Links for Keyword: Sexual Behavior

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By BENEDICT CAREY and PAM BELLUCK He was a graduate student who seemingly had it all: drive, a big idea and the financial backing to pay for a sprawling study to test it. In 2012, as same-sex marriage advocates were working to build support in California, Michael LaCour, a political science researcher at the University of California, Los Angeles, asked a critical question: Can canvassers with a personal stake in an issue — in this case, gay men and women — actually sway voters’ opinions in a lasting way? He would need an influential partner to help frame, interpret and place into context his findings — to produce an authoritative scientific answer. And he went to one of the giants in the field, Donald P. Green, a Columbia University professor and co-author of a widely used text on field experiments. “I thought it was a very ambitious idea, so ambitious that it might not be suitable for a graduate student,” said Dr. Green, who signed on as a co-author of Mr. LaCour’s study in 2013. “But it’s such an important question, and he was very passionate about it.” Last week, their finding that gay canvassers were in fact powerfully persuasive with people who had voted against same-sex marriage — published in December in Science, one of the world’s leading scientific journals — collapsed amid accusations that Mr. LaCour had misrepresented his study methods and lacked the evidence to back up his findings. On Tuesday, Dr. Green asked the journal to retract the study because of Mr. LaCour’s failure to produce his original data. Mr. LaCour declined to be interviewed, but has said in statements that he stands by the findings. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20979 - Posted: 05.26.2015

Richard A. Friedman AMERICANS disapprove of marital infidelity. Ninety-one percent of them find it morally wrong, more than the number that reject polygamy, human cloning or suicide, according to a 2013 Gallup poll. Yet the number of Americans who actually cheat on their partners is rather substantial: Over the past two decades, the rate of infidelity among married men has been pretty constant at around 21 percent, while the percentage of married women who admitted to cheating has mostly hovered between 10 and 15 percent, according to the General Social Survey at the University of Chicago’s independent research organization, NORC. We are accustomed to thinking of sexual infidelity as a symptom of an unhappy relationship, a moral flaw or a sign of deteriorating social values. When I was trained as a psychiatrist we were told to look for various emotional and developmental factors — like a history of unstable relationships or a philandering parent — to explain infidelity. But during my career, many of the questions we asked patients were found to be insufficient because for so much behavior, it turns out that genes, gene expression and hormones matter a lot. Now that even appears to be the case for infidelity. We have long known that men have a genetic, evolutionary impulse to cheat, because that increases the odds of having more of their offspring in the world. But now there is intriguing new research showing that some women, too, are biologically inclined to wander, although not for clear evolutionary benefits. Women who carry certain variants of the vasopressin receptor gene are much more likely to engage in “extra pair bonding,” the scientific euphemism for sexual infidelity. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 20970 - Posted: 05.23.2015

By SINDYA N. BHANOO Male Java sparrows are songbirds — and, scientists reported on Wednesday, natural percussionists. The sparrows click their bills against a hard surface while singing. That clicking is done in coordination with the song, much as a percussion instrument accompanies a melody. Researchers at Hokkaido University in Japan observed the birds producing clicks frequently toward the beginning of their songs and around specific notes. Birds that were related produced similar percussive patterns, but whether this behavior is learned or innate is unclear. Next the scientists, who described their findings on Wednesday in the journal PLOS One, would like to know whether male sparrows use bill clicks during courtship communication. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20963 - Posted: 05.21.2015

Margaret Wente Child psychiatrist Susan Bradley was a pioneer in treating kids with gender-identity disorders. In the 1970s, she founded the child and adolescent gender identity clinic at the Clarke Institute in Toronto, which eventually became part of the Centre for Addiction and Mental Health (CAMH). Back then, the field was virtually unknown. Today, it is Ground Zero in a fierce battle between oldfangled psychiatry and transgender activists who insist that practitioners like Dr. Bradley are guilty of child abuse. Caught in the middle are confused parents, well-meaning schools, and – most important of all – troubled and bewildered kids. The new rush to turn little Jason into Janey, or Sally into Sam, is generally regarded (in the media, at least) as progress – proof of what a tolerant and progressive society we’ve become. But what if it’s just another fad? What if the radical step of changing genders isn’t always the right answer for a child’s emotional distress – especially when that child is only 10 or 6, or 3? “Some of these kids are quite significantly ill,” says Dr. Bradley. “They often have serious family problems and anxiety disorders. Or they’ve had serious trauma. A girl I saw had been raped, and after that she decided she was going to be a male. If you didn’t pay attention to the trauma you’re not doing that kid a service.” These days, that eminently reasonable view is being challenged by people who believe that children’s sexual confusion should automatically be taken at face value. The clinic that Dr. Bradley helped to found – which does, in fact, support gender transition for a sizable minority of its patients – is being pilloried as transphobic. “Is CAMH trying to turn trans kids straight?” screamed a headline in NOW magazine. Under pressure from activists, CAMH has put its gender clinic under six-month review. And a new bill before the Ontario legislature, which is supported by Premier Kathleen Wynne, would explicitly bar the therapeutic approach taken by the clinic, wrongly equating it to the notorious “conversion” therapy that seeks to turn gay people straight. © Copyright 2015 The Globe and Mail Inc.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 20907 - Posted: 05.11.2015

|By Brian Bienkowski and Environmental Health News Male minnows exposed to a widely used diabetes drug ubiquitous in wastewater effluent had feminized reproductive parts and were smaller and less fertile, according to a new study. It is the first study to examine the drug metformin’s impact on fish endocrine systems and suggests that non-hormone pharmaceuticals pervasive in wastewater may cause reproductive and development problems in exposed fish. Metformin is largely used to combat insulin resistance associated with type-2 diabetes, which accounts for about 90 percent of all diagnosed U.S. adult diabetes cases. Researchers from the University of Wisconsin-Milwaukee exposed young fathead minnows to water containing levels of metformin commonly found in wastewater effluent. Eighty-four percent of 31 metformin-exposed male fish exhibited feminized reproductive organs. “Normally in females you see eggs developed in ova, in males, you see a different structure – producing tiny sperm instead of an egg structure,” said Rebecca Klaper, an associate professor at the University of Wisconsin-Milwaukee and senior author of the study. “We saw development of larger egg structures within the [male’s] testis.” © 2015 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20867 - Posted: 04.30.2015

Boer Deng Universities in the United States employ many more male scientists than female ones. Men are paid more, and in fields such as mathematics, engineering and economics, they hold the majority of top-level jobs. But in a sign of progress, a 13 April study finds that faculty members prefer female candidates for tenure-track jobs in science and engineering — by a ratio of two to one. That result, based on experiments involving hypothetical job seekers, held true regardless of the hirer’s gender, department, career status or university type, researchers report in the Proceedings of the National Academy of Sciences1. “We were shocked,” says Wendy Williams, a psychologist at Cornell University in Ithaca, New York, and a co-author of the study. With fellow Cornell psychologist Stephen Ceci, she surveyed 873 tenure-track faculty members in biology, psychology, economics and engineering at 371 US universities. One experiment presented participants with three hypothetical job candidates, of which two were identical except for their gender. Another experiment added descriptions of marital and parental status, to test whether underlying assumptions about gender choices affected hiring. “You don’t frequently see that level of attention and sophistication” in statistical analysis, says Robert Santos, vice-president of the American Statistical Association in Alexandria, Virginia. Nothing seemed to sway study participants’ preference for female job candidates. The authors say that this is interesting given their previous finding that a relatively low percentage of female PhDs in the social and biological sciences secure academic positions — in part because they are less likely than men to apply for these jobs. Other research suggests that in the physical sciences, women and men are just as likely to secure a tenure-track position within five years of earning a PhD. © 2015 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20792 - Posted: 04.14.2015

by Bethany Brookshire In 2011, a group of scientists “turned mice gay.” The only issue is, of course, they didn’t. Rather, Yi Rao and colleagues at Peking University in Beijing, China, showed that male mice will cheerfully mount both male and female mice, as long as their brains are deficient in one chemical messenger: serotonin. The paper, published in Nature, received plenty of media coverage. Now, two other research groups report seemingly opposite findings: Male mice with no serotonin in their brains still prefer female mice to males. The researchers contend that serotonin is about social communication and impulsive behaviors, not sex. Mounting behavior aside, sexual preference in mice is not about “turning mice gay.” It never has been. Instead, it’s about the role that a single chemical can play in animal behavior. And it’s about what, exactly, those behaviors really mean. Serotonin serves as a messenger between cells. It plays important roles in mood. Serotonin-related drugs are used to treat some forms of migraine. And of course, serotonin plays a role in the psychedelic effects of recreational drugs such as hallucinogens. So when the Peking University group set out to show serotonin’s role in sexual preference, they attacked it from several angles. They used mice that had been genetically engineered to lack the brain cells that usually produce serotonin. They used a chemical to deplete serotonin in the brains of normal mice. And they created another strain of mice that lacked the enzyme that makes serotonin in the brain. © Society for Science & the Public 2000 - 2015

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 20787 - Posted: 04.11.2015

Drawing on the widest survey of sexual behaviour since the Kinsey Report, David Spiegelhalter, in his book Sex By Numbers, answers key questions about our private lives. Here he reveals how Kinsey’s contested claim that 10% of us are gay is actually close to the mark For a single statistic to be the primary propaganda weapon for a radical political movement is unusual. Back in 1977, the US National Gay Task Force (NGTF) was invited into the White House to meet President Jimmy Carter’s representatives – a first for gay and lesbian groups. The NGTF’s most prominent campaigning slogan was “we are everywhere”, backed up by the memorable statistical claim that one in 10 of the US population was gay – this figure was deeply and passionately contested. So where did Bruce Voeller, a scientist who was a founder and first director of the NGTF, get this nice round 10% from? To find out, we have to delve back into Alfred Kinsey’s surveys in 1940s America, which were groundbreaking at the time but are now seen as archaic in their methods: he sought out respondents in prisons and the gay underworld, made friends with them and, over a cigarette, noted down their behaviours using an obscure code. Kinsey did not believe that sexual identity was fixed and simply categorised, and perhaps his most lasting contribution was his scale, still used today, in which individuals are rated from exclusively heterosexual to exclusively homosexual on a scale of 0 to 6. Kinsey’s headline finding was that “at least 37% of the male population has some homosexual experience between the beginning of adolescence and old age”, meaning physical contact to the point of orgasm. © 2015 Guardian News and Media Limited

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20760 - Posted: 04.06.2015

by Alison George Misguided notions about our sexual appetites are missing the bigger picture and making people unhappy, says Emily Nagoski Why is there no such thing as a sex drive? A drive is a motivational system to deal with life-or-death issues, like hunger or being too cold. You're not going to die if you don't have sex. But biologists might say that if you don't reproduce, that is a form of death Yes. That's the argument that was used when desire was being added to the way sexual dysfunctions were diagnosed in the 1970s, to justify the framing of sexual desire as a drive. But when it comes to sex, there just isn't any physical evidence of a drive mechanism. So what's going on? If sex is a drive then desire should be spontaneous, like a hunger. When you see a sexy person or have a stray sexy thought, it activates an internal craving or urge for sex. That's called "spontaneous desire". It feels like it comes out of the blue. But there is another way of experiencing desire which is also healthy and normal, called "responsive desire", where your interest only emerges in response to arousal. So, your partner comes over and starts kissing your neck and you're like, "oh, right, sex, that's a good idea". Do you think an absence of spontaneous desire is normal? Yes. If our metaphor for desire is hunger, if you are never hungry for food there will be dire consequences and that's clearly a disorder, right? That's a medical problem that needs to be fixed. But not experiencing spontaneous hunger for sex doesn't have dire consequences; it is not a medical disorder. I think the reason we expect everyone to have spontaneous desire is because that's how most men experience it. © Copyright Reed Business Information Ltd

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 20759 - Posted: 04.06.2015

By Anna Azvolinsky Differences in male and female rodent sexual behaviors are programmed during brain development, but how exactly this occurs is not clear. In the preoptic area (POA) of the brain—a region necessary for male sex behavior—the female phenotype results from repression of male-linked genes by DNA methylation, according to a study published today (March 30) in Nature Neuroscience. There is very little known about how the brain is masculinized—and even less about how it is feminized—even though the question has been studied for more than 50 years, said Bridget Nugent, study author and now a postdoctoral fellow at the University of Pennsylvania. These sex differences in the brain are programmed toward the end of fetal development, through to one week after birth in rodents. In males, testicular hormones drive masculinization of the brain; this was thought to occur by direct induction of gene expression by hormone-associated transcription factors. Because a feminized brain occurred in the absence of ovarian hormone signals, most researchers assumed that the female brain and behavior was a sort of default state, programmed during development when no male hormones are present. But the downstream mechanisms of how hormones can modify gene expression were not previously known. “This study reveals that DNA methylation plays an important role in regulating sexual differentiation,” said Nirao Shah, who also studies the neural basis for sex-specific behaviors at the University of California, San Francisco, but was not involved with the work. © 1986-2015 The Scientist

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20740 - Posted: 03.31.2015

By BONNIE ROCHMAN Reasons Why I Shouldn’t Have to Go Tonight: If I wanted to talk about it, I would. / It’s my body. / It’s a waste of time. / It’s a waste of money. / I know what I need to know. / It sounds pretty stupid to me. PLEASE DON’T MAKE ME GO. I DON’T WANT TO GO. The plea came from Leah Likin, a fifth grader. It was addressed to her mother, who had registered both of them for a two-part course on puberty called “For Girls Only.” The missive, which included additional objections, failed: Mother took daughter anyway. But Leah had plenty of company, peers who shared her resistance, their arms crossed, their eyes downcast. Last year, the course, which is split into sessions for preteen boys and girls and held mostly in and around Seattle, and also in the Bay Area, pulled in 14,000 attendees. They heard about it from their pediatricians, or through word of mouth. The creator of the course, Julie Metzger, has been trying for nearly three decades to turn what’s so often at best a blush-inducing experience — the “facts of life” talk — into a candid dialogue between parents and children. In the mid-1980s, she was a graduate student at the University of Washington School of Nursing when she reviewed survey data on how women had learned about menarche, or the onset of menstruation, for her master’s thesis. Most reported getting information from gym class or their mothers. “You can picture those conversations lasting from 10 seconds to 10 hours,” Metzger says. “And I thought, Wouldn’t it be interesting if you actually had a class where you sit with your parents and hear these things from someone? What if that class were fun and funny and interactive?” Metzger, who is 56 and vigorous, with flushed cheeks and blue eyes, says she has always been comfortable talking about sexuality; her father was a urologist, her mother a nurse. “Hand me a microphone,” she says. “I get so into this topic that I can make myself cry in front of the class, and it’s real.” © 2015 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20722 - Posted: 03.26.2015

By Camilla Turner It is one of life’s most enduring mysteries. A question that music, poetry, myth and legend has, for thousands of years, tried but failed to answer. However, we may now be a step closer to discovering what love is, thanks to a scientific study that has obtained the first empirical evidence of love-related alterations in the brain. A team of researchers from universities in China and New York used MRI scans to track the physical effects of love on the brain and has pieced together a “love map” of the human mind. The study found that several areas of the brain showed increased activity in those who were in love, including in the parts of the brain linked to reward and motivation. The researchers said their results shed light on the “underlying mechanisms of romantic love” and would pave the way for a brain scan that could act as a “love test”. Scientists recruited 100 students from Southwest University in Chongqing, China, who were divided into three groups according to their relationship status: an “in-love” group, comprised of those who were in love at the time; an “ended-love” group, who had recently ended loving relationships; and a “single” group, who had never been in love. Participants were told not to think of anything while their brains were scanned, so that researchers could monitor the differences between the brains of students in all three groups. © Copyright of Telegraph Media Group Limited 2015

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 20692 - Posted: 03.17.2015

by Penny Sarchet For some of us, it might have been behind the bikeshed. Not so the African cotton leafworm moth (Spodoptera littoralis), which can choose any one of a vast number of plant species to mate on. But these moths remember their first time, returning to the same species in search of other mates. In the wild, this moth feeds and mates on species from as many as 40 different plant families. That much choice means there's usually something available to eat, but selecting and remembering the best plants is tricky. So, recalling what you ate as a larva, or where you first copulated, may help narrow down which plants provide better quality food or are more likely to attract other potential mates. Magali Proffit and David Carrasco of the Swedish University of Agricultural Sciences in Alnarp and their colleagues have discovered that this moth's first mating experience shapes its future preferences. These moths have an innate preference for cotton plants over cabbage. But when the researchers made them mate for the first time on cabbage, the moths later showed an increased preference for mating or laying eggs on this plant. Further experiments revealed that moths didn't just favour plants they were familiar with, even in combination with a sex pheromone – mating had to be involved. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 20665 - Posted: 03.09.2015

By David Masci Potential Republican presidential candidate Dr. Ben Carson made news earlier this week when he said that being gay is a “choice,” but when it comes to public opinion, polls show that Americans remain divided over whether “nature” or “nurture” is ultimately responsible for sexual orientation. Four-in-ten Americans (42%) said that being gay or lesbian is “just the way some choose to live,” while a similar share (41%) said that “people are born gay or lesbian,” according to the most recent Pew Research Center poll on the issue, conducted in 2013. Fewer U.S. adults (8%) said that people are gay or lesbian due to their upbringing, while another one-in-ten (9%) said they didn’t know or declined to give a response. People with the most education are the most likely to say that gays and lesbians were born that way. Indeed, 58% of Americans with a postgraduate degree say that people are born gay or lesbian, compared with just 35% of those with a high school diploma or less. The percentage of all Americans who believe that people are born gay or lesbian has roughly doubled (from 20% to 41%) since 1985, when the question was asked in a Los Angeles Times survey. More than three decades of Gallup polls also show a considerable rise in the view that being gay or lesbian is a product of “nature” rather than “nurture.” But the most recent survey, in 2014, still finds that the nation remains split in its feelings on the origins of sexual orientation. Copyright 2015 Pew Research Center

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20658 - Posted: 03.07.2015

By Nicholas Weiler The grizzled wolf stalks from her rival’s den, her mouth caked with blood of the pups she has just killed. It’s a brutal form of birth control, but only the pack leader is allowed to keep her young. For her, this is a selfish strategy—only her pups will carry on the future of the pack. But it may also help the group keep its own numbers in check and avoid outstripping its resources. A new survey of mammalian carnivores worldwide proposes that many large predators have the ability to limit their own numbers. The results, though preliminary, could help explain how top predators keep the food chains beneath them in balance. Researchers often assume that predator numbers grow and shrink based on their food supply, says evolutionary biologist Blaire Van Valkenburgh of the University of California, Los Angeles, who was not involved in the new study. But several recent examples, including an analysis of the resurgent wolves of Yellowstone National Park, revealed that some large predators keep their own numbers in check. The new paper is the first to bring all the evidence together, Van Valkenburgh says, and presents a “convincing correlation.” Hunting and habitat loss are killing off big carnivores around the world, just as ecologists are discovering how important they are for keeping ecosystems in balance. Mountain lions sustain woodlands by hunting deer that would otherwise graze the landscape bare. Coyotes protect scrub-dwelling birds by keeping raccoons and foxes in line. Where top carnivores disappear, these smaller predators often explode in numbers, with potentially disastrous consequences for small birds and mammals. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20629 - Posted: 02.28.2015

Claire Ainsworth As a clinical geneticist, Paul James is accustomed to discussing some of the most delicate issues with his patients. But in early 2010, he found himself having a particularly awkward conversation about sex. A 46-year-old pregnant woman had visited his clinic at the Royal Melbourne Hospital in Australia to hear the results of an amniocentesis test to screen her baby's chromosomes for abnormalities. The baby was fine — but follow-up tests had revealed something astonishing about the mother. Her body was built of cells from two individuals, probably from twin embryos that had merged in her own mother's womb. And there was more. One set of cells carried two X chromosomes, the complement that typically makes a person female; the other had an X and a Y. Halfway through her fifth decade and pregnant with her third child, the woman learned for the first time that a large part of her body was chromosomally male1. “That's kind of science-fiction material for someone who just came in for an amniocentesis,” says James. Sex can be much more complicated than it at first seems. According to the simple scenario, the presence or absence of a Y chromosome is what counts: with it, you are male, and without it, you are female. But doctors have long known that some people straddle the boundary — their sex chromosomes say one thing, but their gonads (ovaries or testes) or sexual anatomy say another. Parents of children with these kinds of conditions — known as intersex conditions, or differences or disorders of sex development (DSDs) — often face difficult decisions about whether to bring up their child as a boy or a girl. Some researchers now say that as many as 1 person in 100 has some form of DSD2. © 2015 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20589 - Posted: 02.18.2015

By Anne Harding NEW YORK (Reuters Health) - Reduced sexual activity could cause a dip in testosterone levels in older men, new findings suggest. Among men 70 and older, those who reported a decline in sexual activity and desire over a two-year period also showed small declines in serum testosterone, Dr. David Handelsman of the ANZAC Research Institute at the University of Sydney and Concord Hospital in New South Wales, Australia, and colleagues found. They report their findings in the Journal of Clinical Endocrinology and Metabolism, online January 28. "Decline in serum testosterone is more likely to be the result rather than the cause of sexual dysfunction among older men who don't have reproductive disorders," Dr. Handelsman told Reuters Health by email. "The widely prevalent misinterpretation of this (as if the mild lowering of serum testosterone needs or might benefit from testosterone treatment) is one of the main drivers of the massive over-use of testosterone prescriptions in North America over the last decade." While declines in androgens and sexual function are both thought to be aging-related, Dr. Handelsman and his colleagues note in their report, the relationship between androgen levels and sexual function is not clear. To better understand the temporal and predictive relationship between androgen levels and sexual function, the researchers looked at 1,226 men participating in the Concord Health and Ageing in Men Project (CHAMP), measuring their levels of testosterone, dihydrotestosterone, estradiol, and estrone with liquid chromatography-tandem mass spectrometry. Men also reported on their sexual function using standardized questions, at baseline and two years later. © 2015 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 20559 - Posted: 02.07.2015

By Nicholas Weiler When you spend your days battling giant squid, it’s good to have friends you can rely on. New research from the Caribbean suggests that female sperm whales (Physeter macrocephalus, pictured) swim with favored companions and form long-term family allegiances. Sperm whales raise their young in communal family groups of about a dozen related females, but mapping out the giant animals' social lives in much detail has been a challenge for scientists. The whales spend 60% of their lives hunting squid hundreds of meters below the waves, and researchers can watch them interact for only a few minutes at a time when they surface to breathe. But a new multiyear study has created the most detailed map yet of sperm whales’ social networks. Between 2005 and 2010, scientists followed nine whale families along the west coast of the Caribbean island of Dominica and mapped their social relationships by counting which females spent the most time together at the surface between dives. As expected, whales mostly preferred to relax with family members, but within families they played favorites, frequently swimming with the same sister, auntie, or aged granny, the researchers report online this week in Animal Behaviour. The network diagram also revealed three pairs of families that mingled frequently over the years to socialize and share babysitting duty. One of these pairs has been fraternizing since 1995, according to data from other researchers, suggesting that such allegiances can last more than a decade. These observations suggest sperm whale families may be similar to the matriarchal clans of elephants, which also form long-lasting family bonds, the researchers say. Further research may determine whether allied families are actually distant cousins and investigate whether whales use signature songs to find their best friends. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20557 - Posted: 02.07.2015

Helen Fisher, a biological anthropologist at Rutgers University responds: Several years ago I embarked on a project to see if the seven-year itch really exists. I began by studying worldwide data on marriage and divorce and noticed that although the median duration of marriage was seven years, of the couples who divorced, most did so around their fourth year together (the “mode”). I also found that divorce occurred most frequently among couples at the height of their reproductive and parenting years—for men, ages 25 to 29, and for women, ages 20 to 24 and 25 to 29—and among those with one dependent child. To try to explain these findings, I began looking at patterns of pair bonding in birds and mammals. Although only about 3 percent of mammals form a monogamous bond to rear their young, about 90 percent of avian species team up. The reason: the individual that sits on the eggs until they hatch will starve unless fed by a mate. A few mammals are in the same predicament. Take the female fox: the vixen produces very thin milk and must feed her young almost constantly, so she relies on her partner to bring her food while she stays in the den to nurse. But here's the key: although some species of birds and mammals bond for life, more often they stay together only long enough to rear their young through infancy and early toddlerhood. When juvenile robins fly away from the nest or maturing foxes leave the den for the last time, their parents part ways as well. Humans retain traces of this natural reproductive pattern. In more contemporary hunter-gatherer societies, women tend to bear their children about four years apart. Moreover, in these societies after a child is weaned at around age four, the child often joins a playgroup and is cared for by older siblings and relatives. This care structure allows unhappy couples to break up and find a more suitable partner with whom to have more young. © 2015 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20496 - Posted: 01.20.2015

ByDavid Malakoff This bird might look like a holiday ornament, but it is actually a rare half-female, half-male northern cardinal (Cardinalis cardinalis, pictured with female plumage on the left and male plumage on the right) spotted a few years ago in Rock Island, Illinois. Researchers have long known such split-sex “gynandromorphs” exist in insects, crustaceans, and birds. But scientists rarely get to extensively study a gynandromorph in the wild; most published observations cover just a day or so. Observers got to follow this bird, however, for more than 40 days between December 2008 and March 2010. They documented how it interacted with other birds and even how it responded to recorded calls. The results suggest being half-and-half carries consequences: The cardinal didn’t appear to have a mate, and observers never heard it sing, the researchers report this month in The Wilson Journal of Ornithology. On the other hand, it wasn’t “subjected to any unusual agonistic behaviors from other cardinals,” according to the paper. Intriguingly, another gynandromorph cardinal sighted briefly in 1969 had the opposite plumage, they note: the male’s bright red plumes on the right, the drabber female feathers on the left. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20442 - Posted: 12.27.2014