What is it good for? Absolutely one thing: Luna moths use their tails solely for bat evasion

In a pair of complementary studies, researchers took a close look at Luna moth (Actias luna) tails through the eyes of birds and female moths to test the tails' role in predation and sexual selection. Scientists have known for about a decade that Luna moths -- and other related silkmoths -- use their long, trailing tails to misdirect bat attacks.

"They have projections off the back of the hindwing that end in twisted, cupped paddles," said Juliette Rubin, a doctoral student at the Florida Museum of Natural History and lead author of both studies. "From experimental work with bats and moths in a flight room, we've found that these structures seem to reflect bat sonar in such a way that bats often aim their attacks at the tails instead of the main body."

Traits that evolve for one specific function can often be co-opted by natural selection for another, and Rubin wondered whether the twisted tails of Luna moths might come with any additional benefits or hidden costs.

Male Luna moths doff their tails, retain their charm

Silkmoths have independently evolved tails on multiple occasions across three continents, and the appendages can vary significantly in length. Hind wings in some species can extend to more than twice the size of the moth's wingspan, and the longer the tail, the more likely a moth will successfully thwart a prowling bat.

But far from being drab, utilitarian decoys meant only for sonar-sensing bats, silkmoth tails are often visually stunning, like decorative streamers trailing behind a kite. Across the animal and plant kingdoms, many of the most colorful and alluring structures are used to attract mates or pollinators, and scientists suspected the same might be true of silkmoth tails.

This type of dual function for a single trait isn't without precedent. The vivid colors of strawberry poison dart frogs (Oophaga pumilio) both deter predators and help males attract mates; male deer and other ungulates use their antlers to fight off rivals and signal their vigor to females; and moths that use clicks or chirruping sounds to disrupt bat echolocation can compose duets using the same sounds during courtship.

Luna moths have neither mouths to produce sound nor ears to hear it, but they do have sensitive eyes and powerful scent-detecting antennae. When female Luna moths are ready to mate, they perch in one place and emit a pheromone, a single molecule of which is enough to trigger a male antenna. The males of closely related Indian moon moths (Actias selene) can find females from more than six miles away by following the pheromone plume to its source.

"We don't know how many males are traveling to a female each night," Rubin said. "It's entirely possible she's able to call in multiple suitors and potentially have her pick."

Rubin put this idea to the test, setting up mating experiments in which a female Luna moth was enclosed in a flight box with two males: one with normal hind wings, and one with its tails removed.

Initially, the data seemed to suggest that females preferred males whose wings remained intact, but additional controlled experiments demonstrated that this was more likely an incidental effect of the tail removal. During trials in which both males had their wings clipped, and one had the tails glued back on, there was no difference in their mating success.

Do tails make Luna moths invisible to bats but conspicuous to birds?

Having demonstrated tail wings likely weren't conferring any additional benefits beyond survival, Rubin wanted to see whether they had any obvious drawbacks. Their long tails effectively throw off pursuing bats by creating a decoy target, but bats aren't the only adversaries Luna moths have to avoid. Their electric green tails with bright, pink parfait borders might make Luna moths noticeable to birds and other visually oriented predators that hunt during the day.

Other organisms contend with similar tradeoffs. The bioluminescent displays of fireflies make it easier for males to locate potential mates, but it also makes them stand out to nocturnal frogs and geckoes.

Luna moths live incredibly short lives, during which they can afford to lose a tail or two. Once they emerge from their cocoons, the moths have about a week to find a mate and reproduce before dying. "This creates a very intense period of adulthood, where surviving the night is of the utmost importance," Rubin said.

Luna moths are mostly inactive during the day, reducing their chances of being nabbed midair. If they don't do a good enough job concealing themselves, however, they run the risk of not surviving to nightfall.

Rubin wanted to know if their visually elaborate tails put Luna moths at a disadvantage in this high-stakes game of hide-and-seek. To find out, she and her colleagues wrapped mealworms in pastry dough in the shape and size of Luna moth bodies, to which they attached real wings, half of which had tails. They partially hid these moth replicas among branches and leaves in an aviary, then introduced a succession of Carolina wrens (Thryothorus ludovicianus), recording how many of the snacks the birds located and ate.

The results conclusively indicate that the tails had no effect on the birds' ability to locate the fake moths. This might seem odd to us, Rubin said, because we're such visually oriented animals. But there's evidence that suggests birds might rely on search images when trying to distinguish food items from patterns in the background.

Humans do this too. When trying to complete a Where's Waldo puzzle, people often look for the characteristic red, horizontal lines of Waldo's shirt while scanning across the page. It's possible that Luna moth tails don't match the typical moth and butterfly mold that birds expect to see while foraging, the equivalent of Waldo wearing a solid red shirt rather than his signature stripes.

While not indicative of all silkmoths, the studies suggest that these stunning and complex structures evolved for a single function in Luna moths.

"When we see these really obvious physical features in animals, we're often drawn into stories we've heard about them," Rubin said. "One is that conspicuous traits are for attracting mates or competing with rivals, and another is that these very showy traits must come with a cost. Both of these studies show it's really important to test those assumptions. A trait that's obvious to us, as visual creatures, might not stand out to the predators that hunt them, and the traits that we think are dynamic and alluring might not seem that way to a potential mate."

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Cities will need more resilient electricity networks to cope with extreme weather

Dense urban areas amplify the effects of higher temperatures, due to the phenomenon of heat islands in cities. This makes cities more vulnerable to extreme climate events. Large investments in the electricity network will be necessary to cool us down during heatwaves and keep us warm during cold snaps, according to a new study led by Lund University in Sweden.

"Unless we account for extreme climate events and continued urbanisation, the reliability of electricity supply will fall by up to 30%. An additional outlay of 20-60 per cent will be required during the energy transition in order to guarantee that cities can cope with different kinds of climate," says Vahid Nik, Professor of Building Physics at Lund University and one of the authors of the article in Nature Energy.

The study presents a modelling platform that ties together climate, building and energy system models in order to facilitate simulation and evaluation of cities' energy transition. The aim is to secure the cities' resilience against future climate changes at the same time as densification of urban areas is taking place. In particular, researchers have looked closely at extreme weather events (e.g. heatwaves and cold snaps) by producing simulations of urban microclimates.

"Our results show that high density areas give rise to a phenomenon called urban heat islands, which make cities more vulnerable to the effects of extreme climate events, particularly in southern Europe. For example, the outdoor temperature can rise by 17% while the wind speed falls by 61%. Urban densification -- a recommended development strategy in order to reach the UN's energy and climate goals -- could make the electricity network more vulnerable. This must be taken into consideration when designing urban energy systems, says Kavan Javanroodi, Assistant Professor in Building and Urban Physics.

"The framework we have developed connects future climate models to buildings and energy systems at city level, taking the urban microclimate into account. For the first time, we are getting to grips with several challenges around the issues of future climate uncertainty and extreme weather situations, focussing in particular on what are known as 'HILP' or High Impact Low Probability events," says Vahid Nik.

There is still a large gap between future climate modelling and building and energy analyses and their links to one another. According to Vahid Nik, the model now being developed makes a great contribution to closing that gap.

"Our results answer questions like 'how big an effect will extreme weather events have in the future, given the predicted pace of urbanisation and several different future climate scenarios?', 'how do we take them and the connections between them into account?' and 'how does the nature of urban development contribute to exacerbating or mitigating the effects of extreme events at regional and municipal level?' "

The results show that the peaks in demand in the energy system increase more than previously thought when extreme microclimates are taken into account, for example with an increase in cooling demand for 68% in Stockholm and 43% in Madrid on the hottest day of the year. Not considering this can lead to incorrect estimates of cities' energy requirements, which can turn into power shortage and even blackouts.

"There is a marked deviation between the heat and cooling requirements shown in today's urban climate models, compared to the outcomes of our calculations when urban morphology, the physical design of the city, is more complex. For example, if we fail to take into account the urban climate in Madrid, we could underestimate the need for cooling by around 28%," says Kavan Javanroodi.

Vahid Nik explains that an increasing number of countries have become interested in extreme weather events, energy issues and the impact on public health. At the same time, there are no methods of quantifying the effects of climate change and planning for adapting to them, especially when it comes to extreme weather events and climate variations across space and time.

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Shutting down nuclear power could increase air pollution

Nearly 20 percent of today's electricity in the United States comes from nuclear power. The U.S. has the largest nuclear fleet in the world, with 92 reactors scattered around the country. Many of these power plants have run for more than half a century and are approaching the end of their expected lifetimes.

Policymakers are debating whether to retire the aging reactors or reinforce their structures to continue producing nuclear energy, which many consider a low-carbon alternative to climate-warming coal, oil, and natural gas.

Now, MIT researchers say there's another factor to consider in weighing the future of nuclear power: air quality. In addition to being a low carbon-emitting source, nuclear power is relatively clean in terms of the air pollution it generates. Without nuclear power, how would the pattern of air pollution shift, and who would feel its effects?

The MIT team took on these questions in a new study appearing in Nature Energy. They lay out a scenario in which every nuclear power plant in the country has shut down, and consider how other sources such as coal, natural gas, and renewable energy would fill the resulting energy needs throughout an entire year.

Their analysis reveals that indeed, air pollution would increase, as coal, gas, and oil sources ramp up to compensate for nuclear power's absence. This in itself may not be surprising, but the team has put numbers to the prediction, estimating that the increase in air pollution would have serious health effects, resulting in an additional 5,200 pollution-related deaths over a single year.

If, however, more renewable energy sources become available to supply the energy grid, as they are expected to by the year 2030, air pollution would be curtailed, though not entirely. The team found that even under this heartier renewable scenario, there is still a slight increase in air pollution in some parts of the country, resulting in a total of 260 pollution-related deaths over one year.

When they looked at the populations directly affected by the increased pollution, they found that Black or African American communities -- a disproportionate number of whom live near fossil-fuel plants -- experienced the greatest exposure.

"This adds one more layer to the environmental health and social impacts equation when you're thinking about nuclear shutdowns, where the conversation often focuses on local risks due to accidents and mining or long-term climate impacts," says lead author Lyssa Freese, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

"In the debate over keeping nuclear power plants open, air quality has not been a focus of that discussion," adds study author Noelle Selin, a professor in MIT's Institute for Data, Systems, and Society (IDSS) and EAPS. "What we found was that air pollution from fossil fuel plants is so damaging, that anything that increases it, such as a nuclear shutdown, is going to have substantial impacts, and for some people more than others."

The study's MIT-affiliated co-authors also include Principal Research Scientist Sebastian Eastham and Guillaume Chossière SM '17, PhD '20, along with Alan Jenn of the University of California at Davis.

Future phase-outs

When nuclear power plants have closed in the past, fossil fuel use increased in response. In 1985, the closure of reactors in Tennessee Valley prompted a spike in coal use, while the 2012 shutdown of a plant in California led to an increase in natural gas. In Germany, where nuclear power has almost completely been phased out, coal-fired power increased initially to fill the gap.

Noting these trends, the MIT team wondered how the U.S. energy grid would respond if nuclear power were completely phased out.

"We wanted to think about what future changes were expected in the energy grid," Freese says. "We knew that coal use was declining, and there was a lot of work already looking at the impact of what that would have on air quality. But no one had looked at air quality and nuclear power, which we also noticed was on the decline."

In the new study, the team used an energy grid dispatch model developed by Jenn to assess how the U.S. energy system would respond to a shutdown of nuclear power. The model simulates the production of every power plant in the country and runs continuously to estimate, hour by hour, the energy demands in 64 regions across the country.

Much like the way the actual energy market operates, the model chooses to turn a plant's production up or down based on cost: Plants producing the cheapest energy at any given time are given priority to supply the grid over more costly energy sources.

The team fed the model available data on each plant's changing emissions and energy costs throughout an entire year. They then ran the model under different scenarios, including: an energy grid with no nuclear power, a baseline grid similar to today's that includes nuclear power, and a grid with no nuclear power that also incorporates the additional renewable sources that are expected to be added by 2030.

They combined each simulation with an atmospheric chemistry model to simulate how each plant's various emissions travel around the country and to overlay these tracks onto maps of population density. For populations in the path of pollution, they calculated the risk of premature death based on their degree of exposure.

System response

Their analysis showed a clear pattern: Without nuclear power, air pollution worsened in general, mainly affecting regions in the East Coast, where nuclear power plants are mostly concentrated. Without those plants, the team observed an uptick in production from coal and gas plants, resulting in 5,200 pollution-related deaths across the country, compared to the baseline scenario.

They also calculated that more people are also likely to die prematurely due to climate impacts from the increase in carbon dioxide emissions, as the grid compensates for nuclear power's absence. The climate-related effects from this additional influx of carbon dioxide could lead to 160,000 additional deaths over the next century.

"We need to be thoughtful about how we're retiring nuclear power plants if we are trying to think about them as part of an energy system," Freese says. "Shutting down something that doesn't have direct emissions itself can still lead to increases in emissions, because the grid system will respond."

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Scientists map gusty winds in a far-off neutron star system

An accretion disk is a colossal whirlpool of gas and dust that gathers around a black hole or a neutron star like cotton candy as it pulls in material from a nearby star. As the disk spins, it whips up powerful winds that push and pull on the sprawling, rotating plasma. These massive outflows can affect the surroundings of black holes by heating and blowing away the gas and dust around them.

At immense scales, "disk winds" can offer clues to how supermassive black holes shape entire galaxies. Astronomers have observed signs of disk winds in many systems, including accreting black holes and neutron stars. But to date, they've only ever glimpsed a very narrow view of this phenomenon.

Now, MIT astronomers have observed a wider swath of winds, in Hercules X-1, a system in which a neutron star is drawing material away from a sun-like star. This neutron star's accretion disk is unique in that it wobbles, or "precesses," as it rotates. By taking advantage of this wobble, the astronomers have captured varying perspectives of the rotating disk and created a two-dimensional map of its winds, for the first time.

The new map reveals the wind's vertical shape and structure, as well as its velocity -- around hundreds of kilometers per second, or about a million miles per hour, which is on the milder end of what accretion disks can spin up.

If astronomers can spot more wobbling systems in the future, the team's mapping technique could help determine how disk winds influence the formation and evolution of stellar systems, and even entire galaxies.

"In the future, we could map disk winds in a range of objects and determine how wind properties change, for instance, with the mass of a black hole, or with how much material it is accreting," says Peter Kosec, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research. "That will help determine how black holes and neutron stars influence our universe."

Kosec is the lead author of a study appearing in Nature Astronomy. His MIT co-authors include Erin Kara, Daniele Rogantini, and Claude Canizares, along with collaborators from multiple institutions, including the Institute of Astronomy in Cambridge, U.K.

Fixed sight

Disk winds have most often been observed in X-ray binaries -- systems in which a black hole or a neutron star is pulling material from a less dense object and generating a white-hot disk of inspiraling matter, along with outflowing wind. Exactly how winds are launched from these systems is unclear. Some theories propose that magnetic fields could shred the disk and expel some of the material outward as wind. Others posit that the neutron star's radiation could heat and evaporate the disk's surface in white-hot gusts.

Clues to a wind's origins may be deduced from its structure, but the shape and extent of disk winds has been difficult to resolve. Most binaries produce accretion disks that are relatively even in shape, like thin donuts of gas that spins in a single plane. Astronomers who study these disks from far-off satellites or telescopes can only observe the effects of disk winds within a fixed and narrow range, relative to their rotating disk. Any wind that astronomers manage to detect is therefore a small sliver of its larger structure.

"We can only probe the wind properties at a single point, and we're completely blind to everything around that point," Kosec notes.

In 2020, he and his colleagues realized that one binary system could offer a wider view of disk winds. Hercules X-1 has stood out from most known X-ray binaries for its warped accretion disk, which wobbles as it rotates around the system's central neutron star.

"The disk is really wobbling over time every 35 days, and the winds are originating somewhere in the disk and crossing our line of sight at different heights above the disk with time," Kosec explains. "That's a very unique property of this system which allows us to better understand its vertical wind properties."

A warped wobble

In the new study, the researchers observed Hercules X-1 using two X-ray telescopes -- the European Space Agency's XMM Newton and NASA's Chandra Observatory.

"What we measure is an X-ray spectrum, which means the amount of X-ray photons that arrive at our detectors, versus their energy. We measure the absorption lines, or the lack of X-ray light at very specific energies," Kosec says. "From the ratio of how strong the different lines are, we can determine the temperature, velocity, and the amount of plasma within the disk wind."

With Hercules X-1's warped disk, astronomers were able to see the line of the disk moving up and down as it wobbled and rotated, similar to the way a warped record appears to oscillate when seen from edge-on. The effect was such that the researchers could observe signs of disk winds at changing heights with respect to the disk, rather than at a single, fixed height above a uniformly rotating disk.

By measuring X-ray emissions and the absorption lines as the disk wobbled and rotated over time, the researchers could scan properties such as the temperature and density of winds at various heights with respect to its disk and construct a two-dimensional map of the wind's vertical structure.

"What we see is that the wind rises from the disk, at an angle of about 12 degrees with respect to the disk as it expands in space," Kosec says. "It's also getting colder and more clumpy, and weaker at greater heights above the disk."

The team plans to compare their observations with theoretical simulations of various wind-launching mechanisms, to see which could best explain the wind's origins. Further out, they hope to discover more warped and wobbling systems, and map their disk wind structures. Then, scientists could have a broader view of disk winds, and how such outflows influence their surroundings -- particularly at much larger scales.

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Scientists show how we can anticipate rather than react to extinction in mammals

Most conservation efforts are reactive. Typically, a species must reach threatened status before action is taken to prevent extinction, such as establishing protected areas. A new study published in the journal Current Biology on April 10 shows that we can use existing conservation data to predict which currently unthreatened species could become threatened and take proactive action to prevent their decline before it is too late.

"Conservation funding is really limited," says lead author Marcel Cardillo of Australian National University. "Ideally, what we need is some way of anticipating species that may not be threatened at the moment but have a high chance of becoming threatened in the future. Prevention is better than cure."

To predict "over-the-horizon" extinction risk, Cardillo and colleagues looked at three aspects of global change -- climate change, human population growth, and the rate of change in land use -- together with intrinsic biological features that could make some species more vulnerable. The team predicts that up to 20% of land mammals will have a combination of two or more of these risk factors by the year 2100.

"Globally, the percentage of terrestrial mammal species that our models predict will have at least one of the four future risk factors by 2100 ranges from 40% under a middle-of-the-road emissions scenario with broad species dispersal to 58% under a fossil-fueled development scenario with no dispersal," say the authors.

"There's a congruence of multiple future risk factors in Sub-Saharan African and southeastern Australia: climate change (which is expected to be particularly severe in Africa), human population growth, and changes in land use," says Cardillo. "And there are a lot of large mammal species that are likely to be more sensitive to these things. It's pretty much the perfect storm."

Larger mammals in particular, like elephants, rhinos, giraffes, and kangaroos, are often more susceptible to population decline since their reproductive patterns influence how quickly their populations can bounce back from disturbances. Compared to smaller mammals, such as rodents, which reproduce quickly and in larger numbers, bigger mammals, such as elephants, have long gestational periods and produce fewer offspring at a time.

"Traditionally, conservation has relied heavily on declaring protected areas," says Cardillo. "The basic idea is that you remove or mitigate what is causing the species to become threatened."

"But increasingly, it's being recognized that that's very much a Western view of conservation because it dictates separating people from nature," says Cardillo. "It's a sort of view of nature where humans don't play a role, and that's something that doesn't sit well with a lot of cultures in many parts of the world."

In preventing animal extinction, the researchers say we must also be aware of how conservation impacts Indigenous communities. Sub-Saharan Africa is home to many Indigenous populations, and Western ideas of conservation, although well-intended, may have negative impacts.

Australia has already begun tackling this issue by establishing Indigenous Protected Areas (IPAs), which are owned by Indigenous peoples and operate with the help of rangers from local communities. In these regions, humans and animals can coexist, as established through collaboration between governments and private landowners outside of these protected areas.

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Early crop plants were more easily 'tamed'

The story of how ancient wolves came to claim a place near the campfire as humanity's best friend is a familiar tale (even if scientists are still working out some of the specifics). In order to be domesticated, a wild animal must be tamable -- capable of living in close proximity to people without exhibiting dangerous aggression or debilitating fear. Taming was the necessary first step in animal domestication, and it is widely known that some animals are easier to tame than others.

But did humans also favor certain wild plants for domestication because they were more easily "tamed"? Research from Washington University in St. Louis calls for a reappraisal of the process of plant domestication, based on almost a decade of observations and experiments. The behavior of erect knotweed, a buckwheat relative, has WashU paleoethnobotanists completely reassessing our understanding of plant domestication.

"We have no equivalent term for tameness in plants," said Natalie Mueller, assistant professor of archaeology in Arts & Sciences at Washington University. "But plants are capable of responding to people. They have a developmental capacity to be tamed."

Her work with early indigenous North American crops shows that some wild plants respond quickly to clearing, fertilizing, weeding or thinning. Plants that respond in ways that make cultivation easier or more productive could be considered more easily tamed than those that cannot.

"If plants responded rapidly in ways that were beneficial to early cultivators -- for example by producing higher yields, larger seeds, seeds that were easier to sprout, or a second crop in a single growing season -- this would have encouraged humans to continue investing in the co-evolutionary relationship," she said.

This capacity to express different traits and characteristics in response to the environment is called plasticity, and not all species are equally plastic.

"Some plants respond quickly and obviously to cultivation and care," Mueller said. "I think ancient people would have noticed that they could double their yields just by thinning out dense stands of plants. This is one of the simplest and most common gardening techniques, but it has many important effects on the development of plants."

What would an early farmer do?

Mueller's study, published April 7 in PLOS ONE, focuses on work with a plant called erect knotweed, a member of the buckwheat family that was domesticated by indigenous farmers in eastern North America. The domesticated sub-species is now extinct; humans don't eat it anymore. But Mueller and others have previously uncovered caches of seeds stored in caves, charred plant remnants in ancient hearths, and even the seeds of erect knotweed in human feces, clear evidence that this species was once consumed as a staple food.

Mueller, who studies lost crops, has spent years growing erect knotweed and other crop progenitors in experimental gardens, including at Washington University's environmental field station, Tyson Research Center. She hasn't always been successful with growing the plants she collects in the wild. In that way, Mueller can relate to the early farmers who similarly experimented with plants to discover their potential.

Her efforts have often been stymied by seed dormancy, a common feature among wild plants.

Unlike seeds you buy at the garden store, the seeds of most wild plants will not germinate if you simply sprinkle some water on them. Their requirements for germination are diverse and shaped by their evolutionary history. For example, if a plant has evolved in a place with a winter, like the Midwest, its seeds may not germinate unless they experience a long cold period. This prevents them from germinating too soon in the wild -- they are waiting for spring. Domesticated plants have lost their diverse germination requirements.

The loss of germination inhibitors has presented a paradox to theorists of domestication. Many of the selective pressures that could have favored the evolution of this trait derive from planting seeds. But why would ancient people have started planting seeds if none of them germinated?

With erect knotweed, Mueller experienced a breakthrough of sorts. Based on four seasons of observations, Mueller determined that growing wild plants in the low-density conditions typical of a cultivated garden (i.e. spaced out and weeded) triggers plants to produce seeds that germinate more easily. This makes the harvests easier to plant successfully the next time around, eliminating a key barrier to further selection.

"Our results show that erect knotweed grown in low-density agroecosystems spontaneously 'act domesticated' in a single growing season, before any selection has occurred," Mueller said.

Think of it as the plant equivalent to that first wolf who, though still a wild animal, sat down with its human friend around the fire. This is a behavioral shift, rather than an evolutionary one, but it allows new evolutionary pathways to open up.

A role for plant behavior

Mueller believes there is a bias in domestication studies toward viewing this changeability, or plasticity, as noise that is getting in the way of attempts to explain evolutionary change. Instead, this paper argues that we need to understand the development and behavior of wild crop relatives in order to explain the evolutionary process of domestication.

"Because we lack the practical experience with crop progenitors that ancient people had, these effects of the environment on plant development have gone mostly unnoticed and understudied," Mueller said.

Her findings could have applications for developing new food crops: there is no reason why we have to be limited to the plants that our ancestors domesticated thousands of years ago.

Some researchers have been calling for de novo domestication -- selecting wild plants with desirable characteristics and intentionally domesticating them. It may make sense to start looking to wild plants that are easily tamed as potential crops that could be developed for the future, Mueller said.

This paper also contributes to a growing awareness that plants are responsive and communicative beings. Though this idea is cutting-edge and hotly debated in biology and ecology, it is widespread in indigenous North American philosophies and probably would have been held by the people who domesticated erect knotweed and other plants thousands of years ago.

Recent research has shown how plants warn relatives about herbivores using chemical signaling, share resources through mycorrhizal networks and even emit noises when they are injured or stressed.

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This elephant's self-taught banana peeling offers glimpse of elephants' broader abilities

Elephants like to eat bananas, but they don't usually peel them first in the way humans do. A new report in the journal Current Biology on April 10, however, shows that one very special Asian elephant named Pang Pha picked up banana peeling all on her own while living at the Berlin Zoo. She reserves it for yellow-brown bananas, first breaking the banana before shaking out and collecting the pulp, leaving the thick peel behind.

The female elephant most likely learned the unusual peeling behavior from watching her caretakers peel bananas for her, the study authors report. The findings in a single elephant show that elephants more broadly have special cognitive and manipulative abilities, they say.

"We discovered a very unique behavior," said Michael Brecht of Humboldt-Universität zu Berlin's Bernstein Center for Computational Neuroscience. "What makes Pang Pha's banana peeling so unique is a combination of factors -- skillfulness, speed, individuality, and the putatively human origin -- rather than a single behavioral element."

Like other elephants, Pha eats green or yellow bananas whole. She rejects brown bananas outright. But when it comes to yellow bananas spotted with brown -- the kind one might reserve for banana bread -- she eats after peeling them first.

Brecht and colleagues including Lena Kaufmann, also at Humboldt-Universität zu Berlin, and Andreas Ochs, Berlin Zoological Garden, made the discovery after learning from Pha's caretakers about her unusual banana-peeling talent. At first, they were confused. They brought Pha nice yellow and green bananas, and she never peeled them.

"It was only when we understood that she peels only yellow-brown bananas that our project took off," Brecht said.

When yellow-brown bananas are offered to a group of elephants, Pha changes her behavior, they report. She eats as many bananas as she can whole and then saves the last one to peel later.

Banana-peeling appears to be rare in elephants as far as anyone knows, and none of the other Berlin elephants engage in peeling. It's not clear why Pha peels them. The researchers note, however, that she was hand raised by human caretakers in the Berlin Zoo. They never taught her to peel bananas, but they did feed her peeled bananas.

Based on this, the researchers suggest she acquired peeling through observational learning from humans. Earlier reports on African elephants suggest elephants can interpret human pointing gestures and classify people into ethnic groups, but complex human-derived manipulation behaviors, like banana-peeling, appear rather unique, according to the researchers. The findings in Pha nevertheless suggest that elephants overall have surprising cognitive abilities and impressive manipulative skill.

"Elephants have truly remarkable trunk skills and that their behavior is shaped by experience," says Brecht.

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Twinkling stars fuel interstellar dust

Of the many different kinds of stars, asymptotic giant branch (AGB) stars, usually slightly larger and older than our own sun, are known producers of interstellar dust. Dusty AGBs are particularly prominent producers of dust, and the light they shine happens to vary widely. For the first time, a long-period survey has found the variable intensity of dusty AGBs coincides with variations in the amount of dust these stars produce. As this dust can lead to the creation of planets, its study can shed light on our own origins.

You've probably heard of the James Webb Space Telescope (JWST) which has been in the news lately. It's famous for being the largest and most sensitive space telescope designed to observe infrared (IR) light. But long before the JWST took to the skies, two other IR space telescopes, AKARI and WISE, have been surveying the cosmos, both of which have ended their initial missions, but produced so much valuable data that astronomers are still finding new discoveries with it. The latest finding from that data by doctoral student Kengo Tachibana from the University of Tokyo's Institute of Astronomy and his team, could have implications for the study of the origins of life itself.

"We study stars, and IR light from them is a key source of information that helps us unlock their secrets," said Tachibana. "Until recently, most IR data was from very short-period surveys due to the lack of advanced dedicated platforms. But missions like AKARI and WISE have allowed us to take longer-period surveys of things. This means we can see how things might change over greater time periods, and what these changes might imply. Lately, we turned our attention to a certain class of star known as asymptotic giant branch stars, which are interesting because they are the main producers of interstellar dust."

This interstellar dust is not the same stuff that accumulates on your floor when you forget to vacuum for a few days; it's a name given to heavy elements that disperse from stars and lead to the formation of solid objects including planets. Although it's long been known that AGBs, and especially so-called dusty AGBs, are the main producers of dust, it's not known what the main drivers of dust production are and where we should be looking to find this out.

"Our latest study has pointed us in the right direction," said Tachibana. "Thanks to long-period IR observations, we have found that the light from dusty AGBs varies with periods longer than several hundred days. We also found that the spherical shells of dust produced by and then ejected by these stars have concentrations of dust that vary in step with the stars' changes in luminosity. Of the 169 dusty AGBs surveyed, no matter their variability period, the concentrations of dust around them would coincide. So, we're certain these are connected."

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Lonely people's divergent thought processes may contribute to feeling 'alone in a crowded room'

Common wisdom suggests that a core difference between solitude and loneliness is choice. Whereas a person who appreciates solitude might choose to enjoy a quiet night in or a solo trip abroad, a lonely person may feel disconnected from other people even in a crowded room. New research published in Psychological Science supports this notion, suggesting that lonely people may think differently regardless of the size of their social networks.

"We found that lonely individuals are exceptionally dissimilar to their peers in the way that they process the world around them … even when taking into account the number of friends that they have," said lead author Elisa C. Baek (University of Southern California) in an interview. Her study showed that lonely individuals' neural responses differ from those of other people, suggesting that "seeing the world differently than those around you may be a risk factor for loneliness, even if you regularly socialize with them."

Baek and colleagues Ryan Hyon, Karina López, Meng Du, Mason A. Porter, and Carolyn Parkinson (University of California, Los Angeles [UCLA]) came to this conclusion by comparing the functional magnetic resonance imaging (fMRI) scans of 63 first-year university students.

During each 90-minute scan, participants viewed 14 engaging video clips in the same order. After the scan, they self-reported their feelings of social connection using the UCLA Loneliness Scale. Earlier in the academic year, each participant had also completed a social network survey in which they were asked to list the names of each person with whom they studied, ate meals, or otherwise hung out during their first several months as students.

In order to analyze these data, Baek and colleagues divided participants into two groups: a "lonely" group with participants who scored higher than the median on the loneliness scale and a nonlonely group with participants who scored under the median.

When the researchers compared these participants' scans, they found that the brain activity of lonely participants was very dissimilar to that of both nonlonely participants and other lonely participants. By comparison, the brain activity of nonlonely participants was similar to that of other nonlonely participants. This was especially true in the default-mode network, in which shared brain activity appears to be associated with interpreting narratives and friendships in a similar manner, and in the reward-processing areas of the brain, the researchers wrote. These findings remained significant even when the researchers controlled for demographic characteristics and the size of participants' social networks.

"Lonely people process the world idiosyncratically, which may contribute to the reduced sense of being understood that often accompanies loneliness," the researchers explained.

Additional research is needed in order to determine the underlying cause of these results, however, Baek said.

"One possibility is that lonely individuals do not find value in the same aspects of situations or scenes as their peers," Baek and colleagues wrote. "This may result in a reinforcing feedback loop in which lonely individuals perceive themselves to be different from their peers, which may in turn lead to further challenges in achieving social connection."

Another possibility is that loneliness itself could lead people to process information differently, the researchers added.

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How were amino acids, one of the key building blocks of life, formed before the origin of life on Earth?

Our solar system formed from a molecular cloud, which was composed of gas and dust that was emitted into the interstellar medium (ISM), a vast space between stars. On collapse of the molecular cloud, the early sun was formed, with a large disk of gas and dust orbiting it. The dusty material collided to produce rocky material that would eventually grow in size to give large bodies called planetesimals.

The planetesimals that formed far enough from the sun, also contained large quantities of ice. The ice consisted of water and other volatile compounds, such as carbon monoxide (CO), carbon dioxide (CO2), methanol (CH3OH) and ammonia (NH3), as well as many other organic compounds, likely including some amino acids. Eventually, the ice melted due to the presence of radioactive material that heated up the bodies. This period of liquid water (termed aqueous alteration) enabled many reactions to occur, including Strecker synthesis and Formose-like reactions, the result being the production of new organic material, including amino acids. The same process also changed the rocky materials from their original minerals to new secondary minerals, such as phyllosilicates, carbonates, Fe-oxides and Fe-sulfides.

After several millions of years, the planetesimals began to freeze, as the radioactive material was used up. Later catastrophic collisions and interaction with the solar systems planets broke up the large bodies and sent their asteroidal and cometary fragments close to Earth. Further impact events have since delivered fragments of these asteroids and comets to the Earth's surface, supplying the Earth with large quantities of organic material, including amino acids, over the course of its history.

Amino acids are within all living things on Earth, being the building blocks of proteins. Proteins are essential for many processes within living organisms, including catalysing reactions (enzymes), replicating genetic material (ribosomes), transporting molecules (transport proteins) and providing a structure to cells and organisms (e.g. collagen). Therefore, amino acids would have been needed in significant amounts within the region where life began on Earth.

Previous work has identified a number of possible settings both on the Early Earth and in extraterrestrial environments that can form amino acids. Interestingly, most amino acids come in at least two forms, whose structures represent mirror images of each other, similar to human hands. Accordingly, these are often referred to as the right-handed or left-handed optical isomers. One interesting characteristic of life on Earth is that it uses one particular type of amino acids in its proteins, the left-handed optical isomer. Currently, only a certain class of meteorites (carbonaceous chondrites) are known to contain excesses of left-handed optical isomers, which has led to the idea that the amino acids used by life may have originated from these meteorites. Despite this, the amino acids in meteorites could have formed before their incorporation into the meteorites or after the meteorites had already formed.

Here, a team of scientists analysed several fragments of the asteroid Ryugu and calculated the abundance of amino acids within them. The abundance of the mineral phases within the particles had been previously reported in another publication, which allowed for a comparison between the abundance of amino acids and minerals. It was found that one particle (A0022) contained a high abundance of an amino acid that is uncommon in extraterrestrial materials, called dimethylglycine (DMG), whereas the other particle (C0008) did not contain this amino acid above detection limit. Meanwhile, the abundance of the amino acid glycine was found to be lower in A0022 compared to C0008, while the abundance of β-Alanine showed the opposite trend. Accordingly, the ratio of β-Alanine to glycine was higher for A0022 than for C0008. This ratio was shown previously to be indicative of the extent of aqueous alteration operating on planetesimals. Accordingly, it was hypothesised that some reaction related to higher levels of aqueous alteration in A0022 may explain the high abundance of DMG in this particle, compared to C0008.

As such, the mineral phases were examined to see if any additional evidence for what reaction may be causing the different amino acids abundances between the Ryugu particles. It was found that the abundance of secondary minerals (formed after aqueous alteration), including carbonate, magnetite and Fe-sulfides, was higher in A0022 than in C0008. In particular, the high abundance of carbonate pointed towards a larger quantity of CO or CO2 within the region of the planetesimal where A0022 had been altered, compared to C0008. In conjunction with the evidence for more intense aqueous alteration from the β-Alanine to glycine ratio, this indicated that more ice in general may have been present in the precursor of A0022 than in C0008.

One way to commercially produce DMG, an important nutrient for humans, is the through the Eschweiler-Clarke reaction. This reaction requires the interaction of glycine with formic acid and formaldehyde in water and also produces CO2. Glycine, formaldehyde and formic acid are all found in comets and so it is expected that they would be present in the planetesimal precursors of asteroids. Therefore, if the Eschweiler-Clarke reaction occurred during aqueous alteration within the precursor of A0022, then it could explain the high level of DMG and lower abundance of glycine in this particle, compared to C0008. Additionally, the CO2 produced could have further contributed to the formation of carbonates in A0022.

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