Chapter 6. Evolution of the Brain and Behavior
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By Sam Wong Six years ago, a chimpanzee had the bright idea to use moss to soak up water, then drink from it, and seven others soon learned the trick. Three years later, researchers returned to the site to see if the practice had persisted to become part of the local chimp culture. They now report that the technique has continued to spread, and it’s mostly been learned by relatives of the original moss-spongers. This adds to earlier evidence that family ties are the most important routes for culture to spread in animals. After the first report of chimps using moss as a sponge in Budongo Forest, Uganda, researchers rarely saw the behaviour again, and wondered whether chimps still knew how to do it. So they set up an experiment, providing moss and leaves at the clay pit where the chimps had demonstrated the technique before. Then they watched to see whether chimpanzees would use leaves – a more common behaviour – or moss to soak up the mineral-rich water from the pit. The eight original moss-spongers all used moss again during the experiment, and so did another 15 chimps, showing the practice had become more widespread. The researchers wondered what factors influenced which individuals adopted it: were they connected socially, or through families, for instance? © Copyright Reed Business Information Ltd.
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.
Link ID: 23541 - Posted: 04.26.2017
By Virginia Morell Humpback whales are known for their operatic songs that carry across the seas. Their calves, however, whisper, uttering soft squeaks and grunts to their mothers (which you can hear above). Now, a new study suggests that loud calf voices can also attract some unwanted visitors: male humpbacks, who might separate the pair by trying to mate with the mother, and killer whales, who dine on young humpbacks. To record their sounds, scientists placed temporary tagging devices on eight humpback whale mothers and calves in the Exmouth Gulf off Western Australia, where the young whales spend months suckling to gain enough weight for their annual migrations to the Antarctic or Arctic. After listening to the recordings, scientists say the calves’ careful whispers are not cries for food, as previously thought. Instead, they may help them stay in close contact with their mothers when swimming. And, say researchers, writing today in Functional Ecology, the low decibel sounds help keep would-be predators away from the “nursery.” © 2017 American Association for the Advancement of Science
Keyword: Animal Communication
Link ID: 23534 - Posted: 04.26.2017
Amber Dance Biologist Leo Smith held an unusual job while an undergraduate student in San Diego. Twice a year, he tagged along on a chartered boat with elderly passengers. The group needed him to identify two particular species of rockfish, the chilipepper rockfish and the California shortspine thornyhead. Once he’d found the red-orange creatures, the passengers would stab themselves in the arms with the fishes’ spines. Doing so, the seniors believed, would relieve their aching arthritic joints. Smith, now at the University of Kansas in Lawrence, didn’t think much of the practice at the time, but now he wonders if those passengers were on to something. Though there’s no evidence that anything in rockfish venom can alleviate pain — most fish stings are, in fact, quite painful themselves — some scientists suspect fish venom is worth a look. Studying the way venom molecules from diverse fishes inflict pain might help researchers understand how nerve cells sense pain and lead to novel ways to dull the sensation. Smith is one of a handful of scientists who are studying fish venoms, and there’s plenty to investigate. An estimated 7 to 9 percent of fishes, close to 3,000 species, are venomous, Smith’s work suggests. Venomous fishes are found in freshwater and saltwater, including some stingrays, catfishes and stonefishes. Some, such as certain fang blennies, are favorites in home aquariums. Yet stinging fishes haven’t gotten the same attention from scientists as snakes and other venomous creatures. |© Society for Science & the Public 2000 - 2017
By Elizabeth Pennisi By standing on the shoulders of giants, humans have built the sophisticated high-tech world we live in today. Tapping into the knowledge of previous generations—and those around us—was long thought to be a “humans-only” trait. But homing pigeons can also build collective knowledge banks, behavioral biologists have discovered, at least when it comes to finding their way back to the roost. Like humans, the birds work together and pass on information that lets them get better and better at solving problems. “It is a really exciting development in this field,” says Christine Caldwell, a psychologist at the University of Stirling in the United Kingdom who was not involved with the work. Researchers have admired pigeon intelligence for decades. Previous work has shown the birds are capable of everything from symbolic communication to rudimentary math. They also use a wide range of cues to find their way home, including smell, sight, sound, and magnetism. On its own, a pigeon released multiple times from the same place will even modify its navigation over time for a more optimal route home. The birds also learn specific routes from one another. Because flocks of pigeons tend to take more direct flights home than individuals, scientists have long thought some sort of “collective intelligence” is at work. © 2017 American Association for the Advancement of Science
By Niall Firth The firing of every neuron in an animal’s body has been recorded, live. The breakthrough in imaging the nervous system of a hydra – a tiny, transparent creature related to jellyfish – as it twitches and moves has provided insights into how such simple animals control their behaviour. Similar techniques might one day help us get a deeper understanding of how our own brains work. “This could be important not just for the human brain but for neuroscience in general,” says Rafael Yuste at Columbia University in New York City. Instead of a brain, hydra have the most basic nervous system in nature, a nerve net in which neurons spread throughout its body. Even so, researchers still know almost nothing about how the hydra’s few thousand neurons interact to create behaviour. To find out, Yuste and colleague Christophe Dupre genetically modified hydra so that their neurons glowed in the presence of calcium. Since calcium ions rise in concentration when neurons are active and fire a signal, Yuste and Dupre were able to relate behaviour to activity in glowing circuits of neurons. For example, a circuit that seems to be involved in digestion in the hydra’s stomach-like cavity became active whenever the animal opened its mouth to feed. This circuit may be an ancestor of our gut nervous system, the pair suggest. © Copyright Reed Business Information Ltd.
Nicola Davis Apes are on a par with human infants in being able to tell when people have an accurate belief about a situation or are actually mistaken, researchers say. While previous work has shown that great apes understand the goals, desires and perceptions of others, scientists say the latest finding reveals an important cognitive ability. “For the last 30 or more years people thought that belief understanding is the key marker of humans and really differentiates us from other species – and this does not seem to be the case,” said David Buttelmann, co-author of the research from the Max Planck Institute for Evolutionary Anthropology in Germany. Apes can guess what others are thinking - just like humans, study finds Read more The results follow on the heels of a study published last year which also suggests that apes understand the concept of false beliefs – after research that used eye-tracking technology to monitor the gaze of apes exposed to various pranks carried out by an actor dressed in a King Kong suit. But the new study, says Buttelmann, is an important step forward, showing that apes not only understand false belief in others, but apply that understanding to their own actions. Writing in the journal Plos One, Buttelmann and colleagues described exploring the understanding of false belief in 34 great apes, including bonobos, chimpanzees and orangutans, using a test that can be passed by human infants at one to two years of age. © 2017 Guardian News and Media Limited
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)
Erin Ross The sex of a sea lamprey may be determined by how fast it grows as a larva. Sex is determined by chromosomes in mammals and by temperature in many reptiles. But for sea lampreys — eel-like creatures that dine on blood — the growth rate of their larvae seems to control whether they are male or female. They are the first creatures known to undergo sex determination in this way. Researchers know next to nothing about sex determination in sea lampreys (Petromyzon marinus) and have long been puzzled by the observation that some adult populations are mostly male, and others female. The fish begin their lives as larvae with undifferentiated sexual organs. After a year or so, they develop gonads, and after a few more years — the timing can vary — they metamorphose into adult sucker-mouthed parasites. A team led by biologist Nick Johnson, at the US Geological Survey in Millersburg, Michigan, identified lamprey habitats in and near streams leading to the Great Lakes. Some areas were productive, with lots of food, whereas others were unproductive sites with little food. After taking measures to ensure no wild lamprey were present, they released between 1,500 and 3,000 wire-tagged larval lamprey into each of the study sites. The researchers recaptured the tagged lamprey and checked their sex after the larvae had metamorphosed into adults and migrated upstream. They found that lamprey in productive streams with lots of food were larger, reached maturity earlier and were more likely to be female. But in unproductive sites, smaller, male lamprey dominated, Johnson’s team reports in a paper published on 29 March in Proceedings of the Royal Society B1. © 2017 Macmillan Publishers Limited
By Erik Vance The world’s smallest arachnid, the Samoan moss spider, is at a third of a millimeter nearly invisible to the human eye. The largest spider in the world is the goliath birdeater tarantula, which weighs 5 ounces and is about the size of a dinner plate. For reference, that is about the same difference in scale between that same tarantula and a bottlenose dolphin. And yet the bigger spider does not act in more complex ways than its tiny counterpart. “Insects and spiders and the like—in terms of absolute size—have among the tiniest brains we’ve come across,” says William Wcislo, a scientist at the Smithsonian Tropical Research Institute in Panama City. “But their behavior, as far as we can see, is as sophisticated as things that have relatively large brains. So then there’s the question: How do they do that?” No one would argue that a tarantula is as smart as a dolphin or having a really big brain is not an excellent way to perform complicated tasks. But a growing number of scientists are asking the question: Is it the only way? Do you need a big brain to hunt elusive prey, design complicated structures or produce complex social dynamics? For generations scientists have wondered how intelligent creatures developed large brains to perform complicated tasks. But Wcislo is part of a small community of scientists less interested in how brains have grown than how they have shrunk and yet shockingly still perform tasks as well or better than similar species that are much larger in size. In other words, it’s what scientists call brain miniaturization, not unlike the scaling down in size of the transistors in a computer chip. This research, in fact, may hold clues to innovative design strategies that engineers might incorporate in future generations of computers. © 2017 Scientific American
Link ID: 23418 - Posted: 03.29.2017
By Lizzie Wade Ask any biologist what makes primates special, and they’ll tell you the same thing: big brains. Those impressive noggins make it possible for primates from spider monkeys to humans to use tools, find food, and navigate the complex relationships of group living. But scientists disagree on what drove primates to evolve big brains in the first place. Now, a new study comes to an unexpected conclusion: fruit. “The paper is enormously valuable,” says Richard Wrangham, a biological anthropologist at Harvard University who was not involved in the work. For the last 20 years, many scientists have argued that primates evolved bigger brains to live in bigger groups, an idea known as the “social brain hypothesis.” The new study’s large sample size and robust statistical methods suggest diet and ecology deserve more attention, Wrangham says. But not everyone is convinced. Others say that although a nutrient-rich diet allows for bigger brains, it wouldn’t be enough by itself to serve as a selective evolutionary pressure. When the authors compare diet and social life, “they’re comparing apples and oranges,” says Robin Dunbar, an evolutionary psychologist at the University of Oxford in the United Kingdom and one of the original authors of the social brain hypothesis. Alex DeCasien, the new study’s author, didn’t set out to shake up this decades-long debate. The doctoral student in biological anthropology at New York University in New York City wanted to tease out whether monogamous primates had bigger or smaller brains than more promiscuous species. She collected data about the diets and social lives of more than 140 species across all four primate groups—monkeys, apes, lorises, and lemurs—and calculated which features were more likely to be associated with bigger brains. To her surprise, neither monogamy nor promiscuity predicted anything about a primate’s brain size. Neither did any other measure of social complexity, such as group size. The only factor that seemed to predict which species had larger brains was whether their diets were primarily leaves or fruit, DeCasien and her colleagues report today in Nature Ecology & Evolution. © 2017 American Association for the Advancement of Science
If your parrot is feeling glum, it might be tweetable. Wild keas spontaneously burst into playful behaviour when exposed to the parrot equivalent of canned laughter – the first birds known to respond to laughter-like sounds. The parrots soared after one another in aerobatic loops, exchanged foot-kicking high fives in mid-air and tossed objects to each other, in what seems to be emotionally contagious behaviour. And when the recording stops, so does the party, and the birds go back to whatever they had been doing. We already knew that these half-metre-tall parrots engage in playful behaviour, especially when young. What’s new is that a special warbling call they make has been shown to trigger behaviour that seems to be an equivalent of spontaneous, contagious laughter in humans. Moreover, it’s not just the young ones that respond, adults of both sexes join in the fun too. Raoul Schwing of the University of Veterinary Medicine in Vienna, Austria, and his team played 5-minute recordings to gatherings of between two and a dozen wild keas on a mountainside of New Zealand’s Arthur’s Pass National Park, on the southern island. The group played recordings of the warble sound, or other sounds, including two other frequent kea sounds – a screech and a whistle – plus the alarm call of a local robin species and a bland tone. © Copyright Reed Business Information Lt
By Sam Wong It takes brains to choose a good partner. In one of the first experiments to look at the cognitive demands of choosing a mate, female guppies with big brains showed a preference for more colourful males, while those with smaller brains showed no preference. In guppies, like most animals, females are choosy about who to mate with, since they invest more in their offspring than males, which don’t help care for them. They tend to prefer males with striking colour patterns and big tails, traits that have been linked to good foraging ability and health. By choosing a male with these qualities, female guppies give their offspring a good chance of inheriting the same useful traits. Despite this, females often go on to make different choices. Alberto Corral López and colleagues at Stockholm University wanted to find out if brain size could account for this. Corral López and his team tested 36 females bred to have large brains, 36 bred to have small brains, and 16 females similar to guppies found in the wild. Previous studies have shown that large-brained guppies perform better in cognitive tests, suggesting that they are smarter. Each female was given the opportunity to associate with two males, one more colourful than the other. Females are known to spend more time close to males they would prefer to mate with, so the team timed how long they spent with each male. © Copyright Reed Business Information Ltd
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.
Link ID: 23386 - Posted: 03.22.2017
Cris Ledón-Rettig Picture a lion: The male has a luxuriant mane, the female doesn’t. This is a classic example of what biologists call sexual dimorphism – the two sexes of the same species exhibit differences in form or behavior. Male and female lions pretty much share the same genetic information, but look quite different. We’re used to thinking of genes as responsible for the traits an organism develops. But different forms of a trait – mane or no mane – can arise from practically identical genetic information. Further, traits are not all equally sexually dimorphic. While the tails of peacocks and peahens are extremely different, their feet, for example, are pretty much the same. Understanding how this variation of form – what geneticists call phenotypic variation – arises is crucial to answering several scientific questions, including how novel traits appear during evolution and how complex diseases emerge during a lifetime. So researchers have taken a closer look at the genome, looking for the genes responsible for differences between sexes and between traits within one sex. The key to these sexually dimorphic traits appears to be a kind of protein called a transcription factor, whose job it is to turn genes “on” and “off.” In our own work with dung beetles, my colleagues and I are untangling how these transcription factors actually lead to the different traits we see in males and females. A lot of it has to do with something called “alternative gene splicing” – a phenomenon that allows a single gene to encode for different proteins, depending on how the building blocks are joined together. © 2010–2017, The Conversation US, Inc.
Jon Hamilton An orangutan named Rocky is helping scientists figure out when early humans might have uttered the first word. Rocky, who is 12 and lives at the Indianapolis Zoo, has shown that he can control his vocal cords much the way people do. He can learn new vocal sounds and even match the pitch of sounds made by a person. "Rocky, and probably other great apes, can do things with their vocal apparatus that, for decades, people have asserted was impossible," says Rob Shumaker, the zoo's director, who has studied orangutans for more than 30 years. Rocky's abilities suggest that our human ancestors could have begun speaking 10 million years ago, about the time humans and great apes diverged, Shumaker says. Until now, many scientists thought that speech required changes in the brain and vocal apparatus that evolved more recently, during the past 2 million years. The vocal abilities of orangutans might have gone undetected had it not been for Rocky, an ape with an unusual past and a rare relationship with people. Rocky was separated from his mother soon after he was born, and spent his early years raised largely by people, and working in show business. "He was certainly the most visible orangutan in entertainment at the time," says Shumaker. "TV commercials, things like that."
If I was the late Andy Rooney, I’d say “You know what really bothers me? When science shows some facts about nature, and then someone rejects those facts because they’re inconvenient or uncomfortable for their ideology.” Indeed, when people ignore such inconvenient truths, it not only makes their cause look bad, but can produce palpable harm. Case in point: the damage that the Russian charlatan-agronomist Lysenko did to Soviet agriculture under Stalin. Rejecting both natural selection and modern genetics, Lysenko made all sorts of wild promises about improving Soviet agriculture based on bogus treatment of plants that would supposedly change their genetics. It not only didn’t work, failing to relieve Russia of its chronic famines, but Lyesnko’s Stalin-supported resistance to modern (“Western”) genetics led to the imprisonment and even the execution of really good geneticists and agronomists like Niklolia Vavilov. The ideological embrace of an unevidenced but politically amenable view of science set back Russian genetics for decades. Other cases in point: the denial of evolution by creationists, and of anthropogenic global warming by conservatives. I needn’t belabor these. But the opposition to research on group and sex differences continues. One of its big exponents is the author Cordelia Fine, who has written two books with the explicit aim of showing that there are no reliably accepted evolved and biological differences in behavior between men and women. I read her first book, Delusions of Gender, and found it a mixed bag: some of her targets did indeed do bad science, and she properly called them out; but the book was also tendentious, and wasn’t objective about other studies. I’m now about to read her second book, Testosterone Rex: Myths of Sex, Science, and Society. Judging from the reviews, which have been positive, it’s just as much a polemic as the first book, and has an ideological aim.
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.
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.
Link ID: 23328 - Posted: 03.08.2017
Bruce Bower The social lives of macaques and baboons play out in what primatologist Julia Fischer calls “a magnificent opera.” When young Barbary macaques reach about 6 months, they fight nightly with their mothers. Young ones want the “maternal embrace” as they snooze; mothers want precious alone time. Getting pushed away and bitten by dear old mom doesn’t deter young macaques. But they’re on their own when a new brother or sister comes along. In Monkeytalk, Fischer describes how the monkey species she studies have evolved their own forms of intelligence and communication. Connections exist between monkey and human minds, but Fischer regards differences among primate species as particularly compelling. She connects lab studies of monkeys and apes to her observations of wild monkeys while mixing in offbeat personal anecdotes of life in the field. Fischer catapulted into a career chasing down monkeys in 1993. While still in college, she monitored captive Barbary macaques. That led to fieldwork among wild macaques in Morocco. In macaque communities, females hold central roles because young males move to other groups to mate. Members of closely related, cooperative female clans gain an edge in competing for status with male newcomers. Still, adult males typically outrank females. Fischer describes how the monkeys strategically alternate between attacking and forging alliances. After forging her own key scientific alliances, Fischer moved on to study baboons in Africa, where she entered the bureaucratic jungle. Obtaining papers for a car in Senegal, for instance, took Fischer several days. She first had to shop for a snazzy outfit to impress male paper-pushers, she says. |© Society for Science & the Public 2000 - 2017.