Chapter 6. Evolution of the Brain and Behavior

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Links 1 - 20 of 1987

By Jason Bittel The first mammals first lived some 160 million years ago, in a world ruled by reptiles. And now scientists suggest that hiding in the dark from these terrifying beasts may have left an imprint in mammals’ genes that can still be seen today. Most mammals were no bigger than a squirrel back then, and it would have been much safer to come out only at night, thereby avoiding most of the nastiest maws and claws. A new study published Thursday in Current Biology suggests that living largely in the dark for millions of years might explain how mammals lost a light-sensitive trick that nearly every other living thing possesses. You see, if you were to examine the DNA of a turtle, an orchid, a coral, or even a bacterium, you would find a quirky little set of genes that allows these organisms to repair damage caused by one kind of sunlight with energy absorbed from another kind of sunlight. Think of it like a solar panel that is both harmed and healed by the sun. How is it possible that we lost an evolutionary strategy so advantageous it’s been found in every other living thing where scientists have looked for it? Well, you might blame the dinosaurs—or at least how scary they were. All that time spent in darkness, when most dinosaurs weren’t active, may have affected the way placental mammals evolved. Scientists call this theory the “nocturnal bottleneck,” and it’s supported by various mammalian oddities such as the shape of our eyes, the composition of our retinas, and our heightened senses of smell and hearing—all of which point to a long history of living in the dark.

Keyword: Biological Rhythms; Evolution
Link ID: 25572 - Posted: 10.15.2018

By Ann Gibbons When it comes to gorillas, the males who help females out with their infants get benefits. The benefits? More babies. A new study of male gorillas in the wild in Rwanda has found that those who spend the most time grooming infants and resting with them—others’ offspring as well as their own—have about five times more offspring than males who don’t help out with the little ones. This is surprising, scientists say, because male caretaking isn’t usually considered a smart reproductive strategy in primate species where access to females is intensely competitive. Instead, researchers thought the most successful strategy for males would be to put more time and energy into outcompeting other males for a mate, as chimps do. That strategy still works for many male gorillas, who dominate small harems of females. But in 40% of the groups of mountain gorillas studied at the Dian Fossey Gorilla Fund’s Karisoke Research Center in Volcanoes National Park in Rwanda there is more than one male in a group, sometimes as many as nine. And those males need to be resourceful to get a female’s attention. © 2018 American Association for the Advancement of Science

Keyword: Sexual Behavior; Evolution
Link ID: 25571 - Posted: 10.15.2018

By Laura M. Holson Cat lovers of the world rejoice! In the long-simmering dispute over whether dogs are smarter than cats, a recent study published in the journal Learning & Behavior suggests that dogs are no more exceptional than other animals when it comes to canniness and intelligence. The news is sure to ignite debate (watch the fur fly!) among dog owners and scientists who study canine behavior. The authors reviewed existing studies and data on animal cognition and found that while dogs are smart and trainable, they are not “super smart,” despite what most dog owners will tell you. The idea for the study came about when Stephen Lea, an emeritus professor in the psychology department at the University of Exeter in Britain, was editor of Animal Cognition, a journal that seeks to explain cognition among humans and animals in the context of evolution. Dog research, he said in an interview last week, was quite popular in the 1990s and continues to be so. “I was getting a number of papers showing how remarkable the things were that dogs could do,” he said. When it came to other animals, though, scientific studies on intelligence barely trickled in, despite evidence to suggest that horses, chimpanzees and cats had tricks of their own. “Almost everything a dog claimed to do, other animals could do too,” Dr. Lea said. “It made me quite wary that dogs were special.” Sure, there is Chaser, a Border collie from Spartanburg, S.C., who was trained to understand 1,022 nouns. (His owner, John Pilley, a scientist who studied canine cognition, recently died.) Before that was a Border collie named Rico who learned to recognize the names of 200 items. But beyond those examples, Dr. Lea wondered: Had dog lovers (and scientists, for that matter) imbued their pets with extraordinary capabilities they did not possess? © 2018 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 25544 - Posted: 10.08.2018

By Elizabeth Pennisi The melodious call of many birds comes from a mysterious organ buried deep within their chests: a one-of-a-kind voice box called a syrinx. Now, scientists have concluded that this voice box evolved only once, and that it represents a rare example of a true evolutionary novelty. “It’s something that comes out of nothing,” says Denis Dubuole, a geneticist at the University of Geneva in Switzerland who was not involved with the work. “There is nothing that looks like a syrinx in any related animal groups in vertebrates. This is very bizarre.” Reptiles, amphibians, and mammals all have a larynx, a voice box at the top of the throat that protects the airways. Folds of tissue there—the vocal cords—can also vibrate to enable humans to talk, pigs to grunt, and lions to roar. Birds have larynxes, too. But the organ they use to sing their tunes is lower down—where the windpipe splits to go into the two lungs. The syrinx, named in 1872 after a Greek nymph who was transformed into panpipes, has a similar structure: Both are tubes supported by cartilage with folds of tissue. The oldest known syrinx belongs to a bird fossil some 67 million years old; that’s about the same time all modern bird groups became established. To figure out where the bizarre organ came from, Julia Clarke, a paleontologist at the University of Texas in Austin, who made the syrinx discovery in 2013, assembled a team of developmental biologists, evolutionary biologists, and other researchers. © 2018 American Association for the Advancement of Science.

Keyword: Animal Communication; Evolution
Link ID: 25535 - Posted: 10.06.2018

By Carl Zimmer People of Asian and European descent — almost anyone with origins outside of Africa — have inherited a sliver of DNA from some unusual ancestors: the Neanderthals. These genes are the result of repeated interbreeding long ago between Neanderthals and modern humans. But why are those genes still there 40,000 years after Neanderthals became extinct? As it turns out, some of them may protect humans against infections. In a study published on Thursday, scientists reported new evidence that modern humans encountered new viruses — including some related to influenza, herpes and H.I.V. — as they expanded out of Africa roughly 70,000 years ago. Some of those infections may have been picked up directly from Neanderthals. Without immunity to pathogens they had never encountered, modern humans were particularly vulnerable. “We were actually able to not only say, ‘Yes, modern humans and Neanderthals exchanged viruses,’” said David Enard, an evolutionary biologist at the University of Arizona and co-author of the new paper, published in the journal Cell. “We are able to start saying something about which types of viruses were involved.” But if Neanderthals made us sick, they also helped keep us well. Some of the genes inherited from them through interbreeding also protected our ancestors from these infections, just as they protected the Neanderthals. Lluis Quintana-Murci, a geneticist at the Pasteur Institute in Paris who was not involved in the new research, said that until now, scientists had not dreamed of getting such a glimpse at the distant medical history of our species. “Five years ago, we would never have imagined that,” he said. © 2018 The New York Times Company

Keyword: Evolution; Genes & Behavior
Link ID: 25533 - Posted: 10.05.2018

Susan Milius It’s a lovely notion, but tricky to prove. Still, lemurs sniffing around wild fruits in Madagascar are bolstering the idea that animal noses contributed to the evolution of aromas of fruity ripeness. The idea sounds simple, says evolutionary ecologist Omer Nevo of the University of Ulm in Germany. Plants can use mouth-watering scents to lure animals to eat fruits, and thus spread around the seeds. But are those odors really advertising, or are they just the way fruits happen to smell as they ripen? For some wild figs and a range of other fruits in eastern Madagascar, a strong scent of ripeness does seem to have evolved in aid of allure, Nevo and his colleagues argue October 3 in Science Advances. A lot of fruit collecting and odor chemistry suggest that fruits dispersed by lemurs, with their sensitive noses, change more in scent than fruits that rely more on birds with acute color vision. Earlier studies had sniffed around several species, such as figs. But for a broader look, Nevo and his colleagues analyzed scents from 25 other kinds of fruits as well as five kinds of figs. All grew wild in a “really magnificent” mountainous rainforest preserved as a park in eastern Madagascar, Nevo says. The researchers classified 19 of the plants as depending largely on red-bellied and other local lemurs to spread seeds. Most of these lemurs are red-green color-blind, not great for spotting the ripe fruits among foliage. But the researchers following some lemurs foraging in daylight noticed that sniffing at fruits was a big deal for the primates. |© Society for Science & the Public 2000 - 2018

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 25528 - Posted: 10.04.2018

By Steph Yin Termites are often dismissed as nothing but home-destroying pests, less charismatic than bees, ants or even spiders. In fact, termites have been doing incredible things since the time of dinosaurs, maintaining complex societies with divisions of labor, farming fungus and building cathedrals that circulate air the way human lungs do. Now, add “overthrowing the patriarchy” to that list. In a study published this week in BMC Biology, scientists reported the first discovery of all-female termite societies. Among more than 4,200 termites collected from coastal sites in southern Japan, the researchers did not find a single male. Toshihisa Yashiro, a postdoctoral fellow at the University of Sydney and lead author of the paper, said in an email that he was utterly surprised by the discovery: “I got a headache, because we believed that having both males and females is the rule in termite societies.” The complete loss of males is rare across the animal kingdom, especially in animals with advanced societies. All-female lineages have previously been documented in a few ant and honey bee species, but their colonies are already dominated by queens and female workers. Termites, in contrast, are known for having colonies in which males and females both participate in social activities. Dr. Yashiro’s research is the first, in other words, to demonstrate that males can be discarded from advanced societies in which they once played an active role. His team collected 74 mature colonies of Glyptotermes nakajimai, a termite that nests in drywood, from 15 sites in Japan. Thirty-seven of the colonies were asexual and exclusively female, while the rest were mixed-sex. Egg-laying queens in asexual colonies stored no sperm in their reproductive organs and laid unfertilized eggs. © 2018 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 25505 - Posted: 09.29.2018

By JoAnna Klein Plants have no eyes, no ears, no mouth and no hands. They do not have a brain or a nervous system. Muscles? Forget them. They’re stuck where they started, soaking up the sun and sucking up nutrients from the soil. And yet, when something comes around to eat them, they sense it. And they fight back. How is this possible? “You’ve got to think like a vegetable now,” says Simon Gilroy, a botanist who studies how plants sense and respond to their environments at the University of Wisconsin-Madison. “Plants are not green animals,” Dr. Gilroy says. “Plants are different, but sometimes they’re remarkably similar to how animals operate.” To reveal the secret workings of a plant’s threat communication system for a study published Thursday in Science, Masatsugu Toyota (now a professor at Saitama University in Japan) and other researchers in Dr. Gilroy’s lab sent in munching caterpillars like in the video above. They also slashed leaves with scissors. They applied glutamate, an important neurotransmitter that helps neurons communicate in animals. In these and about a dozen other videos, they used a glowing, green protein to trace calcium and accompanying chemical and electrical messages in the plant. And they watched beneath a microscope as warnings transited through the leafy green appendages, revealing that plants aren’t as passive as they seem. The messages start at the point of attack, where glutamate initiates a wave of calcium that propagates through the plant’s veins, or plumbing system. The deluge turns on stress hormones and genetic switches that open plant arsenals and prepare the plant to ward off attackers — with no thought or movement. © 2018 The New York Times Company

Keyword: Evolution
Link ID: 25450 - Posted: 09.14.2018

By Emily Underwood On a moonless night, the light that reaches Earth is a trillion–fold less than on a sunny day. Yet most mammals still see well enough to get around just fine—even without the special light-boosting membranes in the eyes of cats and other nocturnal animals. A new study in mice hints at how this natural night vision works: Motion-sensing nerve cells in the retina temporarily change how they wire to each other in dark conditions. The findings might one day help visually impaired humans, researchers say. Scientists already knew a bit about how night vision works in rabbits, mice, humans, and other mammals. Mammalian retinas can respond to “ridiculously small” numbers of photons, says Joshua Singer, a neuroscientist at the University of Maryland in College Park who was not involved in the new study. A single photon can activate a light-sensitive cell known as a rod cell in the retina, which sends a minute electrical signal to the brain through a ganglion cell. One kind of ganglion cell specializes in motion detection—a vital function if you’re a mouse being hunted by an owl, or a person darting to avoid oncoming traffic. Some of these direction-selective ganglion cells (DSGCs) get excited only when an object is moving upward. Others fire only when objects are moving down, or to the left or right. Together, the cells decide where an object is headed and relay that information to the brain, which decides how to act. © 2018 American Association for the Advancement of Science

Keyword: Vision; Evolution
Link ID: 25449 - Posted: 09.14.2018

By Carl Zimmer How generous is an ape? It’s a hard question for scientists to tackle, but the answer could tell us a lot about ourselves. People in every culture can be generous, whether they’re loaning a cellphone to an office mate or sharing an antelope haunch with a hungry family. While it’s easy to dwell on our capacity for war and violence, scientists see our generosity as a remarkable feature of our species. “One of the things that stands out about humans is how helpful we are,” said Christopher Krupenye, a primate behavior researcher at the University of St. Andrews in Scotland. This generosity may have been crucial to the survival of our early ancestors who lived in small bands of hunter-gatherers. “When our own attempts to find food are unsuccessful, we rely on others to share food with us — otherwise we starve,” said Jan Engelmann, a researcher at Göttingen University. To understand the origin of this impulse — known as prosociality — a number of researchers have turned to our closest living relatives. For example, a new study involving bonobo apes suggests that the roots of human generosity run deep, but only came into full flower over the course of the evolution of our species. Roughly seven million years ago, our lineage split from the ancestors of chimpanzees and their cousin species, bonobos. Chimpanzees and bonobos share a common ancestor that lived about two million years ago. These two closely related species of apes look almost identical to the untrained eye. But they have evolved some intriguing differences in their behavior, including which objects — food or tools — prompt them to behave with generosity. © 2018 The New York Times Company

Keyword: Emotions; Evolution
Link ID: 25442 - Posted: 09.12.2018

By James Gorman Chalk up another achievement for parrots, with an odd twist that raises questions about whether the experimenters or the birds know best. Anastasia Krasheninnikova and colleagues at the Max Planck Institute for Ornithology in Germany tested four species of parrots in an experiment that required trading tokens for food and recently reported their findings in the journal Scientific Reports. Would the birds resist an immediate reward to trade for something better? Many species have shown the ability to hold off on an immediate treat — like a dry corn kernel — for something tastier later on, like a bit of walnut. Chimpanzees, monkeys and cockatoos, among other species, can defer gratification. But using tokens for trading had not been tried before in birds, Dr. Krasheninnikova said. Here’s how it worked. First the birds, great green macaws, blue-throated macaws, blue-headed macaws and African grey parrots, learned that they could barter tokens for foods of different value — to the birds, that is. A metal hoop could be traded for a piece of dry corn, the lowest value food, a metal bracket for a medium value sunflower seed and a plastic ring for the highest value food, a piece of shelled walnut. The birds were then offered various choices, like a piece of corn or the ring. They all reliably chose to forego the corn and take the ring. Then they were able to trade the ring for a piece of walnut. © 2018 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 25437 - Posted: 09.11.2018

By Jake Buehler Whether it’s avoiding the slap of a flyswatter or shooting a tongue out at just the right moment to capture prey, fast reflexes can mean the difference between life and death in the animal kingdom. But a new study finds that not all reflexes are created equal: Larger animals are slower on the draw than smaller ones and because of that, they can’t move nearly as fast as they should be able to. When it comes to reflexes, there’s no doubt that bigger animals are a little slower. Big animals have longer neurons, and that means more time for a signal to travel from the spine to a leg muscle, for example. But nerve speed isn’t the only thing that slows down reflexes. So in the new study, researchers decided to look at myriad factors, like how fast muscles can generate force. They combed through data from other studies on electrically stimulated nerves and muscles in animals as small as shrews to as large as elephants. They also looked at the gaits of these mammals to calculate how long their stride and foot-down positions were in relation to their body size, which allowed researchers to look at how relatively quick their reflexes are. As size scales up, so does the total time it takes for muscles to respond, the team reported yesterday in the Proceedings of the Royal Society B. Large mammals experience a delay between nerve firing and muscle movement that is more than 15 times longer than small mammals. But, relative to the speed of their body movements, that delay is only twice as long—which means to compensate for slow signals, they’re moving more slowly. If this didn’t happen, a running 250-kilogram elk would be a cartoonish blur of legs, taking steps far faster than its reflexes could ever respond to. Call it a biological speed limit. © 2018 American Association for the Advancement of Science

Keyword: Evolution
Link ID: 25398 - Posted: 08.31.2018

By Steph Yin Pipefish, along with their cousins sea horses and sea dragons, defy convention in love and fertility. In a striking role reversal, fathers give birth instead of mothers. During courtship, females pursue males with flashy ornaments or elaborate dances, and males tend to be choosy about which females’ eggs they’ll accept. Once pregnant, these gender-bending fathers invest heavily in their young, supplying embryos with nutrients and oxygen through a setup similar to the mammalian placenta. But this investment may also be cruelly conditional, according to a new study in Proceedings of the Royal Society B. Studying pipefish, scientists found evidence that pregnant fathers spontaneously abort or divert fewer resources to their embryos when faced with the prospects of a superior mate — in this case, an exceptionally large female. The researchers named their finding the “woman in red” effect, after the eponymous 1984 Gene Wilder film about a married man’s obsession with a woman in a red dress that becomes damaging to his family life. The reported effect is an interesting instance of sexual conflict, which is ubiquitous among animals, said Sarah Flanagan, a pipefish expert at the University of Canterbury in New Zealand. If you’re a romantic, you might think of mating as harmonious. But in nature, reproduction is more often a vicious power struggle between mothers and fathers with competing interests. A maternal analogue to the “woman in red” effect occurs among mice. Males are willing to kill a female’s offspring, if they are unrelated to him, before mating with her. In anticipation, a pregnant mother may terminate her pregnancy when exposed to a new male, rather than spending resources on doomed offspring. © 2018 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 25378 - Posted: 08.25.2018

By Carl Zimmer In a limestone cave nestled high above the Anuy River in Siberia, scientists have discovered the fossil of an extraordinary human hybrid. The 90,000-year-old bone fragment came from a female whose mother was Neanderthal, according to an analysis of DNA discovered inside it. But her father was not: He belonged to another branch of ancient humanity known as the Denisovans. Scientists have been recovering genomes from ancient human fossils for just over a decade. Now, with the discovery of a Neanderthal-Denisovan hybrid, the world as it was tens of thousands of years ago is coming into remarkable new focus: home to a marvelous range of human diversity. In 2010, researchers working in the Siberian cave, called Denisova, announced they had found DNA from a scrap of bone representing an unknown group of humans. Subsequent discoveries in the cave confirmed that the Denisovans were a lineage distinct from modern humans. Scientists can’t yet say what Denisovans looked like or how they behaved, but it’s clear they were separated from Neanderthals and modern humans by hundreds of thousands of years of evolution. Until now, scientists had indirect clues that Neanderthals, Denisovans and modern humans interbred, at least a few times. But the new study, published on Wednesday in the journal Nature, offers clear evidence. “They managed to catch it in the act — it’s an amazing discovery,” said Sharon Browning, a statistical geneticist at the University of Washington who was not involved in the new study. © 2018 The New York Times Company

Keyword: Evolution; Genes & Behavior
Link ID: 25367 - Posted: 08.23.2018

James R. Howe VI In May 2007, Wim Hof went on a short hike in well-worn summer clothes, a pair of shorts and open-toed sandals. But it may have been a poor choice: his foot started to hurt and he had to turn back after four and a half miles. There are two crucial details to this story: Hof began his hike at Base Camp on Mount Everest, and the pain in his foot was caused by severe frostbite. He had reason to think he could withstand the extreme conditions; Wim Hof is also known as “The Iceman,” holder of 26 world records and one of the most successful extreme athletes of all time. He attributes his success to a breathing method that he thinks exploits his “reptilian brain,” helping him acquire a superhuman tolerance to punishing cold. According to some, tricks like these fool the lizard part of your brain – the more primitive, unconscious mind – and can be used to make us vulnerable to marketing, lose us money, or maybe even elect Donald Trump. Paul MacLean first proposed the idea of the “lizard brain” in 1957 as part of his triune brain concept, theorizing that the human brain supposedly consists of three sections, nested based on their evolutionary age. He believed the neocortex, which he thought arose in primates, is the largest, outermost, and newest part of the human brain: It houses our conscious mind and handles learning, language, and abstract thought. MacLean thought the older, deeper limbic system – which mediates emotion and motivation – began in mammals. Finally, he traced the brainstem and basal ganglia back to primordial reptiles, theorizing that they controlled our reflexes, as well as our four major instincts: to fight, flee, feed, and fornicate.

Keyword: Evolution
Link ID: 25356 - Posted: 08.21.2018

Jules Howard And so, the killer whale known as J35 is back to her old self. She is no longer carrying the dead body of a calf she held aloft in the water for more than two weeks. Her so-called tour of grief has ended, to the relief of a global audience who had become wrapped up in this heart-wrenching animal drama. Great news, right? Sure. Yet I have a strange feeling in my stomach. It’s a familiar one. The pedant in me is stirring, eager to get us to consider what we know about animals and what we don’t – and may never – know about their lives. It isn’t my aim to belittle J35 and her apparent pain, far from it. It’s rather to make sure we don’t accidentally dilute the emotions of a killer whale by making it all about us. First, I have form on this issue. A while ago, I published a book called Death on Earth and episodes of apparent animal grief was one of the areas upon which I focused. During my research, I drew up a list of all sorts of anecdotes about animals labelled (by respectable researchers) as evidence of “mourning” and “grief”. These included police dogs pawing at their master’s coffins, macaques resuscitating fallen loved ones and turtles appearing on beaches to mourn at makeshift graves made by humans for the turtles that didn’t make it. I was told by members of the public on Twitter about dogs going off food after losing kennel-mates and horses burying dead stablemates in hay and I was reminded regularly of those BBC documentaries featuring elephants in apparent (but I would argue edited) tears at the loss of a loved one. © 2018 Guardian News and Media Limited

Keyword: Emotions; Evolution
Link ID: 25343 - Posted: 08.17.2018

Yao-Hua Law What can males wear to look sexier? For zebra finches, the trick seemed simple: add a dash of red to their legs. Research conducted in the 1980s found that slipping red bands onto the legs of male birds turned them into sex magnets. Those studies became iconic in sexual selection research because they provided something rare in the discipline: strong, consistent effects. But data accumulated in recent years question these influential findings. Zebra finches (Taeniopygia guttata) are native Australian birds with a bright red-orange beak. They form monogamous breeding pairs in which the male and female cooperate to raise young. Easy to rear in captivity, zebra finches are model organisms for research in cognition and sexual selection. In the 1980s, ornithologist Nancy Burley, then at the University of Illinois, found that placing plastic leg bands of different colors—used by scientists to identify individual birds—on the legs of zebra finches affected the birds’ chances of mating. Burley reported, first in Science and then in other leading journals, that females preferred red-banded males and disliked green-banded males. Females also spent more time caring for nestlings sired by red-banded males. Burley’s results inspired subsequent research in female choice and maternal effects. But results contradictory to Burley’s began to emerge in the late 1990s. And this March, Wolfgang Forstmeier of the Max Planck Institute for Ornithology and colleagues published the strongest disagreement yet. Forstmeier’s lab ran eight experiments and analyzed unpublished data from four other labs and found no effects of leg-band colors on the reproductive success of male or female zebra finches. The new study also included a meta-analysis of 39 published studies, including 22 that supported leg-band color effects. The meta-analysis found that effect sizes shrank as sample sizes increased—a sign of selective reporting. © 1986 - 2018 The Scientist

Keyword: Sexual Behavior; Evolution
Link ID: 25333 - Posted: 08.15.2018

By Victoria Gill Science correspondent, BBC News Our primate cousins have surprised and impressed scientists in recent years, with revelations about monkeys' tool-using abilities and chimps' development of complex sign language. But researchers are still probing the question: why are we humans the only apes that can talk? That puzzle has now led to an insight into how different non-human primates' brains are "wired" for vocal ability. A new study has compared different primate species' brains. It revealed that primates with wider "vocal repertoires" had more of their brain dedicated to controlling their vocal apparatus. That suggests that our own speaking skills may have evolved as our brains gradually rewired to control that apparatus, rather than purely because we're smarter than non-human apes. Humans and other primates have very similar vocal anatomy - in terms of their tongues and larynx. That's the physical machinery in the throat which allows us to turn air into sound. So, as lead researcher Dr Jacob Dunn from Anglia Ruskin University in Cambridge explained, it remains a mystery that only human primates can actually talk. "That's likely due to differences in the brain," Dr Dunn told BBC News, "but there haven't been comparative studies across species." So how do our primate brains differ? That comparison is exactly what Dr Dunn and his colleague Prof Jeroen Smaers set out to do. They ranked 34 different primate species based on their vocal abilities - the number of distinct calls they are known to make in the wild. They then examined the brain of each species, using information from existing, preserved brains that had been kept for research. © 2018 BBC

Keyword: Language; Evolution
Link ID: 25314 - Posted: 08.10.2018

By Bilal Choudhry Killifish are a family of freshwater fish that have evolved to survive in the most difficult of situations. Here in the United States, for instance, the Atlantic killifish is known for having adapted to live in heavily polluted places like the Lower Passaic River. But in small murky puddles that come after heavy rains in parts of East Africa, another killifish, called Nothobranchius furzeri, or the African annual fish, has developed its own unique adaptations to its environment. Its embryos are able to enter a state of diapause, similar to hibernation in bears, when conditions aren’t right. It turns out that entering dormancy isn’t the only thing that’s unusual about this African killifish. In a paper published on Monday in Current Biology, a team of Czech researchers report that N. furzeri has the quickest known rate of sexual maturity of any vertebrate — approximately two weeks. By studying the fish’s unusual life cycle, they hope to gain insights into the process of aging in other vertebrates, including us. Dr. Martin Reichard, a biologist who is studying the evolution of aging at the Czech Academy of Sciences’ Institute of Vertebrate Biology, led a team of colleagues to Mozambique to study the fish’s developmental stages in the wild. There, they were able to observe embryos buried in the sand that had entered a dormant state. They also documented their maturation after rainfall. When N. furzeri receive cues from their environment, they can be flexible in sexual development. Under these circumstances, their embryos enter a stage of dormancy called embryonic diapause, a reproductive strategy that extends their gestational period and helps them survive unfavorable conditions, like a dry season. But when it rains, they undergo rapid growth, going from juvenile fish to mature adults that are able to reproduce in about two weeks. © 2018 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 25304 - Posted: 08.07.2018

By Susana Martinez-Conde The house cricket (Acheta domesticus) walked around the arena comfortably, certain of its surroundings. It looked about, perhaps hoping for food or mates, ignoring the scattered, browning, dead leaves. On previous visits to the arena, the cricket had been wary of the dead leaves, not knowing what to make of them. Then, after a prudent interval, it had ventured to feel them with its segmented antennae—tentatively at first, and later with growing confidence. Once the cricket determined the leaves were neither edible nor harmful, it quickly lost interest in them. Now it rarely bothered to explore the leaves, but took no great pains to avoid them either. The cricket’s conviction about the safety of the leaves was its fatal mistake: on this visit, one seemingly dead leaf lying on the arena was no such, but a masquerading ghost mantis (Phyllocrania paradoxa) waiting in ambush. Unaware of the concealed peril, the cricket drew ever closer to the predator. That’s when the mantis struck forth, grasping the cricket by one of its long jumping legs. As the cricket struggled against the mantis’ clutch, the predator started to feed. Dr John Skelhorn, Lecturer in Animal Cognition, has witnessed dozens of similar life-and-death encounters in his lab at Newcastle University’s Institute of Neuroscience. Skelhorn and his colleagues previously found that some animals masquerade as inanimate, inedible objects, to look less appealing to potential predators. Some examples include the orb web spider (Cyclosa ginnaga) and the larva of the giant swallowtail butterfly (Papilio cresphontes), both of which masquerade as bird droppings, and the larva of the feathered thorn moth (Selenia dentaria), which masquerades as a twig. © 2018 Scientific American

Keyword: Vision; Evolution
Link ID: 25299 - Posted: 08.06.2018