Chapter 6. Evolution of the Brain and Behavior

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By Erik Vance The world’s smallest arachnid, the Samoan moss spider, is at a third of a millimeter nearly invisible to the human eye. The largest spider in the world is the goliath birdeater tarantula, which weighs 5 ounces and is about the size of a dinner plate. For reference, that is about the same difference in scale between that same tarantula and a bottlenose dolphin. And yet the bigger spider does not act in more complex ways than its tiny counterpart. “Insects and spiders and the like—in terms of absolute size—have among the tiniest brains we’ve come across,” says William Wcislo, a scientist at the Smithsonian Tropical Research Institute in Panama City. “But their behavior, as far as we can see, is as sophisticated as things that have relatively large brains. So then there’s the question: How do they do that?” No one would argue that a tarantula is as smart as a dolphin or having a really big brain is not an excellent way to perform complicated tasks. But a growing number of scientists are asking the question: Is it the only way? Do you need a big brain to hunt elusive prey, design complicated structures or produce complex social dynamics? For generations scientists have wondered how intelligent creatures developed large brains to perform complicated tasks. But Wcislo is part of a small community of scientists less interested in how brains have grown than how they have shrunk and yet shockingly still perform tasks as well or better than similar species that are much larger in size. In other words, it’s what scientists call brain miniaturization, not unlike the scaling down in size of the transistors in a computer chip. This research, in fact, may hold clues to innovative design strategies that engineers might incorporate in future generations of computers. © 2017 Scientific American

Keyword: Miscellaneous
Link ID: 23418 - Posted: 03.29.2017

By Lizzie Wade Ask any biologist what makes primates special, and they’ll tell you the same thing: big brains. Those impressive noggins make it possible for primates from spider monkeys to humans to use tools, find food, and navigate the complex relationships of group living. But scientists disagree on what drove primates to evolve big brains in the first place. Now, a new study comes to an unexpected conclusion: fruit. “The paper is enormously valuable,” says Richard Wrangham, a biological anthropologist at Harvard University who was not involved in the work. For the last 20 years, many scientists have argued that primates evolved bigger brains to live in bigger groups, an idea known as the “social brain hypothesis.” The new study’s large sample size and robust statistical methods suggest diet and ecology deserve more attention, Wrangham says. But not everyone is convinced. Others say that although a nutrient-rich diet allows for bigger brains, it wouldn’t be enough by itself to serve as a selective evolutionary pressure. When the authors compare diet and social life, “they’re comparing apples and oranges,” says Robin Dunbar, an evolutionary psychologist at the University of Oxford in the United Kingdom and one of the original authors of the social brain hypothesis. Alex DeCasien, the new study’s author, didn’t set out to shake up this decades-long debate. The doctoral student in biological anthropology at New York University in New York City wanted to tease out whether monogamous primates had bigger or smaller brains than more promiscuous species. She collected data about the diets and social lives of more than 140 species across all four primate groups—monkeys, apes, lorises, and lemurs—and calculated which features were more likely to be associated with bigger brains. To her surprise, neither monogamy nor promiscuity predicted anything about a primate’s brain size. Neither did any other measure of social complexity, such as group size. The only factor that seemed to predict which species had larger brains was whether their diets were primarily leaves or fruit, DeCasien and her colleagues report today in Nature Ecology & Evolution. © 2017 American Association for the Advancement of Science

Keyword: Evolution; Genes & Behavior
Link ID: 23416 - Posted: 03.28.2017

If your parrot is feeling glum, it might be tweetable. Wild keas spontaneously burst into playful behaviour when exposed to the parrot equivalent of canned laughter – the first birds known to respond to laughter-like sounds. The parrots soared after one another in aerobatic loops, exchanged foot-kicking high fives in mid-air and tossed objects to each other, in what seems to be emotionally contagious behaviour. And when the recording stops, so does the party, and the birds go back to whatever they had been doing. We already knew that these half-metre-tall parrots engage in playful behaviour, especially when young. What’s new is that a special warbling call they make has been shown to trigger behaviour that seems to be an equivalent of spontaneous, contagious laughter in humans. Moreover, it’s not just the young ones that respond, adults of both sexes join in the fun too. Raoul Schwing of the University of Veterinary Medicine in Vienna, Austria, and his team played 5-minute recordings to gatherings of between two and a dozen wild keas on a mountainside of New Zealand’s Arthur’s Pass National Park, on the southern island. The group played recordings of the warble sound, or other sounds, including two other frequent kea sounds – a screech and a whistle – plus the alarm call of a local robin species and a bland tone. © Copyright Reed Business Information Lt

Keyword: Emotions; Evolution
Link ID: 23400 - Posted: 03.24.2017

By Sam Wong It takes brains to choose a good partner. In one of the first experiments to look at the cognitive demands of choosing a mate, female guppies with big brains showed a preference for more colourful males, while those with smaller brains showed no preference. In guppies, like most animals, females are choosy about who to mate with, since they invest more in their offspring than males, which don’t help care for them. They tend to prefer males with striking colour patterns and big tails, traits that have been linked to good foraging ability and health. By choosing a male with these qualities, female guppies give their offspring a good chance of inheriting the same useful traits. Despite this, females often go on to make different choices. Alberto Corral López and colleagues at Stockholm University wanted to find out if brain size could account for this. Corral López and his team tested 36 females bred to have large brains, 36 bred to have small brains, and 16 females similar to guppies found in the wild. Previous studies have shown that large-brained guppies perform better in cognitive tests, suggesting that they are smarter. Each female was given the opportunity to associate with two males, one more colourful than the other. Females are known to spend more time close to males they would prefer to mate with, so the team timed how long they spent with each male. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Evolution
Link ID: 23394 - Posted: 03.23.2017

by Helen Thompson Aside from being adorable, sea otters and Indo-Pacific bottlenose dolphins share an ecological feat: Both species use tools. Otters crack open snails with rocks, and dolphins carry cone-shaped sponges to protect their snouts while scavenging for rock dwelling fish. Researchers have linked tool use in dolphins to a set of differences in mitochondrial DNA — which passes from mother to offspring — suggesting that tool-use behavior may be inherited. Biologist Katherine Ralls of the Smithsonian Institution in Washington, D.C., and her colleagues looked for a similar pattern in otters off the California coast. The team tracked diet (primarily abalone, crab, mussels, clams, urchins or snails) and tool use in the wild and analyzed DNA from 197 individual otters. Otters that ate lots of hard-shelled snails — and used tools most frequently — rarely shared a common pattern in mitochondrial DNA, nor were they more closely related to other tool-users than any other otter in the population. Unlike dolphins, sea otters may all be predisposed to using tools because their ancestors probably lived off mollusks, which required cracking open. However, modern otters only take up tools when their diet requires them, the researchers report March 21 in Biology Letters. |© Society for Science & the Public 2000 - 2017.

Keyword: Evolution
Link ID: 23386 - Posted: 03.22.2017

Cris Ledón-Rettig Picture a lion: The male has a luxuriant mane, the female doesn’t. This is a classic example of what biologists call sexual dimorphism – the two sexes of the same species exhibit differences in form or behavior. Male and female lions pretty much share the same genetic information, but look quite different. We’re used to thinking of genes as responsible for the traits an organism develops. But different forms of a trait – mane or no mane – can arise from practically identical genetic information. Further, traits are not all equally sexually dimorphic. While the tails of peacocks and peahens are extremely different, their feet, for example, are pretty much the same. Understanding how this variation of form – what geneticists call phenotypic variation – arises is crucial to answering several scientific questions, including how novel traits appear during evolution and how complex diseases emerge during a lifetime. So researchers have taken a closer look at the genome, looking for the genes responsible for differences between sexes and between traits within one sex. The key to these sexually dimorphic traits appears to be a kind of protein called a transcription factor, whose job it is to turn genes “on” and “off.” In our own work with dung beetles, my colleagues and I are untangling how these transcription factors actually lead to the different traits we see in males and females. A lot of it has to do with something called “alternative gene splicing” – a phenomenon that allows a single gene to encode for different proteins, depending on how the building blocks are joined together. © 2010–2017, The Conversation US, Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 23380 - Posted: 03.21.2017

Jon Hamilton An orangutan named Rocky is helping scientists figure out when early humans might have uttered the first word. Rocky, who is 12 and lives at the Indianapolis Zoo, has shown that he can control his vocal cords much the way people do. He can learn new vocal sounds and even match the pitch of sounds made by a person. "Rocky, and probably other great apes, can do things with their vocal apparatus that, for decades, people have asserted was impossible," says Rob Shumaker, the zoo's director, who has studied orangutans for more than 30 years. Rocky's abilities suggest that our human ancestors could have begun speaking 10 million years ago, about the time humans and great apes diverged, Shumaker says. Until now, many scientists thought that speech required changes in the brain and vocal apparatus that evolved more recently, during the past 2 million years. The vocal abilities of orangutans might have gone undetected had it not been for Rocky, an ape with an unusual past and a rare relationship with people. Rocky was separated from his mother soon after he was born, and spent his early years raised largely by people, and working in show business. "He was certainly the most visible orangutan in entertainment at the time," says Shumaker. "TV commercials, things like that."

Keyword: Language; Evolution
Link ID: 23354 - Posted: 03.14.2017

If I was the late Andy Rooney, I’d say “You know what really bothers me? When science shows some facts about nature, and then someone rejects those facts because they’re inconvenient or uncomfortable for their ideology.” Indeed, when people ignore such inconvenient truths, it not only makes their cause look bad, but can produce palpable harm. Case in point: the damage that the Russian charlatan-agronomist Lysenko did to Soviet agriculture under Stalin. Rejecting both natural selection and modern genetics, Lysenko made all sorts of wild promises about improving Soviet agriculture based on bogus treatment of plants that would supposedly change their genetics. It not only didn’t work, failing to relieve Russia of its chronic famines, but Lyesnko’s Stalin-supported resistance to modern (“Western”) genetics led to the imprisonment and even the execution of really good geneticists and agronomists like Niklolia Vavilov. The ideological embrace of an unevidenced but politically amenable view of science set back Russian genetics for decades. Other cases in point: the denial of evolution by creationists, and of anthropogenic global warming by conservatives. I needn’t belabor these. But the opposition to research on group and sex differences continues. One of its big exponents is the author Cordelia Fine, who has written two books with the explicit aim of showing that there are no reliably accepted evolved and biological differences in behavior between men and women. I read her first book, Delusions of Gender, and found it a mixed bag: some of her targets did indeed do bad science, and she properly called them out; but the book was also tendentious, and wasn’t objective about other studies. I’m now about to read her second book, Testosterone Rex: Myths of Sex, Science, and Society. Judging from the reviews, which have been positive, it’s just as much a polemic as the first book, and has an ideological aim.

Keyword: Sexual Behavior; Evolution
Link ID: 23336 - Posted: 03.10.2017

By Colin Barras What a difference 1000 kilometres make. Neanderthals living in prehistoric Belgium enjoyed their meat – but the Neanderthals who lived in what is now northern Spain seem to have survived on an almost exclusively vegetarian diet. This is according to new DNA analysis that also suggests sick Neanderthals could self-medicate with naturally occurring painkillers and antibiotics, and that they shared mouth microbiomes with humans – perhaps exchanged by kissing. Neanderthals didn’t clean their teeth particularly well – which is lucky for scientific investigators. Over time, plaque built up into a hard substance called dental calculus, which still clings to the ancient teeth even after tens of thousands of years. Researchers have already identified tiny food fragments in ancient dental calculus to get an insight into the diets of prehistoric hominins. Now Laura Weyrich at the University of Adelaide, Australia, and her colleagues have shown that dental calculus also carries ancient DNA that can reveal both what Neanderthals ate and which bacteria lived in their mouths. The team focused on three Neanderthals – two 48,000-year-old specimens from a site called El Sidrón in Spain and a 39,000-year-old specimen from a site called Spy in Belgium. The results suggested that the Spy Neanderthal often dined on woolly rhinoceros, sheep and mushrooms – but no plants. The El Sidrón Neanderthals ate more meagre fare: moss, bark and mushrooms – and, apparently, no meat. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Pain & Touch
Link ID: 23331 - Posted: 03.09.2017

By Andy Coghlan In primates such as humans, living in cooperative societies usually means having bigger brains — with brainpower needed to navigate complex social situations. But surprisingly, in birds the opposite may be true. Group-living woodpecker species have been found to have smaller brains than solitary ones. Cooperative societies might in fact enable birds to jettison all that brainpower otherwise needed on their own to constantly out-think, outfox and outcompete wily rivals, say researchers. Socialism in birds may therefore mean the individuals can afford to get dumber. The results are based on a comparison of brain sizes in 61 woodpecker species. The eight group-living species identified typically had brains that were roughly 30 per cent smaller than solitary and pair-living ones. “It’s a pretty big effect,” says lead researcher Richard Byrne at the University of St Andrews in the UK. Byrne’s explanation is that a solitary life is more taxing on the woodpecker brain than for those in cooperative groups, in which a kind of group-wide “social brain” takes the strain off individuals when a challenge arises. Group-living acorn woodpeckers in North America, for example, are well known for creating collective “granaries” of acorns by jamming them into crevices accessible to the whole group during hard times. © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 23328 - Posted: 03.08.2017

Bruce Bower The social lives of macaques and baboons play out in what primatologist Julia Fischer calls “a magnificent opera.” When young Barbary macaques reach about 6 months, they fight nightly with their mothers. Young ones want the “maternal embrace” as they snooze; mothers want precious alone time. Getting pushed away and bitten by dear old mom doesn’t deter young macaques. But they’re on their own when a new brother or sister comes along. In Monkeytalk, Fischer describes how the monkey species she studies have evolved their own forms of intelligence and communication. Connections exist between monkey and human minds, but Fischer regards differences among primate species as particularly compelling. She connects lab studies of monkeys and apes to her observations of wild monkeys while mixing in offbeat personal anecdotes of life in the field. Fischer catapulted into a career chasing down monkeys in 1993. While still in college, she monitored captive Barbary macaques. That led to fieldwork among wild macaques in Morocco. In macaque communities, females hold central roles because young males move to other groups to mate. Members of closely related, cooperative female clans gain an edge in competing for status with male newcomers. Still, adult males typically outrank females. Fischer describes how the monkeys strategically alternate between attacking and forging alliances. After forging her own key scientific alliances, Fischer moved on to study baboons in Africa, where she entered the bureaucratic jungle. Obtaining papers for a car in Senegal, for instance, took Fischer several days. She first had to shop for a snazzy outfit to impress male paper-pushers, she says. |© Society for Science & the Public 2000 - 2017.

Keyword: Language; Animal Communication
Link ID: 23315 - Posted: 03.06.2017

Susan Milius Fitbit-style tracking of two wild African elephants suggests their species could break sleep records for mammals. The elephants get by just fine on about two hours of sleep a day. Much of that shut-eye comes while standing up — the animals sleep lying down only once every three or four days, new data show. Most of what scientists previously knew about sleeping elephants came from captive animals, says neuroethologist Paul Manger of the University of the Witwatersrand, Johannesburg. In zoos and enclosures, elephants have been recorded snoozing about three hours to almost seven over a 24-hour period. Monitoring African elephants in the wild, however, so far reveals more extreme behavior. Data are hard to collect, but two females wearing activity recorders for about a month averaged less sleep than other recorded mammals. Especially intriguing is the elephants’ ability to skip a night’s sleep without needing extra naps later, Manger and colleagues report March 1 in PLOS ONE. “The remarkably short amount of sleep in wild elephants is a real elephant in the room for several theories for the function of sleep,” says Niels Rattenborg of the Max Planck Institute for Ornithology in Seewiesen, Germany. Ideas that sleep restores or resets aspects of the brain for peak performance can’t explain animals that sleep only a little and don’t need catch-up rest, says Rattenborg, who wasn’t involved in the elephant study. The results also don’t fit well with the thought that animals need sleep to consolidate memories. “Elephants are usually not considered to be forgetful animals,” he says. |© Society for Science & the Public 2000 - 2017.

Keyword: Sleep; Evolution
Link ID: 23304 - Posted: 03.02.2017

By Hanoch Ben-Yami Human intelligence, even in its most basic forms, is expressed in our language, and is also partly dependent on our linguistic capacity. Homer, Darwin and Einstein could obviously not have achieved what they did without language—but neither could a child in kindergarten. And this raises an important question about animal intelligence. Although we don’t expect a chimpanzee to write an epic or a dolphin to develop a scientific theory, it has frequently been asked whether these or other animals are close in intelligence to children in young children. If so, we must wonder whether animals can acquire a language. In the last half century, much effort has been put trying answer that question by teaching animals, primarily apes, a basic language. There have been some limited successes, with animals using signs to obtain things in which they were interested, for instance. But no animal has yet acquired the linguistic capability that children have already in their third year of life. “Why?” This is a question children start asking during by the age of three at the latest. No animal has yet asked anything. “Why?” is a very important question: it shows that those asking it are aware they don’t know something they wish to know. Understanding the why-question is also necessary for the ability to justify our actions and thoughts. The fact that animals don’t ask “why?” shows they don’t aspire to knowledge and are incapable of justification. “No!” © 2017 Scientific American,

Keyword: Language; Evolution
Link ID: 23298 - Posted: 03.01.2017

By Carolyn Gramling Trilobites—three-sectioned, crablike critters that dominated the early Paleozoic—are so abundant that they have become the gateway fossil for most collectors. But paleontologists have found little evidence of how the extinct arthropods reproduced—until now. Researchers studying a fossil specimen of the trilobite Triarthrus eatoni spotted something odd just next to the animal’s head: a collection of small (about 200 micrometers across), round objects (in light blue, above). Those, they determined, are actually eggs—the first time anyone had observed fossil trilobite eggs right next to the critters themselves. The structures were exceptionally well preserved, the eggs and exoskeletons of the trilobites replaced with an iron sulfide ore called pyrite. They came from the Lorraine Group, a rock formation that spans much of the northeastern United States and dates to the Ordovician period (about 485 million to 444 million years ago); it has long been a mecca for trilobite hunters because of the pyritization. The placement of the eggs is suggestive, the researchers report in the March issue of Geology: They hypothesize that trilobites released their eggs and sperm through a genital pore somewhere in the head—much like modern horseshoe crabs do today. One possible reason for the rarity of the find may be that the brooding behavior of T. eatoni was relatively unusual in the trilobite world: The species tended to prefer a harsh, low-oxygen environment, and may have kept a closer eye on their eggs than other trilobite species. But, the authors note, one idea this finding does lay to rest is that trilobites might reproduce via copulation—a titillating but little-regarded hypothesis based on the fact that trilobites are sometimes found clustered on top of one another. Instead, trilobites were most likely spawners—and, in fact, that clustering behavior may be another parallel to horseshoe crabs, which can climb on top of one another in competition to fertilize released eggs. © 2017 American Association for the Advancement of Science

Keyword: Sexual Behavior; Evolution
Link ID: 23279 - Posted: 02.25.2017

Rae Ellen Bichell Initially, Clint Perry wanted to make a vending machine for bumblebees. He wanted to understand how they solve problems. Perry, a cognitive biologist at Queen Mary University of London, is interested in testing the limits of animal intelligence. "I want to know: How does the brain do stuff? How does it make decisions? How does it keep memory?" says Perry. And how big does a brain need to be in order to do all of those things? He decided to test this on bumblebees by presenting the insects with a puzzle that they'd likely never encounter in the wild. He didn't end up building that vending machine, but he did put bees through a similar scenario. Perry and his colleagues wrote Thursday in the journal Science that, despite bees' miniature brains, they can solve new problems quickly just by observing a demonstration. This suggests that bees, which are important crop pollinators, could in time adapt to new food sources if their environment changed. As we have reported on The Salt before, bee populations around the world have declined in recent years. Scientists think a changing environment is at least partly responsible. Perry and colleagues built a platform with a porous ball sitting at the center of it. If a bee went up to the ball, it would find that it could access a reward, sugar water. One by one, bumblebees walked onto the platform, explored a bit, and then slurped up the sugar water in the middle. "Essentially, the first experiment was: Can bees learn to roll a ball?" says Perry. © 2017 npr

Keyword: Learning & Memory; Evolution
Link ID: 23278 - Posted: 02.24.2017

Tina Hesman Saey Humans and Neandertals are still in an evolutionary contest, a new study suggests. Geneticist Joshua Akey of the University of Washington in Seattle and colleagues examined gene activity of more than 700 genes in which at least one person carried a human and a Neandertal version of the gene. Human versions of some genes are more active than Neandertal versions, especially in the brain and testes, the researchers report February 23 in Cell. In other tissues, some Neandertal versions of genes were more active than their human counterparts. In the brain, human versions were favored over Neandertal variants in the cerebellum and basal ganglia. That finding may help explain why Neandertals had proportionally smaller cerebellums than humans do. Neandertal versions of genes in the testes, including some needed for sperm function, were also less active than human varieties. That finding is consistent with earlier studies that suggested male human-Neandertal hybrids may have been infertile, Akey says. But Neandertal genes don’t always lose. In particular, the Neandertal version of an immunity gene called TLR1 is more active than the human version, the researchers discovered. Lopsided gene activity may help explain why carrying Neandertal versions of some genes has been linked to human diseases, such as lupus and depression (SN: 3/5/16, p. 18). Usually, both copies contribute equally to a gene’s total activity. Less robust activity of a version inherited from Neandertals might cause total activity to dip to unhealthy levels, for instance. |© Society for Science & the Public 2000 - 2017

Keyword: Evolution; Genes & Behavior
Link ID: 23272 - Posted: 02.24.2017

By Michael Price BOSTON--Among mammals, primates are unique in that certain species have three different types of light-sensitive cone cells in their eyes rather than two. This allows humans and their close relatives to see what we think of as the standard spectrum of color. (Humans with red-green color blindness, of course, see a different spectrum.) The standard explanation for why primates developed trichromacy, as this kind of vision is called, is that it allowed our early ancestors to see colorful ripe fruit more easily against a background of mostly green forest. A particular Old World monkey, the rhesus macaque (pictured), has a genetic distinction that offers a convenient natural test of this hypothesis: a common genetic variation makes some females have three types of cone cells and others have two. Studies with captive macaques has shown that trichromatic females are faster than their dichromatic peers at finding fruit, but attempts to see whether that’s true for wild monkeys has been complicated by the fact that macaques are hard to find, and age and rank also play big roles in determining who eats when. A vision researcher reported today at the annual meeting of AAAS, which publishes Science, that after making more than 20,000 individual observations of 80 different macaques feeding from 30 species of trees on Cayo Santiago, Puerto Rico, she can say with confidence that wild trichromatic female monkeys do indeed appear to locate and eat fruit more quickly than dichromatic ones, lending strong support to the idea that this advantage helped drive the evolution of trichromacy in humans and our relatives. © 2017 American Association for the Advancement of Science.

Keyword: Vision; Evolution
Link ID: 23252 - Posted: 02.20.2017

Elizabeth Eaton A prehistoric marine reptile may have given birth to its young alive. A fossil from South China may be the first evidence of live birth in the animal group Archosauromorpha, scientists report February 14 in Nature Communications. Today Archosauromorpha is represented by birds and crocodiles — which both lay eggs. Whether this fossil really is the first evidence of live birth in Archosauromorpha depends on how another group of semiaquatic animals is classified, says Michael Caldwell, a vertebrate paleontologist with the University of Alberta in Canada. Placement of Choristodera, a now-extinct group that included a freshwater reptile that gave live birth, remains murky, with some researchers putting them with Archosauromorpha and others with a group that includes snakes and lizards. “Our discovery is the first of live birth in reptiles with undoubted archosauromorph affinity,” says Jun Liu, a paleontologist at Hefei University of Technology in China. Researchers have speculated that the biology of archosauromorphs prevented their reproductive traits from evolving, says study coauthor Chris Organ, an evolutionary biologist with Montana State University in Bozeman. This find may disprove that view. “Ancestrally, the science suggests that live birth is not absolutely prohibited,” Organ says. Even though birds and crocodiles haven’t yet evolved to give life birth, this discovery suggests that it’s possible. |© Society for Science & the Public 2000 - 2016

Keyword: Sexual Behavior; Evolution
Link ID: 23230 - Posted: 02.15.2017

By Virginia Morell Strange as it might seem, not all animals can immediately recognize themselves in a mirror. Great apes, dolphins, Asian elephants, and Eurasian magpies can do this—as can human kids around age 2. Now, some scientists are welcoming another creature to this exclusive club: carefully trained rhesus monkeys. The findings suggest that with time and teaching, other animals can learn how mirrors work, and thus learn to recognize themselves—a key test of cognition. “It’s a really interesting paper because it shows not only what the monkeys can’t do, but what it takes for them to succeed,” says Diana Reiss, a cognitive psychologist at Hunter College in New York City, who has given the test to dolphins and Asian elephants in other experiments. The mirror self-recognition test (MSR) is revered as a means of testing self-awareness. A scientist places a colored, odorless mark on an animal where it can’t see it, usually the head or shoulder. If the animal looks in the mirror and spontaneously rubs the mark, it passes the exam. Successful species are said to understand the concept of “self” versus “other.” But some researchers wonder whether failure is simply a sign that the exam itself is inadequate, perhaps because some animals can’t understand how mirrors work. Some animals—like rhesus monkeys, dogs, and pigs—don’t recognize themselves in mirrors, but can use them to find food. That discrepancy puzzled Mu-ming Poo, a neurobiologist at the Shanghai Institutes for Biological Sciences in China, and one of the study’s authors. “There must be some transition between that simple mirror use and recognizing yourself,” he says. © 2017 American Association for the Advancement of Science.

Keyword: Consciousness; Evolution
Link ID: 23224 - Posted: 02.14.2017

By Sam Wong Here’s looking at you, squid. Cock-eyed squid have one huge, bulging eye and another normal-sized eye, but the reason has remained a mystery. Now we have an answer. Kate Thomas of Duke University in North Carolina studied 161 videos of the creatures collected over 26 years by remotely operated submarines in Monterey Bay, California. The findings provide the first behavioural evidence that the two eyes are adapted to look in different directions. The large one points upwards to spot prey silhouetted against the sky. The smaller one points downwards to spot bioluminescent organisms against the darkness below. The squid, from the histioteuthid family, live at depths of 200 to 1000 metres, where little light penetrates. The videos show that the squid normally swims with its tail end pointing upwards, but tilted so the large eye is consistently oriented towards the sky. Based on measurements of the eyes and the light levels they would be exposed to, Thomas and her colleagues calculated that having a big upward-pointing eye greatly improves visual perception, while a downward-pointing eye would gain little from being large. “That gives you the context for how this trait might have evolved,” says Thomas. Some of the squid’s prey, such as lanternfish and shrimp, have luminescent undersides so they are camouflaged against the sunlight when seen from below. Yellow pigmentation in the lens of the squid’s large eye may help it distinguish between sunlight and bioluminescence. © Copyright Reed Business Information Ltd.

Keyword: Vision; Evolution
Link ID: 23222 - Posted: 02.14.2017