Chapter 6. Evolution of the Brain and Behavior

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By Cara Giaimo Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. It’s tough out there for a mouse. Outdoors, its enemies lurk on all sides: owls above, snakes below, weasels around the bend. Indoors, a mouse may find itself targeted by broom-wielding humans or bored cats. Mice compensate with sharp senses of sight, hearing and smell. But they may have another set of tools we’ve overlooked. A paper published last week in Royal Society Open Science details striking similarities between the internal structures of certain small mammal and marsupial hairs and those of man-made optical instruments. In this paper as well as other unpublished experiments, the author, Ian Baker, a physicist who works in private industry, posits that these hairs may act as heat-sensing “infrared antennae” — further cluing the animals into the presence of warm-blooded predators. Although much more work is necessary to connect the structure of these hairs to this potential function, the study paints an “intriguing picture,” said Tim Caro, a professor of evolutionary ecology at the University of Bristol in England who was not involved. Dr. Baker has spent decades working with thermal imaging cameras, which visualize infrared radiation produced by heat. For his employer, the British defense company Leonardo UK Ltd., he researches and designs infrared sensors. But in his spare time he often takes the cameras to fields and forests near his home in Southampton, England, to film wildlife. Over the years, he has developed an appreciation for “how comfortable animals are in complete darkness,” he said. That led him to wonder about the extent of their sensory powers. © 2021 The New York Times Company

Keyword: Pain & Touch; Evolution
Link ID: 28120 - Posted: 12.18.2021

Rafael Yuste Michael Levin In the middle of his landmark book On the Origin of Species, Darwin had a crisis of faith. In a bout of honesty, he wrote, “To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I confess, absurd in the highest degree.” While scientists are still working out the details of how the eye evolved, we are also still stuck on the question of how intelligence emerges in biology. How can a biological system ever generate coherent and goal-oriented behavior from the bottom up when there is no external designer? In fact, intelligence—a purposeful response to available information, often anticipating the future—is not restricted to the minds of some privileged species. It is distributed throughout biology, at many different spatial and temporal scales. There are not just intelligent people, mammals, birds and cephalopods. Intelligent, purposeful problem-solving behavior can be found in parts of all living things: single cells and tissues, individual neurons and networks of neurons, viruses, ribosomes and RNA fragments, down to motor proteins and molecular networks. Arguably, understanding the origin of intelligence is the central problem in biology—one that is still wide open. In this piece, we argue that progress in developmental biology and neuroscience is now providing a promising path to show how the architecture of modular systems underlies evolutionary and organismal intelligence. © 2021 Scientific American

Keyword: Evolution; Development of the Brain
Link ID: 28118 - Posted: 12.18.2021

By Bruce Bower Evidence that cross-continental Stone Age networking events powered human evolution ramped up in 2021. A long-standing argument that Homo sapiens originated in East Africa before moving elsewhere and replacing Eurasian Homo species such as Neandertals has come under increasing fire over the last decade. Research this year supported an alternative scenario in which H. sapiens evolved across vast geographic expanses, first within Africa and later outside it. The process would have worked as follows: Many Homo groups lived during a period known as the Middle Pleistocene, about 789,000 to 130,000 years ago, and were too closely related to have been distinct species. These groups would have occasionally mated with each other while traveling through Africa, Asia and Europe. A variety of skeletal variations on a human theme emerged among far-flung communities. Human anatomy and DNA today include remnants of that complex networking legacy, proponents of this scenario say. It’s not clear precisely how often or when during this period groups may have mixed and mingled. But in this framework, no clear genetic or physical dividing line separated Middle Pleistocene folks usually classed as H. sapiens from Neandertals, Denisovans and other ancient Homo populations. “Middle Pleistocene Homo groups were humans,” says paleoanthropologist John Hawks of the University of Wisconsin–Madison. “Today’s humans are a remix of those ancient ancestors.” © Society for Science & the Public 2000–2021.

Keyword: Evolution; Sexual Behavior
Link ID: 28111 - Posted: 12.15.2021

By Sabrina Imbler The male Bornean rock frog cannot scream over the sound of a waterfall. Instead, he threatens other frogs with his feet. The frog intimidates his male competitors with a can-can-like gesture: kicking his leg up into the air, fully extending his splayed foot, and dragging it down toward the ground. This foot-flagging display may not sound threatening to a human, but its effect has to do with a frog’s visual perception. To a frog, the world contains two kinds of objects: things that are worms, and things that are not worms. If a frog sees a skinny object moving parallel to its long axis — like how a worm travels along the ground — it sees dinner. But if a frog sees a similar shape moving perpendicular its long axis — very unlike a worm — it sees a threat to flee from. Scientists call this latter movement the anti-worm stimulus, and it strikes fear into the hearts of frogs. Frogs likely evolved this visual system to hunt worms and stay safe from larger predators. Now, researchers suggest some male frogs have evolved to take advantage of their froggy brethren’s fears by kicking and lowering their legs in a gesture that looks a lot like an anti-worm signal, as a way to frighten their competition. In a paper published Wednesday in Proceedings of the Royal Society B, researchers reveal that they could amplify the foot-flagging behavior of Bornean rock frogs by giving the frogs a dose of testosterone. The hormone acts on the muscles in the frog’s leg to exaggerate the gesture, meaning the more testosterone coursing through the frog, the bigger the foot-flagging display. This flamboyant foot display, intensified by the sex hormone, suggests the frogs evolved a way to exploit their competitors’ unusual visual system to appear more dangerous to other frogs. © 2021 The New York Times Company

Keyword: Aggression; Hormones & Behavior
Link ID: 28087 - Posted: 11.20.2021

By Bruce Bower A child’s partial skull found in a remote section of a South African cave system has fueled suspicion that an ancient hominid known as Homo naledi deliberately disposed of its dead in caves. An international team led by paleoanthropologist Lee Berger of University of the Witwatersrand, Johannesburg pieced together 28 skull fragments and six teeth from a child’s skull discovered in a narrow opening located about 12 meters from an underground chamber where cave explorers first found H. naledi fossils (SN: 9/10/15). Features of the child’s skull qualify it as H. naledi, a species with an orange-sized brain and skeletal characteristics of both present-day people and Homo species from around 2 million years ago. “The case is building for deliberate, ritualized body disposal in caves by Homo naledi,” Berger said at a November 4 news conference held in Johannesburg. While that argument is controversial, there is no evidence that the child’s skull was washed into the tiny space or dragged there by predators or scavengers (SN: 4/19/16). Berger’s group describes the find in two papers published November 4 in PaleoAnthropology. In one, Juliet Brophy, a paleoanthropologist at Louisiana State University in Baton Rouge and colleagues describe the youngster’s skull. In the other, paleoanthropologist Marina Elliott of Canada’s Simon Fraser University in Burnaby and colleagues detail new explorations in South Africa’s Rising Star cave system. © Society for Science & the Public 2000–2021.

Keyword: Evolution
Link ID: 28068 - Posted: 11.09.2021

By Laura Sanders Brains are like sponges, slurping up new information. But sponges may also be a little bit like brains. Sponges, which are humans’ very distant evolutionary relatives, don’t have nervous systems. But a detailed analysis of sponge cells turns up what might just be an echo of our own brains: cells called neuroids that crawl around the animal’s digestive chambers and send out messages, researchers report in the Nov. 5 Science. The finding not only gives clues about the early evolution of more complicated nervous systems, but also raises many questions, says evolutionary biologist Thibaut Brunet of the Pasteur Institute in Paris, who wasn’t involved in the study. “This is just the beginning,” he says. “There’s a lot more to explore.” The cells were lurking in Spongilla lacustris, a freshwater sponge that grows in lakes in the Northern Hemisphere. “We jokingly call it the Godzilla of sponges” because of the rhyme with Spongilla, say Jacob Musser, an evolutionary biologist in Detlev Arendt’s group at the European Molecular Biology Laboratory in Heidelberg, Germany. Simple as they are, these sponges have a surprising amount of complexity, says Musser, who helped pry the sponges off a metal ferry dock using paint scrapers. “They’re such fascinating creatures.” © Society for Science & the Public 2000–2021.

Keyword: Evolution; Development of the Brain
Link ID: 28065 - Posted: 11.06.2021

By Elizabeth Pennisi Dive among the kelp forests of the Southern California coast and you may spot orange puffball sponges (Tethya californiana)—creatures that look like the miniature pumpkins used for pies. No researchers paid them much mind until 2017, when William Joiner, a neuroscientist at the University of California (UC), San Diego, decided to look into whether sponges take naps. That’s not as silly a question as it seems. Over the past few years, studies in worms, jellyfish, and hydra have challenged the long-standing idea that sleep is unique to creatures with brains. Now, “The real frontier is finding an animal that sleeps that doesn’t have neurons at all,” says David Raizen, a neurologist at the University of Pennsylvania (UPenn) Perelman School of Medicine. Sponges, some of the earliest animals to appear on Earth, fit that description. To catch one snoozing could upend researchers’ definition of sleep and their understanding of its purpose. Scientists have often defined sleep as temporary loss of consciousness, orchestrated by the brain and for the brain’s benefit. That makes studying sleep in brainless creatures controversial. “I do not believe that many of these organisms sleep—at least not the way you and I do,” says John Hogenesch, a genome biologist at Cincinnati Children’s Hospital Medical Center. Calling the restful, unresponsive state seen in jellyfish and hydra “sleeplike” is more acceptable to him. But others in the field are pushing for a much more inclusive view: that sleep evolved not with modern vertebrates as previously assumed, but perhaps a half-billion years ago when the first animals appeared. “I think if it’s alive, it sleeps,” says Paul Shaw, a neuroscientist from Washington University in St. Louis. The earliest life forms were unresponsive until they evolved ways to react to their environment, he suggests, and sleep is a return to the default state. “I think we didn’t evolve sleep, we evolved wakefulness.” © 2021 American Association for the Advancement of Science.

Keyword: Sleep; Evolution
Link ID: 28061 - Posted: 11.03.2021

By Emily Anthes The brain of a fruit fly is the size of a poppy seed and about as easy to overlook. “Most people, I think, don’t even think of the fly as having a brain,” said Vivek Jayaraman, a neuroscientist at the Janelia Research Campus of the Howard Hughes Medical Institute in Virginia. “But, of course, flies lead quite rich lives.” Flies are capable of sophisticated behaviors, including navigating diverse landscapes, tussling with rivals and serenading potential mates. And their speck-size brains are tremendously complex, containing some 100,000 neurons and tens of millions of connections, or synapses, between them. Since 2014, a team of scientists at Janelia, in collaboration with researchers at Google, have been mapping these neurons and synapses in an effort to create a comprehensive wiring diagram, also known as a connectome, of the fruit fly brain. The work, which is continuing, is time-consuming and expensive, even with the help of state-of-the-art machine-learning algorithms. But the data they have released so far is stunning in its detail, composing an atlas of tens of thousands of gnarled neurons in many crucial areas of the fly brain. And now, in an enormous new paper, being published on Tuesday in the journal eLife, neuroscientists are beginning to show what they can do with it. By analyzing the connectome of just a small part of the fly brain — the central complex, which plays an important role in navigation — Dr. Jayaraman and his colleagues identified dozens of new neuron types and pinpointed neural circuits that appear to help flies make their way through the world. The work could ultimately help provide insight into how all kinds of animal brains, including our own, process a flood of sensory information and translate it into appropriate action. © 2021 The New York Times Company

Keyword: Brain imaging; Evolution
Link ID: 28057 - Posted: 10.30.2021

By Emily Anthes The brain of a fruit fly is the size of a poppy seed and about as easy to overlook. “Most people, I think, don’t even think of the fly as having a brain,” said Vivek Jayaraman, a neuroscientist at the Janelia Research Campus of the Howard Hughes Medical Institute in Virginia. “But, of course, flies lead quite rich lives.” Flies are capable of sophisticated behaviors, including navigating diverse landscapes, tussling with rivals and serenading potential mates. And their speck-size brains are tremendously complex, containing some 100,000 neurons and tens of millions of connections, or synapses, between them. Since 2014, a team of scientists at Janelia, in collaboration with researchers at Google, have been mapping these neurons and synapses in an effort to create a comprehensive wiring diagram, also known as a connectome, of the fruit fly brain. The work, which is continuing, is time-consuming and expensive, even with the help of state-of-the-art machine-learning algorithms. But the data they have released so far is stunning in its detail, composing an atlas of tens of thousands of gnarled neurons in many crucial areas of the fly brain. And now, in an enormous new paper, being published on Tuesday in the journal eLife, neuroscientists are beginning to show what they can do with it. By analyzing the connectome of just a small part of the fly brain — the central complex, which plays an important role in navigation — Dr. Jayaraman and his colleagues identified dozens of new neuron types and pinpointed neural circuits that appear to help flies make their way through the world. The work could ultimately help provide insight into how all kinds of animal brains, including our own, process a flood of sensory information and translate it into appropriate action. It is also a proof of principle for the young field of modern connectomics, which was built on the promise that constructing detailed diagrams of the brain’s wiring would pay scientific dividends. “It’s really extraordinary,” Dr. Clay Reid, a senior investigator at the Allen Institute for Brain Science in Seattle, said of the new paper. “I think anyone who looks at it will say connectomics is a tool that we need in neuroscience — full stop.” © 2021 The New York Times Company

Keyword: Brain imaging; Evolution
Link ID: 28055 - Posted: 10.27.2021

Nicola Davis They have fluffy ears, a penetrating stare and a penchant for monogamy. But it turns out that indris – a large, critically endangered species of lemur – have an even more fascinating trait: an unexpected sense of rhythm. Indri indri are known for their distinctive singing, a sound not unlike a set of bagpipes being stepped on. The creatures often strike up a song with members of their family either in duets or choruses, featuring sounds from roars to wails. Now scientists say they have analysed the songs of 39 indris living in the rainforest of Madagascar, revealing that – like humans – the creatures employ what are known as categorical rhythms. These rhythms are essentially distinctive and predictable patterns of intervals between the onset of notes. For example in a 1:1 rhythm, all the intervals are of equal length, while a 1:2 rhythm has some twice as long as those before or after – like the opening bars of We Will Rock You by Queen. “They are quite predictable [patterns], because the next note is going to come either one unit or two whole units after the previous note,” said Dr Andrea Ravignani, co-author of the research from the Max Planck Institute for Psycholinguistics. While the 1:1 rhythms have previously been identified in certain songbirds, the team say their results are the first time categorical rhythms have been identified in a non-human mammal. “The evidence is even stronger than in birds,” said Ravignani. © 2021 Guardian News & Media Limited

Keyword: Animal Communication; Language
Link ID: 28050 - Posted: 10.27.2021

Abby Olena Most people enjoy umami flavor, which is perceived when a taste receptor called T1R1/T1R3 senses the amino acid glutamate. In some other mammals, such as mice, however, this same receptor is much less sensitive to glutamate. In a new study published August 26 in Current Biology, researchers uncover the molecular basis for this difference. They show that the receptor evolved in humans and some other primates away from mostly binding free nucleotides, which are common in insects, to preferentially binding glutamate, which is abundant in leaves. The authors argue that the change facilitated a major evolutionary shift in these primates toward a plant-heavy diet. “The question always comes up about the evolution of umami taste: In humans, our receptor is narrowly tuned to glutamate, and we never had a good answer for why,” says Maude Baldwin, a sensory biologist at the Max Planck Institute for Ornithology in Germany. She was not involved in the new work, but coauthored a 2014 study with Yasuka Toda, who is also a coauthor on the new paper, showing that the T1R1/T1R3 receptor is responsible for sweet taste in hummingbirds. In the new study, the authors find “that this narrow tuning has evolved convergently multiple times [and] that it’s related to folivory,” she says, calling the paper “a hallmark, fantastic study, and one that will become a textbook example of how taste evolution can relate to diet and how to address these types of questions in a rigorous, comprehensive manner.” © 1986–2021 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28037 - Posted: 10.16.2021

By Trishla Ostwal Juan Negro crouched in the shadows just outside a cave, wearing his headlamp. For a brief moment, he wasn’t an ornithologist at the Spanish National Research Council’s Doñana Biological Station in Seville. He was a Neandertal, intent on catching dinner. As he waited in the cold, dark hours of the night, crowlike birds called choughs entered the cave. The “Neandertal” then stealthily snuck in and began the hunt. This idea to role-play started with butchered bird bones. Piles of ancient tool- and tooth-nicked choughs bones have been found in the same caves that Neandertals frequented, evidence suggesting that the ancient hominids chowed down on the birds. But catching choughs is tricky. During the day, they fly far to feed on invertebrates, seeds and fruits. At night though, their behavior practically turns them into sitting ducks. The birds roost in groups and often return to the same spot, even if they’ve been disturbed or preyed on there before. So the question was, how might Neandertals have managed to catch these avian prey? To find out, Negro and his colleagues decided to act like, well, Neandertals. Wielding bare hands along with butterfly nets and lamps — proxy for nets (SN: 04/09/20) and fire (SN: 2/20/14) that Neandertals may have had at hand— teams of two to 10 researchers silently snuck into caves and other spots across Spain, where the birds roost to see how many choughs they could catch. a person inside a building attempting to catch a bird © Society for Science & the Public 2000–2021

Keyword: Evolution
Link ID: 28026 - Posted: 10.09.2021

Linda Geddes Your dog might follow commands such as “sit”, or become uncontrollably excited at the mention of the word “walkies”, but when it comes to remembering the names of toys and other everyday items, most seem pretty absent-minded. Now a study of six “genius dogs” has advanced our understanding of dogs’ memories, suggesting some of them possess a remarkable grasp of the human language. Hungarian researchers spent more than two years scouring the globe for dogs who could recognise the names of their various toys. Although most can learn commands to some degree, learning the names of items appears to be a very different task, with most dogs unable to master this skill. Max (Hungary), Gaia (Brazil), Nalani (Netherlands), Squall (US), Whisky (Norway), and Rico (Spain) made the cut after proving they knew the names of more than 28 toys, with some knowing more than 100. They were then enlisted to take part in a series of livestreamed experiments known as the Genius Dog Challenge. “These gifted dogs can learn new names of toys in a remarkable speed,” said Dr Claudia Fugazza at Eötvös Loránd University in Budapest, who led the research team. “In our previous study we found that they could learn a new toy name after hearing it only four times. But, with such short exposure, they did not form a long-term memory of it.” To further push the dogs’ limits, their owners were tasked with teaching them the names of six, and then 12 new toys in a single week. © 2021 Guardian News & Media Limited

Keyword: Animal Communication; Language
Link ID: 28023 - Posted: 10.06.2021

By Sam Roberts Washoe was 10 months old when her foster parents began teaching her to talk, and five months later they were already trumpeting her success. Not only had she learned words; she could also string them together, creating expressions like “water birds” when she saw a pair of swans and “open flower” to gain admittance to a garden. Washoe was a chimpanzee. She had been born in West Africa, probably orphaned when her mother was killed, sold to a dealer, flown to the United States for use of testing by the Air Force and adopted by R. Allen Gardner and his wife, Beatrix. She was raised as if she were a human child. She craved oatmeal with onions and pumpkin pudding. “The object of our research was to learn how much chimps are like humans,” Professor Gardner told Nevada Today, a University of Nevada publication, in 2007. “To measure this accurately, chimps would be needed to be raised as human children, and to do that, we needed to share a common language.” Washoe ultimately learned some 200 words, becoming what researchers said was the first nonhuman to communicate using sign language developed for the deaf. Professor Gardner, an ethologist who, with his wife, raised the chimpanzee for nearly five years, died on Aug. 20 at his ranch near Reno, Nev. He was 91. His death was announced by the University of Nevada, Reno, where he had joined the faculty in 1963 and conducted his research until he retired in 2010. When scientific journals reported in 1967 that Washoe (pronounced WA-sho), named after a county in Nevada, had learned to recognize and use multiple gestures and expressions in sign language, the news electrified the world of psychologists and ethologists who study animal behavior. © 2021 The New York Times Company

Keyword: Language; Evolution
Link ID: 28013 - Posted: 10.02.2021

By Tara Ellison As menopause hit, I found I wasn’t as interested in intimacy as I used to be. Sex started to feel like a box that needed to be checked a couple of times a week, and that was causing problems in my marriage. But it wasn’t just sex. I felt was slowing down in many areas. After hot flashes in my 40s had sent me running to the gynecologist for help, I’d been using bioidentical creams to balance my declining hormones. When, at 51, I confided to a friend that I’d had limited success with what my doctor prescribed, she said that she was thriving on something called hormonal “pellets.” I grilled her about them and then made an appointment with her practitioner, an internal medicine doctor. He ordered extensive lab work, which showed that my testosterone levels were very low, which can happen with aging. The doctor said I had two options: do nothing, which he said would eventually likely lead to loss of muscle, decreased bone density and a host of other health complications. Or up my testosterone. Testosterone therapy for women is a hotly debated subject. Studies suggest that testosterone can heighten libido in women with hypoactive sexual desire disorder (HSDD), at least in the short term. A recent statement by a group of international medical societies involved with women’s health endorsed the use of testosterone therapy in women for HSDD, and specifically excluded pellets and injectables as “not recommended.” It also cautioned there was not enough data to support the use of testosterone therapy for cognitive performance.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28009 - Posted: 09.29.2021

By Carl Zimmer Ancient human footprints preserved in the ground across the White Sands National Park in New Mexico are astonishingly old, scientists reported on Thursday, dating back about 23,000 years to the Ice Age. The results, if they hold up to scrutiny, would rejuvenate the scientific debate about how humans first spread across the Americas, implying that they did so at a time when massive glaciers covered much of their path. Researchers who have argued for such an early arrival hailed the new study as firm proof. “I think this is probably the biggest discovery about the peopling of America in a hundred years,” said Ciprian Ardelean, an archaeologist at Autonomous University of Zacatecas in Mexico who was not involved in the work. “I don’t know what gods they prayed to, but this is a dream find.” For decades, many archaeologists have maintained that humans spread across North and South America only at the end of the last ice age. They pointed to the oldest known tools, including spear tips, scrapers and needles, dating back about 13,000 years. The technology was known as Clovis, named for the town of Clovis, N.M., where some of these first instruments came to light. The age of the Clovis tools lined up neatly with the retreat of the glaciers. That alignment bolstered a scenario in which Siberian hunter-gatherers moved into Alaska during the Ice Age, where they lived for generations until ice-free corridors opened and allowed them to expand southward. But starting in the 1970s, some archaeologists began publishing older evidence of humanity’s presence in North America. Last year, Dr. Ardelean and his colleagues published a report of stone tools in a mountain cave in Mexico dating back 26,000 years. © 2021 The New York Times Company

Keyword: Evolution
Link ID: 28006 - Posted: 09.25.2021

By Jonathan Lambert Vampire bats may be bloodthirsty, but that doesn’t mean they can’t share a drink with friends. Fights can erupt among bats over gushing wounds bit into unsuspecting animals. But bats that have bonded while roosting often team up to drink blood away from home, researchers report September 23 in PLOS Biology. Vampire bats (Desmodus rotundus) can form long-term social bonds with each other through grooming, sharing regurgitated blood meals and generally hanging out together at the roost (SN: 10/31/19). But whether these friendships, which occur between both kin and nonkin, extend to the bats’ nightly hunting had been unclear. “They’re flying around out there, but we didn’t know if they were still interacting with each other,” says Gerald Carter, an evolutionary biologist at Ohio State University in Columbus. To find out, Carter and his colleague Simon Ripperger of the Museum für Naturkunde in Berlin, built on previous research that uncovered a colony’s social network using bat backpacks. Tiny computer sensors glued to 50 female bats in Tolé, Panama, continuously registered proximity to other sensors both within the roost and outside, revealing when bats met up while foraging. Two common vampire bats feed on a cow near La Chorrera, Panama. It can take 10 to 40 minutes for a bat to bite a small, diamond-shaped wound into an animal’s flesh, and fights can sometimes break out over access to wounds. But researchers found that bats who are friendly back at the roost likely feed together in the field, potentially saving time and energy. © Society for Science & the Public 2000–2021

Keyword: Evolution
Link ID: 28005 - Posted: 09.25.2021

By Kimberly Hickok Seahorses are some of the most dazzling fish in the sea. They’re also the only group of animals in which the males, not the females, go through pregnancy and give birth. Now, new research finds the male’s brood pouch—which can hold up to 1000 baby seahorses at a time—develops and functions like a human placenta. “Evolution is just mind boggling,” says Camilla Whittington, an evolutionary biologist at the University of Sydney who led the new work. The study is the first to thoroughly examine how males nurture their young brood while they’re still in the pouch, says Mari Kawaguchi, an evolutionary biologist at Sophia University in Tokyo. Kawaguchi, who has studied seahorses for some 2 decades, has long suspected pregnant seahorses develop something resembling a placenta. Now, at last, there’s proof. Male seahorses start their path toward fatherhood with a dance. They twirl together with their chosen female under the water, changing colors and linking tails as they pirouette around a shared holdfast. Next, they align the female’s ovipositor with the male’s pouch opening so the female can deposit her eggs. Once the deed is done, the male gently sways to settle the eggs. Ten days to 6 weeks later, depending on the species, the male spends hours in labor, pumping and thrusting to force hundreds of tiny babies out into the water. There, they drift until they are grown. As for dad, he is ready for another round of courtship within hours after birth. But during pregnancy, males have one goal: Provide the embryos with everything they need, from oxygen to nutrients to antibodies. “One of the biggest challenges that all pregnant parents have is getting oxygen to their embryos and carbon dioxide away from the embryos,” Whittington says. “That’s really what motivated our study–how do those baby seahorses actually breathe, if you will, inside the brood pouch?” © 2021 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 28004 - Posted: 09.25.2021

By Carl Zimmer Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. For half a billion years or so, our ancestors sprouted tails. As fish, they used their tails to swim through the Cambrian seas. Much later, when they evolved into primates, their tails helped them stay balanced as they raced from branch to branch through Eocene jungles. But then, roughly 25 million years ago, the tails disappeared. Charles Darwin first recognized this change in our ancient anatomy. But how and why it happened has remained a mystery. Now a team of scientists in New York say they have pinpointed the genetic mutation that may have erased our tails. When the scientists made this genetic tweak in mice, the animals didn’t grow tails, according to a new study that was posted online last week. This dramatic anatomical change had a profound impact on our evolution. Our ancestors’ tail muscles evolved into a hammock-like mesh across the pelvis. When the ancestors of humans stood up and walked on two legs a few million years ago, that muscular hammock was ready to support the weight of upright organs. Although it’s impossible to definitively prove that this mutation lopped off our ancestors’ tails, “it’s as close to a smoking gun as one could hope for,” said Cedric Feschotte, a geneticist at Cornell who was not involved in the study. Darwin shocked his Victorian audiences by claiming that we descended from primates with tails. He noted that while humans and apes lack a visible tail, they share a tiny set of vertebrae that extend beyond the pelvis — a structure known as the coccyx. “I cannot doubt that it is a rudimentary tail,” he wrote. © 2021 The New York Times Company

Keyword: Evolution; Genes & Behavior
Link ID: 28001 - Posted: 09.22.2021

Christie Wilcox If it walks like a duck and talks like a person, it’s probably a musk duck (Biziura lobata)—the only waterfowl species known that can learn sounds from other species. The Australian species’ facility for vocal learning had been mentioned anecdotally in the ornithological literature; now, a paper published September 6 in Philosophical Transactions of the Royal Society B reviews and discusses the evidence, which includes 34-year-old recordings made of a human-reared musk duck named Ripper engaging in an aggressive display while quacking “you bloody fool.” Ripper quacking "you bloody fool" while being provoked by a person separated from him by a fence The Scientist spoke with the lead author on the paper, Leiden University animal behavior researcher Carel ten Cate, to learn more about these unique ducks and what their unexpected ability reveals about the evolution of vocal learning. The Scientist: What is vocal learning? Carel ten Cate: Vocal learning, as it is used in this case, is that animals and humans, they learn their sounds from experience. So they learn from what they hear around them, which will usually be the parents, but it can also be other individuals. And if they don’t get that sort of exposure, then they will be unable to produce species-specific vocalizations, or in the human case, speech sounds and proper spoken language. © 1986–2021 The Scientist.

Keyword: Language; Evolution
Link ID: 27987 - Posted: 09.13.2021