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Katharina Kropshofer Life is not so different beneath the ocean waves. Bottlenose dolphins use simple tools, orcas call each other by name, and sperm whales talk in local dialects. Many cetaceans live in tight-knit groups and spend a good deal of time at play. That much scientists know. But in a new study, researchers compiled a list of the rich behaviours spotted in 90 different species of dolphins, whales and porpoises, and found that the bigger the species’ brain, the more complex – indeed, the more “human-like” – their lives are likely to be. This suggests that the “cultural brain hypothesis” – the theory that suggests our intelligence developed as a way of coping with large and complex social groups – may apply to whales and dolphins, as well as humans. Writing in the journal, Nature Ecology and Evolution, the researchers claim that complex social and cultural characteristics, such as hunting together, developing regional dialects and learning from observation, are linked to the expansion of the animals’ brains – a process known as encephalisation. The researchers gathered records of dolphins playing with humpback whales, helping fishermen with their catches, and even producing signature whistles for dolphins that are absent – suggesting the animals may even gossip. Another common behaviour was adult animals raising unrelated young. “There is the saying that ‘it takes a village to raise a child’ [and that] seems to be true for both whales and humans,” said Michael Muthukrishna, an economic psychologist and co-author on the study at the London School of Economics. © 2017 Guardian News and Media Limited

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24202 - Posted: 10.17.2017

Rae Ellen Bichell Abstinence may have found its most impressive poster child yet: Diploscapter pachys. The tiny worm is transparent, smaller than a poppy seed and hasn't had sex in 18 million years. It's basically just been cloning itself this whole time. Usually, that's a solid strategy for going extinct, fast. What's its secret? "Scientists have been trying to understand how some animals can survive for millions of years without sex, because such strict, long-term abstinence is very rare in the animal world," says David Fitch, a biologist at New York University. Most plants and animals use sex to reproduce. As he and his colleagues report in the recent issue of Current Biology, this seemingly unimpressive roundworm seems to have developed a different way of copying its genes — one that leads to just enough mutations to give the worms room to adapt, but not enough to cause crippling defects. Sex is pretty great for a lot of reasons (unless, perhaps, you're a duck), but one is that's it's a good way to dodge the effects of bad mutations. "All organisms accumulate mutations," says Kristin Gunsalus, a developmental geneticist at New York University and a co-author of the study. Usually, the machinery that copies DNA makes a few mistakes each time a cell divides. In humans, says Gunsalus, there are about six errors per cell division. © 2017 npr

Related chapters from BN8e: 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: 24179 - Posted: 10.12.2017

Barbara J. King In 1981, the evolutionary biologist Stephen Jay Gould's book The Mismeasure of Man hit the presses. A take-down of studies purporting to demonstrate that the intelligence of humans is genetically determined — and that some human groups (read "white Western Europeans") are innately superior — the book exposed interpretive bias and scientific racism in the measurement of human intelligence. Different environmental histories across human groups, in fact, affect testing outcomes in significant ways: There is no innate superiority due to genes. The Mismeasure of Man ignited ferocious discussion (and the occasional subsequent correction) that has continued even in recent years across biology, anthropology, psychology and philosophy: Its argument mattered not only for how we do science, but how science entangles with issues of social justice. Now, psychologists David A. Leavens of the University of Sussex, Kim A. Bard of the University of Portsmouth, and William D. Hopkins of Georgia State University have framed their new Animal Cognition article, "The mismeasure of ape social cognition," around Gould's book. Ape (especially chimpanzee) social intelligence, the authors say, has been routinely mismeasured because apes are tested in comprehensively different circumstances from the children with whom they are compared — and against whose performance theirs is found to be lacking. Leavens et al. write: "All direct ape-human comparisons that have reported human superiority in cognitive function have universally failed to match the groups on testing environment, test preparation, sampling protocols, and test procedures." © 2017 npr

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior; Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 24123 - Posted: 09.29.2017

By Mary Bates North American walnut sphinx moth caterpillars (Amorpha juglandis) look like easy meals for birds, but they have a trick up their sleeves—they produce whistles that sound like bird alarm calls, scaring potential predators away. At first, scientists suspected birds were simply startled by the loud noise. But a new study presented at the International Symposium on Acoustic Communication by Animals in Omaha in July suggests a more sophisticated mechanism: the caterpillar’s whistle appears to mimic a bird alarm call, sending avian predators scrambling for cover. “This is the first instance of deceptive alarm calling between an insect and a bird, and it’s a novel defense form for an insect,” says Jessica Lindsay, the study’s first author and a graduate student in the lab of Kristin Laidre at the University of Washington. “I think that’s pretty wild.” When pecked by a bird, the caterpillars whistle by compressing their bodies like an accordion and forcing air out through specialized holes in their sides. The whistles are impressively loud, considering they are made by a two-inch long insect. They have been measured at over 80 dB from 5 cm away from the caterpillar, similar to the loudness of a garbage disposal. In a laboratory experiment a few years ago, birds responded to caterpillar whistles by jumping away and abandoning their predation attempts. The authors of that study had attributed their behavior to a general startle response. © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24112 - Posted: 09.26.2017

By Ann Gibbons Neandertals have long been seen as the James Deans of human evolution—they grew up fast, died young, and became legends. But now, a rare skeleton of a Neandertal child suggests that our closest cousins didn’t all lead such fast lives—and that our own long childhoods aren’t unique. The find may reveal how Neandertals, like humans, had enough energy to grow bigger brains. “We like the paper because it puts the idea of ‘Neanderthal exceptionalism’ to rest,” wrote anthropologist Marcia Ponce de León and neurobiologist Christoph Zollikofer from the University of Zurich in Switzerland (who are not authors of the new study) in an email. “RIP.” Researchers have long known that modern humans take almost twice as long as chimpanzees to reach adulthood and have wondered when and why our ancestors evolved the ability to prolong childhood and delay reproduction. Our distant ancestors, such as the famous fossil Lucy and other australopithecines, matured quickly and died young like chimps. Even early members of our own genus Homo, such as the 1.6-million-year-old skeleton of an H. erectus boy, grew up faster than we do. By providing your email address, you agree to send your email address to the publication. Information provided here is subject to Science's Privacy Policy. But by the time the earliest known members of our species, H. sapiens, were alive 300,000 years ago at Jebel Irhoud in Morocco, they were taking longer to grow up. A leading theory is that big brains are so metabolically expensive that humans have to delay the age of reproduction—and, hence, have longer childhoods—so first-time mothers are older and, thus, bigger and strong enough to have the energy to feed babies with such big brains after birth when their brains are doubling in size. © 2017 American Association for the Advancement of Science

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 24098 - Posted: 09.22.2017

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.

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24080 - Posted: 09.20.2017

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.

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 23943 - Posted: 08.10.2017

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

Related chapters from BN8e: 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 BN8e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Lateralization
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 BN8e: 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 BN8e: 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 BN8e: 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 BN8e: 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 BN8e: 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 BN8e: 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 BN8e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Lateralization
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 BN8e: 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 BN8e: 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 BN8e: 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 BN8e: 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