Links for Keyword: Evolution

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Bruce Bower NEW ORLEANS — A relatively small brain can pack a big evolutionary punch. Consider Homo naledi, a famously puzzling fossil species in the human genus. Despite having a brain only slightly larger than a chimpanzee’s, H. naledi displays key humanlike neural features, two anthropologists reported April 20 at the annual meeting of the American Association of Physical Anthropologists. Those brain characteristics include a region corresponding to Broca’s area, which spans parts of the right and left sides of the brain in present-day people. The left side is typically involved in speech and language. “It looks like Homo naledi’s brain evolved a huge amount of shape change that supported social emotions and advanced communication of some type,” said Shawn Hurst of Indiana University Bloomington, who presented the new findings. “We can’t say for sure whether that included language.” Frontal brain locations near Broca’s area contribute to social emotions such as empathy, pride and shame. As interactions within groups became more complex in ancient Homo species, neural capacities for experiencing social emotions and communicating verbally blossomed, Hurst suspects. Scientists don’t know how long ago H. naledi inhabited Africa’s southern tip. If H. naledi lived 2 million or even 900,000 years ago, as some researchers have suggested (SN: 8/6/16, p. 12), humanlike brains with a language-related area would be shocking. A capacity for language is thought to have emerged in Homo over the last few hundred thousand years at most. |© Society for Science & the Public 2000 - 2017.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 23541 - Posted: 04.26.2017

Elle Hunt Inches above the seafloor of Sydney’s Cabbage Tree Bay, with the proximity made possible by several millimetres of neoprene and a scuba diving tank, I’m just about eyeball to eyeball with this creature: an Australian giant cuttlefish. Even allowing for the magnifying effects of the mask snug across my nose, it must be about 60cm (two feet) long, and the peculiarities that abound in the cephalopod family, that includes octopuses and squid, are the more striking writ so large. ADVERTISING Its body – shaped around an internal surfboard-like shell, tailing off into a fistful of tentacles – has the shifting colour of velvet in light, and its W-shaped pupils lend it a stern expression. I don’t think I’m imagining some recognition on its part. The question is, of what? It was an encounter like this one – “at exactly the same place, actually, to the foot” – that first prompted Peter Godfrey-Smith to think about these most other of minds. An Australian academic philosopher, he’d recently been appointed a professor at Harvard. While snorkelling on a visit home to Sydney in about 2007, he came across a giant cuttlefish. The experience had a profound effect on him, establishing an unlikely framework for his own study of philosophy, first at Harvard and then the City University of New York. The cuttlefish hadn’t been afraid – it had seemed as curious about him as he was about it. But to imagine cephalopods’ experience of the world as some iteration of our own may sell them short, given the many millions of years of separation between us – nearly twice as many as with humans and any other vertebrate (mammal, bird or fish)

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 23429 - Posted: 03.30.2017

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

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 23416 - Posted: 03.28.2017

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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23386 - Posted: 03.22.2017

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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 23328 - Posted: 03.08.2017

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

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23272 - Posted: 02.24.2017

By NICHOLAS ST. FLEUR The tale of the Tasmanian tiger was tragic. Once numerous across Tasmania, the doglike marsupial was branded a sheep killer by colonists in the 1830s and hunted to extinction. The last of its kind, Benjamin, died in a zoo in 1936, and with it many secrets into the animals’ lives were lost. The striped creature, which is also known as the thylacine, was hardly studied when it was alive, depriving scientists of understanding the behavior of an important predator from Australia’s recent biological past. Now, for the first time, researchers have performed neural scans on the extinct carnivore’s brain, revealing insights that had been lost since the species went extinct. “Part of the myth about them is what exactly did they eat, how did they hunt and were they social?” said Dr. Gregory Berns, a neuroscientist at Emory University and lead author on the study, which was published Wednesday in the journal PLOS One. “These are questions nobody really knows the answers to.” Dr. Berns’s main research pertains to dogs and the inner workings of the canine brain, but after learning more about Tasmanian tigers, he became fascinated by the beasts. With their slender bodies, long snouts and sharp teeth, Tasmanian tigers looked as if they could be related to dogs, wolves or coyotes. But actually they are separated by more than 150 million years of evolution. It is a classic example of convergent evolution, in which two organisms that are not closely related develop similar features because of the environment they adapted to and the ecological role they played. To better understand thylacines, Dr. Berns spent two years tracking down two preserved Tasmanian tiger brains, one at the Smithsonian Institution and the other at the Australian Museum. Their brains, like those of all marsupials, are very different from the brains of placental mammals. The biggest difference is that they lack a corpus callosum, which is the part of the brain that connects the left and right hemispheres. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 23131 - Posted: 01.21.2017

Claudia Dreifus Geneticists tell us that somewhere between 1 and 5 percent of the genome of modern Europeans and Asians consists of DNA inherited from Neanderthals, our prehistoric cousins. At Vanderbilt University, John Anthony Capra, an evolutionary genomics professor, has been combining high-powered computation and a medical records databank to learn what a Neanderthal heritage — even a fractional one — might mean for people today. We spoke for two hours when Dr. Capra, 35, recently passed through New York City. An edited and condensed version of the conversation follows. Q. Let’s begin with an indiscreet question. How did contemporary people come to have Neanderthal DNA on their genomes? A. We hypothesize that roughly 50,000 years ago, when the ancestors of modern humans migrated out of Africa and into Eurasia, they encountered Neanderthals. Matings must have occurred then. And later. One reason we deduce this is because the descendants of those who remained in Africa — present day Africans — don’t have Neanderthal DNA. What does that mean for people who have it? At my lab, we’ve been doing genetic testing on the blood samples of 28,000 patients at Vanderbilt and eight other medical centers across the country. Computers help us pinpoint where on the human genome this Neanderthal DNA is, and we run that against information from the patients’ anonymized medical records. We’re looking for associations. What we’ve been finding is that Neanderthal DNA has a subtle influence on risk for disease. It affects our immune system and how we respond to different immune challenges. It affects our skin. You’re slightly more prone to a condition where you can get scaly lesions after extreme sun exposure. There’s an increased risk for blood clots and tobacco addiction. To our surprise, it appears that some Neanderthal DNA can increase the risk for depression; however, there are other Neanderthal bits that decrease the risk. Roughly 1 to 2 percent of one’s risk for depression is determined by Neanderthal DNA. It all depends on where on the genome it’s located. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 23128 - Posted: 01.21.2017

By Victoria Gill Science reporter, BBC News Researchers have used camera traps to film tool-use that is unique to chimpanzees in Ivory Coast. The footage revealed that the clever primates habitually make special water-dipping sticks - chewing the end of the stick to turn it into a soft, water-absorbing brush. Primate researchers examined the "dipping sticks" and concluded they were made specifically for drinking. The findings are reported in the American Journal of Primatology. Lead researcher Juan Lapuente, from the Comoe Chimpanzee Conservation Project, in Ivory Coast, explained that using similar brush-tipped sticks to dip into bees' nests for honey was common in chimpanzee populations across Africa. "But the use of brush-tipped sticks to dip for water is completely new and had never been described before," he told BBC News. "These chimps use especially long brush tips that they make specifically for water - much longer than those used for honey." The researchers tested the chimps' drinking sticks in an "absorption experiment", which showed that the particularly long brush-tips provided an advantage. "The longer the brush, the more water they collect," said Mr Lapuente. "This technology allows Comoe chimpanzees to obtain water from extremely narrow and deep tree holes that only they - and no other animal - can exploit, which [gives] them a superb adaptive advantage to survive in this dry and unpredictable environment." © 2017 BBC.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23075 - Posted: 01.10.2017

By Drake Baer Convergent evolution is what happens when nature takes different courses from different starting points to arrive at similar results. Consider bats, birds, and butterflies developing wings; sharks and dolphins finding fins; and echidnas and porcupines sporting spines. Or, if you want to annoy a traditionalist scientist, talk about humans and octopuses — and how they may both have consciousness. This is the thrust of Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness, a new book by the scuba-diving, biology-specializing philosopher Peter Godfrey-Smith, originally of Australia and now a distinguished professor at the City University of New York’s graduate center. The book was written up by Olivia Judson in The Atlantic, and you should read the whole thing, but what I find mesmerizing is how categorically other the eight-tentacled ink-squirters are, and how their very nature challenges our conceptualizations of intelligence. “If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over,” Godfrey-Smith is quoted as saying. “This is probably the closest we will come to meeting an intelligent alien.” (He’s not the first to think so: The Hawaiian creation myth holds that octopuses are the only creatures left over from an earlier incarnation of the Earth, making them more proto-terrestrials than extraterrestrials.) © 2016, New York Media LLC.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 23020 - Posted: 12.26.2016

By STEPH YIN Inuit who live in Greenland experience average temperatures below freezing for at least half of the year. For those who live in the north, subzero temperatures are normal during the coldest months. Given these frigid conditions, anthropologists have wondered for decades whether the Inuit in Greenland and other parts of the Arctic have unique biological adaptations that help them tolerate the extreme cold. A new study, published on Wednesday in Molecular Biology and Evolution, identifies gene variants in Inuit who live in Greenland, which may help them adapt to the cold by promoting heat-generating body fat. These variants possibly originated in the Denisovans, a group of archaic humans who, along with Neanderthals, diverged from modern humans about half a million years ago. “As modern humans spread around the world, they interbred with Denisovans and Neanderthals, who had already been living in these different environments for hundreds of thousands of years,” said Rasmus Nielsen, a professor of integrative biology at the University of California, Berkeley and an author of the paper. “This gene exchange may have helped some modern humans adapt to and conquer new environments.” The new study follows earlier research by Dr. Nielsen and colleagues, which found genetic mutations that might help the Inuit metabolize unsaturated fatty acids common in their diet of whales, seals and fish. In this study, Dr. Nielsen’s team focused on another distinct region in the Inuit genome, which seems to affect body fat distribution and other aspects of development. The researchers compared the genomes of nearly 200 Inuit with genomes of Neanderthals, Denisovans and modern populations around the world. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 23011 - Posted: 12.23.2016

By Helen Briggs BBC News Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex. They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees. Now, researchers have found a tiny DNA change - a point mutation - that appears to have changed the function of the gene, sparking the process of expansion of the neocortex. It may have paved the way for the brain's expansion by dramatically boosting the number of brain cells found in this region. Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research. "A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big," he told BBC News. "This one, as it is fixed in the human genome - so all living humans have the gene - apparently gave a tremendous selection advantage, and that's why we believe it spread in the human population." Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 22965 - Posted: 12.08.2016

By Ann Gibbons On a promontory high above the sweeping grasslands of the Georgian steppe, a medieval church marks the spot where humans have come and gone along Silk Road trade routes for thousands of years. But 1.77 million years ago, this place was a crossroads for a different set of migrants. Among them were saber-toothed cats, Etruscan wolves, hyenas the size of lions—and early members of the human family. Here, primitive hominins poked their tiny heads into animal dens to scavenge abandoned kills, fileting meat from the bones of mammoths and wolves with crude stone tools and eating it raw. They stalked deer as the animals drank from an ancient lake and gathered hackberries and nuts from chestnut and walnut trees lining nearby rivers. Sometimes the hominins themselves became the prey, as gnaw marks from big cats or hyenas on their fossilized limb bones now testify. "Someone rang the dinner bell in gully one," says geologist Reid Ferring of the University of North Texas in Denton, part of an international team analyzing the site. "Humans and carnivores were eating each other." This is the famous site of Dmanisi, Georgia, which offers an unparalleled glimpse into a harsh early chapter in human evolution, when primitive members of our genus Homo struggled to survive in a new land far north of their ancestors' African home, braving winters without clothes or fire and competing with fierce carnivores for meat. The 4-hectare site has yielded closely packed, beautifully preserved fossils that are the oldest hominins known outside of Africa, including five skulls, about 50 skeletal bones, and an as-yet-unpublished pelvis unearthed 2 years ago. "There's no other place like it," says archaeologist Nick Toth of Indiana University in Bloomington. "It's just this mother lode for one moment in time." © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22899 - Posted: 11.23.2016

By STEPH YIN Neanderthals and modern humans diverged from a common ancestor about half a million years ago. Living in colder climes in Eurasia, Neanderthals evolved barrel chests, large skulls and strong hands. In Africa, modern humans acquired shorter faces, a prominent chin and slender limbs. Then, roughly 50,000 years ago, the two species encountered one another and interbred, as modern humans spread out of Africa. The legacy of this interbreeding has been the subject of much scientific inquiry in the past few years. Today, up to 4 percent of the genes of non-Africans are Neanderthal in origin.. These may have influenced a diverse range of traits, including keratin production, disease risk and the propensity to sneeze after eating dark chocolate. Where did all the other Neanderthal DNA go? Why did a Neanderthal-human hybrid not prevail? Two recent studies converge on an explanation. They suggest the answer comes down to different population sizes between Neanderthals and modern humans, and this principle of population genetics: In small populations, natural selection is less effective. “Neanderthals have this small population over hundreds of thousands of years, presumably because they’re living in very rough conditions,” said Graham Coop, a genetics professor at the University of California, Davis, and an author of one of the studies, published Tuesday in PLOS Genetics. As a result, Neanderthals were more inbred than modern humans and accumulated more mutations that have a slightly adverse effect, such as increasing one’s risk of disease, but do not prevent one from reproducing (and thus, passing such mutations along). © 2016 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22845 - Posted: 11.09.2016

Erin Wayman SALT LAKE CITY — The earliest primate was a tiny, solitary tree dweller that liked the night life. Those are just some conclusions from new reconstructions of the primate common ancestor, presented October 27 at the annual meeting of the Society of Vertebrate Paleontology. Eva Hoffman, now a graduate student at the University of Texas at Austin, and colleagues at Yale University looked at behavioral and ecological data from 178 modern primate species. Examining patterns of traits across the primate family tree, the researchers inferred the most likely characteristics of ancestors at different branching points in the tree — all the way back to the common ancestor. This ancient primate, which may have lived some 80 million to 70 million years ago, was probably no bigger than a guinea pig, lived alone and gave birth to one offspring at a time, the researchers suggest. Living in trees and active at night, the critter probably ventured out to the ends of tree branches to eat fruits, leaves and insects. But this mix of traits probably didn’t arise in primates, Hoffman says. After adding tree shrews and colugos — primates’ closest living relatives — to the analysis, the researchers concluded these same attributes were also present in the three groups’ common ancestor. So explanations of early primate evolution that rely on these features need to be reconsidered, Hoffman says. |© Society for Science & the Public 2000 - 2016.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22808 - Posted: 10.31.2016

Nicola Davis A brown, pebble-sized object found in a rock pool on a beach near Bexhill, Sussex bears the first evidence of fossilised dinosaur brain tissue, scientists say. Found in 2004 by an amateur fossil collector, the object is the cast of a dinosaur’s brain cavity, and appears to show a thin veneer of mineralised tissues on its surface. Scientists say the find is most likely from a relative of the Iguanodon, which lived around 125 million years ago. Large, hefty herbivores, Iguanodons reached up around eight metres in length, could walk on either two legs or all fours and boasted sharp spikes on their thumbs - a feature initially thought to be a horn on the nose and immortalised as such in the Victorian dinosaur sculptures of Crystal Palace Park. While casts of the inside of dinosaur brain cases have been found before, it is the first time fossilised brain soft tissue has been discovered for any land-living vertebrate. “The most striking thing is that something as delicate as brain tissue, and which you wouldn’t expect to ever see, has been preserved,” said Alex Liu, co-author of the research from the University of Cambridge. “It just speaks volumes [about] the spectacular preservational quality that can be obtained in the fossil record even 130 million years after this dinosaur is alive.” Writing in a special publication from the Geological Society of London to commemorate the work of the late co-author Martin Brasier, an international team of researchers describe how the cast was discovered near other dinosaur remains, including ribs and leg bones. “We can’t say it is from the same organism, but it is from a fairly large dinosaur,” said Liu. © 2016 Guardian News and Media Limited

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22799 - Posted: 10.28.2016

By Brian Owens Chimpanzees and their relatives bonobos are closer than we thought. Bonobos seem to have donated genes to chimps at least twice in the roughly two million years since they last shared an ancestor. The two closely related apes have occasionally interbred in captivity, and bonobos are renowned for their free and easy sex life. But the finding that they interbred in the wild was unexpected. The two species split sometime between 1.5 and 2.1 million years ago, around the same time that the Congo River system formed. Wild bonobo populations are entirely contained in that river system, separated from two nearby subspecies of chimps, the eastern and central subspecies. Scientists assumed the river was an impenetrable barrier, says Christina Hvilsom from Copenhagen Zoo in Denmark, one of the researchers who worked on the genetic project. But it turns out that it must have been breached more than once – although it’s not clear how that happened. Hvilsom and her colleagues weren’t actually looking for genetic evidence of ancient interspecies erotica. They were mapping genetic markers that could be used to determine where illegally traded chimps came from so they could be returned to their homes in the wild. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22798 - Posted: 10.28.2016

Hannah Devlin Science correspondent Monkeys have been observed producing sharp stone flakes that closely resemble the earliest known tools made by our ancient relatives, proving that this ability is not uniquely human. Previously, modifying stones to create razor-edged fragments was thought to be an activity confined to hominins, the family including early humans and their more primitive cousins. The latest observations re-write this view, showing that monkeys unintentionally produce almost identical artefacts simply by smashing stones together. The findings put archaeologists on alert that they can no longer assume that stone flakes they discover are linked to the deliberate crafting of tools by early humans as their brains became more sophisticated. Tomos Proffitt, an archaeologist at the University of Oxford and the study’s lead author, said: “At a very fundamental level - if you’re looking at a very simple flake - if you had a capuchin flake and a human flake they would be the same. It raises really important questions about what level of cognitive complexity is required to produce a sophisticated cutting tool.” Unlike early humans, the flakes produced by the capuchins were the unintentional byproduct of hammering stones - an activity that the monkeys pursued decisively, but the purpose of which was not clear. Originally scientists thought the behaviour was a flamboyant display of aggression in response to an intruder, but after more extensive observations the monkeys appeared to be seeking out the quartz dust produced by smashing the rocks, possibly because it has a nutritional benefit. © 2016 Guardian News and Media Limited

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 22771 - Posted: 10.20.2016

By Emily Underwood When you let forth a big, embarrassing yawn during a boring lecture or concert, you succumb to a reflex so universal among animals that Charles Darwin mentioned it in his field notes. “Seeing a dog & horse & man yawn, makes me feel how much all animals are built on one structure,” he wrote in 1838. Scientists, however, still don’t agree on why we yawn or where it came from. So in a new study, researchers watched YouTube videos of 29 different yawning mammals, including mice, kittens, foxes, hedgehogs, walruses, elephants, and humans. (Here is a particularly cute montage used in the study.) They discovered a pattern: Small-brained animals with fewer neurons in the wrinkly outer layer of the brain, called the cortex, had shorter yawns than large-brained animals with more cortical neurons, the scientists report today in Biology Letters. Primates tended to yawn longer than nonprimates, and humans, with about 12,000 million cortical neurons, had the longest average yawn, lasting a little more than 6 seconds. African elephants, whose brains are close to the same weight as humans’ and have a similar number of cortical neurons, lasted about 6 seconds. The yawns of tiny-brained mice, in contrast, were less than 1.5 seconds in duration. The study lends support to a long-held hypothesis that yawning has an important physiological effect, such as increasing blood flood to the brain and cooling it down, the scientists say. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 22723 - Posted: 10.05.2016