Chapter 6. Evolution of the Brain and Behavior
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by Colin Barras Enough of the cheap jibes: Neanderthals may have been just as clever as modern humans. Anthropologists have already demolished the idea that Neanderthals were dumb brutes, and now a review of the archaeological record suggests they were our equals. Neanderthals were one of the most successful of all hominin species, occupying much of Europe and Asia. Their final demise about 40,000 years ago, shortly after Homo sapiens walked into their territory, is often put down to the superiority of our species. It's time to lay that idea to rest, say Paola Villa at the University of Colorado in Boulder and Wil Roebroeks at Leiden University in the Netherlands. Just as smart as you For instance, there is evidence that Homo sapiens could use fire to chemically transform natural materials into glue 70,000 years ago, but Neanderthals were performing similarly complex chemical syntheses at least 200,000 years ago. And although 70,000-year-old engraved ochre from South Africa is seen as evidence that our species had developed sophisticated symbolism and perhaps even language, similar artefacts have been found at 50,000-year-old Neanderthal sites in Spain. What's more, Neanderthals might have been able to talk. Late last year we learned that our extinct cousins had a hyoid, a small bone in the neck that plays a big role in speech, very like ours. Evidence has even emerged that Homo sapiens may have learned some skills by copying Neanderthals. Yet despite all of this evidence, the idea that Neanderthals were our inferiors still persists. © Copyright Reed Business Information Ltd.
Fork-tailed drongos, glossy black African songbirds with ruby-colored eyes, are the avian kingdom’s masters of deception. They mimic the alarm calls of other species to scare animals away and then swipe their dupes’ dinner. But like the boy who cried wolf, drongos can raise the alarm once too often. Now, scientists have discovered that when one false alarm no longer works, the birds switch to another species’ warning cry, a tactic that usually does the trick. “The findings are astounding,” says John Marzluff, a wildlife biologist at the University of Washington, Seattle, who was not involved in the work. “Drongos are exceedingly deceptive; their vocabularies are immense; and they match their deception to both the target animal and [its] past response. This level of sophistication is incredible.” Since 2008, Tom Flower, an evolutionary biologist at the University of Cape Town, has followed drongos in the Kuruman River Reserve in the Kalahari Desert. He’s habituated and banded about 200 of the robin-sized birds, and, using food rewards, has trained individuals to come to him when he calls. After getting its snack, the drongo quickly returns to its natural behavior—catching insects and following other bird species or meerkats—while Flower tags along. Drongos also keep an eye out for raptors and other predators. When they spot one, they utter metallic alarm cries. Meerkats and pied babblers, a highly social bird, pay attention to the drongos and dash for cover when the drongos raise an alarm—just as they do when one of their own calls out a warning. Studies have shown that having drongos around benefits animals of other species, which don’t have to be as vigilant and can spend more time foraging. But there’s a trade-off: The drongos’ cries aren’t always honest. When a meerkat has caught a fat grub or gecko, a drongo is apt to change from trustworthy sentinel to wily deceiver. © 2014 American Association for the Advancement of Science.
Intelligence is hard to test, but one aspect of being smart is self-control, and a version of the old shell game that works for many species suggests that brain size is very important. When it comes to animal intelligence, says Evan MacLean, co-director of Duke University’s Canine Cognition Center, don’t ask which species is smarter. “Smarter at what?” is the right question. Many different tasks, requiring many different abilities, are given to animals to measure cognition. And narrowing the question takes on particular importance when the comparisons are across species. So Dr. MacLean, Brian Hare and Charles Nunn, also Duke scientists who study animal cognition, organized a worldwide effort by 58 scientists to test 36 species on a single ability: self-control. This capacity is thought to be part of thinking because it enables animals to override a strong, nonthinking impulse, and to solve a problem that requires some analysis of the situation in front of them. The testing program, which took several international meetings to arrange, and about seven years to complete, looked at two common tasks that are accepted ways to judge self-control. It then tried to correlate how well the animals did on the tests with other measures, like brain size, diet and the size of their normal social groups. Unsurprisingly, the great apes did very well. Dogs and baboons did pretty well. And squirrel monkeys, marmosets and some birds were among the worst performers. Surprisingly, absolute brain size turned out to be a much better predictor of success than relative brain size, which has been thought to be a good indication of intelligence. Social group size was not significant, but variety of diet was. The paper, published last week in the journal Proceedings of the National Academy of Sciences, is accompanied online by videos showing the animals doing what looks for all the world like the shell game in which a player has to guess where the pea is. © 2014 The New York Times Company
by Laura Sanders When a baby cries at night, exhausted parents scramble to figure out why. He’s hungry. Wet. Cold. Lonely. But now, a Harvard scientist offers more sinister explanation: The baby who demands to be breastfed in the middle of the night is preventing his mom from getting pregnant again. This devious intention makes perfect sense, says evolutionary biologist David Haig, who describes his idea in Evolution, Medicine and Public Health. Another baby means having to share mom and dad, so babies are programmed to do all they can to thwart the meeting of sperm and egg, the theory goes. Since babies can’t force birth control pills on their mothers, they work with what they’ve got: Nighttime nursing liaisons keep women from other sorts of liaisons that might lead to another child. And beyond libido-killing interruptions and extreme fatigue, frequent night nursing also delays fertility in nursing women. Infant suckling can lead to hormone changes that put the kibosh on ovulation (though not reliably enough to be a fail-safe birth control method, as many gynecologists caution). Of course, babies don’t have the wherewithal to be interrupting their mothers’ fertility intentionally. It’s just that in our past, babies who cried to be nursed at night had a survival edge, Haig proposes. The timing of night crying seems particularly damning, Haig says. Breastfed babies seem to ramp up their nighttime demands around 6 months of age and then slowly improve — precisely the time when a baby would want to double down on its birth control efforts. © Society for Science & the Public 2000 - 2013
By David Grimm “We did one study on cats—and that was enough!” Those words effectively ended my quest to understand the feline mind. I was a few months into writing Citizen Canine: Our Evolving Relationship With Cats and Dogs, which explores how pets are blurring the line between animal and person, and I was gearing up for a chapter on pet intelligence. I knew a lot had been written about dogs, and I assumed there must be at least a handful of studies on cats. But after weeks of scouring the scientific world for someone—anyone—who studied how cats think, all I was left with was this statement, laughed over the phone to me by one of the world’s top animal cognition experts, a Hungarian scientist named Ádám Miklósi. We are living in a golden age of canine cognition. Nearly a dozen laboratories around the world study the dog mind, and in the past decade scientists have published hundreds of articles on the topic. Researchers have shown that Fido can learn hundreds of words, may be capable of abstract thought, and possesses a rudimentary ability to intuit what others are thinking, a so-called theory of mind once thought to be uniquely human. Miklósi himself has written an entire textbook on the canine mind—and he’s a cat person. I knew I was in trouble even before I got Miklósi on the phone. After contacting nearly every animal cognition expert I could find (people who had studied the minds of dogs, elephants, chimpanzees, and other creatures), I was given the name of one man who might, just might, have done a study on cats. His name was Christian Agrillo, and he was a comparative psychologist at the University of Padova in Italy. When I looked at his website, I thought I had the wrong guy. A lot of his work was on fish. But when I talked to him he confirmed that, yes, he had done a study on felines. Then he laughed. “I can assure you that it’s easier to work with fish than cats,” he said. “It’s incredible.” © 2014 The Slate Group LLC.
It looks like a standardized test question: Is the sum of two numbers on the left or the single number on the right larger? Rhesus macaques that have been trained to associate numerical values with symbols can get the answer right, even if they haven’t passed a math class. The finding doesn’t just reveal a hidden talent of the animals—it also helps show how the mammalian brain encodes the values of numbers. Previous research has shown that chimpanzees can add single-digit numbers. But scientists haven’t explained exactly how, in the human or the monkey brain, numbers are being represented or this addition is being carried out. Now, a new study helps begin to answer those questions. Neurobiologist Margaret Livingstone of Harvard Medical School in Boston and her colleagues had already taught three rhesus macaques (Macaca mulatta) in the lab to associate the Arabic numbers 0 through 9 and 15 select letters with the values zero through 25. When given the choice between two symbols, monkeys reliably chose the larger to get a correspondingly larger number of droplets of water, apple juice, or orange soda as a reward. To test whether the monkeys could add these values, the researchers began giving them a choice between a sum and a single symbol rather than two single symbols. Within 4 months, the monkeys had learned how the task worked and were able to effectively add two symbols and compare the sum to a third, single symbol. To ensure that the monkeys hadn’t simply memorized every possible combination of symbols and associated a value with the combination—this wouldn’t be true addition—Livingstone’s team next taught the animals an entirely new set of symbols —Tetris-like blocks rather than letters and numbers. With the new symbols, the monkeys were again able to add—this time calculating the value of combinations they’d never seen before and confirming the ability to do basic addition, the team reports online today in the Proceedings of the National Academy of Sciences. © 2014 American Association for the Advancement of Science.
Link ID: 19518 - Posted: 04.22.2014
By David Brown, At the very least, the new experiment reported in Science is going to make people think differently about what it means to be a “rat.” Eventually, though, it may tell us interesting things about what it means to be a human being. In a simple experiment, researchers at the University of Chicago sought to find out whether a rat would release a fellow rat from an unpleasantly restrictive cage if it could. The answer was yes. The free rat, occasionally hearing distress calls from its compatriot, learned to open the cage and did so with greater efficiency over time. It would release the other animal even if there wasn’t the payoff of a reunion with it. Astonishingly, if given access to a small hoard of chocolate chips, the free rat would usually save at least one treat for the captive — which is a lot to expect of a rat. The researchers came to the unavoidable conclusion that what they were seeing was empathy — and apparently selfless behavior driven by that mental state. “There is nothing in it for them except for whatever feeling they get from helping another individual,” said Peggy Mason, the neurobiologist who conducted the experiment along with graduate student Inbal Ben-Ami Bartal and fellow researcher Jean Decety. “There is a common misconception that sharing and helping is a cultural occurrence. But this is not a cultural event. It is part of our biological inheritance,” she added. The idea that animals have emotional lives and are capable of detecting emotions in others has been gaining ground for decades. Empathic behavior has been observed in apes and monkeys, and described by many pet owners (especially dog owners). Recently, scientists demonstrated “emotional contagion” in mice, a situation in which one animal’s stress worsens another’s. © 1996-2014 The Washington Post
The two marmosets—small, New World monkeys—had been a closely bonded couple for more than 3 years. Then, one fateful day, the female had a terrible accident. She fell out of a tree and hit her head on a ceramic vase that happened to be underneath on the forest floor. Her partner left two of their infants alone in the tree and jumped down to apparently comfort her, until she died an agonizing death a couple of hours later. According to the researchers who recorded the events with a video camera (see video above), this is the first time such compassionate mourning behavior has been observed outside of humans and chimpanzees, and it could indicate that mourning is more widespread among primates than previously thought. Humans mourn their dead, of course, and some recent studies have strongly suggested that chimpanzees do as well. Scientists have recorded cases of adult chimps apparently caring for fellow animals before they die, and chimp mothers have been observed carrying around the bodies of infants for days after their death—although scientists have debated whether the latter behavior represents true grieving or if the mothers didn’t realize their infants were really dead. But there has been little or no evidence that other primates engage in these kinds of behaviors. Indeed, a recent review of the evidence led by anthropologist Peter Fashing of California State University, Fullerton, concluded that there were no convincing observations of “compassionate caretaking” of dying individuals among other nonhuman primates, such as monkeys. © 2014 American Association for the Advancement of Science.
James Gorman Crows and their relatives, like jays and rooks, are definitely in the gifted class when it comes to the kinds of cognitive puzzles that scientists cook up. They recognize human faces. They make tools to suit a given problem. Sometimes they seem, as humans like to say, almost human. But the last common ancestor of humans and crows lived perhaps 300 million years ago, and was almost certainly no intellectual giant. So the higher levels of crow and primate intelligence evolved on separate tracks, but somehow reached some of the same destinations. And scientists are now asking what crows can’t do, as one way to understand how they learn and how their intelligence works. One very useful tool for this research comes from an ancient Greek (or perhaps Ethiopian), the fabulist known as Aesop. One of his stories is about a thirsty crow that drops pebbles into a pitcher to raise the level of water high enough that it can get a drink. Researchers have modified this task by adding a floating morsel of food to a tube with water and seeing which creatures solve the problem of using stones to raise the water enough to get the food. It can be used for a variety of species because it’s new to all of them. “No animal has a natural predisposition to drop stones to change water levels,” said Sarah Jelbert, a Ph.D. student at Auckland University in New Zealand, who works with crows. But in the latest experiment to test the crows, Ms. Jelbert, working with Alex Taylor and Russell Gray of Auckland and Lucy Cheke and Nicola Clayton of the University of Cambridge in England, found some clear limitations to what the crows can learn. And those limitations provide some hints to how they think. © 2014 The New York Times Company
Claudia Dreifus To Neil H. Shubin’s long résumé — paleontologist, molecular biologist, dean and professor of anatomy at the University of Chicago School of Medicine, best-selling author — can now be added “television host.” Dr. Shubin, 53, who helped discover the 375-million-year-old fish called Tiktaalik, hailed as a missing link between sea and land animals, will preside over “Your Inner Fish,” a three-part series on evolution (based on his book of the same title) that makes its debut Wednesday on PBS. We spoke in Chicago in February and in New York last month. What follows is an edited and condensed version of the conversations. Q. Where did you grow up? A. Suburban Philadelphia. My mom’s a retired nursing home administrator. My father, Seymour Shubin, is a fiction writer. He writes mysteries. My favorite is “The Captain”; it won an Edgar award. He’s an educated man, but science kind of scares him. So when I’m writing, my dad is my target audience. Whenever I hit a tricky scientific concept, I think, “How would I communicate this to him?” This is why my books are written, intentionally, without jargon, which can lead to some gyrations because jargon does have precision. The funny thing is, I’m not sure he always gets what I do. When I first started working on the book version of “Your Inner Fish,” he asked, “Neil, how did you become a scientist?” I thought, “All these years he’s seen me run off to the Arctic, but he’s never been quite sure what I do up there.” So let me ask you his question: How did you become a paleontologist? I was one of those kids with lots of hobbies: astronomy, dinosaurs, collecting rocks, collecting stamps. It all came together when I went to college in New York — Columbia — and volunteered at the American Museum of Natural History. That place was like a playground for me. © 2014 The New York Times Company
Link ID: 19466 - Posted: 04.10.2014
Neandertals and modern Europeans had something in common: They were fatheads of the same ilk. A new genetic analysis reveals that our brawny cousins had a number of distinct genes involved in the buildup of certain types of fat in their brains and other tissues—a trait shared by today’s Europeans, but not Asians. Because two-thirds of our brains are built of fatty acids, or lipids, the differences in fat composition between Europeans and Asians might have functional consequences, perhaps in helping them adapt to colder climates or causing metabolic diseases. “This is the first time we have seen differences in lipid concentrations between populations,” says evolutionary biologist Philipp Khaitovich of the CAS-MPG Partner Institute for Computational Biology in Shanghai, China, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, lead author of the new study. “How our brains are built differently of lipids might be due to Neandertal DNA.” Ever since researchers at the Max Planck sequenced the genome of Neandertals, including a super high-quality genome of a Neandertal from the Altai Mountains of Siberia in December, researchers have been comparing Neandertal DNA with that of living people. Neandertals, who went extinct 30,000 years ago, interbred with modern humans at least once in the past 60,000 years, probably somewhere in the Middle East. Because the interbreeding happened after moderns left Africa, today’s Africans did not inherit any Neandertal DNA. But living Europeans and Asians have inherited a small amount—1% to 4% on average. So far, scientists have found that different populations of living humans have inherited the Neandertal version of genes that cause diabetes, lupus, and Crohn’s disease; alter immune function; and affect the function of the protein keratin in skin, nails, and hair. © 2014 American Association for the Advancement of Science.
By NATALIE ANGIER The “Iliad” may be a giant of Western literature, yet its plot hinges on a human impulse normally thought petty: spite. Achilles holds a festering grudge against Agamemnon (“He cheated me, wronged me ... He can go to hell...”) turning down gifts, homage, even the return of his stolen consort Briseis just to prolong the king’s suffering. Now, after decades of focusing on such staples of bad behavior as aggressiveness, selfishness, narcissism and greed, scientists have turned their attention to the subtler and often unsettling theme of spite — the urge to punish, hurt, humiliate or harass another, even when one gains no obvious benefit and may well pay a cost. Psychologists are exploring spitefulness in its customary role as a negative trait, a lapse that should be embarrassing but is often sublimated as righteousness, as when you take your own sour time pulling out of a parking space because you notice another car is waiting for it and you’ll show that vulture who’s boss here, even though you’re wasting your own time, too. Evolutionary theorists, by contrast, are studying what might be viewed as the brighter side of spite, and the role it may have played in the origin of admirable traits like a cooperative spirit and a sense of fair play. The new research on spite transcends older notions that we are savage, selfish brutes at heart, as well as more recent suggestions that humans are inherently affiliative creatures yearning to love and connect. Instead, it concludes that vice and virtue, like the two sides of a V, may be inextricably linked. “Spitefulness is such an intrinsically interesting subject, and it fits with so many people’s everyday experience, that I was surprised to see how little mention there was of it in the psychology literature,” said David K. Marcus, a psychologist at Washington State University. At the same time, he said, “I was thrilled to find something that people haven’t researched to exhaustion.” © 2014 The New York Times Company
By SINDYA N. BHANOO Monogamy is rare in animals. Even among species that pair off, there is often philandering. But a new genetic analysis adds to the evidence that the South American primates called Azara’s owl monkeys are remarkably faithful to their partners. The study confirms what one of its authors, Eduardo Fernandez-Duque, an evolutionary anthropologist at the University of Pennsylvania who leads the Owl Monkey Project, had long suspected. For 18 years, he and other Penn researchers have been observing the Azara’s owl monkey in the Chaco region of Argentina. Not only have they never witnessed a philanderer, but they have also found that infant owl monkeys get an unusual amount of care from their fathers. “The male plays with the infant and the male shares food with the infant even more than the mother,” Dr. Fernandez-Duque said. “The males care because these are their offspring, and this has a direct benefit in terms of reproductive success.” In the new study, published in the Proceedings of the Royal Society B, the researchers performed genetic analysis on 35 offspring born to 17 owl monkey pairs and confirmed that the parents were monogamous for the mating season. The monkey is the first primate and only the fifth mammal for which monogamy has been verified through genetics. Because paternal care is also seen in other species of owl monkeys, the scientists suspect that they, too, are serially monogamous. © 2014 The New York Times Company
by Hal Hodson Software has performed the first real-time translation of a dolphin whistle – and better data tools are giving fresh insights into primate communication too IT was late August 2013 and Denise Herzing was swimming in the Caribbean. The dolphin pod she had been tracking for the past 25 years was playing around her boat. Suddenly, she heard one of them say, "Sargassum". "I was like whoa! We have a match. I was stunned," says Herzing, who is the director of the Wild Dolphin Project. She was wearing a prototype dolphin translator called Cetacean Hearing and Telemetry (CHAT) and it had just translated a live dolphin whistle for the first time. It detected a whistle for sargassum, or seaweed, which she and her team had invented to use when playing with the dolphin pod. They hoped the dolphins would adopt the whistles, which are easy to distinguish from their own natural whistles – and they were not disappointed. When the computer picked up the sargassum whistle, Herzing heard her own recorded voice saying the word into her ear. As well as boosting our understanding of animal behaviour, the moment hints at the potential for using algorithms to analyse any activity where information is transmitted – including our daily activities (see "Scripts for life"). "It sounds like a fabulous observation, one you almost have to resist speculating on. It's provocative," says Michael Coen, a biostatistician at the University of Wisconsin-Madison. © Copyright Reed Business Information Ltd.
Ewen Callaway An equine oddity with the head of a zebra and the rump of a donkey, the last quagga (Equus quagga quagga) died in 1883. A century later, researchers published1 around 200 nucleotides sequenced from a 140-year-old piece of quagga muscle. Those scraps of DNA — the first genetic secrets pulled from a long-dead organism — revealed that the quagga was distinct from the mountain zebra (Equus zebra). More significantly, the research showed that from then on, examining fossils would no longer be the only way to probe extinct life. “If the long-term survival of DNA proves to be a general phenomenon,” geneticists Russell Higuchi and Allan Wilson of the University of California, Berkeley, and their colleagues noted in their quagga paper1, “several fields including palaeontology, evolutionary biology, archaeology and forensic science may benefit.” At first, progress was fitful. Concerns over the authenticity of ancient-DNA research fuelled schisms in the field and deep scepticism outside it. But this has faded, thanks to laboratory rigour that borders on paranoia and sequencing techniques that help researchers to identify and exclude contaminating modern DNA. These advances have fostered an ancient-genomics boom. In the past year, researchers have unveiled the two oldest genomes on record: those of a horse that had been buried in Canadian permafrost for around 700,000 years2, and of a roughly 400,000-year-old human relative from a Spanish cavern3. A Neanderthal sequence every bit as complete and accurate as a contemporary human genome has been released4, as has the genome of a Siberian child connecting Native Americans to Europeans5. © 2014 Nature Publishing Group
by Aviva Rutkin Eureka! Like Archimedes in his bath, crows know how to displace water, showing that Aesop's fable The Crow and the Pitcher isn't purely fictional. To see if New Caledonian crows could handle some of the basic principles of volume displacement, Sarah Jelbert at the University of Auckland in New Zealand and her colleagues placed scraps of meat just out of a crow's reach, floating in a series of tubes that were part-filled with water. Objects potentially useful for bringing up the water level, like stones or heavy rubber erasers, were left nearby. The crows successfully figured out that heavy and solid objects would help them get a treat faster. They also preferred to drop objects in tubes where they could access a reward more easily, picking out tubes with higher water levels and choosing tubes of water over sand-filled ones. However, the crows failed at more challenging tasks that required an understanding of the effect of tube width or the ability to infer a hidden connection between two linked tubes. The crows displayed reasoning skills equivalent to an average 5 to 7 year old human child, the researchers claim. Previously, Eurasian jays have shown some understanding of water displacement, as have chimpanzees and orang-utans, but using similar experiments could assess and compare their skill levels. "Any animal capable of picking up stones could potentially participate," write the researchers. © Copyright Reed Business Information Ltd.
by Bethany Brookshire Spring will be here soon. And with daffodils, crocuses and other signs of spring comes a burst of birdsong as males duke it out to get female attention. While the males trill loud songs, the females sit quietly, choosing who will be the lucky male. Vocal male and quiet female songbirds are common in temperate zones, and have given rise to a common assumption. The best male songs get picked for reproduction, and this sexual selection results in complex song; females just listen and choose, so female song should be rare. After all, females don’t need to sing to attract mates. But it turns out this commonly held assumption is not true. A new study shows that the majority of females of songbird species do sing, and it’s likely that the ancestor of modern songbirds was also a vocal diva. The results challenge the old wisdom about female songbirds, and suggest that when it comes to female song, it’s not all about sex. Karan Odom, a behavioral ecologist at the University of Maryland, Baltimore County, has always been interested in birdsong. “As I began to study it in depth,” she says, “I realized there was a lot that’s unknown, and one area was the extent to which females were singing and the role that song plays in males and females.” Odom and her colleagues did a survey of 44 songbird families, going through bird handbooks and other sources to find records of whether males, females or both were singers. In results published March 4 in Nature Communications, they showed that female melodies are not rare at all. In fact, 71 percent of the species surveyed have singing ladies. So much for that quiet, retiring female bird. © Society for Science & the Public 2000 - 2013.
Matt Kaplan Humans are among the very few animals that constitute a threat to elephants. Yet not all people are a danger — and elephants seem to know it. The giants have shown a remarkable ability to use sight and scent to distinguish between African ethnic groups that have a history of attacking them and groups that do not. Now a study reveals that they can even discern these differences from words spoken in the local tongues. Biologists Karen McComb and Graeme Shannon at the University of Sussex in Brighton, UK, guessed that African elephants (Loxodonta africana) might be able to listen to human speech and make use of what they heard. To tease out whether this was true, they recorded the voices of men from two Kenyan ethnic groups calmly saying, “Look, look over there, a group of elephants is coming,” in their native languages. One of these groups was the semi-nomadic Maasai, some of whom periodically kill elephants during fierce competition for water or cattle-grazing space. The other was the Kamba, a crop-farming group that rarely has violent encounters with elephants. The researchers played the recordings to 47 elephant family groups at Amboseli National Park in Kenya and monitored the animals' behaviour. The differences were remarkable. When the elephants heard the Maasai, they were much more likely to cautiously smell the air or huddle together than when they heard the Kamba. Indeed, the animals bunched together nearly twice as tightly when they heard the Maasai. “We knew elephants could distinguish the Maasai and Kamba by their clothes and smells, but that they can also do so by their voices alone is really interesting,” says Fritz Vollrath, a zoologist at the University of Oxford, UK (see video below). © 2014 Nature Publishing Group
Why do some humans have lighter skin than others? Researchers have longed chalked up the difference to tens of thousands of years of evolution, with darker skin protecting those who live nearer to the equator from the sun’s intense radiation. But a new study of ancient DNA concludes that European skin color has continued to change over the past 5000 years, suggesting that additional factors, including diet and sexual attraction, may also be at play. Our species, Homo sapiens, first arose in Africa about 200,000 years ago, and researchers assume that its first members were as dark-skinned as Africans are today, because dark skin is advantageous in Africa. Dark skin stems from higher levels of the pigment melanin, which blocks UV light and protects against its dangers, such as DNA damage—which can lead to skin cancer—and the breakdown of vitamin B. On the other hand, skin cells need exposure to a certain amount of UV light in order to produce vitamin D. These competing pressures mean that as early humans moved away from the equator, it makes sense that their skin lightened. Recent research, however, has suggested that the picture is not so simple. For one thing, a number of genes control the synthesis of melanin (which itself comes in two different forms in humans), and each gene appears to have a different evolutionary history. Moreover, humans apparently did not begin to lighten up immediately after they migrated from Africa to Europe beginning about 40,000 years ago. In 2012, for example, a team led by Jorge Rocha, a geneticist at the University of Porto in Portugal, looked at variants of four pigmentation genes in modern Portuguese and African populations and calculated that at least three of them had only been strongly favored by evolution tens of thousands of years after humans left Africa. In January, another team, led by geneticist Carles Lalueza-Fox of the University of Barcelona in Spain, sequenced the genome of an 8000-year-old male hunter-gatherer skeleton from the site of La Braña-Arintero in Spain and found that he was dark rather than light-skinned—again suggesting that natural selection for light skin acted relatively late in prehistory. © 2014 American Association for the Advancement of Science
By PAUL VITELLO Alison Jolly, an American-born primatologist whose research in the forests of Madagascar shed new light on the evolution of social intelligence and helped disprove a longstanding scientific tenet that males were dominant in every primate species, died on Feb. 6 in Lewes, East Sussex, England. She was 76. The cause was breast cancer, said Barbara Orlando, a longtime friend. Dr. Jolly’s two major insights emerged from her 1960s field studies of the lemur, a primate whose development in relative isolation on the island of Madagascar makes the species something akin to a living fossil. Dr. Jolly cited lemurs’ complex social relationships as evidence of an unexplored trail in one of anthropology’s great mysteries: the evolution of higher intelligence. Writing in the journal Science in 1966, she suggested that the many hours lemurs spent in play, mutual grooming and social networking — activities that establish the social ties and hierarchies that determine access to food, mate selection and migration patterns — may have been as important to the evolution of intelligence as the development of weapons and tools of hunting and protection, then considered the hallmarks of evolutionary advance. More unnerving to colleagues was her discovery that in some primate species, females run the show. The finding upended a bedrock assertion in evolutionary biology — based on studies of chimpanzees and orangutans in captivity — that males dominated females in every primate species, including humans. “Females have social, spatial and feeding priority over males,” Dr. Jolly wrote in describing the feeding, mating, child-rearing and recreational habits of the ring-tailed lemur, one of about 100 recognized species of lemur, of which more than a dozen are female-dominant. Among the ring-tailed lemurs, Dr. Jolly wrote in “Lemur Behavior: A Madagascar Field Study,” “all females, whether dominant or subordinate in the female hierarchy, are dominant over males.” © 2014 The New York Times Company