Biological Psychology Links

By CARL ZIMMER Why are worker ants sterile? Why do birds sometimes help their parents raise more chicks, instead of having chicks of their own? Why do bacteria explode with toxins to kill rival colonies? In 1964, the British biologist William Hamilton published a landmark paper to answer these kinds of questions. Sometimes, he argued, helping your relatives can spread your genes faster than having children of your own. For the past 46 years, biologists have used Dr. Hamilton’s theory to make sense of how animal societies evolve. They’ve even applied it to the evolution of our own species. But in the latest issue of the journal Nature, a team of prominent evolutionary biologists at Harvard try to demolish the theory. The scientists argue that studies on animals since Dr. Hamilton’s day have failed to support it. The scientists write that a close look at the underlying math reveals that Dr. Hamilton’s theory is superfluous. “It’s precisely like an ancient epicycle in the solar system,” said Martin Nowak, a co-author of the paper with Edward O. Wilson and Corina Tarnita. “The world is much simpler without it.” Other biologists are sharply divided about the paper. Some praise it for challenging a concept that has outlived its usefulness. But others dismiss it as fundamentally wrong. “Things are just bouncing around right now like a box full of Ping-Pong balls,” said James Hunt, a biologist at North Carolina State University. Copyright 2010 The New York Times Company

Women who report feeling stressed early in their monthly cycle were more likely than those who were less stressed to report more pronounced symptoms before and during menstruation, according to a study by researchers at the National Institutes of Health and other institutions. The association raises the possibility that feeling stressed in the weeks before menstruation could worsen the symptoms typically associated with premenstrual syndrome and menstruation. Women who reported feeling stressed two weeks before the beginning of menstruation were two to four times more likely to report moderate to severe symptoms than were women who did not feel stressed. Premenstrual syndrome (http://www.nichd.nih.gov/health/topics/menstruation_and_the_menstrual_cycle.cfm.)is a group of physical and psychological symptoms occurring around the time of ovulation, which may extend into the early days of menstruation. Symptoms include feelings of anger, anxiety, mood swings, depression, fatigue, decreased concentration, breast swelling and tenderness, general aches, and abdominal bloating. "We were interested in identifying factors that might predict who might be most at risk for having more severe symptoms," said Audra Gollenberg, Ph.D., a postdoctoral fellow in NICHD's Division of Epidemiology, Statistics and Prevention Research. "It may be possible to lessen or prevent the severity of these symptoms with techniques that help women to cope more effectively with stress, such as biofeedback, exercise, or relaxation techniques."

By KATHERINE BOUTON “Delusions of Gender” takes on that tricky question, Why exactly are men from Mars and women from Venus?, and eviscerates both the neuroscientists who claim to have found the answers and the popularizers who take their findings and run with them. The author, Cordelia Fine, who has a Ph.D. in cognitive neuroscience from University College London, is an acerbic critic, mincing no words when it comes to those she disagrees with. But her sharp tongue is tempered with humor and linguistic playfulness, as the title itself suggests. Academics like Simon Baron-Cohen and Dr. Louann Brizendine will want to come to this volume well armed. So would Norman Geschwind if he were still alive. Popular authors like John Gray (“Men are from Mars”), Michael Gurian (“What Could He Be Thinking?”) and Dr. Leonard Sax (“Why Gender Matters”) may want to read something else. Sometimes all it takes is their own words, as in this example from Dr. Brizendine’s 2007 book “The Female Brain”: “Maneuvering like an F-15, Sarah’s female brain is a high-performance emotion machine — geared to tracking, moment by moment, the nonverbal signals of the innermost feelings of others.” Is Sarah some kind of psychic? Dr. Fine clarifies: “She is simply a woman who enjoys the extraordinary gift of mind reading that, apparently, is bestowed on all owners of a female brain.” Experts used to attribute gender inequality to the “delicacy of the brain fibers” in women ; then to the smaller dimensions of the female brain (the “missing five ounces,” the Victorians called it); then to the ratio of skull length to skull breadth. In 1915 the neurologist Dr. Charles L. Dana wrote in this newspaper that because a woman’s upper spinal cord is smaller than a man’s it affects women’s “efficiency” in the evaluation of “political initiative or of judicial authority in a community’s organization” — and thus compromises their ability to vote. Copyright 2010 The New York Times Company

By Rebecca Kessler In greylag geese, nearly a fifth of all long-term couples are composed of two males. They're not alone: More than 130 bird species are known to engage in homosexual behavior at least occasionally, a fact that has puzzled scientists. After all, in evolutionary terms same-sex mating seems to reduce the birds' chances of reproductive success. But that's not necessarily so, according to a new study. In a given species, the sex with lighter parental duties tends to mate more, period whether with the same or the opposite sex. Birds engage in all kinds of same-sex hanky panky, from elaborate courtship displays to mounting and genital contact to setting up house together. In some species the same-sex pairs even raise young (conceived with outside partners, obviously) and stay together for several years. In 2007, a team led by Geoff MacFarlane, a biologist at the University of Newcastle in Australia, reported that male homosexual behavior was more common in polygynous bird species, where males mate with numerous females, and that female homosexual behavior was more common in monogamous species. Intrigued, MacFarlane looked for help explaining the pattern in a theory predicting that whichever gender spends less time caring for young tends to have sex with more partners. © 2010 LiveScience.com.

By LARRY O'HANLON Everyone looks better after you've tipped back a pint or two, and now we may know why. It turns out that alcohol dulls our ability to recognize cockeyed, asymmetrical faces, according to researchers who tested the idea on both sober and inebriated college students in England. To find out if alcohol interfered with the ability to distinguish faces where the left and right sides were uneven, he and his colleagues designed an experiment involving images of faces that were tinkered with to make them perfectly symmetrical or subtly asymmetrical. The results of the study were published by Halsey, Joerg Huber, Richard Bufton and A.C. Little in a recent issue of the journal Alcohol. "Over an evening Joerg, Richard and I went out to the university campus bars with a laptop and asked students to participate," Halsey said. Men appear to be less prone to losing this ability than women when drinking. This included students taking a quick breathalyzer test to confirm their alcohol consumption. The students were classified as either sober or intoxicated, then examined the images. © 2010 ABC News Internet Ventures.

By Emily Sohn When a woman is ovulating, her behavior changes in a startling number of ways from the way she walks, talks and dresses to the men she flirts with, according to new research. The findings might offer some practical tips for women to boost their online dating prospects; for scientists to develop new kinds of ovulation detection kits; or for marketers to target sales of clothes and jewelry. The work also suggests that going on or off the birth control pill might influence a woman's choice in men. Why does ovulation change women's behavior in such subtle yet fundamental ways? Experts propose that it's an innate and subtle strategy to both attract the most desirable guys and convince them to stick around for the long haul. "The idea is that women turn up everything that has to do with femininity" at ovulation, said Greg Bryant, an evolutionary psychologist at the University of California, Los Angeles. "This is showing that there are all sorts of phenomena that happen in our behavior that we're not actually aware of." For a long time, scientists assumed that the hormonal shifts of ovulation happened without measurable changes in how women behaved. That's because women have a strong motivation to hide the fact that they're fertile, unlike other members of the animal kingdom. While a female baboon's swollen red rump encourages males to mate and go, for example, a female human's ability to keep a man guessing should up the chances of him mating and then staying to help take care of their children. © 2010 Discovery Communications, LLC.

by Michael Balter Why cooperate when you can be selfish? Many animal behaviors are self-centered and apparently evolved to pass on an individual's genes to future generations. Yet cooperative breeding, in which some members of a group help others to raise their young, has evolved independently many times, especially in birds and insects. A new study of birds concludes that parents get more help when they are sexually faithful to each other. Cooperation has been called an evolutionary paradox, and cooperative breeding is relatively rare, with members of only 3% to 10% of bird species helping to raise one another's young. Among the apes, only humans are cooperative breeders, although monkeys such as marmosets and tamarins do it, too. In the 1960s, British biologist William Hamilton proposed that natural selection could favor cooperation if individuals pass on their own genes by helping relatives raise offspring. But Hamilton argued that cooperation can arise only if such helpers are closely related to recipients and if the benefits outweigh the costs. Over the past few years, Jacobus Boomsma, an evolutionary biologist at the University of Copenhagen, has argued that strict monogamous behavior, such as an ant queen mating for life, spurred the evolution of cooperative breeding in some social insects. Monogamy helps fulfill Hamilton's conditions, because all siblings are equally related to each other and to each parent. Promiscuity, on the other hand, leads to many half-siblings and lowers the relatedness of individuals in a group. © 2010 American Association for the Advancement of Science.

By Brian Mossop Last May, I took a trip to San Diego for my brother-in-law’s graduation from college, and to meet his 4-month old son, Landon, for the first time. Throughout the weekend, I couldn’t suppress my inner science nerd, and often found myself probing my nephew’s foot reflexes. Pressured from my wife’s disapproving looks and the blank stares I received from her family as I explained why his toes curled this way or that, I dropped the shop-talk in favor of baby-talk. Having spent my postdoctoral career in neuroscience, brain development is particularly fascinating to me. But on this family visit, more striking than the baby’s neurodevelopment was the re-development of my 26-year-old brother-in-law. In just a few months’ time, Jack went from my wife’s little brother to a hands-on, first-time father. When I first met Jack, he was a tall, lanky, wet-behind-the-ears nineteen-year-old kid, who enlisted in the U.S. Navy right after graduating high school. As a two-tour Iraq war veteran, Jack saw more of the world in six years than most of us ever will, and had a large repertoire of crazy sailor stories to boot. Still, raising Landon will no doubt be the biggest challenge Jack’s ever faced. Whether he knows it or not, and whether he likes it or not, things are about to drastically change for him. By the end of the weekend trip, I saw glimpses that Jack had come to terms (well, sort of) with the fact that his life will never be the same: After struggling with securing Landon’s car seat in the back of his souped-up Mazda RX-8 for several weeks, Jack finally broke down and traded it in for a more sensible car that will make it easier to transport the little guy. © 2010 Scientific American

By Dan Vergano, USA TODAY If something offers easy answers for not-so-easy questions, you might be reading a popular science book. Malcom Gladwell's Outliers: The Story of Success, centers around the idea of practicing anything for 10,000 hours to be a genius. SuperFreakonomics: Global Cooling, Patriotic Prostitutes, and Why Suicide Bombers Should Buy Life Insurance discovers that economics explains terrorism and climate change. Sex at Dawn suggests evolution explains straying spouses. And then there's Delusions of Gender: How Our Minds, Society and Neurosexism Create Difference by Cordelia Fine. A research associate at the Centre for Agency, Values and Ethics at Australia's Macquarie University, Fine turns the popular science book formula on its head. Chapter-by-chapter, she introduces ideas about the innate differences between the sexes — "it's all fetal hormones" or "men have better-wired brains" or "brain scans show men's brains light up differently" — and then tartly smacks around the studies supposedly supporting them. In particular, Fine joins critics, such as Nikos Logothetis of Germany's Max Planck Institute for Biological Cybernetics, to argue that brain images constructed from functional magnetic resonance imaging studies, often on just a few dozen people at most, have become the latest way to slap a scientific-sounding paint job on old ideas about women being intrinsically dumber than men. "The main message of the book is that our comforting beliefs about gender — that everything's fair now, that sex inequality should be blamed on 'hardwired' differences between the sexes, and that our failure to rear unisex children just points the same way — just don't bear up to scrutiny," Fine says, by e-mail. Copyright 2010 USA TODAY,

Women are more likely to select clingy clothes when they are ovulating, a study has found. But the University of Minnesota study of 100 women found these hormonal shopping habits were triggered by the proximity of attractive women. The researchers suggest in selecting tighter clothes, the women were trying to stand out from love rivals. The Journal of Consumer Research study said there should be more analysis of how hormones affected shopping habits. Women at different stages of their menstrual cycle were shown images of attractive women living locally or far away. They were then asked to choose clothes and accessories which they would like to buy. Women who were ovulating and who had seen photos of attractive local women were most likely to buy "sexier" clothes compared with those shown photographs of unattractive local women or women who lived more than 1,000 miles (1,600km) away. Dr Kristina Durante, who led the research, said: "The desire for women at peak fertility to unconsciously choose products that enhance appearance is driven by a desire to outdo attractive rival women. If you look more desirable than your competition, you are more likely to stand out." The team said even though the end result was about attracting the best romantic partner available, ovulating women's choice of dress was motivated by the other women in their environment. (C)BBC

By Janet Raloff Cash register and other receipts may expose consumers to substantial amounts of bisphenol A, a hormone-mimicking chemical that has been linked with a host of potential health risks, according to a trio of recent studies. Each study offers preliminary evidence that a large number of retail outlets print sales receipts on certain types of heat-sensitive, or thermal, paper that use BPA as a color developer. Two of the new studies also showed that the BPA coating easily rubs off onto fingers. And one found evidence that BPA from receipts may penetrate skin. The pollutant, which mimics the biological activity of estrogen, has been tied to health risks from behavioral problems in children to obesity and heart ailments. In animals, exposures in the womb put moms and their offspring at risk for later metabolic diseases. Based on growing concern about possible risks from ubiquitous exposure to BPA, especially in children, the federal government recently issued warnings to parents about where their families were most likely to encounter the chemicals. Store receipts did not make the list, although there have been hints for years that thermal receipt paper could be a rich source. Chemist John Warner learned about the chemistry of thermal- and pressure-sensitive papers while working for Polaroid years ago. Manufacturers lay a powdery coating containing BPA, a dye and a solvent onto one side of a piece of paper. When heat or pressure is applied, the coating’s constituents merge to release the ink’s color, he explains. © Society for Science & the Public 2000 - 2010

By Susan Milius WILLIAMSBURG, Va. — Putting a female lemur on birth control turns her normally informative scents to nonsense, researchers report. Doses of Depo-Provera, a common contraceptive for people, shift the odor secretions of female lemurs so dramatically that their scents no longer give clear cues to kinship, identity and genetic quality, says study coauthor Christine Drea of Duke University in Durham, N.C. A female lemur whose hormones are disrupted by contraceptives may have real trouble attracting a compatible mate, Drea said July 26 at the annual meeting of the Animal Behavior Society. As for people, men and women might not think they’re influenced by each others’ scents, but “Oh, we are!” said behavioral biologist Susan Jenks of the Sage Colleges in Troy, N.Y., after Drea’s presentation. If women react to the hormones the way lemurs do, “maybe you don’t want to be on contraceptives when you’re picking your mate.” Also, said behavioral ecologist Jill Mateo of the University of Chicago, “For any zoo that is chemically contracepting animals, this could have big implications.” Drea and her colleagues have identified more than 300 compounds in the scent secretions of female lemurs. “There is a rich communication system,” she said. Glands on the forelimbs, tail and other parts of the body secrete chemical cues that the lemurs rub onto branches or other community bulletin boards, where neighbors sniff out the news. © Society for Science & the Public 2000 - 2010

by Mairi Macleod FROM feckless fathers and teenaged mothers to so-called feral kids, the media seems to take a voyeuristic pleasure in documenting the lives of the "underclass". Whether they are inclined to condemn or sympathise, commentators regularly ask how society got to be this way. There is seldom agreement, but one explanation you are unlikely to hear is that this kind of "delinquent" behaviour is a sensible response to the circumstances of a life constrained by poverty. Yet that is exactly what some evolutionary biologists are now proposing. There is no reason to view the poor as stupid or in any way different from anyone else, says Daniel Nettle of the University of Newcastle in the UK. All of us are simply human beings, making the best of the hand life has dealt us. If we understand this, it won't just change the way we view the lives of the poorest in society, it will also show how misguided many current efforts to tackle society's problems are - and it will suggest better solutions. Evolutionary theory predicts that if you are a mammal growing up in a harsh, unpredictable environment where you are susceptible to disease and might die young, then you should follow a "fast" reproductive strategy - grow up quickly, and have offspring early and close together so you can ensure leaving some viable progeny before you become ill or die. For a range of animal species there is evidence that this does happen. Now research suggests that humans are no exception. © Copyright Reed Business Information Ltd.

By NICHOLAS WADE Some 300 million years ago, the living ancestor of humans was a reptile. Like turtles and alligators today, it let the temperature at which its eggs were incubated decide their sex. Birds and mammals, two groups that descended from the reptiles, put sex under the more reliable control of genes, not of temperature. But sex-determining genes pose a severe problem for the organization of a genome. In a series of experiments over the past 15 years, David Page of the Whitehead Institute has reconstructed many of the steps in the evolution of the human sex chromosomes, which he calls “an infinitely rich experiment of nature.” He has now started to analyze a parallel experiment, the sex chromosomes of birds. In humans, men have an X and a Y chromosome, and women two X’s. In reptilian times, the X and the Y were an ordinary pair of chromosomes until the male-determining gene landed on the Y. Thereupon the Y started shedding the genes it held in common with the X and shriveled to a fraction of its former size. Birds have evolved a similar system with a twist — it’s the male that has two of the same chromosomes. Their sex chromosomes are called the Z and W, with males having two Z’s and females a Z and a W. The Z and W are derived from a different pair of ancestral chromosomes than the X and Y, a team led by Daniel W. Bellott and Dr. Page report in the current issue of Nature. The Z’s evolution has in several ways paralleled that of the X, even though each is associated with a different sex. Copyright 2010 The New York Times Company

by Lise Eliot IN 2010 we need to ask afresh just how deep the rabbit hole goes when it comes to gender politics - and how far we are from digging ourselves out. Our beliefs about differences between the sexes have an impact on society vastly out of proportion to the magnitude of those differences, from female scientists defending their mathematical and technical expertise to boys accused of lacking the communication and emotional skills to succeed at school. In truth, women are doing well in science: since 1970, the number of doctorates awarded to women in the US has increased five-fold in physics, nine-fold in computer science and 24-fold in engineering, according to the US Department of Education. And yet just last month we heard John Tierney of The New York Times appearing to echo former Harvard University president Larry Summers's claim that women may be intrinsically incapable of performing at the highest level in such fields. At the same time, boys are stepping away from pursuits like creative writing, foreign languages, art and singing in choirs as they hear they are not "hard-wired" for words or feelings. While young women get the message they can do anything, young men are put off careers in journalism, design, teaching, veterinary practice and psychotherapy, where they were once quite successful. When I set out to write my book Pink Brain, Blue Brain, I had little sense of the controversy surrounding gender differences. I was just a neuroscientist with a daughter and two sons, curious about how their brains might differ and how best to raise them. Now I see how little the science of gender differences has penetrated popular culture and am hoping to set the record straight on behalf of both sexes. © Copyright Reed Business Information Ltd.

By SINDYA N. BHANOO Handsome men may turn the heads of women, but for those less attractive, sociability and friendliness also seem to seduce the fairer sex. The same is true for male house finches, according to a new study. Female house finches prefer to mate with males with the reddest feathers, but dull-colored males make themselves more appealing by acting more social before mating season, according to a study in the September issue of the American Naturalist. The researchers found that the duller a male bird was in color, the more likely he was to engage with multiple social groups. Birds in a social group flock and forage together and any bird can belong to multiple groups. Drab-looking male finches drifted from group to group in the winter, the researchers found. By mating season in the spring, the less attractive males tended to have the same level of mating success as the most colorful, attractive males. “Females have limited options to chose from and this is a way for males to manipulate their chances to find mates, by placing themselves in certain settings,” said Kevin Oh, an evolutionary biologist at Cornell University and the study’s lead author. The least attractive, or most yellow, males were four times as likely to interact with multiple social groups then the most attractive, or reddest, males, Dr. Oh said. House finches are found across North America, but Dr. Oh and his co-author, Alexander Badyaev of the University of Arizona, studied wild populations in Arizona. Copyright 2010 The New York Times Company

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.

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.

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,

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,

Chapter 12. Sex: Evolutionary, Hormonal, and Neural Bases