By John Cloud Men who cheat on their spouses have always enjoyed an expedient explanation: Evolution made me do it. Many articles (here is one, and here is another), especially in recent years, have explored the theory that men sleep around because evolution has programmed them to seek fertile (and, conveniently, younger) wombs. (See the top 10 political sex scandals.) But what about women? If it's really true that evolution can cause a man to risk his marriage, what effect does it have on women's sexuality? A new journal article suggests that evolutionary forces also push women to be more sexual, although in some unexpected ways. University of Texas psychologist David Buss wrote the article, which appears in the July issue of Personality and Individual Differences, with the help of three grad students, Judith Easton (who is listed as lead author), Jaime Confer and Cari Goetz. Buss, Easton and their colleagues found that women in their 30s and early 40s are significantly more sexual than younger women. Women ages 27 through 45 report not only having more sexual fantasies (and more intense sexual fantasies) than women ages 18 through 26; the older women also report having more sex, period. And they are more willing than younger women to have casual sex, even one-night stands. In other words, despite the girls-gone-wild image of promiscuous college women, it is women in their middle years who are America's most sexually industrious. © 2010 Time Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 14247 - Posted: 07.12.2010

by Susan Heavey and Lisa Richwine WASHINGTON — The first of three new fat-fighting pills faces public scrutiny by U.S. regulatory advisers next week, as small biotechs target the growing number of obese Americans despite a checkered past for weight-loss drugs. Vivus Inc, Arena Pharmaceuticals Inc and Orexigen Therapeutics Inc are trying to succeed where earlier efforts flopped after several weight-loss drugs were linked to serious side effects. The U.S. Food and Drug Administration will seek input from outside advisers July 15 on Vivus' pill, Qnexa, for use with diet and exercise. If approved, it would be the first new prescription weight-loss drug in a decade in the United States, where two out of every three people are overweight. The FDA's review by a panel of outside experts follows a troubled history with obesity pills that either never gained approval, were pulled from the market after sales began, or were slapped with severe warnings. "The history of weight-loss drugs is such that it's a no-brainer that the FDA is going to take each and every one to an advisory panel," said analyst Ira Loss, who follows the agency for Washington Analysis Corp. An advisory panel is one of the last hurdles in a drug's route to market. The FDA will make the final decision, but usually follows the advice of its advisers. Copyright 2010 Reuters

Keyword: Obesity
Link ID: 14246 - Posted: 07.10.2010

Janelle Weaver Birds that spend less time parenting engage more frequently in homosexual behaviour, according to a study published this week. The findings offer a possible explanation for the evolution of homosexuality: parents that devote less time to their offspring have more time and energy to interact with members of the same sex while still producing offspring. Biologists had thought that homosexuality is disadvantageous on an evolutionary level because it distracts animals from pursuing sexual encounters that could result in offspring. Yet more than 130 species of birds participate in homosexual activity — and sometimes a lot of it. In the Laysan albatross (Phoebastria immutabilis), for example, up to 31% of pairs are female–female in some populations, and up to 20% of pairings in graylag geese (Anser anser) are male–male. Scientists have struggled to explain such patterns. But homosexuality may not be costly for birds that have plenty of mating opportunities because of lower parenting demands, says Geoff MacFarlane, an ecologist at the University of Newcastle in Callaghan, Australia. The less effort that females or males put into parental care, the more they participate in homosexual activities, according to a survey of the literature his team published this week in the journal Animal Behaviour1. Vincent Savolainen, a biologist at Imperial College London, says homosexual behaviour is sometimes considered a Darwinian paradox because it does not result in offspring. "This is one of the few studies that explains homosexual behaviour from the evolutionary point of view," he says. © 2010 Nature Publishing Group,

Keyword: Sexual Behavior; Evolution
Link ID: 14245 - Posted: 07.10.2010

By Larry Greenemeier For many, the warm glow of fireflies in the night air is a sure sign that summer has arrived. After dark, these bioluminescent beetles are generally visible only when they emit flashes of yellow, green or pale red from their lower abdomen as part of their mating ritual. Some species of firefly have found their own key to successful coupling— synchronous flashing patterns, a phenomenon that has attracted the attention of a team of researchers studying what pattern recognition tells us about how the brain is wired. To better understand how the brains of humans and other animals process visual signals, Andrew Moiseff, a professor of physiology and neurobiology at the University of Connecticut in Storrs, and Jonathan Copeland, a biology professor at Georgia Southern University in Statesboro, over the past four summers have studied the role that synchronized flashing plays in the mating of the Photinus carolinus species of firefly found in Tennessee's Smoky Mountains National Park.Firefly, bioluminescence, mating In synchronous flashing by P. carolinus fireflies, many males produce flashes simultaneously, rhythmically and repeatedly, according to the researchers, who published their findings in the July 9 issue of Science. These patterns consist of a burst of several flashes (typically six) followed by a period of no flashing that lasts about six-to-eight seconds. During these pauses, the female responds with two flashes in rapid succession, with the second flash beginning almost immediately after the first one is finished. The female may produce one to four of these "doublets" while perched on leaves or branches, says Moiseff, the study's lead author. © 2010 Scientific American,

Keyword: Sexual Behavior; Evolution
Link ID: 14244 - Posted: 07.10.2010

by Linda Geddes, Amsterdam THE discovery of an antibody that binds to certain brain receptors could reduce the side effects of a common stroke drug and buy additional time in which to use it. The preferred treatment for ischaemic stroke, in which a blood clot cuts off the blood supply to brain tissue, is a drug called rtPA, which dissolves the clot. However, that drug has to be given within the first few of hours of a stroke, otherwise the risks of treatment outweigh the benefits. Dissolving the clot can lead to a sudden rise in blood pressure, increasing the chance that a blood vessel will rupture and bleed into the brain. Only 5 to 10 per cent of people who suffer a stroke make it to hospital early enough to be treated with rtPA, says Denis Vivien of the University of Caen Basse-Normandie in France. The rest are given drugs that do not destroy the initial clot but reduce the chance of further clots forming. One reason for a delay in administering rtPA is that a brain scan must be carried out to determine the nature of the stroke. People with haemorrhagic stroke, in which a blood vessel in the brain bursts, should not receive rtPA as it increases the risk of bleeding. Now a startling discovery by Vivien has put a different perspective on this relatively simple picture: rtPA is actually released by brain cells. "This was completely unexpected," he says. © Copyright Reed Business Information Ltd.

Keyword: Stroke
Link ID: 14243 - Posted: 07.10.2010

by Andy Coghlan A GENE has been discovered that appears to dictate the sexual preferences of female mice. Delete the gene and the modified mice reject the advances of the males and attempt to mate with other females instead. While it is impossible to say whether the finding has any relevance for human sexuality, it provides a clue as to how sexuality develops in mammals. Chankyu Park and colleagues at the Korea Advanced Institute of Science and Technology in Daejon, South Korea, deleted the FucM gene in mouse embryos to see what effect it would have on behaviour. Female mice lacking the gene avoided the advances of males, stopped sniffing male urine and attempted to mate with other females, though their ability to have pups was unaffected (BMC Genetics, DOI: 10.1186/1471-2156-11-62). The gene the team deleted is for an enzyme called fucose mutarotase, which adds the sugar fucose to proteins. Park believes that disabling the gene exposes parts of the developing mouse brain linked with sexual preference in adult life to extra oestrogen. The hormone masculinises the brain in mice - though not in people. In a normal female mouse fetus, this extra oestrogen would be "filtered out" by a substance called alpha-fetoprotein. But AFP only functions properly when adorned with fucose. So without the gene that makes the enzyme, AFP cannot keep the flood of oestrogen at bay. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 14242 - Posted: 07.10.2010

By James Dao NEW YORK — The government is preparing to issue new rules that will make it substantially easier for veterans who have been found to have posttraumatic stress disorder to receive disability benefits for the illness, a change that could affect hundreds of thousands of veterans from the wars in Iraq, Afghanistan, and Vietnam. The regulations from the Department of Veterans Affairs— which will take effect as early as Monday and cost as much as $5 billion over several years, according to congressional analysts — will essentially eliminate a requirement that veterans document specific events like bomb blasts, firefights, or mortar attacks that might have caused post-traumatic stress disorder, an illness characterized by emotional numbness, irritability, and flashbacks. For decades, veterans have complained that finding such records was extremely time consuming and sometimes impossible. And in the wars in Afghanistan and Iraq, veterans groups assert, the current rules discriminate against tens of thousands of service members — many of them women — who did not serve in combat roles but nevertheless suffered traumatic experiences. Under the new rule, which applies to veterans of all wars, the department will grant compensation to those with the illness if they can simply show that they served in a war zone and in a job consistent with the events that they say caused their conditions. They would not have to prove, for instance, that they came under fire, served in a front-line unit, or saw a friend killed. © Copyright 2010 Globe Newspaper Company.

Keyword: Stress
Link ID: 14241 - Posted: 07.08.2010

By Lindsey Tanner Want happier, more alert teenagers? Let them sleep in a little. A new study reveals that delaying the school day by 30 minutes results in teens who are less sleepy and depressed. Scientists say that teens tend to be in their deepest sleep around dawn, when they typically need to arise for school. Interrupting that sleep can leave them groggy. Giving teens 30 extra minutes to start their school day leads to more alertness in class, better moods, less tardiness, and even healthier breakfasts, a small study found. "The results were stunning. There's no other word to use," said Patricia Moss, academic dean at the Rhode Island boarding school where the study was done. "We didn't think we'd get that much bang for the buck." The results appear in July's Archives of Pediatrics & Adolescent Medicine. The results mirror those at a few schools that have delayed starting times more than half an hour. Researchers say there's a reason why even 30 minutes can make a big difference. Teens tend to be in their deepest sleep around dawn -- when they typically need to arise for school. Interrupting that sleep can leave them groggy, especially since they also tend to have trouble falling asleep before 11 p.m. © 2010 Associated Press/AP Online

Keyword: Biological Rhythms; Development of the Brain
Link ID: 14240 - Posted: 07.08.2010

By GRETCHEN REYNOLDS What goes on inside your brain when you exercise? That question has preoccupied a growing number of scientists in recent years, as well as many of us who exercise. In the late 1990s, Dr. Fred Gage and his colleagues at the Laboratory of Genetics at the Salk Institute in San Diego elegantly proved that human and animal brains produce new brain cells (a process called neurogenesis) and that exercise increases neurogenesis. The brains of mice and rats that were allowed to run on wheels pulsed with vigorous, newly born neurons, and those animals then breezed through mazes and other tests of rodent I.Q., showing that neurogenesis improves thinking. But how, exactly, exercise affects the staggeringly intricate workings of the brain at a cellular level has remained largely mysterious. A number of new studies, though, including work published this month by Mr. Gage and his colleagues, have begun to tease out the specific mechanisms and, in the process, raised new questions about just how exercise remolds the brain. Some of the most reverberant recent studies were performed at Northwestern University’s Feinberg School of Medicine in Chicago. There, scientists have been manipulating the levels of bone-morphogenetic protein or BMP in the brains of laboratory mice. BMP, which is found in tissues throughout the body, affects cellular development in various ways, some of them deleterious. In the brain, BMP has been found to contribute to the control of stem cell divisions. Your brain, you will be pleased to learn, is packed with adult stem cells, which, given the right impetus, divide and differentiate into either additional stem cells or baby neurons. As we age, these stem cells tend to become less responsive. They don’t divide as readily and can slump into a kind of cellular sleep. It’s BMP that acts as the soporific, says Dr. Jack Kessler, the chairman of neurology at Northwestern and senior author of many of the recent studies. The more active BMP and its various signals are in your brain, the more inactive your stem cells become and the less neurogenesis you undergo. Your brain grows slower, less nimble, older. Copyright 2010 The New York Times Company

Keyword: Learning & Memory; Neurogenesis
Link ID: 14239 - Posted: 07.08.2010

The undersea world isn't as quiet as we thought, according to a New Zealand researcher who found fish can "talk" to each other. Fish communicate with noises including grunts, chirps and pops, University of Auckland marine scientist Shahriman Ghazali has discovered according to newspaper reports Wednesday. "All fish can hear, but not all can make sound -- pops and other sounds made by vibrating their swim bladder, a muscle they can contract," Ghazali told the New Zealand Herald. Fish are believed to communicate with each other for different reasons, including attracting mates, scaring off predators or orienting themselves. The gurnard species has a wide vocal repertoire and keeps up a constant chatter, Ghazali found after studying different species of fish placed into tanks. On the other hand, cod usually kept silent, except when they were spawning. "The hypothesis is that they are using sound as a synchronization so that the male and female release their eggs at the same time for fertilization," he said. Some reef fish, such as the damselfish, made sounds to attempt to scare off threatening fish and even divers, he said. But anyone hoping to strike up a conversation with their pet goldfish is out of luck. © 2010 Discovery Communications, LLC.

Keyword: Animal Communication; Hearing
Link ID: 14238 - Posted: 07.08.2010

by Linda Geddes, Amsterdam When children learn to read and write, they often get things back to front: confusing the letters "b" and "d", and sometimes even writing their entire names in the mirror image. This strange phenomenon might be a consequence of children "recycling" an area of the brain that recognises shapes and patterns as they learn to read, says Stanislas Dehaene of INSERM, the National Institute of Health and Medical Research in Saclay, France. Previous studies in macaques have shown that individual neurons in an area of the brain's left hemisphere fire in response to pictures and patterns. We also know that animals and human infants alike find it hard to distinguish between mirror images of the same picture. Still other studies have established that this brain region, called the visual word form area (VWFA), is activated as people learn to read. To investigate what happens in the VWFA when humans look at words and pictures and their mirror images, Dehaene used functional magnetic resonance imaging to record the brain activity of adults when they were shown pictures, written words and letters both in the normal and the reverse orientation. © Copyright Reed Business Information Ltd.

Keyword: Language; Dyslexia
Link ID: 14237 - Posted: 07.08.2010

By Tina Hesman Saey Little things can make a big difference in the brain. Case in point: A tiny snippet of RNA may help guard cocaine-using rats against addiction to the drug, a new study shows. The minuscule molecular guard is a hairpin-shaped piece of RNA known as a microRNA. Raising levels of a microRNA called miR-212 in the brains of cocaine-using rats led the animals to take less of the drug than rats with normal microRNA levels, researchers report in the July 8 Nature. Similarly, blocking the microRNA’s action increased the rats’ cocaine use. If the results hold true in people, researchers may be able to develop new therapies for treating addiction to cocaine and other drugs of abuse. “Once you get out of whack, this is something that might help bring you back,” says Yale neuroscientist Marina Picciotto, who was not involved in the study. It’s unlikely that the research will lead to gene therapy to raise levels of microRNAs in people’s brains. But small-molecule drugs that mimic the microRNA’s action might be helpful. Just 21 to 23 RNA units long, microRNAs are major regulatory molecules (SN: 3/1/08, p. 136) that govern part of the process by which instructions contained in DNA are transformed into proteins. The molecules generally block protein production. So it was a surprise to find levels of a protein called CREB increase with rising levels of miR-212, says Paul Kenny, a neuroscientist at the Scripps Research Institute in Jupiter, Fla. © Society for Science & the Public 2000 - 2010

Keyword: Drug Abuse
Link ID: 14236 - Posted: 07.08.2010

By Steve Connor, Science Editor Aggressive teenagers with severe behavioural problems may have developed a biological abnormality in their brain, causing them to be aggressive and anti-social, a study has found. Scientists believe they have discovered the first hard evidence showing that conduct disorder in adolescents has a biological basis connected with brain chemistry, rather than being the result of the desire in teenagers to ape their badly-behaved peers. The findings suggest that it may be possible to diagnose a predisposition to conduct disorder in early childhood so that child psychologists could intervene before the behaviour starts to deteriorate. Conduct disorder affects five per cent of teenagers and costs society millions of pounds in terms of remedial education. "Detecting conduct disorder in adolescence may be too late to do anything about it. Early identification of a biological abnormality may be a route to take in terms of early intervention," said Andy Calder of the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, where the study was carried out. "These are pretty severe kids. They are frequently excluded from school over and over again. Some of them will go into young offenders institutions, so they are not just badly behaved kids," Dr Calder said. "Psychiatrists in the past have not really considered conduct disorder as a medical condition. This is research that's saying that actually it has a biological basis and this is soomething we should consider as a medical issue," he said. ©independent.co.uk

Keyword: Aggression; Development of the Brain
Link ID: 14235 - Posted: 07.06.2010

By Patrick House What if I told you that last week I predicted all eight winners of a round of the World Cup? And that instead of rankings or divination all I did was look up how many people in each team's home country had a tiny parasite lurking in their amygdalas? Would you believe me? A decade ago, Discover Magazine concluded that parasites ruled the world, and now I'm going to try to tell you that, at the very least, parasites rule the World Cup. Toxo is one of the most successful parasites in the world and is found in almost every type of mammal. Goats, cows, pigs, sheep, humans. But it spends its time trying to get into the stomach of a cat, the only place where it can successfully reproduce. Thus the organism has evolved an unusual lifecycle relating to the brains of rats and mice. Rodents ingest little bits of Toxo from cat feces and Toxo goes straight to their heads. Once there, it scrambles the neurons around and reverses the animals' natural aversion to cat urine. Soon after, a recently relieved cat returns to the scene and takes its supper. In other words, the rat plays taxi to the parasite, finding it a new feline host and completing the Toxo lifecycle. Livestock fields are full of fertilizer made from, you guessed it, bits of cat feces. When the cows and goats graze, they ingest Toxo, and it sneaks its way into their brains. Eat one of these livestock uncooked and you'll get Toxo in your brain, too. Thanks to the urbanization of cats (and their feces), almost a third of the human population now has a chronic, latent, and seemingly innocuous Toxo infection. This is, of course, an average: Rates vary a great deal from one country to another, from 6 percent in South Korea to 92 percent in Ghana. © Copyright 2010 Washington Post.Newsweek Interactive Co. LLC

Keyword: Emotions
Link ID: 14234 - Posted: 07.06.2010

By NATALIE ANGIER I was walking through the neighborhood one afternoon when, on turning a corner, I nearly tripped over a gray squirrel that was sitting in the middle of the sidewalk, eating a nut. Startled by my sudden appearance, the squirrel dashed out to the road — right in front of an oncoming car. Before I had time to scream, the squirrel had gotten caught in the car’s front hubcap, had spun around once like a cartoon character in a clothes dryer, and was spat back off. When the car drove away, the squirrel picked itself up, wobbled for a moment or two, and then resolutely hopped across the street. You don’t get to be one of the most widely disseminated mammals in the world — equally at home in the woods, a suburban backyard or any city “green space” bigger than a mousepad — if you’re crushed by every Acme anvil that happens to drop your way. “When people call me squirrely,” said John L. Koprowski, a squirrel expert and professor of wildlife conservation and management at the University of Arizona, “I am flattered by the term.” The Eastern gray tree squirrel, or Sciurus carolinensis, has been so spectacularly successful that it is often considered a pest. The International Union for Conservation of Nature includes the squirrel on its list of the top 100 invasive species. The British and Italians hate gray squirrels for outcompeting their beloved native red squirrels. Manhattanites hate gray squirrels for reminding them of pigeons, and that goes for the black, brown and latte squirrel morphs, too. Copyright 2010 The New York Times Company

Keyword: Learning & Memory
Link ID: 14233 - Posted: 07.06.2010

By SINDYA N. BHANOO It takes an elephant much longer to notice a fly and flick it away than it takes a shrew, and the reason is not that the elephant’s great brain is too busy with philosophy, or that it simply does not concern itself with flies. It’s a matter of round-trip travel time — in the nervous system. The trip from the elephant’s skin to the brain and back again to the muscles to flick the tail is 100 times as long as the same trip in a shrew, according to a new study published in the Proceedings of the Royal Society B. The nervous system acts like an information superhighway, sending messages back and forth from the brain throughout the body. The bigger the animal, the greater the distance traveled. Nerves have a maximum speed limit of about 180 feet per second, said Maxwell Donelan, the study’s lead author. “It makes sense that in a large animal, like an elephant, messages have a longer way to travel,” he said. Dr. Donelan believes that large animals may have to compensate for this handicap by thinking ahead, and avoiding risky situations. “That’s what we want to study next,” he said. “It could be that the nervous systems of large animals have evolved to become excellent predictive machines.” Copyright 2010 The New York Times Company

Keyword: Miscellaneous
Link ID: 14232 - Posted: 07.06.2010

By SINDYA N. BHANOO When it comes to singing, male zebra finches outdo prima donnas, singing over a wide range that starts almost an octave above middle C but soars higher than any coloratura soprano. Female zebra finches, on the other hand, are limited to a few one-note low frequency calls. The vocal range is critical for males during mating season, when they use their songs to attract females. Scientists have known that the vocal muscles in a male bird’s syrinx, or voice box, are about twice the size of those in a female bird’s. Now, a study finds that male birds are able to better control their vocal muscles than female birds. It is this ability that allows them such a wide range. The study appears in the Public Library of Science journal PLoS ONE. Researchers operated on male and female birds, cutting the nerves that control vocal muscles in the syrinx. The males still sang, but they could no longer produce high frequencies in their songs. Instead, they had the same low frequency range of females. Further research into how the vocal muscles of zebra finches remain strong and hardy over time may help lead to treatments for humans who use their vocal chords extensively, said Tobias Riede, a biologist at the University of Utah and the study’s lead author. Copyright 2010 The New York Times Company

Keyword: Sexual Behavior
Link ID: 14231 - Posted: 07.06.2010

by Bob Holmes, Eugene, Oregon EXTROVERTS are born not made - or at least, that's what they say. But what if it's more subtle than that? What if we tailor our personalities to our surroundings to make the most of our genes? Conventional comparisons between identical and fraternal twins indicate that nearly half of individual differences in personality traits have some underlying genetic cause. So people have tended to think of personality traits as largely determined by genes, says evolutionary psychologist Aaron Lukaszewski of the University of California at Santa Barbara. He felt there was a flaw in this thinking: if personality were rigidly determined, individuals could end up with the "wrong" personality type for their circumstances. Being extrovert, for instance, exposes people to social conflict. Wimpy men are more likely to suffer in such encounters, while hunkier men may benefit from putting good genes on display. To avoid mismatches, Lukaszewski reasoned, evolution must have favoured a more flexible system. To test this idea, he measured the strength of 85 male and 89 female students and asked them to rate their own attractiveness relative to their peers. Then he gave each a standard personality test to measure how extrovert they were. Sure enough, stronger and more attractive men, and more attractive women, were more extrovert, Lukaszewski reported at a June meeting of the Human Behavior and Evolution Society in Eugene, Oregon. © Copyright Reed Business Information Ltd.

Keyword: Genes & Behavior
Link ID: 14230 - Posted: 07.06.2010

Genetic engineers, move over: the latest scheme for creating children to a parent’s specifications requires no DNA tinkering, but merely giving mom a steroid while she’s pregnant, and presto—no chance that her daughters will be lesbians or (worse?) ‘uppity.’ Or so one might guess from the storm brewing over the prenatal use of that steroid, called dexamethasone. In February, bioethicist Alice Dreger of Northwestern University and two colleagues blew the whistle on the controversial practice of giving pregnant women dexamethasone to keep the female fetuses they are carrying from developing ambiguous genitalia. (That can happen to girls who have congenital adrenal hyperplasia (CAH), a genetic disorder in which unusually high prenatal exposure to masculinizing hormones called androgens can cause girls to develop a deep voice, facial hair, and masculine-looking genitalia.) The response Dreger got from physicians and scientists who were outraged over this unapproved use of dexamethasone caused her to dig deeper into the scientific papers of the researcher who has promoted it. The result of that digging is a discovery that is much less outrageous than the PR push, and some media coverage, would have you believe, but one that nonetheless raises important questions about gender, sexuality, and research on unknowing patients. In an essay titled “Preventing Homosexuality (and Uppity Women) in the Womb?” and posted on the bioethics forum of The Hastings Center, a think tank in Garrison, N.Y., Dreger and her colleagues pluck numerous brow-raising statements from the writings of pediatric endocrinologist Maria New of Mount Sinai Medical Center in New York, who has long promoted prenatal dexamethasone to treat CAH. But if that position is controversial (as I’ll explain below), what Dreger and her colleagues claim to have uncovered is even more so. New, they say, wants to use dexamethasone to prevent CAH girls from becoming lesbians, from rejecting motherhood, and from choosing traditionally masculine careers. © 2010 Newsweek, Inc

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 14229 - Posted: 07.06.2010

by Michael Balter Want to live a long life? Have lots of friends. Studies in humans have made clear that people with stronger social networks have greater longevity. Now a new analysis shows the same is true for baboons. The research adds to growing evidence that friendship is an adaptation with deep evolutionary roots. Little is known about how social bonds influence longevity in nonhuman animals, in part because tracking animal relationships over many years is very difficult. Nevertheless, recent evidence shows that social bonding enhances reproductive success, an important indicator of evolutionary fitness. A study last year of female horses, led by Elissa Cameron, a zoologist at the University of Pretoria, showed that mares with the weakest social ties had about half as many surviving foals as those who were most sociable. And in 2006, a team led by University of California, Los Angeles, anthropologist Joan Silk reported that the infants of female baboons with close social ties to unrelated females survive longer than those that do not have such ties. In the new work, a team led by Silk looked at the correlation between social bonding and longevity, another important indicator of fitness. Silk studied wild baboons in Botswana's Moremi Game Reserve, teaming up with a long-term project led by University of Pennsylvania biologist Dorothy Cheney and psychologist Robert Seyfarth. From 2001 to 2007, the researchers closely watched 44 female baboons, recording how often they approached each other, how long they groomed each other, and other measures of social interaction. (The researchers looked at females because, in many species, only females form these kinds of social bonds, whereas males are off doing other things and are competitive with each other rather than cooperative.) From these data, the researchers determined each baboon's top three partners in any given year. Thus the team could estimate the strength of each baboon's relationships with its closest partners over the years and the extent to which each baboon stuck to her best buddies. © 2010 American Association for the Advancement of Science.

Keyword: Emotions; Stress
Link ID: 14228 - Posted: 07.03.2010