Chapter 6. Evolution of the Brain and Behavior

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Links 21 - 40 of 1903

Amy Maxmen Male ducks respond to sexual competition by growing either an extra-long penis or a nub of flesh, a new study finds. The unusual phenomena occurred in two species studied: the lesser scaup (Aythya affinis) and the ruddy duck (Oxyura jamaicensis). It suggests that penis size — in line with many traits and behaviours meant to impress or allow impregnation of the opposite sex — involves a trade-off between the potential to reproduce and to survive. Patricia Brennan, an evolutionary biologist at Mount Holyoke College in South Hadley, Massachusetts, compared the penises of ducks kept in male–female pairs to those housed with multiple males per female. The findings are published in a study on 20 September in The Auk: Ornithological Advances1. “If they were alone with a female, the males just grew a normal-sized penis, but if there were other males around, they had the ability to change dramatically,” Brennan says. “So evolution must be acting on the ability to be plastic — the ability to invest only in what is needed in your current circumstance.” Because evolutionary success relies on reproduction, genitals are adapted to meet the varied circumstances that every animal faces. Some male ducks, for example, have penises in the shape of corkscrews to navigate the labyrinth-like vaginas of their female counterparts. An earlier study by Brennan found that females’ anatomy evolved to prevent access to undesirable males who force copulation2. To mate successfully with their chosen partners, Brennan says, female ducks assume a posture that allows males to enter them fully and deposit sperm near eggs. © 2017 Macmillan Publishers Limited,

Keyword: Sexual Behavior; Evolution
Link ID: 24086 - Posted: 09.21.2017

By Aylin Woodward HUMANS aren’t the only primate to have pushed their prey towards extinction. Monkeys have also over-exploited animals for food. Long-tailed macaques forage for shellfish on islands off Thailand, then crack them open with stone tools. They target the largest rock oysters, bludgeoning them with stone hammers, and pry open the meatiest snail and crab shells with the flattened edges of their tools. These macaques are one of three primates that use stone tools, alongside chimpanzees in Africa and bearded capuchins in South America. “Stone tools open up an opportunity for foods they otherwise wouldn’t even be able to harvest,” says Lydia Luncz at the University of Oxford. Luncz wanted to investigate the impact of the monkeys’ shellfish snacking on the prey themselves. Her team followed 18 macaques on their daily foraging routes along the shores of Koram and NomSao, two neighbouring islands off eastern Thailand, recording their tool selection and use. On Koram – the more densely populated island, home to 80 macaques compared with NomSao’s nine – Luncz’s group saw not only smaller oysters and snails, but also fewer of each species. Multiple prey species were less abundant on Koram than NomSao, with four times as many tropical periwinkles on NomSao as on Koram (eLife, doi.org/cc7d). © Copyright New Scientist Ltd.

Keyword: Evolution
Link ID: 24080 - Posted: 09.20.2017

By Michael Le Page We are still evolving – very slowly. In the 20th century, people in the UK evolved to be less likely to smoke heavily, but the effect was tiny. So claims a study of 200,000 genomes. A population can be described as evolving when the frequency of gene variants changes over time. Because most people in rich countries now live well beyond reproductive age, some argue that we have stopped evolving because natural selection has been weakened. But several recent studies claim we are still evolving, albeit slowly. Now Joseph Pickrell at Columbia University in New York and his team have analysed human genome sequences to spot gene variants that are becoming rarer. One variant, of a gene called CHRNA3, is associated with heavier smoking in those that smoke, raising their risk of a smoking-related death. Comparing people over the age of 80 with people over the age of 60, Pickrell estimates that the variant has declined by 1 per cent between generations. However, his team was not able to prove this, as they did not have any genomic data from people under the age of 40. A variant of the ApoE4 gene that is known to increase the risk of late-onset Alzheimer’s disease, as well as cardiovascular disease, may also be getting rarer. © Copyright New Scientist Ltd.

Keyword: Alzheimers; Genes & Behavior
Link ID: 24038 - Posted: 09.06.2017

By Andy Coghlan How and when did we first become able to speak? A new analysis of our DNA reveals key evolutionary changes that reshaped our faces and larynxes, and which may have set the stage for complex speech. The alterations were not major mutations in our genes. Instead, they were tweaks in the activity of existing genes that we shared with our immediate ancestors. These changes in gene activity seem to have given us flat faces, by retracting the protruding chins of our ape ancestors. They also resculpted the larynx and moved it further down in the throat, allowing our ancestors to make sounds with greater subtleties. The study offers an unprecedented glimpse into how our faces and vocal tracts were altered at the genetic level, paving the way for the sophisticated speech we take for granted. However, other anthropologists say changes in the brain were at least equally important. It is also possible that earlier ancestors could speak, but in a more crude way, and that the facial changes simply took things up a notch. Liran Carmel of the Hebrew University of Jerusalem and his colleagues examined DNA from two modern-day people and four humans who lived within the last 50,000 years. They also looked at extinct hominins: two Neanderthals and a Denisovan. Finally, they looked at genetic material from six chimpanzees and data from public databases supplied by living people. © Copyright New Scientist Ltd.

Keyword: Language; Evolution
Link ID: 24004 - Posted: 08.28.2017

By Sam Wong It seems you can judge an athlete by their face – if they are a man, that is. Male athletes with a higher world ranking tend to be judged as more attractive by women, but there is no such trend among women. Several studies have previously reported a link between facial attractiveness and sporting performance in men, leading to suggestions that women respond to facial cues that reflect athletic ability in potential partners. Some have suggested this is because, in our evolutionary past, women might have benefited from choosing a partner with speed, skill and endurance. As a better hunter, the idea goes, he would have brought home more food, and he might pass on his fitness to their children. But these studies have been criticised, notably for only looking at men. They also tended to focus on team sports, therefore failing to isolate individual performance. To find more evidence, Tim Fawcett and colleagues at the University of Exeter, UK, collected photos of 156 men and women who competed at the 2014 Winter Olympics in the biathlon – an event combining cross-country skiing and shooting. Each athlete was rated for their facial attractiveness by members of the opposite sex, who didn’t know the purpose of the study. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 23992 - Posted: 08.25.2017

By Denise D. Cummins Looking directly at the camera, NPR's Skunk Bear host Adam Cole laments, "It's pretty clear that I'll never be able to have a real human-style conversation with an ape.” In his short and very entertaining video, Cole summarizes decades of research aimed at teaching apes human language, all of which, we are to understand, came to naught. But what the video actually shows us is how little the average person (and many scientists) understands about language. At one point, Cole tells his dog to sit, and the dog sits. This, he tells us, is not evidence that the dog knows English. But actually, it is. The dog's behavior shows us that he is capable of understanding the simple concept of sitting, that he is capable of distinguishing the verbal signal "sit" from other verbal signals, and that he is capable of connecting the two. This isn't rocket science, it isn't magic, and it isn't anthropomorphizing. It is just the way word learning works. In studies conducted at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, a border collie named Rico was taught the meanings of 200 words. He could even use theprocess of elimination to figure out unfamiliar words: If he already knew the word "ball,” and his trainer showed him a ball and a stick and told him to get the "stick,” he would bring the stick. He could remember new words even after a month of not hearing them. © 2017 Scientific American,

Keyword: Animal Communication; Language
Link ID: 23977 - Posted: 08.19.2017

By Kai Sinclair It’s hard to see underwater, and not just because of the chlorine. The image-producing light rays that enter our eyes have trouble bending and focusing when the water’s density is almost same as that of eye fluid. Sea creatures experience the same problem, but squid use a type of lens notorious for blurry images to correct that, researchers report today in Science. Spherical lenses, like the squids’, usually can’t focus the incoming light to one point as it passes through the curved surface, which causes an unclear image. The only way to correct this is by bending each ray of light differently as it falls on each location of the lens’s surface. S-crystallin, the main protein in squid lenses, evolved the ability to do this by behaving as patchy colloids—small molecules that have spots of molecular glue that they use to stick together in clusters. The S-crystallins feature a pair of loops that act as the proteins’ sticky patches and attract the loops of other S-crystallins. Globs of six proteins link together during the squid’s larval stage and form a gel that eventually becomes the center of the lens. As the gel becomes too dense with protein clumps, smaller particles struggle to diffuse through, and a new layer of protein packages forms with just under six S-crystallins in each clump. The process continues until the outer edge of the lens is formed with pairs of S-crystallins. This allows light rays to bend a little differently in each region of the lens, which yields a clearer image. Some fish eyes are nearly identical to squids’, but it’s unknown whether their eye proteins exhibit patchy colloidlike behavior. Other cephalopods, like octopuses and nautiluses, lack S-crystallin lens proteins. So they, unlike squid, likely have blurry vision. © 2017 American Association for the Advancement of Science

Keyword: Vision; Evolution
Link ID: 23945 - Posted: 08.11.2017

By Michael Price Anthropologists have waited decades to find the complete cranium of a Miocene ape from Africa—one that lived in the hazy period before the human lineage split off from the common ancestors we share with chimpanzees some 7 million years ago. Now, scientists in Kenya have found their prize at last: an almost perfectly preserved skull roughly the size of a baseball. The catch? It’s from an infant. That means that although it can give scientists a rough idea of what the common ancestor to all living apes and humans would have looked like, drawing other meaningful conclusions could be challenging. “This is the sort of thing that the fossil record loves to do to us,” says James Rossie, a biological anthropologist at the State University of New York in Stony Brook who wasn’t involved with the study. “The problem is that we learn from fossils by comparing them to others. When there are no other infant Miocene ape skulls to which to make those comparisons, your hands are tied.” The remarkably complete skull was discovered in the Turkana Basin of northern Kenya 3 years ago. As the sun sank behind the Napudet Hills west of Lake Turkana, primate paleontologist Isaiah Nengo of De Anza College in Cupertino, California, and his team started walking back to their jeep. Kenyan fossil hunter John Ekusi raced ahead to smoke a cigarette. Suddenly he began circling in place. When Nengo caught up, he saw a dirt-clogged eye socket staring up at him. “There was this skull just sticking out of the ground,” Nengo recalls. “It was incredible because we had been going up and down that path for weeks and never noticed it.” © 2017 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 23943 - Posted: 08.10.2017

By Karl Gruber Are you good with faces? So is the Japanese rice fish – at least, it is if the faces are the right way up. Just like humans, the tiny fish has no problem recognising faces orientated the usual way, but, again like us, it struggles when they are inverted. The finding indicates that the fish may have developed a unique brain pathway for face recognition, just as humans have. We have no problem identifying most objects in our environment – say, a chair – no matter what way up they are. But faces are different. It is relatively easy for us to spot the differences between two faces, even if they are physically similar, if we see them in photographs the right way up. But if the images are upside down, telling them apart gets a bit tricky. “This is because we have a specific brain area for processing faces, and when the face is upside down, we process the image through object processing pathways, and not the face-processing pathways any more,” says Mu-Yun Wang at the University of Tokyo, Japan. Until now, this face-inversion effect was considered exclusive to mammals as it has only been observed in primates and sheep. Enter the Japanese rice fish, also known as the medaka (Oryzias latipes), a 3.5-centimetre-long shoaling fish commonly found in rice paddies, marshes, ponds and slow-moving streams in East Asia. These fish are very social, so identifying the right individuals to associate with is important. © Copyright New Scientist Ltd.

Keyword: Attention; Evolution
Link ID: 23891 - Posted: 07.28.2017

By Giorgia Guglielmi Tits amazing are birds Japanese. If you didn’t get that, you wouldn’t be alone: Humans figure out the meaning of sentences like this using grammatical rules such as word order. It turns out that Japanese tits, social birds that live in Japan and the Russian Far East, do it too. These wild birds respond to calls they’ve never heard before only if the chirps are in the right order, researchers report today in Current Biology. When a predator threatens the flock, Japanese tits produce something called a “mobbing call,” with the sequence ABC-D. By itself, the ABC part of the call means “danger.” But the D part of the call—similar to the “recruitment call” of a close relative, the willow tit—attracts flock members when there’s something to share, such as food. When the two parts are produced together, Japanese tits flock together to mob the intruder. To find out if the order of the calls mattered, researchers created a song that Japanese tits had never heard before—an artificial sequence made up of the Japanese tit’s ABC alert, followed by the willow tit’s recruitment call, tӓӓ. (You can listen to them, above.) They then played it from a loudspeaker for a flock of nearby tits. When Japanese tits heard the ABC- tӓӓ call, they turned their heads, looking for a predator, as they approached the loudspeaker. But when the artificial sequence was reversed (tӓӓ-ABC), the birds didn’t react. © 2017 American Association for the Advancement of Science.

Keyword: Animal Communication; Language
Link ID: 23889 - Posted: 07.28.2017

Ryan Kellman The modern Planet of the Apes reboot begins with a research chimpanzee being raised in an American home. It's a pretty plausible premise — that exact scenario has played out in the real world many times. On June 26, 1931, for example, Luella and Winthrop Kellogg pulled a baby female chimpanzee away from her mother and brought her to live in their home in Orange Park, Fla. The Kelloggs were comparative psychologists. Their plan was to raise the chimpanzee, Gua, alongside their own infant son, Donald, and see if she picked up human language. According to the book they wrote about the experiment, Luella wasn't initially on board: ... the enthusiasm of one of us met with so much resistance from the other that it appeared likely we could never come to an agreement upon whether or not we should even attempt such an undertaking. But attempt it they did. The Kelloggs performed a slew of tests on Donald and Gua. How good were their reflexes? How many words did they recognize? How did they react to the sound of a gunshot? What sound did each infant's skull make when tapped by a spoon? (Donald's produced "a dull thud" while Gua's made the sound of a "mallet upon a wooden croquet ball.") Chimpanzees develop faster than humans, so Gua outshone Donald when it came to most tasks. She even learned to respond to English phrases like "Don't touch!" and "Get down!" But unlike the apes in the movies, Gua never learned to speak. © 2017 npr

Keyword: Language; Evolution
Link ID: 23871 - Posted: 07.25.2017

By Becca Cudmore A mother rat’s care for her pup reaches all the way into her offspring’s DNA. A young rat that gets licked and groomed a lot early on in life exhibits diminished responses to stress thanks to epigenetic changes in the hippocampus, a brain region that helps transform emotional information into memory. Specifically, maternal solicitude reduces DNA methylation and changes the structure of DNA-packaging proteins, triggering an uptick in the recycling of the neurotransmitter serotonin and the upregulation of the glucocorticoid receptor. These changes make the nurtured rat’s brain quicker to sense and tamp down the production of stress hormones in response to jarring experiences such as unexpected sound and light. That pup will likely grow into a calm adult, and two studies have shown that female rats who exhibit a dampened stress response are more likely to generously lick, groom, and nurse their own young. Caring for pups is one example of what casual observers of behavior might call an animal’s instinct—generally considered to be an innate, genetically encoded phenomenon. But could such epigenetic changes, when encoded as ancestral learning, also be at the root of maternal care and other seemingly instinctual behaviors we see across the animal kingdom? “We don’t have a general theory for the mechanics of instinct as we do for learning, and this is something that has troubled me for a very long time,” says University of Illinois entomologist Gene Robinson. He studies social evolution in the Western honey bee and recently coauthored a perspective piece in Science together with neurobiologist Andrew Barron of Macquarie University in Sydney, Australia, suggesting methylation as a possible mechanism for the transgenerational transmission of instinctual behavior, rather than those behaviors being hardwired in the genome (356:26-27, 2017). Robinson and Barron suggest that instinctual traits, such as honey bees’ well-known waggle dance or a bird’s in-born ability to sing its species’ songs, are the result of traits first learned by their ancestors and inherited across generations by the process of methylation. This differs from classical thoughts on animal learning, which say that if a behavior is learned, it is not innate, and will not be inherited. © 1986-2017 The Scientist

Keyword: Epigenetics; Evolution
Link ID: 23861 - Posted: 07.22.2017

Ashley Yeager DNA might reveal how dogs became man’s best friend. A new study shows that some of the same genes linked to the behavior of extremely social people can also make dogs friendlier. The result, published July 19 in Science Advances, suggests that dogs’ domestication may be the result of just a few genetic changes rather than hundreds or thousands of them. “It is great to see initial genetic evidence supporting the self-domestication hypothesis or ‘survival of the friendliest,’” says evolutionary anthropologist Brian Hare of Duke University, who studies how dogs think and learn. “This is another piece of the puzzle suggesting that humans did not create dogs intentionally, but instead wolves that were friendliest toward humans were at an evolutionary advantage as our two species began to interact.” Not much is known about the underlying genetics of how dogs became domesticated. In 2010, evolutionary geneticist Bridgett vonHoldt of Princeton University and colleagues published a study comparing dogs’ and wolves’ DNA. The biggest genetic differences gave clues to why dogs and wolves don’t look the same. But major differences were also found in WBSCR17, a gene linked to Williams-Beuren syndrome in humans. Williams-Beuren syndrome leads to delayed development, impaired thinking ability and hypersociability. VonHoldt and colleagues wondered if changes to the same gene in dogs would make the animals more social than wolves, and whether that might have influenced dogs’ domestication. © Society for Science & the Public 2000 - 2017.

Keyword: Aggression; Genes & Behavior
Link ID: 23855 - Posted: 07.20.2017

Susan Milius Ravens have passed what may be their toughest tests yet of powers that, at least on a good day, let people and other apes plan ahead. Lab-dwelling common ravens (Corvus corax) in Sweden at least matched the performance of nonhuman apes and young children in peculiar tests of advanced planning ability. The birds faced such challenges as selecting a rock useless at the moment but likely to be useful for working a puzzle box and getting food later. Ravens also reached apelike levels of self-control, picking a tool instead of a ho-hum treat when the tool would eventually allow them to get a fabulous bit of kibble 17 hours later, Mathias Osvath and Can Kabadayi of Lund University in Sweden report in the July 14 Science. “The insight we get from the experiment is that [ravens] can plan for the future outside behaviors observed in the wild,” Markus Böckle, of the University of Cambridge, said in an e-mail. Böckle, who has studied ravens, coauthored a commentary in the same issue of Science. In the wild, ravens cache some of their food, but that apparent foresight could be more of a specific adaptation that evolved with diet instead of as some broader power of planning. The Lund tests, based on experiments with apes, tried to challenge ravens in less natural ways. The researchers say the birds aren’t considered much of a tool-using species in nature, nor do they trade for food. “The study for the first time in any animal shows that future planning can be used in behaviors it was not originally selected for” in evolution, Böckle says. © Society for Science & the Public 2000 - 2017.

Keyword: Intelligence; Evolution
Link ID: 23835 - Posted: 07.14.2017

By Abby Olena For more than 50 years, scientists have taken for granted that all snakes share a ZW sex determination system, in which males have two Z chromosomes and females have one Z and one W. But a study, published today (July 6) in Current Biology, reveals that the Central American boa (Boa imperator) and the Burmese python (Python bivittatus) use an XY sex determination system, which evolved independently in the two species. “This work is a culmination of a lot of questions that we’ve had about pythons and boas for a long time,” says Jenny Marshall Graves, a geneticist at La Trobe Univeristy in Melbourne, Australia, who did not participate in the study. Some of these questions came up for Warren Booth, a geneticist and ecologist at the University of Tulsa, as he studied parthenogenesis—the growth and development of offspring in the absence of fertilization. He noticed a pattern for organisms undergoing parthenogenesis: animal species that use a ZW system have only male (ZZ) offspring, and the organisms that use an XY system have only female (XX) offspring. Except this pattern doesn’t hold true for boas and pythons, who consistently produce female offspring by parthenogenesis. Booth contacted Tony Gamble, a geneticist at Marquette University in Milwaukee, Wisconsin, who studies sex chromosomes, to begin a collaboration to investigate whether boas and pythons might actually have X and Y chromosomes. Spurred by Booth’s questions, “I went back and reread some of the early papers” on snake sex chromosomes, says Gamble. “What became clear is that they didn’t show that boas and pythons had a ZW sex chromosome system. They just said it without any evidence.” © 1986-2017 The Scientist

Keyword: Sexual Behavior; Evolution
Link ID: 23815 - Posted: 07.09.2017

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

Keyword: Evolution
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.

Keyword: Evolution; Animal Communication
Link ID: 23802 - Posted: 07.04.2017

By Michael Price Contrary to popular lore that portrays chimpanzees as having “super strength,” studies have only found modest differences with humans. But our closest relatives are slightly stronger by several measures, and now a study comparing the muscle fibers of different primates reveals a potential explanation: Humans may have traded strength for endurance, allowing us to travel farther for food. To determine why chimpanzees are stronger than humans—at least on a pound-for-pound basis—Matthew O’Neill, an anatomy and evolution researcher at the University of Arizona College of Medicine in Phoenix, and colleagues biopsied the thigh and calf muscles of three chimps housed at the State University of New York at Stony Brook. They dissected the samples into individual fibers and stimulated them to figure out how much force they could generate. Comparing their measurements to known data from humans, the team found that, at the individual fiber level, muscle output was about the same. Given that different fibers throughout the muscle might make a difference, the researchers conducted a more thorough analysis of tissue samples from pelvic and hind limb muscles of three chimpanzee cadavers from various zoos and research institutes around the United States. Previous studies in mammals have found that muscle composition between trunk, forelimb, and hind limb muscles is largely the same, O’Neill says, so he’s confident the samples are representative across most of the chimp’s musculature. The team used a technique called gel electrophoresis to break down the muscles into individual muscle fibers, and compared this breakdown to human muscle fiber data. © 2017 American Association for the Advancement of Science.

Keyword: Muscles; Evolution
Link ID: 23782 - Posted: 06.27.2017

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.

Keyword: Evolution
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

Keyword: Evolution
Link ID: 23723 - Posted: 06.08.2017