but their appearance can also vary across their range. In eastern China, coal tits tag along with birds with prominent crest feathers, which they mimic. In the Himalayas and Hengduan Mountains farther west, the same species lacks a crest and flocks with other crestless birds.

If these differences persist long enough, Robinson said, it might ultimately result in one species becoming two. "The possible role this type of mimicry plays in speciation is the most interesting idea from our point of view. Many of these birds have huge ranges, and there may be a lot of differentiation in these traits involved in flocking within a species."

There seem to be two main ingredients required to create this type of mimicry in flocks, both of which might help explain why this pattern appears to be so prominent in China but absent elsewhere.

First, Robinson said, a flock must be composed of just a few species, with some more common than others. "When you have a flock with a really dominant, abundant species, there's a model worth mimicking. If other birds look like that model, they get the same protection, they get access to the same resources, and they get to travel with a compatible group."

In other parts of the world, many flocks have more of an open-door policy, weakening the selective forces that contribute to mimicry. Mating pairs of multiple species join together in patchwork groups, often relying on the warning calls of sentries to avoid predators rather than their ability to fade into the background.

The second ingredient is the winnowing fan of predation. For small to medium flocking birds, the biggest source of danger comes from above, in the form of raptors, and the skies above Southeast Asia are especially fraught. The region encompasses only 3% of Earth's land area, yet it harbors almost 30% of all raptor species. This puts an enormous amount of pressure on flocks, Robinson said, which may promote mimicry.

To determine whether similarity among flocking species is the result of mimicry, the authors say they'll need to conduct widescale genetic analyses to rule out other potential causes.

Read more at Science Daily

ProSocial World: How the principles of evolution can create lasting global change

Evolution goes beyond the genetic code and the transformation of physical form, from land-mammal to whale or dinosaur to bird.

At the core of evolutionary science is a triad: variation, selection and replication, explains Binghamton University Distinguished Professor Emeritus of Biological Sciences David Sloan Wilson, the founder of Binghamton University, State University of New York's Evolutionary Studies (EvoS) program. You can see this triad at work in culture as well, from economics and business, to engineering and the arts, and the functioning of society at all levels.

Knowing how cultural evolution happens also means we can harness it for the larger good, creating a more just and sustainable world. That's a topic of "Multilevel cultural evolution: From new theory to practical applications," a new article by Wilson recently published in Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences.

Co-authors include Binghamton alumnus Guru Madhavan, MBA '07, PhD '09, senior program director at the National Academy of Engineering; Michele J. Gelfand, professor of organizational behavior and psychology at Stanford University; University of Nevada Psychology Professor Steven C. Hayes, who developed Acceptance and Commitment Therapy (ACT); Paul W.B. Atkins, visiting associate professor of psychology with Australian National University's Crawford School of Public Policy and co-founder of the non-profit ProSocial World with Wilson; and microbiologist Rita R. Colwell, former director of the National Science Foundation.

The wide-ranging article explores the three hallmarks of cultural evolution: prosociality, or behavior oriented toward the welfare of others; social control, which enforces prosocial behavior and penalizes those who behave selfishly; and symbolic thought, which relies on a flexible inventory of symbols with shared meaning.

Humans have evolved to live in small, cooperative groups, not as disconnected individuals. To be effective, however, society also requires structure.

Otherwise, strategies that are beneficial on the individual or small-group level become maladaptive: Self-preservation becomes self-dealing, helping friends and family becomes nepotism and cronyism, and patriotism fuels international conflict, for example.

"We have to have the global good in mind and everything that we do in some sense has to be coordinated with the good of the whole," Wilson said.

A roadmap for evolution

Evolutionary concepts have been misused, however. Take social Darwinism, for example, which is often used to justify competition and harsh social inequities as "survival of the fittest," a misunderstanding and misapplication of Darwinian theory. "Social engineering" also has insidious implications, Wilson noted.

"We need to ask: Is there anything about evolutionary theory that is especially dangerous in that regard? Or is it the case that anything that can be used as a tool can also be used as a weapon?" Wilson asked. "I think it's the latter."

These concepts become weapons when they are used as means of control, with little to no input from the people they impact, he explained. When people decide to use evolutionary principles to shape their own actions and goals, however, these principles are largely benign.

Checks and balances are at the core of multilevel cultural evolution to avoid power imbalances, making it the opposite of social Darwinism, which portrayed social inequities as necessary and inevitable. Social Darwinism actually has little to do with Darwin or his theories, Wilson points out; it's a stigmatizing term associated with the moral justification for ruthless competition, and probably closer to the principles behind neoclassical economics.

But fields such as economics and business needn't define themselves with the neoclassical "greed is good" ethos of Milton Freidman. Wilson points to the work of Nobel Prize-winning economist Elinor Ostrom, who proved that groups can self-manage common-pool resources -- avoiding the proverbial "tragedy of the commons" if they implement eight "core design principles."

Wilson collaborated with Ostrom to show that the core design principles can be generalized, providing a key to successful governance for nearly all forms of cooperative activity.

"To begin, you need to have a good, strong sense of identity and purpose; that's the first core design principle," Wilson said.

Other principles involve the equitable distribution of benefits and resources, inclusive decision-making, transparent behavior, and levels of response to helpful and unhelpful behavior, as well as fast and fair conflict resolution, local autonomy and authority, and relationships with other groups.

These principles not only build better workplaces, neighborhoods and nations, they can also heal the mind. As social mammals, our minds interpret social isolation as an emergency situation, the authors note, and social support is key for the treatment of such conditions as anxiety and depression.

The tools used in therapy -- particularly mindfulness -- are also applicable on a societal level, encouraging adaptability and cognitive flexibility, which helps individuals recover from adverse life events. That's true of groups as well, Wilson said.

Planting the seed

Creating a more prosocial world grounded in equity and cooperation isn't some unreachable pipe dream.

"There are practical applications," said Wilson, who established the nonprofit ProSocial World to plant these ideas outside of academia. "Right now, not in some far, distant future, we could be using these ideas to accomplish positive change."

It's important to avoid what Wilson calls the archipelago of knowledge and practice, consisting of "many islands with little communication." Otherwise, ideas and solutions may become trapped in separate silos.

In essence, the EvoS' speaker series functions that way for students, mingling lectures on bacteria with Neanderthals, morality, the arts and more. Students are exposed to ideas they may not have otherwise encountered, which introduces new paths and possibilities. The same can happen in the larger society, too.

While technological changes can spread from one culture to another over decades or centuries, Wilson hopes to spark societal change more quickly. He draws upon the concept of catalysis in chemistry: Added in small amounts, a catalytic molecule hastens the rate of change, he explains.

As catalytic agents, individuals may inspire changes that would otherwise take decades or not happen at all. And this catalysis can happen in ordinary ways, by leaning into the small-group community mindset that fuels our humanity.

Consider a community garden, for example: Reaching out to different community gardens and sharing knowledge can only benefit everyone involved, Wilson said. And those connections don't need to consist of dull meetings; they can involve social interactions such as parties and potlucks, which bring people together and encourage them to make connections.

Read more at Science Daily

Small acts of kindness are frequent and universal, study finds

A study by researchers from UCLA, Australia, Ecuador, Germany, the Netherlands and the U.K. found that people around the world signal others for assistance every couple of minutes. The research, which examined behaviors in towns and rural areas in several different countries, revealed that people comply with these small requests for help far more often than they decline them. The findings suggest that people from all cultures have more similar cooperative behaviors than prior research has established.

A new study by UCLA sociologist Giovanni Rossi and an international team of collaborators finds that people rely on each other for help constantly.

In the study, published in Scientific Reports, the authors -- who also included researchers at universities in Australia, Ecuador, Germany, the Netherlands and the U.K. -- explore the human capacity for cooperation. They found that people signal a need for assistance, such as asking someone to pass them a utensil, once every couple of minutes.

And the research revealed that those requests for help do not go unanswered: Across cultures, people comply with these small requests far more often than they decline them. On the rare occasions when people do decline, they explain why.

Those human tendencies -- to help others when needed and to explain when such help can't be given -- transcends cultural differences, suggesting that, deep down, people from all cultures have more similar cooperative behaviors than prior research has established.

The new findings help solve a puzzle generated by prior anthropological and economic research, which has emphasized variation in rules and norms governing cooperation.

For example, while whale hunters of Lamalera, Indonesia, follow established rules about how to share out a large catch, Hadza foragers of Tanzania share their food more out of a fear of generating negative gossip. In Kenya, wealthier Orma villagers are expected to pay for public goods such as road projects. Wealthy Gnau villagers of Papua New Guinea, on the other hand, would reject such an offer because it creates an awkward obligation to reciprocate for their poorer neighbors.

"Cultural differences like these have created a puzzle for understanding cooperation and helping among humans," said Rossi, the paper's first author. "Are our decisions about sharing and helping shaped by the culture we grew up with? Or are humans generous and giving by nature?"

To answer those questions, the authors analyzed over 40 hours of video recordings of everyday life involving more than 350 people in geographically, linguistically and culturally diverse sites -- towns in England, Italy, Poland and Russia, and rural villages in Ecuador, Ghana, Laos and Aboriginal Australia.

The analysis focused on sequences in which one person sent a signal for help, such as asking directly or visibly struggling with a task, and another person responded. The authors identified more than 1,000 such requests, occurring on average about once every two minutes. The situations involved "low-cost" decisions about sharing items for everyday use or assisting others with tasks around the house or village, for example.

Such decisions are many orders more frequent than "high-cost" decisions such as sharing the spoils of a successful whale hunt or contributing to the construction of a village road, the types of decisions that have been found to be significantly influenced by culture.

People complied with small requests seven times more often than they declined, and six times more often than they ignored them. People did sometimes reject or ignore small requests, but a lot less frequently than they complied. The average rates of rejection (10%) and ignoring (11%) were much lower than the average rate of compliance (79%).

The preference for compliance held across all cultures and was unaffected by whether the interaction was among family or non-family members.

People helped without explanation, but when they declined, 74% of the time they gave an explicit reason. That suggests that while people decline helping only for a good reason, they give help unconditionally, without needing to explain why they are doing it.

"A cross-cultural preference for compliance with small requests is not predicted by prior research on resource-sharing and cooperation, which instead suggest that culture should cause prosocial behavior to vary in appreciable ways due to local norms, values, and adaptations to the natural, technological, and socio-economic environment," said N. J. Enfield, the paper's corresponding author and a linguist at the University of Sydney. "These and other factors could in principle make it easier for people to say 'no' to small requests, but this is not what we find."

The findings suggest that being helpful is an ingrained reflex in the human species, Rossi said.

Read more at Science Daily

Astrophysicists reveal the nature of dark matter through the study of crinkles in spacetime

Most of the matter in the universe, amounting to a staggering 85% by mass, cannot be observed and consists of particles not accounted for by the Standard Model of Particle Physics (see remark 1). These particles are known as Dark Matter, and their existence can be inferred from their gravitational effects on light from distant galaxies. Finding the particle that makes up Dark Matter is an urgent problem in modern physics, as it dominates the mass and, therefore, the gravity of galaxies -- solving this mystery can lead to new physics beyond the Standard Model.

While some theoretical models propose the existence of ultramassive particles as a possible candidate for Dark Matter, others suggest ultralight particles. A team of astrophysicists led by Alfred AMRUTH, a PhD student in the team of Dr Jeremy LIM of the Department of Physics at The University of Hong Kong (HKU), collaborating with Professor George SMOOT, a Nobel Laureate in Physics from the Hong Kong University of Science and Technology (HKUST) and Dr Razieh EMAMI, a Research Associate at the Center for Astrophysics | Harvard & Smithsonian (CFA), has provided the most direct evidence yet that Dark Matter does not constitute ultramassive particles as is commonly thought but instead comprises particles so light that they travel through space like waves. Their work resolves an outstanding problem in astrophysics first raised two decades ago: why do models that adopt ultramassive Dark Matter particles fail to correctly predict the observed positions and the brightness of multiple images of the same galaxy created by gravitational lensing? The research findings were recently published in Nature Astronomy.

Dark Matter does not emit, absorb or reflect light, which makes it difficult to observe using traditional astronomical techniques. Today, the most powerful tool scientists have for studying Dark Matter is through gravitational lensing, a phenomenon predicted by Albert Einstein in his theory of General Relativity. In this theory, mass causes spacetime to curve, creating the appearance that light bends around massive objects such as stars, galaxies, or groups of galaxies. By observing this bending of light, scientists can infer the presence and distribution of Dark Matter -- and, as demonstrated in this study, the nature of Dark Matter itself.

When the foreground lensing object and the background lensed object -- both constituting individual galaxies in the illustration -- are closely aligned, multiple images of the same background object can be seen in the sky. The positions and brightness of the multiply-lensed images depend on the distribution of Dark Matter in the foreground lensing object, thus providing an especially powerful probe of Dark Matter.

Another assumption of the nature of Dark Matter

In the 1970s, after the existence of Dark Matter was firmly established, hypothetical particles referred to as Weakly Interacting Massive Particles (WIMPs) were proposed as candidates for Dark Matter. These WIMPs were thought to be ultramassive -- more than at least ten times as massive as a proton -- and interact with other matter only through the weak nuclear force. These particles emerge from Supersymmetry theories, developed to fill deficiencies in the Standard Model, and have since been widely advocated as the most likely candidate for Dark Matter. However, for the past two decades, adopting ultramassive particles for Dark Matter, astrophysicists have struggled to correctly reproduce the positions and brightness of multiply-lensed images. In these studies, the density of Dark Matter is assumed to decrease smoothly outwards from the centres of galaxies in accordance with theoretical simulations employing ultramassive particles.

Beginning also in the 1970s, but in dramatic contrast to WIMPs, versions of theories that seek to rectify deficiencies in the Standard Model, or those (e.g., String Theory) that seek to unify the four fundamental forces of nature (the three in the Standard Model, along with gravity), advocate the existence of ultralight particles. Referred to as axions, these hypothetical particles are predicted to be far less massive than even the lightest particles in the Standard Model and constitute an alternative candidate for Dark Matter.

According to the theory of Quantum Mechanics, ultralight particles travel through space as waves, interfering with each other in such large numbers as to create random fluctuations in density. These random density fluctuations in Dark Matter give rise to crinkles in spacetime. As might be expected, the different patterns of spacetime around galaxies depending on whether Dark Matter constitutes ultramassive or ultralight particles -- smooth versus crinkly -- ought to give rise to different positions and brightness for multiply-lensed images of background galaxies.

In work led by Alfred AMRUTH, a PhD student in Dr Jeremy LIM's team at HKU, astrophysicists have for the first time computed how gravitationally-lensed images generated by galaxies incorporating ultralight Dark Matter particles differ from those incorporating ultramassive Dark Matter particles.

Their research has shown that the general level of disagreement found between the observed and predicted positions as well as the brightness of multiply-lensed images generated by models incorporating ultramassive Dark Matter can be resolved by adopting models incorporating ultralight Dark Matter particles. Moreover, they demonstrate that models incorporating ultralight Dark Matter particles can reproduce the observed positions and brightness of multiply-lensed galaxy images, an important achievement that reveals the crinkly rather than smooth nature of spacetime around galaxies.

'The possibility that Dark Matter does not comprise ultramassive particles, as has long been advocated by the scientific community, alleviates other problems in both laboratory experiments and astronomical observations,' explains Dr Lim. 'Laboratory experiments have been singularly unsuccessful at finding WIMPs, the long-favoured candidate for Dark Matter. Such experiments are in their final stretch, culminating in the planned DARWIN experiment, leaving WIMPs with no place to hide if not found (see remark 2).'

Professor Tom BROADHURST, an Ikerbasque Professor at the University of the Basque Country, a Visiting Professor at HKU, and a co-author of the paper adds, 'If Dark Matter comprises ultramassive particles, then according to cosmological simulations, there should be hundreds of satellite galaxies surrounding the Milky Way. However, despite intensive searches, only around fifty have been discovered so far. On the other hand, if Dark Matter comprises ultralight particles instead, then the theory of Quantum Mechanics predicts that galaxies below a certain mass simply cannot form owing to the wave interference of these particles, explaining why we observe a lack of small satellite galaxies around the Milky Way.'

'Incorporating ultralight rather than ultramassive particles for Dark Matter resolve several longstanding problems simultaneously in both particle physics and astrophysics,' said Amruth Alfred, 'We have reached a point where the existing paradigm of Dark Matter needs to be reconsidered. Waving goodbye to ultramassive particles, which have long been heralded as the favoured candidate for Dark Matter, may not come easily, but the evidence accumulates in favour of Dark Matter having wave-like properties as possessed by ultralight particles.' The pioneering work used the supercomputing facilities at HKU, without which this work would not have been possible.

The co-author Professor George SMOOT added, 'Understanding the nature of particles that constitute Dark Matter is the first step towards New Physics. This work paves the way for future tests of Wave-like Dark Matter in situations involving gravitational lensing. The James Webb Space Telescope should discover many more gravitationally-lensed systems, allowing us to make even more exacting tests of the nature of Dark Matter.'

Read more at Science Daily

Webb reveals early-universe prequel to huge galaxy cluster

Every giant was once a baby, though you may never have seen them at that stage of their development. NASA's James Webb Space Telescope has begun to shed light on formative years in the history of the universe that have thus far been beyond reach: the formation and assembly of galaxies. For the first time, a protocluster of seven galaxies has been confirmed at a distance that astronomers refer to as redshift 7.9, or a mere 650 million years after the big bang. Based on the data collected, astronomers calculated the nascent cluster's future development, finding that it will likely grow in size and mass to resemble the Coma Cluster, a monster of the modern universe.

"This is a very special, unique site of accelerated galaxy evolution, and Webb gave us the unprecedented ability to measure the velocities of these seven galaxies and confidently confirm that they are bound together in a protocluster," said Takahiro Morishita of IPAC-California Institute of Technology, the lead author of the study published in the Astrophysical Journal Letters.

The precise measurements captured by Webb's Near-Infrared Spectrograph (NIRSpec) were key to confirming the galaxies' collective distance and the high velocities at which they are moving within a halo of dark matter -- more than two million miles per hour (about one thousand kilometers per second).

The spectral data allowed astronomers to model and map the future development of the gathering group, all the way to our time in the modern universe. The prediction that the protocluster will eventually resemble the Coma Cluster means that it could eventually be among the densest known galaxy collections, with thousands of members.

"We can see these distant galaxies like small drops of water in different rivers, and we can see that eventually they will all become part of one big, mighty river," said Benedetta Vulcani of the National Institute of Astrophysics in Italy, another member of the research team.

Galaxy clusters are the greatest concentrations of mass in the known universe, which can dramatically warp the fabric of spacetime itself. This warping, called gravitational lensing, can have a magnifying effect for objects beyond the cluster, allowing astronomers to look through the cluster like a giant magnifying glass. The research team was able to utilize this effect, looking through Pandora's Cluster to view the protocluster; even Webb's powerful instruments need an assist from nature to see so far.

Exploring how large clusters like Pandora and Coma first came together has been difficult, due to the expansion of the universe stretching light beyond visible wavelengths into the infrared, where astronomers lacked high-resolution data before Webb. Webb's infrared instruments were developed specifically to fill in these gaps at the beginning of the universe's story.

The seven galaxies confirmed by Webb were first established as candidates for observation using data from the Hubble Space Telescope's Frontier Fields program. The program dedicated Hubble time to observations using gravitational lensing, to observe very distant galaxies in detail. However, because Hubble cannot detect light beyond near-infrared, there is only so much detail it can see. Webb picked up the investigation, focusing on the galaxies scouted by Hubble and gathering detailed spectroscopic data in addition to imagery.

The research team anticipates that future collaboration between Webb and NASA's Nancy Grace Roman Space Telescope, a high-resolution, wide-field survey mission, will yield even more results on early galaxy clusters. With 200 times Hubble's infrared field of view in a single shot, Roman will be able to identify more protocluster galaxy candidates, which Webb can follow up to confirm with its spectroscopic instruments. The Roman mission is currently targeted for launch by May 2027.

Read more at Science Daily

Searching for ancient bears in an Alaskan cave led to an important human discovery

The first people to live in the Americas migrated from Siberia across the Bering land bridge more than 20,000 years ago. Some made their way as far south as Tierra del Fuego, at the tip of South America. Others settled in areas much closer to their place of origin where their descendants still thrive today.

In "A paleogenome from a Holocene individual supports genetic continuity in Southeast Alaska," published Friday in the journal iScience, University at Buffalo evolutionary biologist Charlotte Lindqvist and collaborators show, using ancient genetic data analyses, that some modern Alaska Natives still live almost exactly where their ancestors did some 3,000 years ago.

Lindqvist, PhD, associate professor of biological sciences in the UB College of Arts and Sciences, is senior author of the paper. In the course of her extensive studies in Alaska, she explored mammal remains that had been found in a cave in the state's southeast coast. One bone was initially identified as coming from a bear. However, genetic analysis showed it to be the remains of a human female.

"We realized that modern Indigenous peoples in Alaska, should they have remained in the region since the earliest migrations, could be related to this prehistoric individual," says Alber Aqil, a UB PhD student in biological sciences and the first author of the paper. This discovery led to efforts to solve this mystery, which DNA analyses are well suited to address when archeological remains are as sparse as these were.

Learning from an ancestor

The earliest peoples had already started moving south along the Pacific Northwest Coast before an inland route between ice sheets became viable. Some, including the female individual from the cave, made their home in the area that surrounds the Gulf of Alaska. That area is now home to the Tlingit Nation and three other groups: Haida, Tsimshian, and Nisga'a.

As Aqil and colleagues analyzed the genome from this 3,000-year-old individual -- "research that was not possible just 20 years ago," Lindqvist noted -- they determined that she is most closely related to Alaska Natives living in the area today. This fact showed it was necessary to carefully document as clearly as possible any genetic connections of the ancient female to present-day Native Americans.

In such endeavors, it is important to collaborate closely with people living in lands where archeological remains are found. Therefore, cooperation between Alaska Native peoples and the scientific community has been a significant component of the cave explorations that have taken place in the region. The Wrangell Cooperative Association named the ancient individual analyzed in this study as "Tatóok yík yées sháawat" (Young lady in cave).

Genetic continuity in Southeast Alaska persists for thousands of years

Indeed, Aqil and Lindqvist's research demonstrated that Tatóok yík yées sháawat is in fact closest related to present-day Tlingit peoples and those of nearby tribes along the coast. Their research therefore strengthens the idea that genetic continuity in Southeast Alaska has continued for thousands of years.

Human migration into North America, although it began some 24,000 years ago, came in waves -- one of which, about 6,000 years ago -- included the Paleo-Inuit, formerly known as Paleo-Eskimos. Importantly for understanding Indigenous peoples' migrations from Asia, Tatóok yík yées sháawat'sDNA did not reveal ancestry from the second wave of settlers, the Paleo-Inuit. Indeed, the analyses performed by Aqil and Lindqvist helped shed light on the continuing discussion of migration routes, mixtures among people from these different waves, as well as modern territorial patterns of inland and coastal people of the Pacific Northwest in the pre-colonial era.

Oral history links an ancient woman to people living in Southeast Alaska today

The oral origin narratives of the Tlingit people include the story of the most recent eruption of Mount Edgecumbe, which would place them exactly in the region by 4,500 years ago. Tatóok yík yées sháawat, their relative, therefore informs not just modern-day anthropological researchers but also the Tlingit people themselves.

Out of respect for the right of the Tlingit people to control and protect their cultural heritage and their genetic resources, data from the study of Tatóok yík yées sháawat will be available only after review of its use by the Wrangell Cooperative Association Tribal Council.

"It's very exciting to contribute to our knowledge of the prehistory of Southeast Alaska," said Aqil.

Read more at Science Daily

Global research reveals countries where record-breaking heatwaves are likely to cause most harm

A new study has highlighted under-prepared regions across the world most at risk of the devastating effects of scorching temperatures.

The University of Bristol-led research, published today in Nature Communications, shows that unprecedented heat extremes combined with socioeconomic vulnerability puts certain regions, such as Afghanistan, Papua New Guinea, and Central America,most in peril.

Countries yet to experience the most intense heatwaves are often especially susceptible, as adaptation measures are often only introduced after the event. A high chance of record-breaking temperatures, growing populations, and limited healthcare and energy provision, increase the risks.

Beijing and Central Europe are also on the list of hotspots, as if record-breaking heatwaves occurred in these densely populated regions millions of people would be adversely affected.

In light of the findings, the researchers are calling for policy makers in hotspot regions to consider relevant action plans to reduce the risk of deaths and associated harms from climate extremes.

Lead author, climate scientist Dr Vikki Thompson at the University of Bristol Cabot Institute for the Environment, said: "As heatwaves are occurring more often we need to be better prepared. We identify regions that may have been lucky so far -- some of these regions have rapidly growing populations, some are developing nations, some are already very hot. We need to ask if the heat action plans for these areas are sufficient."

The researchers used extreme value statistics -- a method to estimate the return periods of rare events -- and large datasets from climate models and observations to pinpoint regions globally where temperature records are most likely to be broken soonest and the communities consequently in greatest danger of experiencing extreme heat.

The researchers also cautioned that statistically implausible extremes, when current records are broken by margins that seemed impossible until they occurred, could happen anywhere. These unlikely events were found to have transpired in almost a third (31%) of the regions assessed where observations were deemed reliable enough between 1959 and 2021, such as the 2021 Western North America heatwave.

Co-author Dann Mitchell, Professor in Atmospheric Sciences at the University of Bristol Cabot Institute for the Environment, said: "Being prepared saves lives. We have seen some of the most unexpected heatwaves around the world lead to heat-related deaths in the tens of thousands. In this study, we show that such record smashing events could occur anywhere. Governments around the world need to be prepared."

Human-induced climate change is causing an increase in the frequency, intensity, and duration of heatwaves, which have the potential to lead to thousands more excess deaths globally.

Read more at Science Daily

120-year-old storm's secrets key to understanding weather risks

A severe windstorm that battered the UK more than a century ago produced some of the strongest winds[OS1] that Britain has ever seen, a team of scientists have found after recovering old weather records.

Old weather measurements, first recorded on paper after Storm Ulysses hit the UK in February 1903, have shed new light on what was one of the most severe storms to have hit the British Isles.

By turning hand-written weather data into digital records, the research team has laid the way to better understand other historical storms, floods and heatwaves. These observations from the past can help experts to understand the risks of extreme weather now and in the future.

Professor Ed Hawkins, a climate scientist at the University of Reading and the National Centre for Atmospheric Science, led the research. He said: "We knew the storm we analysed was a big one, but we didn't know our rescued data would show that it is among the top four storms for strongest winds across England and Wales.

"This study is a great example of how rescuing old paper records can help us to better understand storms from decades gone by. Unlocking these secrets from the past could transform our understanding of extreme weather and the risks they pose to us today."

Into the archives

Published today (Monday, 24 April) in Natural Hazards and Earth System Sciences, the research indicates that many storms that occurred before 1950 are left unstudied as billions of pieces of data exist only on paper, stored in archives around the world.

But a team of scientists led by Professor Hawkins delved into the archives to convert hand-written observations relating to Storm Ulysses from paper to digital. The cyclone caused multiple deaths and heavily damaged infrastructure and ships when it passed across Ireland and the UK between 26 and 27 February 1903.

Using the new digital data, the research team was able to use techniques similar to modern weather forecasting to simulate the storm and accurately assess the strength of Storm Ulysses' winds. Comparisons with independent weather observations, such as rainfall data, as well as photographs and written accounts from 1903 that outlined the devastation caused by the cyclone, helped to provide credibility for the reconstruction.

The reanalysis is beneficial for understanding the risks of extreme weather events as it showed that the winds experienced in some locations during Storm Ulysses would be rarer than once in 100 years. Having information about such a rare event provides valuable insight into the potential damage a similar storm could cause now in the future.

The 1903 storm is named Storm Ulysses because the damage to thousands of trees in Dublin is mentioned in the novel Ulysses by James Joyce, the events of which are set the year after the storm.

Rescuing the weather

The rescuing of atmospheric observations related to Storm Ulysses is not the first time Professor Ed Hawkins has led weather record recovery. National rainfall data from as far back as 1836 became available in 2022 after the University's Department of Meteorology and 16,000 volunteers helped to restore 5.2 million observations.

Read more at Science Daily

Making better measurements of the composition of galaxies

A study using data from telescopes on Earth and in the sky resolves a problem plaguing astronomers working in the infrared and could help make better observations of the composition of the universe with the James Webb Space Telescope and other instruments. The work is published April 20 in Nature Astronomy.

"We're trying to measure the composition of gases inside galaxies," said Yuguang Chen, a postdoctoral researcher working with Professor Tucker Jones in the Department of Physics and Astronomy at the University of California, Davis.

Most elements other than hydrogen, helium and lithium are produced inside stars, so the composition and distribution of heavier elements -- especially the ratio of oxygen to hydrogen -- can help astronomers understand how many and what kinds of stars are being formed in a distant object.

Astronomers use two methods to measure oxygen in a galaxy, but unfortunately, they give different results. One common method, collisionally excited lines, gives a strong signal, but the results are thought to be sensitive to temperature changes, Chen said. A second method uses a different set of lines, called recombination lines, which are fainter but not thought to be affected by temperature.

The recombination line method consistently produces measurements about double those from collisionally excited lines. Scientists attribute the discrepancy to temperature fluctuations in gas clouds, but this has not been directly proven, Chen said.

Chen, Jones and colleagues used optical and infrared astronomy to measure oxygen abundance in dwarf galaxy Markarian 71, about 11 million light years from Earth. They used archived data from the recently retired SOFIA flying telescope and the retired Herschel Space Observatory, as well as making observations with telescopes at the W.M. Keck Observatory in Mauna Kea, Hawaii.

SOFIA (Stratospheric Observatory For Infrared Astronomy) was a telescope mounted in a Boeing 747 aircraft. By flying at 38,000 to 45,000 feet, the aircraft could get above 99% of the water vapor in Earth's atmosphere, which effectively blocks infrared light from deep space from reaching ground level. A joint project of NASA and the German space agency, SOFIA made its last operational flight in September 2022 and is now headed for a museum display in Tucson.

The Herschel Space Observatory, named after astronomers William and Caroline Herschel, was an infrared space telescope operated by the European Space Agency. It was active from 2009 to 2013.

A surprising result

With data from these instruments, Chen and Jones examined oxygen abundance in Markarian 71 while correcting for temperature fluctuations. They found that the result from collisionally excited infrared lines was still 50% less than that from the recombination line method, even after eliminating the effect of temperature.

"This result is very surprising to us," Chen said. There is no consensus on an explanation for the discrepancy, he said. The team plans to look at additional objects to figure out what properties of galaxies correlate with this variation, Chen said.

One of the goals of the James Webb Space Telescope, launched in 2022, is to make infrared observations of the composition of distant galaxies in the first billion years of the universe. The new results provide a framework for making these measurements with the JWST and the Atacama Large Millimeter Array in Chile.

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New programmable smart fabric responds to temperature and electricity

A new smart material developed by researchers at the University of Waterloo is activated by both heat and electricity, making it the first ever to respond to two different stimuli.

The unique design paves the way for a wide variety of potential applications, including clothing that warms up while you walk from the car to the office in winter and vehicle bumpers that return to their original shape after a collision.

Inexpensively made with polymer nano-composite fibres from recycled plastic, the programmable fabric can change its colour and shape when stimuli are applied.

"As a wearable material alone, it has almost infinite potential in AI, robotics and virtual reality games and experiences," said Dr. Milad Kamkar, a chemical engineering professor at Waterloo. "Imagine feeling warmth or a physical trigger eliciting a more in-depth adventure in the virtual world."

The novel fabric design is a product of the happy union of soft and hard materials, featuring a combination of highly engineered polymer composites and stainless steel in a woven structure.

Researchers created a device similar to a traditional loom to weave the smart fabric. The resulting process is extremely versatile, enabling design freedom and macro-scale control of the fabric's properties.

The fabric can also be activated by a lower voltage of electricity than previous systems, making it more energy-efficient and cost-effective. In addition, lower voltage allows integration into smaller, more portable devices, making it suitable for use in biomedical devices and environment sensors.

"The idea of these intelligent materials was first bred and born from biomimicry science," said Kamkar, director of the Multi-scale Materials Design (MMD) Centre at Waterloo.

"Through the ability to sense and react to environmental stimuli such as temperature, this is proof of concept that our new material can interact with the environment to monitor ecosystems without damaging them."

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How alcohol consumption contributes to chronic pain

Chronic alcohol consumption may make people more sensitive to pain through two different molecular mechanisms -- one driven by alcohol intake and one by alcohol withdrawal. That is one new conclusion by scientists at Scripps Research on the complex links between alcohol and pain.

The research, published in the British Journal of Pharmacology on April 12, 2023, also suggests potential new drug targets for treating alcohol-associated chronic pain and hypersensitivity.

"There is an urgent need to better understand the two-way street between chronic pain and alcohol dependence," says senior author Marisa Roberto, PhD, the Schimmel Family Chair of Molecular Medicine, and a professor of neuroscience at Scripps Research. "Pain is both a widespread symptom in patients suffering from alcohol dependence, as well as a reason why people are driven to drink again."

Alcohol use disorder (AUD), which encompasses the conditions commonly called alcohol abuse, alcohol dependence and alcohol addiction, affects 29.5 million people in the U.S. according to the 2021 National Survey on Drug Use and Health. Over time, AUD can trigger the development of numerous chronic diseases, including heart disease, stroke, liver disease and some cancers.

Among the many impacts of long-term alcohol consumption is pain: more than half of people with AUD experience persistent pain of some type. This includes alcoholic neuropathy, which is nerve damage that causes chronic pain and other symptoms. Studies have also found that AUD is associated with changes in how the brain processes pain signals, as well as changes to how immune system activation occurs. In turn, this pain can lead to increased alcohol consumption. Moreover, during withdrawal, people with AUD can experience allodynia, in which a harmless stimulus is perceived as painful.

Roberto and her colleagues were interested in learning the underlying causes of these different types of alcohol-related pain. In the new study, they compared three groups of adult mice: animals that were dependent on alcohol (excessive drinkers), animals that had limited access to alcohol and were not considered dependent (moderate drinkers), and those that had never been given alcohol.

In dependent mice, allodynia developed during alcohol withdrawal, and subsequent alcohol access significantly decreased pain sensitivity. Separately, about half of the mice that were not dependent on alcohol also showed signs of increased pain sensitivity during alcohol withdrawal but, unlike the dependent mice, this neuropathy was not reversed by re-exposure to alcohol.

When Roberto's group then measured levels of inflammatory proteins in the animals, they discovered that while inflammation pathways were elevated in both dependent and non-dependent animals, specific molecules were only increased in dependent mice. This indicates that different molecular mechanisms may drive the two types of pain. It also suggests which inflammatory proteins may be useful as drug targets to combat alcohol-related pain.

"These two types of pain vary greatly, which is why it is important to be able to distinguish between them and develop different ways to treat each type," says first author Vittoria Borgonetti, PhD, a postdoctoral associate at Scripps Research.

Roberto's group is continuing studies on how these molecules might be used to diagnose or treat alcohol-related chronic pain conditions.

"Our goal is to unveil new potential molecular targets that can be used to distinguish these types of pain and potentially be used in the future for the development of therapies," says co-senior author Nicoletta Galeotti, PhD, associate professor of preclinical pharmacology at the University of Florence.

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Algae in Swedish lakes provide insights to how complex life on Earth developed

By studying green algae in Swedish lakes, a research team, led by Lund University in Sweden, has succeeded in identifying which environmental conditions promote multicellularity. The results give us new clues to the amazing paths of evolution.

The evolution of multicellular life has played a pivotal role in shaping biological diversity. However, we have up until now known surprisingly little about the natural environmental conditions that favour the formation of multicellular groups.

The cooperation between cells within multicellular organisms has enabled eyes, wings and leaves to evolve. The predominant explanation for why multicellularity evolves is that being in a group enables species to better cope with environmental challenges -- where being in a large group can, for instance, protect cells against being eaten.

"Our results challenge this idea, showing that multicellular groups form, not because they are inherently beneficial, but rather as a by-product of single-celled strategies to reduce environmental stress. In particular, cells produce a range of substances to protect themselves from the environment and these substances appear to prevent daughter cells from dispersing away from their mother cell," says Charlie Cornwallis, biology researcher at Lund University.

To understand how and why single-celled organisms evolve to be multicellular, the scientists experimented on green algae where some species are always single-celled, some are single-celled but become multicellular under certain conditions, while others are always multicellular containing thousands of cells.They could then identify the environmental conditions that promote multicellularity and find out the benefits and costs for organisms. The researchers then combined data with information on the environments that single-celled and multicellular green algae are adapted to across the whole of Sweden.

"I was surprised that there were no benefits or costs to living in multicellular groups. The conditions that individual cells experience can be extremely different when swimming around on their own, to being stuck to other cells and having to coordinate activities. Imagine you were physically tied to your family members, I think it would have quite an effect on you," says Charlie Cornwallis.

The study was conducted in Swedish lakes, and it not only provides information on which green algae occur where, and why -- it also helps us understand the origins of biological diversity that shape the world around us.

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Colorado's spicy ancient history of chili peppers

Botanists and paleontologists, led by researchers from the University of Colorado Boulder, have identified a fossil chili pepper that may rewrite the geography and evolutionary timeline of the tomato plant family.

The team's findings, published last month in the journal New Phytologist, show that the chili pepper tribe (Capsiceae) within the tomato, or nightshade (Solanaceae), family is much older and was much more widespread than previously thought. Scientists previously believed that chili peppers evolved in South America at most 15 million years ago, but the new research pushes that date to at least 50 million years ago -- and suggests that chili peppers were in fact present in North America at that time.

Rocío Deanna, a postdoctoral researcher in ecology and evolutionary biology, and Abel Campos, an undergraduate double majoring in evolutionary biology and molecular, cellular and developmental biology, weren't planning to rewrite history when they met up one afternoon at the CU Boulder Museum of Natural History in 2021. Yet among a group of specimens in its collections gathered from the Green River Formation -- geological treasure trove in northwestern Colorado and southwestern Wyoming -- Deanna spotted a specific, solanaceous trait embedded in one fossil: little spikes on the end of a fruiting stem.

"At first, I thought 'No way! This can't be true,'" said Rocío Deanna, lead author of the study. "But it was so characteristic of the chili pepper."

After they discovered two of these fossils in the CU Boulder collections, Deanna and Campos, a co-author of the study, found one more from the chili pepper tribe in collections at the Denver Museum of Nature and Science. All three fossils are from the Green River Formation in Colorado: the CU specimens from Garfield County and the DMNS fossil from Rio Blanco County.

These chili pepper fossils from the Eocene geological epoch (34 to 56 million years ago) match the timeline of another nightshade fossil found in the Esmeraldas Formation in Colombia, revealing that the family was already distributed across all of the Americas by as early as 50 million years ago.

"The family is way older than we thought," said Deanna, also a faculty member at the National University of Cordoba.

A fruit-fossil history

The nightshade family comprises 3,000 species and almost 100 different genera, including chili peppers. The ancient chili pepper was technically a fruit -- and a berry, at that. While tomatoes and peppers are commonly associated with vegetables, they have seeds on the inside, which officially categorizes them as fruits.

The researchers cannot be sure of the chili's exact shape or color, but it was probably on the smaller end compared to modern day chili peppers. And like its relatives, it could have been quite spicy, according to Deanna.

Deanna and Campos identified the fossil by the unique shape of its calyx teeth: spikes on the end of the fruiting stem that hold on to the pepper, like those which hold a gemstone in a ring.

"The world has maybe 300,000 plant species. The only plants with that kind of calyx is this group of 80 or 90 species," said Stacey Smith, senior author of the paper and associate professor of evolutionary biology at CU Boulder.

Paleontologists collected the CU Boulder fossil from the Green River Formation in the 1990s. But its exact identity remained a mystery for years, in part because there are only a handful of "solanologists," botanists who study the nightshade family, in the world. When Deanna found these Colorado-based fossils, she had just returned from a global search for tomato family fossil specimens, only to find some "just ripe for the picking" right on campus.

"A lot of discoveries happen decades after the specimens have been collected," said Smith. "Who knows how many other new fossil species are sitting in any of these museums? They're just waiting for the right eyes to look at them."

Trickle-down evolution

These chili pepper fossils were around during the Eocene, a geologic epoch that lasted from about 34 to 56 million years ago as the continents drifted toward their present positions. During this balmy time in Earth's history, carbon dioxide levels ranged between 700 and 900 parts per million (twice as high as they are today), and palm trees grew as far north as Alaska. Because little to no ice was present on Earth, sea level was as much as 500 feet higher than it is today.

Scientists had assumed that the origins of chili peppers began in South America roughly 10 to 15 million years ago, where they then dispersed over land and water to the other continents. While Colorado today is home to very few native nightshades and no chili peppers, this new discovery hints that a plethora of plants from the tomato plant family may have existed in North America 40 to 50 million years ago, which have since largely disappeared.

But how did these peppers first get to North America? It's now a case of "the chicken or the chili pepper?"

Experts have theorized that fruit-eating birds, which existed as early as 60 million years ago, may have carried seeds and plants around the world with them in their guts, stuck to their feathers or in the mud on their feet. But these birds also had to be eating something to fuel their journeys -- and fleshy berries, or peppers, make the perfect fuel. Birds may have distributed peppers from continent to continent, but peppers may also have been crucial to the success of those same birds.

So the nightshade family could have easily started in North America instead of South America, then dispersed in the other direction -- and with this discovery, scientists can no longer say for sure, said Smith.

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Most people feel 'psychologically close' to climate change

When spurring action against climate change, NGOs and governmental agencies frequently operate on the assumption that people are unmotivated to act because they view climate change as a problem that affects distant regions far in the future. While this concept, known as psychological distance, seems intuitive, researchers report in the journal One Earth on April 21 that most people see climate change as an important and timely issue even if its impacts are not immediately noticeable.

"There is no consistent evidence that perceiving climate change as psychologically distant hinders climate action, with studies reporting mixed results," write the authors, led by Dr. Anne M. van Valkengoed of the University of Groningen in the Netherlands.

van Valkengoed and her colleagues collected results from public opinion polls surveying people about their views on climate change, some of which included over 100,000 people from 121 different countries. The polls showed that over 50% of participants actually believe that climate change is happening either now or in the near future and that it will impact their local areas, not just faraway places.

The team also looked at the results of several studies designed to test the relationship between psychological distance and climate action. Out of 26 reviewed studies, only nine found a positive association between psychological distance and climate action. In fact, some studies showed that viewing climate change as impacting distant places and communities made people want to take more action. The researchers also found that 25 out of 30 studies failed to prove that experimentally decreasing psychological distance increased climate action.

The pervasive misconception about the relationship between psychological distance and climate action could actually be impeding progress in mitigating climate change due to social influence, suggest the authors. For example, if people think others perceive climate change as psychologically distant and therefore aren't taking action, they might be less likely to act themselves. Also, they might think that their efforts are futile because real environmental change relies on the combined efforts of many.

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