Biological Psychology Links

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,

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

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

by Bob Holmes Which face is more attractive? If you chose the face on the left, you share the tastes of most heterosexual men. It is a composite face, or "morph", made from the faces of eight women with unusually small feet. The face on the right is a morph of eight women with unusually large feet. It's quite a difference, isn't it? Women with smaller feet have prettier faces, at least according to the men who took part in this study. So do women with longer thigh bones and narrower hips, as well as women who are taller overall. And the contest isn't even a close one. "These are the most strikingly different morphs I've ever seen," says Jeremy Atkinson, an evolutionary psychologist at the University at Albany, New York. Atkinson and his colleague Michelle Rowe measured hand length, foot length, thigh length and hip width on 60 white female college students, then adjusted each measurement to account for individual differences in overall height. For each of 16 body-part measurements, they selected the eight women with the shortest lengths and the eight with the longest, and constructed morphs of their faces. These morphs were then rated for attractiveness by 77 heterosexual male students. The men were three-and-a-half times as likely to pick the short-footed morph as more attractive, and almost 10 times as likely to say it was more feminine, Atkinson and Rowe found. © Copyright Reed Business Information Ltd.

by Eliza Strickland When the housing market crashed in late 2008, most people were surprised by the sudden collapse. John Coates was not among them. He had spent 12 years trading derivatives for New York’s biggest banks—and had left finance for neuroscience, studying what happens in the brains of traders who put billions of dollars on the line in risky financial decisions. Coates, who now studies neuroscience and behavioral economics at the University of Cambridge, has made the London stock market his laboratory. His experiments seem to show that a trader’s success may be determined not by his wits but by the hormones that course through his brain. Hormone-fueled decision making can have powerful effects, intensifying market booms and busts and destabilizing the economy, Coates suggests. The markets’ operations are determined by legions of young men governed by confidence-boosting testosterone and the stress-related hormone cortisol. When hormones spiral out of control, economic behavior can do so as well. How did you get inside the heads of the people working in the financial markets? In our first experiment, we were on a trading floor in London with 250 traders, of which only three were women; the average age was maybe 28. They traded in and out very quickly, which means they would hold positions for minutes or even seconds. They would spot a price anomaly and jump on it, then quickly unwind. And they would make trades of huge value —$1 billion or $2 billion at a crack. We wanted to find out what was going on in the brains and bodies of these men who were taking such huge risks. So we collected saliva samples from the traders to measure their levels of testosterone and cortisol in the morning and the afternoon, bracketing the bulk of the day’s trading. Our hypothesis was that when traders had above-average testosterone their profits would go up, and in fact that’s exactly what we saw. It turned out that their morning testosterone levels were actually predicting their afternoon profits.

By Susan Milius PORTLAND, Ore. — A tendency for daughters to fall for guys that are like their dads helps keep two species of fish from interbreeding. Two distinct species of the threespine stickleback dart about in several lakes of British Columbia, where the two fishes could easily mate with each other. But they don’t; the slimmer ones, which feed on plankton in open water, mate with their own kind, while the larger, bottom-feeding ones mate with theirs. Experiments now show that early in life, females of both kinds pick up some cue from their fathers, probably his odor, that provides a guide later on when it comes time to choose a mate, according to Genevieve Kozak of the University of Wisconsin–Madison. The experiments suggest that this process, known as imprinting, may help the stickleback species stay separate even though they live in the same lakes, Kozak said June 27 at the Evolution 2010 meeting. “One of the coolest talks I've seen,” said evolutionary biologist Daphne Fairbairn of the University of California, Riverside. Just how new species form and stay separate while sharing space remains a lively topic in biology, and for some creatures, such as the extraordinarily diverse cichlid fish in African lakes, biologists are still looking for a good explanation. “I think the cichlid people are going to jump on this,” Fairbairn said. © Society for Science & the Public 2000 - 2010

By Jesse Bering There must be something in the water here in Lanesboro, Minnesota, because last night I dreamt of an encounter with a very muscular African-American centaur, an orgiastic experience with – gasp – drunken members of the opposite sex and (as if that weren’t enough) then being asked by my hostess to wear a white wedding dress while giving a scientific keynote presentation. “Does it make me look too feminine?” “Not at all,” she assured me, “it’s a man’s dress.” Now Freud might raise his eyebrows at such a lurid dreamscape, but if these images represent my repressed sexual yearnings, then there’s a side of me that I apparently have yet to discover. But I doubt that this is the case. Dreams with erotic undertones are like most other dreams during REM sleep—runaway trains with a conductor who is helpless to do anything about the surrealistic directions they take. Rather, if you really want to know about a person’s hidden sexual desires, then find out what’s on his or her mind’s eye during the deepest throes of masturbation. This conjuring ability to create fantasy scenes in our heads that literally bring us to orgasm when conveniently paired with our dexterous appendages is an evolutionary magic trick that I suspect is uniquely human. It requires a cognitive capacity called mental representation (an internal “re-presentation” of a previously experienced image or some other sensory input) that many evolutionary theorists believe is a relatively recent hominid innovation. © 2010 Scientific American,

Researchers conclude men are more attracted to women wearing pheromones, resulting in more formal dates, kissing, affection, sexual intercourse SAN FRANCISCO, — Women’s perfume laced with synthetic pheromones acts as a sexual magnet and increases the sexual attractiveness of women to men, San Francisco State University researchers conclude in a study appearing in the current issue of the quarterly journal Physiology and Behavior. The study, the first of its kind to independently test a sex attractant pheromone for women, showed that of the 36 women tested, 74 percent of those wearing their regular perfume with the pheromone saw an overall increase in three or more of the following sociosexual behaviors: frequency of kissing, heavy petting and affection, sexual intercourse, sleeping next to their partner, and formal dates with men. In contrast, only 23 percent of the women who had a placebo added to their perfume saw an increase in these sociosexual behaviors. Researchers conclude from these data that the pheromone users were more sexually attractive to men.

Hormones have long been considered the solo act that molds brains along gender lines. But in recent years, hints that certain genes on the sex chromosomes might also play a role have been emerging. Now, new research points to the first structural brain difference between male and female mammals attributed to genetics alone. Sex hormones, in particular testosterone, help shape the developing brain of fetuses and newborns. Testosterone, secreted by the gonads, makes male brains distinct from female ones, and it is thought to account for difference in behavior and brain structure. A group of scientists, though, has wondered for years whether genes on the X and Y chromosomes have a hand in shaping brain differences. To find out, neuroendocrinologist Arthur Arnold at the University of California, Los Angeles, collaborated with colleagues in the United Kingdom who had genetically altered mice. Robin Lovell-Badge and Paul Burgoyne, developmental geneticists at the Medical Research Council’s National Institute for Medical Research in London, performed a genetic sex change. By using mice with a deletion in their Y chromosome for a gene called Sry, which kick-starts testes development, they ended up with XY “females” that had ovaries; adding Sry to the genomes of females generated XX "males" with testes. Although these mice had fully developed sex organs, both groups had fertility problems due to the gene manipulations. Copyright © 2002 by the American Association for the Advancement of Science.

Syracuse University researchers pick up where Darwin left off: Groundbreaking study to be published in the Nov. 8 issue of Science When it comes to mating and determining whose sperm reaches the elusive egg, females control both the playing field and the rules of the game, according to a new study on male sperm competition vs. female choice to be published in the Nov. 8 issue of Science. "Our study demonstrates, unambiguously, the active role females play in determining the conditions under which sperm compete inside the female reproductive tract," says Scott Pitnick, professor of biology at Syracuse University, who published the study with co-researcher Gary T. Miller, a postdoctoral research associate at SU. "It's widely known that, throughout the animal kingdom, sperm cells evolve rapidly into some of the most outrageous variations in size and shape. Until now, we didn't know why. Our study shows that it's because of female choice. The shape and physiology of the female reproductive tract is driving this variation in sperm." Most people are familiar with the elaborate competitions that occur between males before mating, such as the ritualistic clash of horns of Big Horn Sheep or the bloody battles between male elephant seals. However, relatively little is understood about how sperm compete after mating has occurred, says Pitnick, an evolutionary biologist who has been studying sexual selection and the nature of sex differences for more than 15 years. In a 1995 study published in Nature, he documented the longest sperm cell known to science. It belongs to a species of fruit fly called Drosophila bifurca and measures some two inches in length when fully uncoiled.

COLUMBUS, Ohio – A new study suggests that men and women might not be as far apart in sexual behaviors as previous research has shown. In many surveys, men typically report engaging in sex at earlier age, more often, and with more sexual partners than do women. However, a new study shows that some reported gender differences might show up because women don’t always answer surveys honestly, but give answers they believe are expected of them. “Women are sensitive to social expectations for their sexual behavior and may be less than totally honest when asked about their behavior in some survey conditions,” said Terri Fisher, co-author of the study and associate professor of psychology at Ohio State University’s Mansfield campus.

Giving people a whiff of a key chemical can make them more inclined to trust strangers with their cash, a new study reveals. Just three puffs of a nasal spray containing a hormone called oxytocin increased the chance that people would part with their money. The research centred around a game in which an “investor” player gives part or all of his money on blind trust to an anonymous “trustee” player who earns interest on the combination of his own money and the invested sum. But the investor is told there is no obligation for the “trustee” to give any money back at all - they risk losing any money they choose to invest. Michael Kosfeld at the University of Zurich, Switzerland, who led the study found that investors gave away their money far more willingly if they had sniffed oxytocin than if they had sniffed a placebo. But this extra willingness disappeared when the trustee’s role was computerised, rather than carried out by another human, confirming that the effect was interpersonal, and not simply a general willingness to gamble. Kosfeld speculates that the hormone reduces people’s aversion to betrayal, overcoming an unwillingness to initiate interaction with strangers. This matches observations in animal studies. “It helps animals to approach one another, which is a parallel with trust in our game,” he says. © Copyright Reed Business Information Ltd.

For women, it seems, sex is a big turn-off, reveals a brain scanning study. It shows that many areas of the brain switch off during the female orgasm - including those involved with emotion. “At the moment of orgasm, women do not have any emotional feelings,” says Gert Holstege of the University of Groningen in the Netherlands. His team recruited 13 healthy heterosexual women and their partners. The women were asked to lie with their heads in a PET scanner while the team compared their brain activity in four states: simply resting, faking an orgasm, having their clitoris stimulated by their partner’s fingers, and clitoral stimulation to the point of orgasm. The results of the study are striking. As the women were stimulated, activity rose in one sensory part of the brain, called the primary somatosensory cortex, but fell in the amygdala and hippocampus, areas involved in alertness and anxiety. During orgasm, activity fell in many more areas of the brain, including the prefrontal cortex, compared with the resting state, Holstege told a meeting of the European Society for Human Reproduction and Development in Copenhagen on Monday. In one sense the findings appear to confirm what is already known, that women cannot enjoy sex unless they are relaxed and free from worries and distractions. "Fear and anxiety levels have to go down for orgasm. Everyone knows this but we can see it happening in the brain," he explains. © Copyright Reed Business Information Ltd.

The best place to sell magazines could be in the gym locker room, according to a study which found that pheromones in male sweat makes men opt for a manly read. Men under the influence of androstenol – a pheromone found in men’s underarm sweat – find men’s lifestyle magazines to be more attractive and are more likely to purchase them than those not exposed to the pheromone, suggests the research. Michael Kirk-Smith, from the University of Ulster, UK, and Claus Ebster, from the University of Vienna, Austria showed 120 student volunteers three magazines: the female lifestyle magazine Allure, the neutrally pitched National Geographic, and the male lifestyle magazine Men’s Health. The students were split into two groups with equal numbers of men and women. The first group wore a mask sprayed with androstenol and the second wore a mask permeated with a control solvent. The concentrations of the solvents in the masks were low enough as to have imperceptible odour to the wearers. The two groups were asked to rate the magazines according to how masculine they found each, how appealing and how likely they were to purchase them. The male participants exposed to androstenol rated Men’s Health as significantly more masculine and more appealing compared with the control group. They also had a higher tendency to report that they might buy the magazine. Women appeared to be completely unaffected by the pheromone. © Copyright Reed Business Information Ltd.

CHICAGO-Researchers from the Rush Alzheimer's Disease Center found that plaques and tangles in the brain, the changes seen in people with Alzheimer's disease (AD), are more likely to be expressed as dementia in women than in men. In the June 2005 issue of Archives of General Psychiatry, "Sex Differences in the Clinical Manifestations of Alzheimer Disease Pathology," principal investigator Lisa L. Barnes, PhD, sought to determine whether the relation between levels of AD pathology and clinical symptoms of AD differed in men and women. Alzheimer's disease is the leading cause of dementia in older people, she noted. The researchers studied older Catholic nuns, priests, and brothers in the Religious Orders Study, a longitudinal clinicopathologic study of aging and AD. The study involves annual clinical evaluations and brain donation at death. The analyses were conducted on 64 men and 77 women. Women were slightly older at death than men; four cortical regions of the brain were counted, and a global measure of AD was derived. Barnes found women had more global AD pathology than did men due primarily to more neurofibrillary tangles. "On a global measure of AD pathology that ranged from 0 to three, each additional unit of pathology increased the odds of clinical AD nearly three-fold in men compared with more than 20-fold in women. The findings suggest that AD pathology is more likely to be expressed clinically as dementia in women than in men. Our results suggest that the clinical manifestation of AD is stronger in women than in men."

No matter how much you might hate hearing it, you know you do have you mother's eyes, or her hair, or her smile. How much you resemble your mother depends on which of her genes you inherit. But looking like her is not the only hold your mom's genes have on your life. There's mounting evidence that mom's genes may indirectly affect your weight and your health all the way into adulthood. "Not only are your genes important, and your environment — that is, how much you eat, how much dietary fat you eat — but also mom's genes are important," says geneticist Joseph Jarvis, perhaps influencing how your body is affected by what you eat. Jarvis, a researcher at Washington University School of Medicine in St. Louis, says that's because our mother's genes somehow affect how our bodies react to our prenatal and early environment (while nursing), switching certain of our genes on or off. This could have consequences throughout our lives, affecting our weight that could lead to health issues such as diabetes and high cholesterol. According to Jarvis, much of the earlier research into this effect had looked at weight gain of very young mice. This is because for "a two-week-old mouse, the only source of food they have is mother's milk. And we know that in mice, milk production has a genetic basis," he explains. "So it makes sense for the two-week weight to depend on who your mother was." © ScienCentral, 2000-2005.

Roxanne Khamsi Women may be able to tell whether a man is child-friendly simply by looking at his face – and this could influence how attractive they find him as a potential long-term partner. But for a spring fling or a summer love, women seek men with high levels of testosterone who don’t care much for children. James Roney at the University of California, Santa Barbara, US, and his colleagues asked 39 undergraduate men to look at pairs of pictures each consisting of a photo of an adult and a photo of an infant. The men were asked which photo they preferred. Researchers also took saliva samples from the male volunteers to determine their testosterone levels. Each man was then asked to maintain a neutral expression while researchers photographed his face. Then, 29 female undergraduates rated the photographed male faces according to how much they believed the men liked children. Researchers found that women could often correctly guess which men preferred the infant photos. The women were also asked which men they would choose for a short fling and which for a long-term relationship. Those men perceived as child-friendly were more likely to be selected for a long-term relationship. In addition, the female volunteers were told to rate the men’s faces in terms of masculinity. The men selected as most masculine by the women were confirmed by their saliva tests to be the ones with the highest testosterone levels. © Copyright Reed Business Information Ltd

New research reveals that a mother's touch early in life could trigger a child's future mothering skills. Columbia University neurobiologist Frances Champagne says that previous research across species showed that maternal behaviors are passed down from mother to daughter. "So if your mother held you a lot, you will hold your infants a lot," Champagne says. But she wanted to know whether mothering tendencies are passed on through genetics or experience. Her team studied mother rats that spent time licking and grooming their babies, and others that didn't. Chemical tags can attach to DNA and act like "stop signs" to turn genes off. As she wrote in the journal Endocrinology, without enough licking and grooming, female rats had certain genes turn off, also known as methylation. When a gene is methylated, chemical tags called methyl groups attach to the DNA, preventing the production of certain hormones key to future mothering behaviors, including estrogen and oxytocin, also known as the love hormone. Licked rats had less of these methyl groups attach to the genes, allowing the production of those hormones. These hormones, in turn, affect behavior when these baby rats become mothers themselves. © ScienCentral, 2000-2006

No one can deny that becoming a dad is a life-changing experience. And despite an increase in sleepless nights and newly acquired diaper-changing duties, most would agree that it's a deeply enriching and positive one. New findings by brain researcher Kelly Lambert, professor and chair of the psychology department at Randolph-Macon College, suggest that fatherhood may change more than just a man's lifestyle – it may actually cause lasting benefits in his brain. Lambert's research on mother rats has provided mounting evidence that motherhood benefits the brain. She found that mom rats do better on learning and memory tests than non-moms, and are also bolder, suggesting that they are protected against the damaging effects of stress. Lambert linked these changes to the flood of hormones that accompany pregnancy and lactation, but as she wrote in Scientific American magazine, even non-mom rats given "foster" pups showed changes in these areas. Lambert got interested in the possibility that the same could be true for rodent dads. Her most recent experiments show that dads actually do outperform bachelors of the same species at locating food and show less stress in new situations, such as when encountering unfamiliar objects. © ScienCentral, 2000-2006.

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