Links for Keyword: Evolution

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Carl Zimmer With fossils and DNA, scientists are piecing together a picture of humanity’s beginnings, an origin story with more twists than anything you would find at the movie theater. The expert consensus now is that Homo sapiens evolved at least 300,000 years ago in Africa. Only much later — roughly 70,000 years ago — did a small group of Africans establish themselves on other continents, giving rise to other populations of people today. To Johannes Krause, the director of the Max Planck Institute for Human History in Germany, that gap seems peculiar. “Why did people not leave Africa before?” he asked in an interview. After all, he observed, the continent is physically linked to the Near East. “You could have just walked out.” In a study published Tuesday in Nature Communications, Dr. Krause and his colleagues report that Africans did indeed walk out — over 270,000 years ago. Based on newly discovered DNA in fossils, the researchers conclude that a wave of early Homo sapiens, or close relatives of our species, made their way from Africa to Europe. There, they interbred with Neanderthals. Then the ancient African migrants disappeared. But some of their DNA endured in later generations of Neanderthals. “This is now a comprehensive picture,” Dr. Krause said. “It brings everything together.” Since the 1800s, paleontologists have struggled to understand how Neanderthals are related to us. Fossils show that they were anatomically distinct, with a heavy brow, a stout body and a number of subtler features that we lack. The oldest bones of Neanderthal-like individuals, found in a Spanish cave called Sima de los Huesos, date back 430,000 years. More recent Neanderthal remains, dating to about 100,000 years ago, can be found across Europe and all the way to southern Siberia. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23809 - Posted: 07.06.2017

By Sandrine Ceurstemont Bird or beast? A cuckoo seems to have learned how to mimic the sounds made by the pig-like peccaries it lives alongside, perhaps to ward off predators. The Neomorphus ground cuckoos live in forests in Central and South America, where they often follow herds of wild peccaries so they can feed on the invertebrates that the peccaries disturb as they plough through the leaf litter. Ecologists have noticed that when the cuckoos clap their beaks together they sound a lot like the tooth clacks the peccaries make to deter large predatory cats. To find out whether this is just coincidence or evidence of mimicry, Cibele Biondo at the Federal University of ABC in Brazil and her team analysed the cuckoo and peccary sounds, and compared them with the beak clapping sounds made by roadrunners – close relatives of the ground cuckoos. Logically, the cuckoos should sound most similar to roadrunners, given that the two are closely related. But the analysis suggested otherwise. “The acoustic characteristics are more similar to the teeth clacking of peccaries,” says Biondo. She suspects that cuckoos have something to gain by imitating the peccaries, particularly in the dark, dense forests where predators rely on hearing as much as vision. “Cuckoos may deceive predators by making it appear that peccaries are present when they are not,” says Biondo. © Copyright New Scientist 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: 23802 - Posted: 07.04.2017

By Michael Price Whether it’s giving to charity or helping a stranger with directions, we often assist others even when there’s no benefit to us or our family members. Signs of such true altruism have been spotted in some animals, but have been difficult to pin down in our closest evolutionary relatives. Now, in a pair of studies, researchers show that chimpanzees will give up a treat in order to help out an unrelated chimp, and that chimps in the wild go out on risky patrols in order to protect even nonkin at home. The work may give clues to how such cooperation—the foundation of human civilization—evolved in humans. “Both studies provide powerful evidence for forms of cooperation in our closest relatives that have been difficult to demonstrate in other animals besides humans,” says Brian Hare, an evolutionary anthropologist at Duke University in Durham, North Carolina, who was not involved with the research. In the first study, psychologists Martin Schmelz and Sebastian Grüneisen at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, trained six chimps at the Leipzig Zoo to play a sharing game. Each chimp was paired with a partner who was given a choice of four ropes to pull, each with a different outcome: give just herself a banana pellet; give just the subject a pellet; give both of them pellets; or forgo her turn and let her partner make the decision instead. © 2017 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: 23753 - Posted: 06.20.2017

Ian Sample Science editor Fossils recovered from an old mine on a desolate mountain in Morocco have rocked one of the most enduring foundations of the human story: that Homo sapiens arose in a cradle of humankind in East Africa 200,000 years ago. Archaeologists unearthed the bones of at least five people at Jebel Irhoud, a former barite mine 100km west of Marrakesh, in excavations that lasted years. They knew the remains were old, but were stunned when dating tests revealed that a tooth and stone tools found with the bones were about 300,000 years old. Why we're closer than ever to a timeline for human evolution Read more “My reaction was a big ‘wow’,” said Jean-Jacques Hublin, a senior scientist on the team at the Max Planck Institute for Evolutionary Anthropology in Leipzig. “I was expecting them to be old, but not that old.” Hublin said the extreme age of the bones makes them the oldest known specimens of modern humans and poses a major challenge to the idea that the earliest members of our species evolved in a “Garden of Eden” in East Africa one hundred thousand years later. “This gives us a completely different picture of the evolution of our species. It goes much further back in time, but also the very process of evolution is different to what we thought,” Hublin told the Guardian. “It looks like our species was already present probably all over Africa by 300,000 years ago. If there was a Garden of Eden, it might have been the size of the continent.” © 2017 Guardian News and Media Limited

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23723 - Posted: 06.08.2017

James Gorman Darwin’s finches, those little birds in the Galápagos with beaks of different sizes and shapes, were instrumental in the development of the theory of evolution. Similar birds had large and small beaks and beaks in between, all related to what kinds of insects and seeds they ate. From one ancestor, it seemed, different adaptations to the environment had evolved, giving the birds that adapted a survival edge in a particular ecological niche — evolution by natural selection. Biologists who came later went on to identify the genetic changes that had produced different beak shapes. Now another group of finch-like birds has provided a similar example, but of a different kind of evolution, one driven not by the demands of the environment, but by the demands of female birds. Their preferences in color and pattern caused the evolution of different species of seedeater, all with the same behavior and diet, but with males that look different. That’s a process called sexual selection, which Darwin also wrote about. Leonardo Campagna, a researcher at Cornell University and the Cornell Lab of Ornithology, and a group of scientists from the United States and South America investigated nine species of southern capuchino seedeaters, doing full genomes for each one and reported their findings in Science Advances. They found that the DNA of all the species is remarkably similar, as are the birds. All the females look alike and all of the species feed on grass seeds plucked from grass stalks of living plants. Only the males are different. They have a wide variety of colorations and their courting songs are also distinct. Dr. Campagna and the other researchers found that differences between species DNA were all minimal, ranging from as little as 0.03 percent to as great as 0.3 percent. All the species showed variation in the same area, DNA that appeared to have a role in regulating genes for the pigment melanin. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23660 - Posted: 05.25.2017

Elle Hunt About 150 years ago, and “almost a lifetime” either side, Charles Darwin was beleaguered by the problem of the peacock’s tail. Just the sight of a feather, he wrote in April 1860, “makes me sick!” The plumage of the male bird represented a hole in his theory of evolution. According to Victorian thinking, beauty was divine creation: God had designed the peacock for his own and humankind’s delight. In, On The Origin of Species, published the previous year, Darwin had challenged the dominant theory of creationism, arguing that man had been made not in God’s image but as a result of evolution, with new species formed over generations in response to their environment. But beauty, and a supposed aesthetic sense in animals (“We must suppose [that peahens] admire [the] peacock’s tail, as much as we do,” he wrote), took Darwin the best part of his life to justify – not least because the theory he eventually landed upon went against the grain of his entire worldview. Sexual selection was of strategic importance to Darwin, says Evelleen Richards, an honorary professor in history and philosophy of science at the University of Sydney: it was a naturalistic account for aesthetic differences between male and female animals of the same species, shoring up his defence of natural selection.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 23642 - Posted: 05.22.2017

Shelby Putt How did humans get to be so smart, and when did this happen? To untangle this question, we need to know more about the intelligence of our human ancestors who lived 1.8 million years ago. It was at this point in time that a new type of stone tool hit the scene and the human brain nearly doubled in size. Some researchers have suggested that this more advanced technology, coupled with a bigger brain, implies a higher degree of intelligence and perhaps even the first signs of language. But all that remains from these ancient humans are fossils and stone tools. Without access to a time machine, it’s difficult to know just what cognitive features these early humans possessed, or if they were capable of language. Difficult – but not impossible. Now, thanks to cutting-edge brain imaging technology, my interdisciplinary research team is learning just how intelligent our early tool-making ancestors were. By scanning the brains of modern humans today as they make the same kinds of tools that our very distant ancestors did, we are zeroing in on what kind of brainpower is necessary to complete these tool-making tasks. The stone tools that have survived in the archaeological record can tell us something about the intelligence of the people who made them. Even our earliest human ancestors were no dummies; there is evidence for stone tools as early as 3.3 million years ago, though they were probably making tools from perishable items even earlier. © 2010–2017, The Conversation US, Inc.

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: 23594 - Posted: 05.09.2017

Bruce Bower Fossils of a humanlike species with some puzzlingly ancient skeletal quirks are surprisingly young, its discoverers say. It now appears that this hominid, dubbed Homo naledi, inhabited southern Africa close to 300,000 years ago, around the dawn of Homo sapiens. H. naledi achieved worldwide acclaim in 2015 as a possibly pivotal player in the evolution of the human genus, Homo. Retrieved from an underground chamber in South Africa, fossils of this species were thought to be anywhere from 900,000 to at least 1.8 million years old (SN: 8/6/16, p. 12). A younger age for H. naledi resolves one mystery about these cave fossils. It doesn’t, however, answer questions about how long ago the species first appeared and when it died out. What is now known is that H. naledi bodies somehow ended up in Dinaledi Chamber, part of South Africa’s Rising Star cave system, between 236,000 and 335,000 years ago, an international team reports in one of three papers published May 9 in eLife. Paleoanthropologist Lee Berger of the University of the Witwatersrand in Johannesburg headed the team. Geoscientist Paul Dirks of James Cook University in Townsville, Australia, directed the dating effort. In the first paper, two methods of measuring the concentration of natural uranium and other radioactive elements, and damage caused by those elements over time, provided key age estimates for three H. naledi teeth. A thin sheet of rock deposited by flowing water just above the fossils was also dated. |© Society for Science & the Public 2000 - 201

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23591 - Posted: 05.09.2017

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