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

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By James Gallagher Health editor, BBC News website Breastfeeding can halve the risk of post-natal depression, according to a large study of 14,000 new mothers. However, there is a large increase in the risk of depression in women planning to breastfeed who are then unable to do so. The study, published in the journal Maternal and Child Health, called for more support for women unable to breastfeed. A parenting charity said mental health was a "huge issue" for many mothers. The health benefits of breastfeeding to the baby are clear-cut and the World Health Organization recommends feeding a child nothing but breast milk for the first six months. However, researchers at the University of Cambridge said the impact on the mother was not as clearly understood. 'Highest risk' One in 10 women will develop depression after the birth of their child. The researchers analysed data from 13,998 births in the south-west of England. It showed that, out of women who were planning to breastfeed, there was a 50% reduction in the risk of post-natal depression if they started breastfeeding. But the risk of depression more than doubled among women who wanted to, but were not able to, breastfeed. Dr Maria Iacovou, one of the researchers, told the BBC: "Breastfeeding does appear to have a protective effect, but there's the other side of the coin as well. "Those who wanted to and didn't end up breastfeeding had the highest risk of all the groups." BBC © 2014

Keyword: Depression; Aggression
Link ID: 19977 - Posted: 08.20.2014

By Kate Yandell Researchers have accumulated detailed knowledge of the neurons that drive male fruit flies’ mating behaviors. But the neurons that prompt females to respond—or not—to male overtures have been less-studied. Three papers published today (July 2) in Neuron and Current Biology begin to change that. They identify sets of neurons in female fruit flies that help process mating signals, modulate the insects’ receptivity to male courtship, and drive mating behavior. “These three groups independently identified important neuronal groups [that] are positioned in different points in the neuronal circuitry for regulating female receptivity,” said Daisuke Yamamoto, a behavioral geneticist at Tohoku University in Japan who was not involved in any of the studies. “We’ve had access to the male circuitry for a while now, and that’s turning out to be a really interesting way to study how behavior works,” said Jennifer Bussell, whose work as a PhD student at Rockefeller University contributed to the Current Biology paper. “Having that complementary circuit in the female can only provide more fodder for interesting experiments.” Female fruit flies’ mating behaviors depend on their reproductive state. They become receptive to mating as they mature, but become less receptive to males’ advances immediately after mating. If a female fruit fly is receptive to mating, she responds to male pheromones and courtship songs by engaging in a behavior called pausing, where she stops in her tracks near males so they can mount her and she opens her vaginal plates—hard coverings that protect her reproductive tract. © 1986-2014 The Scientist

Keyword: Sexual Behavior
Link ID: 19962 - Posted: 08.16.2014

by Laura Sanders In their first year, babies grow and change in all sorts of obvious and astonishing ways. As their bodies become longer, heavier and stronger, so do their brains. Between birth and a child’s first birthday, her brain nearly triples in size as torrents of newborn nerve cells create neural pathways. This incredible growth can be influenced by a baby’s early life environment, scientists have found. Tragic cases of severe neglect or abuse can throw brain development off course, resulting in lifelong impairments. But in happier circumstances, warm caregivers influence a baby’s brain, too. A new study in rats provides a glimpse of how motherly actions influence a pup’s brain. Scientists recorded electrical activity in the brains of rat pups as their mamas nursed, licked and cared for their offspring. The results, published in the July 21 Current Biology, offer a fascinating minute-to-minute look at the effects of parenting. Researchers led by Emma Sarro of New York University’s medical school implanted electrodes near six pups’ brains to record neural activity. Video cameras captured mother-pup interactions, allowing the scientists to link specific maternal behaviors to certain sorts of brain activity. Two types of brain patterns emerged: a highly alert state and a sleepier, zoned-out state, Sarro and colleagues found. Pups’ brains were alert while they were drinking milk and getting groomed by mom. Pups’ brains’ were similarly aroused when the pups were separated from their mom and siblings. Some scientists think that these bursts of brain activity help young brains form the right connections between regions. © Society for Science & the Public 2000 - 2013.

Keyword: Sexual Behavior; Aggression
Link ID: 19927 - Posted: 08.09.2014

By Darryl Fears At first she was surprised. Then she was disturbed. Now she’s a little alarmed. Each time a different batch of male fish with eggs in their testes shows up in the Chesapeake Bay watershed, Vicki Blazer’s eyebrows arch a bit higher. In the latest study, smallmouth bass and white sucker fish captured at 16 sites in the Delaware, Ohio and Susquehanna rivers in Pennsylvania had crossed over into a category called intersex, an organism with two genders. “I did not expect to find it quite as widespread,” said Blazer, a U.S. Geological Survey biologist who studies fish. Since 2003, USGS scientists have discovered male smallmouth and largemouth bass with immature eggs in several areas of the Potomac River, including near the Blue Plains Advanced Wastewater Treatment Plant in the District. The previous studies detected abnormal levels of compounds from chemicals such as herbicides and veterinary pharmaceuticals from farms, and from sewage system overflows near smallmouth-bass nesting areas in the Potomac. Those endocrine-disrupting chemicals throw off functions that regulate hormones and the reproductive system. In the newest findings, at one polluted site in the Susquehanna near Hershey, Pa., 100 percent of male smallmouth bass that were sampled had eggs, Blazer said. With the mutant bass, she said, “we keep seeing . . . a correlation with the percent of agriculture in the watershed where we conduct a study.”

Keyword: Sexual Behavior; Aggression
Link ID: 19916 - Posted: 08.05.2014

by Bethany Brookshire The deep ocean has spawned a new record: the longest egg-brooding period. In April 2007, Bruce Robison of the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., and colleagues sent a remote-operated vehicle down 1,397 meters (4,583 feet) into the Monterey Submarine Canyon. There they saw a deep-sea octopus (Graneledone boreopacifica) making its way toward a stony outcrop. One month later, the scientists spotted the same octopus, which they dubbed ‘Octomom,’ on the rock with a clutch of 155 to 165 eggs. The researchers returned to the site 18 times in total. Each time, there she was with her developing eggs. Most female octopuses lay only one clutch of eggs, staying with the eggs constantly and slowly starving to death while protecting them from predators and keeping them clean. When the eggs hatch, the female dies. The scientists report July 30 in PLOS ONE that the octopus was observed on her eggs for 53 months, until September 2011, the longest brooding period of any known animal. B. Robison et al. Deep-sea octopus (Graneledone boreopacifica) conducts the longest-known egg-brooding period of any animal. PLOS ONE. Published online July 30, 2014. doi: 10.1371/journal.pone.0103437 © Society for Science & the Public 2000 - 2013.

Keyword: Sexual Behavior
Link ID: 19904 - Posted: 07.31.2014

Posted by Celeste Biever | The four females and one male are onboard a satellite as part of an experiment to investigate sexual activity and reproduction in microgravity carried out by Russia’s space agency. Roscosmos launched the lizards using a six-tonne Foton-M4 rocket on 19 July. But the fate of the tiny cosmonauts became uncertain when their satellite briefly lost contact with ground control on Thursday 24 July. Luckily, technicians managed to restore control on Saturday, and Roscosmos announced on its website that since then it has communicated with the satellite 17 times.”Contact is established, the prescribed commands have been conducted according to plan,” said Roscosmos chief Oleg Ostapenko. Keeping the geckos company are Drosophila fruit flies, as well as mushrooms, plant seeds and various microorganisms that are also being studied. There is also a special vacuum furnace on board, which is being used to analyse the melting and solidification of metal alloys in microgravity. Foton-M4 is set to carry out experiments over two months, and involves a “study of the effect of microgravity on sexual behaviour, the body of adult animals and embryonic development”, according to the website of the Institute of Medico-Biological Problems of the Russian Academy of Sciences, which has developed the project along with Roscosmos. Specific aims of the Gecko-F4 mission include: Create the conditions for sexual activity, copulation and reproduction of geckos in orbit Film the geckos’ sex acts and potential egg-laying and maximise the likelihood that any eggs survive Detect possible structural and metabolic changes in the animals, as well as any eggs and foetuses © 2014 Macmillan Publishers Limited.

Keyword: Sexual Behavior
Link ID: 19896 - Posted: 07.30.2014

By PAUL VITELLO The conventional wisdom among animal scientists in the 1950s was that birds were genetically programmed to sing, that monkeys made noise to vent their emotions, and that animal communication, in general, was less like human conversation than like a bodily function. Then Peter Marler, a British-born animal behaviorist, showed that certain songbirds not only learned their songs, but also learned to sing in a dialect peculiar to the region in which they were born. And that a vervet monkey made one noise to warn its troop of an approaching leopard, another to report the sighting of an eagle, and a third to alert the group to a python on the forest floor. These and other discoveries by Dr. Marler, who died July 5 in Winters, Calif., at 86, heralded a sea change in the study of animal intelligence. At a time when animal behavior was seen as a set of instinctive, almost robotic responses to environmental stimuli, he was one of the first scientists to embrace the possibility that some animals, like humans, were capable of learning and transmitting their knowledge to other members of their species. His hypothesis attracted a legion of new researchers in ethology, as animal behavior research is also known, and continues to influence thinking about cognition. Dr. Marler, who made his most enduring contributions in the field of birdsong, wrote more than a hundred papers during a long career that began at Cambridge University, where he received his Ph.D. in zoology in 1954 (the second of his two Ph.D.s.), and that took him around the world conducting field research while teaching at a succession of American universities. Dr. Marler taught at the University of California, Berkeley, from 1957 to 1966; at Rockefeller University in New York from 1966 to 1989; and at the University of California, Davis, where he led animal behavior research, from 1989 to 1994. He was an emeritus professor there at his death. © 2014 The New York Times Company

Keyword: Language; Aggression
Link ID: 19885 - Posted: 07.28.2014

By Michael Brooks Occasionally, scientific research comes up with banal findings that should nonetheless stop us in our tracks. For example, researchers recently published a study showing that a father’s brain will change its hormonal outputs and neural activity depending on his parenting duties. The conclusion of the research is, in essence, that men make good parents, too. Surely this is not news. Yet it does provide evidence that is sadly still useful. Those involved with issues of adoption, fathers’ rights, gay rights, child custody, and religion-fuelled bigotry will all benefit from understanding what we now know about what makes a good parent. The biggest enemy of progress has been the natural world, or at least our view of it. Females are the primary caregivers in 95 percent of mammal species. That is mainly because of lactation. Infants are nourished by their mothers’ milk, so it makes sense for most early caring to be done by females. Human beings, however, have developed more sophisticated means of nourishing and raising our offspring. Should the circumstances require a different set-up, we have ways to cope. It turns out that this is not just in terms of formula milk, nannies or day care: We also have a flexible brain. The new study, published in Proceedings of the National Academy of Sciences, scanned the brains of parents while they watched videos of their interactions with their children. The researchers found that this stimulated activity in two systems of the brain. One is an emotional network that deals with social bonding, ensures vigilance and coordinates responses to distress, providing chemical rewards for behaviours that maintain the child’s well-being. The other network is concerned with mental processing. It monitors the child’s likely state of mind, emotional condition, and future needs, allowing for planning. 2014 © The New Republic.

Keyword: Sexual Behavior
Link ID: 19883 - Posted: 07.26.2014

By Helen Briggs Health editor, BBC News website The timing of when a girl reaches puberty is controlled by hundreds of genes, say scientists. And age at first period may vary in daughters from the same family because of genetic factors, research shows. The findings, published in Nature, could give clues to why early puberty may be linked to an increased risk of health conditions. Scientists at 166 institutions analysed the DNA of more than 180,000 women in one of the largest studies of its kind. They found that hundreds of genes were involved in the timing of puberty. Unusually, a girl's first period was also influenced by imprinted genes - a rare event where genes from either the mother of father are silenced. "Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent," said lead researcher Dr John Perry of the University of Cambridge. He said the biological complexity revealed in the study was "amazing". "We identified more than 100 regions of the genome associated with puberty timing, but our analysis suggests there are likely to be thousands," he told BBC News. Lifestyle BBC © 2014

Keyword: Hormones & Behavior; Aggression
Link ID: 19879 - Posted: 07.26.2014

By Katherine Harmon Courage Octopuses do the darndest things. Like kill their mate during mating—by strangling him with three arms, according to new observations from the wild. Enterprising scientists Christine Huffard and Mike Bartick watched wild octopuses in action. They found that, for males, mating can be a dangerous game. Especially when your lady has long limbs. Some of the more dicey encounters are detailed in a new paper, published online July 11 in Molluscan Research. Hold on a second, you say. Strangling octopuses? Octopuses don’t even have necks—or inhale air. So how, exactly, does that work? The strangulation seems to happen when “an octopus wraps at least one arm around the base of the mantle of the competitor” (or mate), Huffard wrote in 2010. This constriction then keeps the octopus from taking in fresh water to run past its gills—starving the animal of its oxygen source. Octopuses are not known to get cuddly with one another on a day-to-day basis. In fact, “octopuses touch each other with their arms primarily in the context of mating and aggression,” the researchers write. And in this case it seems to have been both. Huffard came across a pair of mating day octopuses (Octopus cyanea) near Fiabacet Island in Indonesia. The female, as is often the case in this species, was larger—with a body about seven-and-a-half inches long; the male was closer to six inches long. They were positioned on a reef, outside the female’s den, the male’s mating arm (hectocotylus) inserted into the female’s mantle from a (presumably) safe distance. © 2014 Scientific American

Keyword: Sexual Behavior
Link ID: 19869 - Posted: 07.23.2014

By JAN HOFFMAN As it has for decades, the Centers for Disease Control and Prevention last week released its annual National Health Interview Survey on the health of Americans. But this year, there was a difference: For the first time, the respondents were asked about their sexual orientation. Of 34,557 adults ages 18 and older, the survey reported, 1.6 percent said they were gay or lesbian. Some critics say the numbers are low, but they fall in the range of other surveys. In the new survey, however, only 0.7 percent of respondents described themselves as bisexual; other studies have reported higher numbers. Adults who identified themselves as gay, lesbian or bisexual reported some different behaviors and concerns — for example, more alcohol consumption and cigarette smoking — than those who said they were straight. But it can be difficult to elicit information that many people consider private. The New York Times spoke about such challenges with Gary J. Gates, a demographer at the Williams Institute at the U.C.L.A. School of Law, which focuses on law and policy issues related to sexual orientation and gender identity. Some of Dr. Gates’s findings were echoed in the new survey. This interview was edited and condensed. Q.How was this survey conducted? A.Survey takers had a computer that guided them through questions which they asked the respondent in person, and they used flash cards to show them potential answers. Q.Why do you think the figure for bisexuality was lower than in other surveys? A.There is evidence that bisexuals perceive more stigma and discrimination than gay and lesbian people. They are much less likely to tell important people around them that they are bisexual. © 2014 The New York Times Company

Keyword: Sexual Behavior
Link ID: 19862 - Posted: 07.22.2014

By Joel Achenbach Friends often look alike. The tendency of people to forge friendships with people of a similar appearance has been noted since the time of Plato. But now there is research suggesting that, to a striking degree, we tend to pick friends who are genetically similar to us in ways that go beyond superficial features. For example, you and your friends are likely to share certain genes associated with the sense of smell. Our friends are as similar to us genetically as you’d expect fourth cousins to be, according to the study published Monday in the Proceedings of the National Academy of Sciences. This means that the number of genetic markers shared by two friends is akin to what would be expected if they had the same great-great-great-grandparents. “Your friends don’t just resemble you superficially, they resemble you genetically,” said Nicholas A. Christakis, a physician and social scientist at Yale University and a co-author of the study. The resemblance is slight, just about 1 percent of the genetic markers, but that has huge implications for evolutionary theory, said James Fowler, a professor of medical genetics and political science at the University of California at San Diego. “We can do better than chance at predicting if two people are going to be friends if all we have is their genetic data,” Fowler said. This is a data-driven study that covers hundreds of friendship pairs and stranger pairs, plus hundreds of thousands of genetic markers. There’s no single “friendship” gene driving people together. There’s no way to say that a person befriended someone else because of any one genetic trait.

Keyword: Genes & Behavior; Aggression
Link ID: 19833 - Posted: 07.15.2014

By ALEX STONE Last summer, in a failed attempt at humor, Clorox ran an online ad that declared, “Like dogs or other house pets, new dads are filled with good intentions but lacking the judgment and fine motor skills to execute well.” Although the company pulled the ad amid a flurry of scorn from the online commentariat, it nevertheless played to a remarkably widespread stereotype — that fathers are somehow unfit to raise children. In “Do Fathers Matter?” — spoiler alert: they do — the veteran science writer Paul Raeburn jumps to Dad’s defense, drawing on several decades of research and his own experience as a five-time father. What emerges is a thought-provoking field piece on the science of fatherhood, studded with insights on how to apply it in the real world. Historically, developmental psychologists have largely dismissed fathers as irrelevant. Nearly half the articles on child and adolescent psychology published in leading journals from 1997 to 2005, for example, make no mention of fathers; before 1970, when fathers weren’t even allowed in delivery rooms, less than a fifth of the research on parental bonding took them into account. This bias reflects a deeply ingrained assumption that fathers play a marginal role in how their children turn out, a belief enshrined in the theory of infant attachment, which grew out of the work of the British psychiatrist John Bowlby in the second half of the 20th century. “It focused exclusively on mothers,” Mr. Raeburn writes. “The role of the father, Bowlby believed, was to provide support for the mother. In the drama of childhood, he was merely a supporting actor.” This was more or less the established view until a few decades ago, when psychologists, motivated in part by the growing number of women entering the work force, finally started paying attention to fathers. © 2014 The New York Times Company

Keyword: Development of the Brain; Aggression
Link ID: 19831 - Posted: 07.15.2014

By Virginia Morell Many moth species sing courtship songs, and until now, scientists knew of only two types of such melodies. Some species imitate attacking bats, causing a female to freeze in place, whereas others croon tunes that directly woo the ladies. But the male yellow peach moth (Conogethes punctiferalis, pictured) belts out a combination song, scientists report online today in the Proceedings of the Royal Society B. These tiny troubadours, which are found throughout Asia, emit ultrasonic refrains composed of short and long pulses by contracting their abdominal tymbals, sound-producing membranes. (Listen to a male’s courtship song above.) The short pulses, the scientists say, are similar to the hunting calls of insectivorous horseshoe bats. However, unlike other moth species, these males aren’t directing the batlike tunes at females, but rather at rival males. Using playback experiments, the scientists showed that a male drives away competitors with the short pulses of his ditty, while inducing a female to mate with the long note. Indeed, a receptive virgin female moth (1 to 3 days old) typically raises her wings after hearing this part of the male’s song—a sign that she accepts the male, the scientists say. It is thus the first moth species known to have a dual-purpose melody. © 2014 American Association for the Advancement of Science

Keyword: Sexual Behavior; Aggression
Link ID: 19804 - Posted: 07.09.2014

Karen Ravn To the west, the skies belong to the carrion crow. To the east, the hooded crow rules the roost. In between, in a narrow strip running roughly north to south through central Europe, the twain have met, and mated, for perhaps as long as 10,000 years. But although the crows still look very different — carrion crows are solid black, whereas hooded crows are grey — researchers have found that they are almost identical genetically. The taxonomic status of carrion crows (Corvus corone) and hooded crows (Corvus cornix) has been debated ever since Carl Linnaeus, the founding father of taxonomy, declared them to be separate species in 1758. A century later, Darwin called any such classification impossible until the term 'species' had been defined in a generally accepted way. But the definition is still contentious, and many believe it always will be. The crows are known to cross-breed and produce viable offspring, so lack the reproductive barriers that some biologists consider essential to the distinction of a species, leading to proposals that they are two subspecies of carrion crow. In fact, evolutionary biologist Jochen Wolf from Uppsala University in Sweden and his collaborators have now found that the populations living in the cross-breeding zone are so similar genetically that the carrion crows there are more closely related to hooded crows than to the carrion crows farther west1. Only a small part of the genome — less than 0.28% — differs between the populations, the team reports in this week's Science1. This section is located on chromosome 18, in an area associated with pigmentation, visual perception and hormonal regulation. It is no coincidence, the researchers suggest, that the main differences between carrion and hooded crows are in colouring, mating preferences (both choose mates whose colouring matches theirs), and hormone-influenced social behaviours (carrion crows lord it over hooded ones). © 2014 Nature Publishing Group,

Keyword: Sexual Behavior; Aggression
Link ID: 19755 - Posted: 06.21.2014

By PAM BELLUCK Cindy Wachenheim was someone people didn’t think they had to worry about. She was a levelheaded lawyer working for the State Supreme Court, a favorite aunt who got down on the floor to play with her nieces and nephews, and, finally, in her 40s, the mother she had long dreamed of becoming. But when her baby was a few months old, she became obsessed with the idea that she had caused him irrevocable brain damage. Nothing could shake her from that certainty, not even repeated assurances from doctors that he was normal. “I love him so much, but it’s obviously a terrible kind of love,” she agonized in a 13-page handwritten note. “It’s a love where I can’t bear knowing he is going to suffer physically and mentally/emotionally for much of his life.” Ms. Wachenheim’s story provides a wrenching case study of one woman’s experience with maternal mental illness in its most extreme and rare form. It also illuminates some of the surprising research findings that are redefining the scientific understanding of such disorders: that they often develop later than expected and include symptoms not just of depression, but of psychiatric illnesses. Now these mood disorders, long hidden in shame and fear, are coming out of the shadows. Many women have been afraid to admit to terrifying visions or deadened emotions, believing they should be flush with maternal joy or fearing their babies would be taken from them. But now, advocacy groups on maternal mental illness are springing up, and some mothers are blogging about their experiences with remarkable candor. A dozen states have passed laws encouraging screening, education and treatment. And celebrities, including Brooke Shields, Gwyneth Paltrow and Courteney Cox, have disclosed their postpartum depression. © 2014 The New York Times Company

Keyword: Depression; Aggression
Link ID: 19743 - Posted: 06.17.2014

By Denali Tietjen Caffeine isn’t healthy, but that’s no news. The withdrawal headaches, jitteriness and dehydration kind of gave that one way. What is news, however, is that starting at puberty, it’s worse for boys than girls. Girls and boys have the same cardiovascular reactions to caffeine in childhood, but begin to react differently in adolescence, finds a new study conducted by researchers from The University of Buffalo. In the double-blind study published in the June issue of Pediatrics, researchers examined the cardiovascular reactions of 52 pre-pubescent (ages eight to nine) and 49 post-pubescent (ages 15 to 17) children to varying levels of caffeine. Participants consumed either the placebo, 1 mg/kg or 2 mg/kg caffeinated sodas, and then had their heart rates and blood pressures taken. The results found that pre-pubescent children had the same reaction to caffeine regardless of gender, while post-pubescent boys had much stronger cardiovascular reactions to caffeine than girls. The study also examined post-pubescent girls’ reactions to caffeine at various phases of their menstrual cycles. At different stages of the cycle, the girls metabolized caffeine differently. “We found differences in responses to caffeine across the menstrual cycle in post-pubertal girls, with decreases in heart rate that were greater in the mid-luteal phase and blood pressure increases that were greater in the mid-follicular phase of the menstrual cycle,” Dr. Jennifer Temple, one of the researchers who conducted the study said in a University at Buffalo press release announcing the study.

Keyword: Sexual Behavior; Aggression
Link ID: 19739 - Posted: 06.17.2014

by Bethany Brookshire Human vocal chords can produce an astonishing array of sounds: shrill and fearful, low and sultry, light and breathy, loud and firm. The slabs of muscle in our throat make the commanding sound of a powerful bass and a baby’s delightful, gurgling laugh. There are voices that must be taken seriously, voices that play and voices that seduce. And then there’s vocal fry. Bringing to mind celebrity voices like Kim Kardashian or Zooey Deschanel, vocal fry is a result of pushing the end of words and sentences into the lowest vocal register. When forcing the voice low, the vocal folds in the throat vibrate irregularly, allowing air to slip through. The result is a low, sizzling rattle underneath the tone. Recent studies have documented growing popularity of vocal fry among young women in the United States. But popular sizzle in women’s speech might be frying their job prospects, a new study reports. The findings suggest that people with this vocal affectation might want to hold the fry on the job market — and that people on the hiring side of the table might want to examine their biases. Vocal fry has been recognized since the 1970s, but now it’s thought of as a fad. Study coauthor Casey Klofstad, a political scientist at the University of Miami in Goral Gables, Fla., says that the media attention surrounding vocal fry generated a lot of speculation. “It is a good thing? Is it bad? It gave us a clear question we could test,” he says. Specifically, they wanted to study whether vocal fry had positive or negative effects on how people who used the technique were perceived. Led by Rindy Anderson from Duke University, the researchers recorded seven young men and seven young women speaking the phrase “Thank you for considering me for this opportunity.” Each person spoke the phrase twice, once with vocal fry and once without. Then the authors played the recordings to 800 participants ages 18 to 65, asking them to make judgments about the candidates based on voice alone. © Society for Science & the Public 2000 - 2013

Keyword: Language; Aggression
Link ID: 19718 - Posted: 06.10.2014

By Jenny Graves The claim that homosexual men share a “gay gene” created a furor in the 1990s. But new research two decades on supports this claim – and adds another candidate gene. To an evolutionary geneticist, the idea that a person’s genetic makeup affects their mating preference is unsurprising. We see it in the animal world all the time. There are probably many genes that affect human sexual orientation. But rather than thinking of them as “gay genes,” perhaps we should consider them “male-loving genes.” They may be common because these variant genes, in a female, predispose her to mate earlier and more often and to have more children. Likewise, it would be surprising if there were not “female-loving genes” in lesbian women that, in a male, predispose him to mate earlier and have more children. We can detect genetic variants that produce differences between people by tracking traits in families that display differences. Patterns of inheritance reveal variants of genes (called “alleles”) that affect normal differences, such as hair color, or disease states, such as sickle cell anemia. Quantitative traits, such as height, are affected by many different genes, as well as environmental factors. It’s hard to use these techniques to detect genetic variants associated with male homosexuality partly because many gay men prefer not to be open about their sexuality. It is even harder because, as twin studies have shown, shared genes are only part of the story. Hormones, birth order and environment play roles, too.

Keyword: Sexual Behavior; Aggression
Link ID: 19699 - Posted: 06.06.2014

Ian Sample, science correspondent Research on children in Denmark has found that boys with autism were more likely to have been exposed to higher levels of hormones in their mother's wombs than those who developed normally. Boys diagnosed with autism and related disorders had, on average, raised levels of testosterone, cortisol and other hormones in the womb, according to analyses of amniotic fluid that was stored after their mothers had medical tests during pregnancy. The findings add to a growing body of evidence that the biological foundations of autism are laid down well before birth and involve factors that go beyond the child's genetic make-up. The results may help scientists to unravel some of the underlying causes of autism and explain why boys are four to five times more likely to be diagnosed with the condition, which affects around one percent of the population. Amniotic fluid surrounds babies in the womb and contains hormones and other substances that they have passed through their urine. The liquid is collected for testing when some women have an amniocentesis around four months into their pregnancy. Scientists in Cambridge and Copenhagen drew on Danish medical records and biobank material to find amniotic fluid samples from 128 boys who were later diagnosed with autism. Compared to a control group, the boys with autism and related conditions had higher levels of four "sex steroid" hormones that form a biological production line in the body that starts with progesterone and ends with testosterone. "In the womb, boys produce about twice as much testosterone as girls, but compared with typical boys, the autism group has even higher levels. It's a significant difference and may have a large effect on brain development," said Simon Baron-Cohen, director of the Autism Research Centre at Cambridge University. © 2014 Guardian News and Media Limited

Keyword: Autism; Aggression
Link ID: 19687 - Posted: 06.03.2014