By Nazeefa Ahmed Humans prefer fruit at its sweetest, whereas many birds happily snack on the sourest of the bunch, from zesty lemons to unripe honey mangoes. Researchers may now know why. A study published today in Science suggests birds have evolved a specialized taste receptor that’s suppressed by high acidity, which effectively dulls the sharp, sour taste of fruits they eat. The finding reveals the evolutionary history of the pucker-inducing diets of many fruit-eating birds around the world—and may also help explain birds’ knack for survival, by broadening their potential food sources. The study is a “robust” addition to our understanding of how birds taste sour foods, which is still a research area in its infancy, says Leanne Grieves, an ornithologist at Cornell University’s Lab of Ornithology. Scientists identified a sour taste receptor in vertebrates—known as OTOP1—only 7 years ago, and few studies focus on why birds eat what they eat, rather than simply what they eat. Grieves, who studies birds’ sense of smell but who was not involved with the current work, adds that the new study “provides a really nice starting point.” To examine how birds approach sour-tasting foods, scientists exposed OTOP1 receptors from mice, domestic pigeons, and canaries to various acidic solutions. The activity of the mouse version of the receptor increased with greater acidity—meaning more acidic foods register to mice, and other mammals like us, as increasingly sour. However, the pigeon and canary versions of OTOP1 became less active in solutions about as acidic as a lemon. As a result, the birds wouldn’t perceive as much of a sour taste, allowing them to take advantage of the fruits mammals can’t stomach. Determining why bird OTOP1 reacted differently was a challenge, according to study author Hao Zhang, an evolutionary biologist at the Chinese Academy of Sciences (CAS). So, the researchers mutated sections of the gene that encodes the OTOP1 receptor, which let them identify four candidate amino acids within the protein that are responsible for sour tolerance. One of them, known as G378, is found almost exclusively in songbirds such as the canary—a species that showed greater sour tolerance than the pigeon, which lacks this variance. “A single amino acid in the bird OTOP1 can increase sour tolerance,” says study author Lei Luo, a biologist at CAS. © 2025 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 29840 - Posted: 06.21.2025

James Doubek Researchers have some new evidence about what makes birds make so much noise early in the morning, and it's not for some of the reasons they previously thought. For decades, a dominant theory about why birds sing at dawn — called the "dawn chorus" — has been that they can be heard farther and more clearly at that time. Sound travels faster in humid air and it's more humid early in the morning. It's less windy, too, which is thought to lessen any distortion of their vocalizations. But scientists from the Cornell Lab of Ornithology's K. Lisa Yang Center for Conservation Bioacoustics and Project Dhvani in India combed through audio recordings of birds in the rainforest. They say they didn't find evidence to back up this "acoustic transmission hypothesis." It was among the hypotheses involving environmental factors. Another is that birds spend their time singing at dawn because there's low light and it's a bad time to look for food. "We basically didn't find much support for some of these environmental cues which have been purported in literature as hypotheses" for why birds sing more at dawn, says Vijay Ramesh, a postdoctoral research associate at Cornell and the study's lead author. The study, called "Why is the early bird early? An evaluation of hypotheses for avian dawn-biased vocal activity," was published this month in the peer-reviewed journal Philosophical Transactions of the Royal Society B. The researchers didn't definitively point to one reason for why the dawn chorus is happening, but they found support for ideas that the early morning racket relates to birds marking their territory after being inactive at night, and communicating about finding food. © 2025 npr

Keyword: Animal Communication; Evolution
Link ID: 29839 - Posted: 06.21.2025

Associated Press Prairie dogs bark to alert each other to the presence of predators, with different cries depending on whether the threat is airborne or approaching by land. But their warnings also seem to help a vulnerable grassland bird. Curlews have figured out that if they eavesdrop on alarms from US prairie dog colonies they may get a jump on predators coming for them, too, according to research published on Thursday in the journal Animal Behavior. “Prairie dogs are on the menu for just about every predator you can think of – golden eagles, red-tailed hawks, foxes, badgers, even large snakes,” said Andy Boyce, a research ecologist in Montana at the Smithsonian’s National Zoo and Conservation Biology Institute. Such animals also gladly snack on grassland nesting birds such as the long-billed curlew, so the birds have adapted. Previous research has shown birds frequently eavesdrop on other bird species to glean information about food sources or danger, said Georgetown University ornithologist Emily Williams, who was not involved in the study. But, so far, scientists have documented only a few instances of birds eavesdropping on mammals. “That doesn’t necessarily mean it’s rare in the wild,” she said, “it just means we haven’t studied it yet.” Prairie dogs, a type of ground squirrel, live in large colonies with a series of burrows that may stretch for miles underground, especially on the vast US plains. When they hear each other’s barks, they either stand alert watching or dive into their burrows. “Those little barks are very loud; they can carry quite a long way,” said research co-author Andrew Dreelin, who also works for the Smithsonian. © 2025 Guardian News & Media Limited

Keyword: Animal Communication; Language
Link ID: 29832 - Posted: 06.18.2025

By Sofia Quaglia When octopuses extend their eight arms into hidden nooks and crannies in search of a meal, they are not just feeling around in the dark for their food. They are tasting their prey, and with even more sensory sophistication than scientists had already imagined. Researchers reported on Tuesday in the journal Cell that octopus arms are fine-tuned to “eavesdrop into the microbial world,” detecting microbiomes on the surfaces around them and deriving information from them, said Rebecka Sepela, a molecular biologist at Harvard and an author of the new study. Where octopus eyes cannot see, their arms can go to identify prey and make sense of their surroundings. Scientists knew that those eight arms (not tentacles) sense whether their eggs are healthy or need to be pruned. And the hundreds of suckers on each arm have over 10,000 chemotactile sensory receptors each, working with 500 million neurons to pick up that information and relay it throughout the nervous system. Yet, what exactly the octopus is tasting by probing and prodding — and how its arms can distinguish, say, a rock from an egg, a healthy egg in its clutch from a sick one or a crab that’s safe to eat from a rotting, toxic one — has long baffled scientists. What about the surfaces are they perceiving? For Dr. Sepela, this question was heightened when her team discovered 26 receptors along the octopuses’ arms that didn’t have a known function. She supposed those receptors were tuned only to molecules found on surfaces, rather than those diffused in water. So she and her colleagues collected swaths of molecules coating healthy and unhealthy crabs and octopus eggs. They grew and cultured the microbes from those surfaces in the lab, then tested 300 microbial strains, one by one, on two of those 26 receptors. During the screening, only particular microbes could switch open the receptors, and these microbes were more abundant on the decaying crabs and dying eggs than on their healthy counterparts. © 2025 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Neuroimmunology
Link ID: 29831 - Posted: 06.18.2025

David Farrier Charles Darwin suggested that humans learned to speak by mimicking birdsong: our ancestors’ first words may have been a kind of interspecies exchange. Perhaps it won’t be long before we join the conversation once again. The race to translate what animals are saying is heating up, with riches as well as a place in history at stake. The Jeremy Coller Foundation has promised $10m to whichever researchers can crack the code. This is a race fuelled by generative AI; large language models can sort through millions of recorded animal vocalisations to find their hidden grammars. Most projects focus on cetaceans because, like us, they learn through vocal imitation and, also like us, they communicate via complex arrangements of sound that appear to have structure and hierarchy. Sperm whales communicate in codas – rapid sequences of clicks, each as brief as 1,000th of a second. Project Ceti (the Cetacean Translation Initiative) is using AI to analyse codas in order to reveal the mysteries of sperm whale speech. There is evidence the animals take turns, use specific clicks to refer to one another, and even have distinct dialects. Ceti has already isolated a click that may be a form of punctuation, and they hope to speak whaleish as soon as 2026. The linguistic barrier between species is already looking porous. Last month, Google released DolphinGemma, an AI program to translate dolphins, trained on 40 years of data. In 2013, scientists using an AI algorithm to sort dolphin communication identified a new click in the animals’ interactions with one another, which they recognised as a sound they had previously trained the pod to associate with sargassum seaweed – the first recorded instance of a word passing from one species into another’s native vocabulary. The prospect of speaking dolphin or whale is irresistible. And it seems that they are just as enthusiastic. In November last year, scientists in Alaska recorded an acoustic “conversation” with a humpback whale called Twain, in which they exchanged a call-and-response form known as “whup/throp” with the animal over a 20-minute period. In Florida, a dolphin named Zeus was found to have learned to mimic the vowel sounds, A, E, O, and U. © 2025 Guardian News & Media Limited

Keyword: Language; Evolution
Link ID: 29821 - Posted: 06.04.2025

Sofia Marie Haley I approach a flock of mountain chickadees feasting on pine nuts. A cacophony of sounds, coming from the many different bird species that rely on the Sierra Nevada’s diverse pine cone crop, fill the crisp mountain air. The strong “chick-a-dee” call sticks out among the bird vocalizations. The chickadees are communicating to each other about food sources – and my approach. Mountain chickadees are a member of the family Paridae, which is known for its complex vocal communication systems and cognitive abilities. Along with my advisers, behavioral ecologists Vladimir Pravosudov and Carrie Branch, I’m studying mountain chickadees at our study site in Sagehen Experimental Forest, outside of Truckee, California, for my doctoral research. I am focusing on how these birds convey a variety of information with their calls. The chilly autumn air on top of the mountain reminds me that it will soon be winter. It is time for the mountain chickadees to leave the socially monogamous partnerships they had while raising their chicks to form larger flocks. Forming social groups is not always simple; young chickadees are joining new flocks, and social dynamics need to be established before the winter storms arrive. I can hear them working this out vocally. There’s an unusual variety of complex calls, with melodic “gargle calls” at the forefront, coming from individuals announcing their dominance over other flock members. Examining and decoding bird calls is becoming an increasingly popular field of study, as scientists like me are discovering that many birds – including mountain chickadees – follow systematic rules to share important information, stringing together syllables like words in a sentence. © 2010–2025, The Conversation US, Inc.

Keyword: Language; Evolution
Link ID: 29807 - Posted: 05.28.2025

Konstantina Kilteni Gargalesis, or tickle, is one of the most trivial yet enigmatic human behaviors. We do not know how a touch becomes ticklish or why we respond to other people’s tickles but not our own. No theory satisfactorily explains why touch on some body areas feels more ticklish than on others or why some people are highly sensitive while others remain unresponsive. Gargalesis is likely the earliest trigger for laughter in life, but it is unclear whether we laugh because we enjoy it. Socrates, Aristotle, Bacon, Galileo, Descartes, and Darwin theorized about tickling, but after two millennia of intense philosophical interest, experimentation remains scarce. This review argues that gargalesis is an exhilarating scientific puzzle with far-reaching implications for developmental, sensorimotor, social, affective, clinical, and evolutionary neuroscience. We reflect on the challenges in defining and eliciting ticklish sensations in the lab and unraveling their neural mechanism, discuss five classic yet unanswered questions about tickle, and suggest directions for future research. Gargalesis, commonly known as tickle, is a very familiar sensation that most of us have experienced at least once in life. Whether actively tickling our babies, family, friends, partners, or pets, or being on the receiving end of a tickle attack, humans undoubtedly engage in tickling behaviors. However, despite its triviality, the scientific understanding of gargalesis is extremely poor. Today, we do not know why certain areas of the body are more ticklish than others and why some people enjoy being tickled, while others dislike it but still burst into laughter. We have also not fully understood why we cannot tickle ourselves and why some people are very ticklish, while others are not responsive at all. Furthermore, the primary function of tickling in humans, as well as in other species, remains a big enigma. Are these questions new, and is that why we do not have any scientific answers yet? Definitely not! Inquiries about the epistemological role of gargalesis have persisted throughout human history, from Ancient Greece to the Renaissance and beyond (1). Socrates (in Plato’s “Philebus”), Aristotle (in “Parts of Animals”), Desiderius Erasmus (in “Adagia”), Francis Bacon (in “Sylva Sylvarum”), Galileo Galilei (in “Il Saggiatore”), René Descartes (in “Treatise on Man” and “The Passions of the Soul”), and Charles Darwin (in “The Expression of the Emotions in Man and Animals”) all theorized about different aspects of gargalesis including its nature and underlying mechanism.

Keyword: Emotions; Evolution
Link ID: 29805 - Posted: 05.24.2025

By Erin Wayman Barbara J. King remembers the first time she met Kanzi the bonobo. It was the late 1990s, and the ape was living in a research center in Georgia. King walked in and told Kanzi she had a present. A small, round object created a visible outline in the front pocket of her jeans. Kanzi picked up a board checkered with colorful symbols and pointed to the one meaning “egg” and then to “question.” An egg? No, not an egg. A ball. But “he asked an on-point question, and even an extremely simple conversation was just amazing,” says King, a biolog­ical anthropologist at William & Mary in Williamsburg, Va. Born in 1980, Kanzi began learn­ing to communicate with symbols as an infant. He ultimately mastered more than 300 symbols, combined them in novel ways and understood spoken English. Kanzi was arguably the most accomplished among a cohort of “talking” apes that scientists in­tensely studied to understand the origins of language and to probe the ape mind. He was also the last of his kind. In March, Kanzi died. “It’s not just Kanzi that is gone; it’s this whole field of inquiry,” says comparative psychologist Heidi Lyn of the University of South Alabama in Mobile. Lyn had worked with Kanzi on and off for 30 years. Kanzi’s death offers an opportu­nity to reflect on what decades of ape-language experiments taught us — and at what cost. A history of ape-language experiments Language — communication marked by using symbols, grammar and syntax — has long been consid­ered among the abilities that make humans unique. And when it comes to delineating the exact boundary separating us from other animals, scientists often turn to our closest living relatives, the great apes. © Society for Science & the Public 2000–2025.

Keyword: Language; Evolution
Link ID: 29797 - Posted: 05.21.2025

By Mikael Angelo Francisco A comic explains the highs and lows of birdsong Mikael Angelo Francisco is a science journalist and illustrator from the Philippines who enjoys writing about paleontology, biodiversity, environment conservation, and science in pop culture. He has written and edited books about media literacy, Filipino scientists, and science trivia. © 2025 NautilusNext Inc.

Keyword: Language; Evolution
Link ID: 29794 - Posted: 05.21.2025

Gemma Conroy Researchers have identified a genetic dial in the human brain that, when inserted in mice, boosts their brain size by about 6.5%.Credit: Sergey Bezgodov/Shutterstock Taking a snippet of genetic code that is unique to humans and inserting it into mice helps the animals to grow bigger brains than usual, according to a report out in Nature today1. The slice of code — a stretch of DNA that acts like a dial to turn up the expression of certain genes — expanded the outer layer of the mouse brain by increasing the production of cells that become neurons. The finding could partially explain how humans evolved such large brains compared with their primate relatives. This study goes deeper than previous work that attempted to unpick the genetic mechanisms behind human brain development, says Katherine Pollard, a bioinformatics researcher at the Gladstone Institute of Data Science and Biotechnology in San Francisco, California. “The story is much more complete and convincing,” she says. How the human brain grew to be so big and complex remains a mystery, says Gabriel Santpere Baró, a neuroscientist who studies genomics at the Hospital del Mar Medical Research Institute in Barcelona, Spain. “We still do not have a definitive answer to how the human brain has tripled in size since our split from chimpanzees” during evolution, he says. Previous studies2,3 have hinted that human accelerated regions (HARs) — short snippets of the genome that are conserved across mammals, but which underwent rapid change in humans after they evolutionarily diverged from chimpanzees — could be key contributors to brain development and size. But the exact mechanisms that underlie the brain-building effects of HARs are yet to be uncovered, says study co-author Debra Silver, a developmental neurobiologist at Duke University in Durham, North Carolina. © 2025 Springer Nature Limited

Keyword: Development of the Brain; Evolution
Link ID: 29791 - Posted: 05.17.2025

By Sydney Wyatt The red nucleus—a pale pink brainstem structure that coordinates limb movements in quadruped animals—also projects to brain areas that shape reward-motivated and action-based movements in people, according to a new functional imaging study. The finding suggests the region, like the cerebral cortex, took on a more complex role over the course of evolution. Many researchers had assumed that brainstem structures remained stuck in evolutionarily ancient roles, says Joan Baizer, professor of physiology and biophysics at the University at Buffalo. Activity in the red nucleus, a structure that emerged once animals began to use limbs for walking, coordinates the speed and accuracy of those movements in rats and helps to control posture in monkeys, previous electrophysiological recordings have shown. And in nonhuman primates, neurons in the red nucleus project to the motor cortex and spinal cord, anatomical studies have demonstrated, seemingly confirming the area’s role in motor function. By contrast, the human red nucleus primarily connects to cortical and subcortical regions involved in action control, reward and motivated behavior, the new work reveals. “If this is such a motor structure, why isn’t it projecting to the spinal cord? That doesn’t really fit with our notion of what this structure is supposed to be doing,” says study investigator Samuel Krimmel, a postdoctoral fellow in Nico Dosenbach’s lab. The new imaging suggests that, at least in people, the neural underpinnings of motivated movement—previously considered to be the role of higher-order brain areas—reach “all the way down into the brainstem,” says Dosenbach, professor of neurology at Washington University School of Medicine, who led the work. The findings were published last month in Nature Communications. © 2025 Simons Foundation

Keyword: Learning & Memory; Evolution
Link ID: 29790 - Posted: 05.17.2025

By Christa Lesté-Lasserre Can a robot arm wave hello to a cuttlefish—and get a hello back? Could a dolphin’s whistle actually mean “Where are you?” And are monkeys quietly naming each other while we fail to notice? These are just a few of the questions tackled by the finalists for this year’s Dolittle prize, a $100,000 award recognizing early breakthroughs in artificial intelligence (AI)-powered interspecies communication. The winning project—announced today—explores how dolphins use shared, learned whistles that may carry specific meanings—possibly even warning each other about danger, or just expressing confusion. The other contending teams—working with marmosets, cuttlefish, and nightingales—are also pushing the boundaries of what human-animal communication might look like. The prize marks an important milestone in the Coller Dolittle Challenge, a 5-year competition offering up to $10 million to the first team that can achieve genuine two-way communication with animals. “Part of how this initiative was born came from my skepticism,” says Yossi Yovel, a neuroecologist at Tel Aviv University and one of the prize’s organizers. “But we really have much better tools now. So this is the time to revisit a lot of our previous assumptions about two-way communication within the animal’s own world.” Science caught up with the four finalists to hear how close we really are to cracking the animal code. This interview has been edited for clarity and length. Cuttlefish (Sepia officinalis and S. bandensis) lack ears and voices, but they apparently make up for this with a kind of sign language. When shown videos of comrades waving their arms, they wave back.

Keyword: Language; Evolution
Link ID: 29788 - Posted: 05.17.2025

Nicola Davis Science correspondent Birds of a feather flock together, so the saying goes. But scientists studying the behaviour of starlings have found their ability to give and take makes their relationships closer to human friendships than previously thought. About 10% of bird species and 5% of mammal species breed “cooperatively”, meaning some individuals refrain from breeding to help others care for their offspring. Some species even help those they are unrelated to. Now researchers studying superb starlings have found the support cuts both ways, with birds that received help in feeding or guarding their chicks returning the favour when the “helper” bird has offspring of its own. Prof Dustin Rubenstein, a co-author of the study from the University of Colombia, said such behaviour was probably necessary for superb starlings as they live in a harsh environment where drought is common and food is limited. “Two birds probably can’t feed their offspring on their own, so they need these helpers to help them,” he said, adding that as each breeding pair produces few offspring, birds must be recruited from outside the family group to help the young survive. “What happens is the non-relatives come into the group, and they breed pretty quickly, usually in the first year, maybe the second year, and then they take some time off and some of the other birds breed – and we never understood why,” said Rubenstein. “But they’re forming these pairwise reciprocal relationships, in the sense that I might help you this year, and then you’ll help me in the future.” The results chime with previous work from Rubenstein and colleagues that found superb starlings living in larger groups have a greater chance of survival and of producing offspring, with the new work suggesting the give-and-take approach helps to stabilise these groups. © 2025 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 29785 - Posted: 05.14.2025

By Jake Buehler Grunts, barks, screams and pants ring through Taï National Park in Cȏte d’Ivoire. Chimpanzees there combine these different calls like linguistic Legos to relay complex meanings when communicating, researchers report May 9 in Science Advances. Chimps can combine and flexibly rearrange pairs of sounds to convey different ideas or meanings, an ability that investigators have not documented in other nonhuman animals. This system may represent a key evolutionary transition between vocal communication strategies of other animals and the syntax rules that structure human languages. “The difference between human language and how other animals communicate is really about how we combine sounds to form words, and how we combine words to form sentences,” says Cédric Girard-Buttoz, an evolutionary biologist at CNRS in Lyon, France. Chimpanzees (Pan troglodytes) were known to have a particularly complicated vocal repertoire, with about a dozen single sounds that they can combine into hundreds of sequences. But it was unclear if the apes used multiple approaches when combining sounds to make new meanings, like in human language. In 2019 and 2020, Girard-Buttoz and his colleagues recorded 53 different adult chimpanzees living in the Taï forest. In all, the team analyzed over 4,300 sounds and described 16 different “bigrams” — short sequences of two sounds, like a grunt followed by a bark, or a panted hoo followed by a scream. The team then used statistical analyses to map those bigrams to behaviors to reveal some of the bigrams’ meanings. The result? Chimpanzees don’t combine sounds in a single, consistent way. They have at least four different methods — a first seen outside of humans. © Society for Science & the Public 2000–2025

Keyword: Language; Evolution
Link ID: 29781 - Posted: 05.11.2025

By Asher Elbein True friends, most people would agree, are there for each other. Sometimes that means offering emotional support. Sometimes it means helping each other move. And if you’re a superb starling — a flamboyant, chattering songbird native to the African savanna — it means stuffing bugs down the throats of your friends’ offspring, secure in the expectation that they’ll eventually do the same for yours. Scientists have long known that social animals usually put blood relatives first. But for a study published Wednesday in the journal Nature, researchers crunched two decades of field data to show that unrelated members of a superb starling flock often help each other raise chicks, trading assistance to one another over years in a behavior that was not previously known. “We think that these reciprocal helping relationships are a way to build ties,” said Dustin Rubenstein, a professor of ecology at Columbia University and an author of the paper. Superb starlings are distinctive among animals that breed cooperatively, said Alexis Earl, a biologist at Cornell University and an author of the paper. Their flocks mix family groups with immigrants from other groups. New parents rely on up to 16 helpers, which bring chicks extra food and help run off predators. Dr. Rubenstein’s lab has maintained a 20-year field study of the species that included 40 breeding seasons. It has recorded thousands of interactions between hundreds of the chattering birds and collected DNA to examine their genetic relationships. When Dr. Earl, then a graduate student in the lab, began crunching the data, she and her colleagues weren’t shocked to see that birds largely helped relatives, the way an aunt or uncle may swoop in to babysit and give parents a break. © 2025 The New York Times Company

Keyword: Evolution; Emotions
Link ID: 29780 - Posted: 05.10.2025

Freda Kreier Some people can function well on little sleep.Credit: Oleg Breslavtsev/Getty Most people need around eight hours of sleep each night to function, but a rare genetic condition allows some to thrive on as little as three hours. In a study published today in the Proceedings of the National Academy of Sciences1, scientists identified a genetic mutation that probably contributes to some people’s limited sleep needs. Understanding genetic changes in naturally short sleepers — people who sleep for three to six hours every night without negative effects — could help to develop treatments for sleep disorders, says co-author Ying-Hui Fu, a neuroscientist and geneticist at the University of California, San Francisco. “Our bodies continue to work when we go to bed”, detoxifying themselves and repairing damage, she says. “These people, all these functions our bodies are doing while we are sleeping, they can just perform at a higher level than we can.” In the 2000s, Fu and her colleagues were approached by people who slept six hours or less each night. After analysing the genomes of a mother and daughter, the team identified a rare mutation in a gene that helps to regulate humans’ circadian rhythm, the internal clock responsible for our sleep–wake cycle. The researchers suggested that this variation contributed to the duo’s short sleep needs. That discovery prompted others with similar sleeping habits to contact the laboratory for DNA testing. The team now knows several hundred naturally short sleepers. Fu and her colleagues have so far identified five mutations in four genes that can contribute to the trait — although different families tend to have different mutations. Short sleeper In the latest study, the researchers searched for new mutations in the DNA of a naturally short sleeper. They found one in SIK3, a gene encoding an enzyme that, among other things, is active in the space between neurons. Researchers in Japan had previously found another mutation in Sik3 that caused mice to be unusually sleepy2. © 2025 Springer Nature Limited

Keyword: Sleep; Genes & Behavior
Link ID: 29778 - Posted: 05.07.2025

Logan S. James It is late at night, and we are silently watching a bat in a roost through a night-vision camera. From a nearby speaker comes a long, rattling trill. The bat briefly perks up and wiggles its ears as it listens to the sound before dropping its head back down, uninterested. Next from the speaker comes a higher-pitched “whine” followed by a “chuck.” The bat vigorously shakes its ears and then spreads its wings as it launches from the roost and dives down to attack the speaker. Bats show tremendous variation in the foods they eat to survive. Some species specialize on fruits, others on insects, others on flower nectar. There are even species that catch fish with their feet. At the Smithsonian Tropical Research Institute in Panama, we’ve been studying one species, the fringe-lipped bat (Trachops cirrhosus), for decades. This bat is a carnivore that specializes in feeding on frogs. Male frogs from many species call to attract female frogs. Frog-eating bats eavesdrop on those calls to find their next meal. But how do the bats come to associate sounds and prey? We were interested in understanding how predators that eavesdrop on their prey acquire the ability to discriminate between tasty and dangerous meals. We combined our expertise on animal behavior, bat cognition and frog communication to investigate. © 2010–2025, The Conversation US, Inc.

Keyword: Hearing; Development of the Brain
Link ID: 29768 - Posted: 05.03.2025

RJ Mackenzie Neuroscientists have identified a brain signal in mice that kick-starts the process of overwriting fearful memories once danger is passed — a process known as fear extinction. The research is at an early stage, but could aid the development of drugs to treat conditions, such as post-traumatic stress disorder (PTSD), that are linked to distressing past experiences. In a study published on 28 April in the Proceedings of the National Academy of Sciences1, the researchers focused on two populations of neurons in a part of the brain called the basolateral amygdala (BLA). These two types of neuron have contrasting effects: one stimulates and the other suppresses fear responses, says co-author Michele Pignatelli, a neuroscientist at Massachusetts Institute of Technology in Cambridge. Until now, scientists didn’t know what activated these neurons during fear extinction, although previous research implicated the neurotransmitter dopamine, released by a specific group of neurons in another part of the brain called the ventral tegmental area (VTA). To investigate this possibility, the authors used fluorescent tracers injected into the brains of mice to show that the VTA sends dopamine signals to the BLA, and that both pro- and anti-fear neurons in the BLA can respond to these signals. They then studied the effects of these circuits on behaviour, using mice that had been genetically modified so that dopamine activity in their brains produced fluorescent light, which allowed the researchers to record the activity of the VTA–BLA connections using fibre optics. They first placed these mice into chambers that delivered mild but unpleasant electrical shocks to their feet, which made them freeze in fear. The next day, they put the mice back in the chambers but did not give them any shocks. Although initially fearful, the mice began to relax after about 15 minutes, and the researchers saw a dopamine current surge through their ‘anti-fear’ BLA neurons. © 2025 Springer Nature Limited

Keyword: Emotions; Stress
Link ID: 29766 - Posted: 04.30.2025

Hannah Thomasy, PhD In recent decades, scientists have demonstrated that prosocial behaviors are not unique to humans, or even to primates. Rats, in particular, have proved surprisingly sensitive to the distress of conspecifics, and will often come to the aid of a fellow rat in trouble. In 2011, researchers showed that when rats were provided with a clear box containing chocolate chips, they usually opened the box and consumed all the chocolate.1 But when one box contained chocolate and another contained a trapped cagemate, the rats were more likely to open both boxes and share the chocolate. But some rats didn’t play as nicely with others. In versions of the test that did not involve chocolate, only a rat and its trapped cagemate, researchers noticed that while some rats consistently freed their compatriots, others did not. In a new Journal of Neuroscience study, neuroscientists Jocelyn Breton at Northeastern University and Inbal Ben-Ami Bartal at Tel-Aviv University explored the behaviors and neural characteristics of helpers and non-helpers.2 They found that helper rats displayed greater social interactions with their cagemates, greater activity in prosocial neural networks, and greater expression of oxytocin receptors in the nucleus accumbens (NAc), providing clues about the mechanisms that govern prosocial behaviour. “We appear to live in an increasingly polarized society where there is a gap in empathy towards others,” said Bartal in a press release. “This work helps us understand prosocial, or helpful, acts better. We see others in distress all the time but tend to help only certain individuals. The similarity between human and rat brains helps us understand the way our brain mediates prosocial decisions.” To undertake these experiments, the researchers first divided the rats into pairs and allowed them to acclimatize to their cagemates for a few weeks. Then they placed the pair in the testing arena, where they allowed one rat to roam free and restrained the other in a clear box that could only be opened from the outside. While they were not trained to open the box, more than half of the rats figured out how to free their trapped companions and did so during multiple days of consecutive testing. © 1986-2025 The Scientist.

Keyword: Emotions; Evolution
Link ID: 29765 - Posted: 04.30.2025

By Nicole M. Baran One of the biggest misconceptions among students in introductory biology courses is that our characteristics are determined at conception by our genes. They believe—incorrectly—that our traits are “immutable.” The much more beautiful, complicated reality is that we are in fact a product of our genes, our environment and their interaction as we grow and change throughout our lives. Nowhere is this truer than in the developmental process of sexual differentiation. Early in development when we are still in the womb, very little about us is “determined.” Indeed, the structures that become our reproductive system start out as multi-potential, capable of taking on many possible forms. A neutral structure called the germinal ridge, for example, can develop into ovaries or testes—the structures that produce reproductive cells and sex hormones—or sometimes into something in between, depending on the molecular signals it receives. Our genes influence this process, of course. But so do interactions among cells, molecules in our body, including hormones, and influences from the outside world. All of these can nudge development in one direction or another. Understanding the well-studied science underlying this process is especially important now, given widespread misinformation about—and the politicization of—sex and gender. I am a neuroendocrinologist, which means that I study and teach about hormones and the brain. In my neuroendocrinology classroom, students learn about the complex, messy process of sexual differentiation in both humans and in birds. Because sexual differentiation in birds is both similar to and subtly different from that in humans, studying how it unfolds in eggs can encourage students to look deeper at how this process works and to question their assumptions. So how does sexual differentiation work in birds? Like us, our feathered friends have sex chromosomes. But their sex chromosomes evolved independently of the X and Y chromosomes of mammals. In birds, a gene called DMRT1 initiates sexual differentiation. (DMRT1 is also important in sexual differentiation in mammals and many other vertebrate animals.) Males inherit two copies of DMRT1 and females inherit only one copy. Reduced dosage of the gene in females leads to the production of the sex hormone estradiol, a potent estrogen, in the developing embryo. © 2025 Simons Foundation

Keyword: Sexual Behavior; Evolution
Link ID: 29759 - Posted: 04.26.2025