Links for Keyword: Sexual Behavior

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 1477

Sara Reardon When it comes to lab mice and antidepressants, it's complicated. Mouse experiments with the popular club drug ketamine may be skewed by the sex of the researcher performing them, a study suggests. The findings, presented on 14 November at the Society for Neuroscience (SfN) meeting in Washington DC, only deepen the mystery of how ketamine, which has powerful mood-lifting properties, interacts with the brain. They also raise questions about the reproducibility of behavioural experiments in mice. Ketamine is best known as a psychoactive recreational drug. But it has caught psychiatrists’ interest because of its potential to treat depression within hours. It’s unclear exactly how the drug works, however, and many researchers are using animal models to suss out the mechanism. Polymnia Georgiou, a neuroscientist at the University of Maryland in Baltimore, is one of them. In 2015, a male colleague asked her to run some experiments for him while he was out of town, including a standard way of testing antidepressants called the forced-swim test. In this assay, researchers inject healthy mice with a drug, place them into a tank of water and measure how long they swim before they give up and wait for someone to rescue them. Antidepressants can cause healthy mice to swim for longer than their untreated counterparts, which is what Georgiou’s male colleague found during his experiments using ketamine. © 2017 Macmillan Publishers Limited

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 24341 - Posted: 11.20.2017

By Jessica Hamzelou Heavy drinkers and abstainers don’t make the best couples. In humans, one partner that drinks more than the other is thought to be a recipe for a breakup. The same appears to be true for prairie voles, one of the only other mammals known to form long-term monogamous relationships. The finding suggests the link between alcohol consumption and relationship failure may have a biological basis, say the researchers. “There is an increase in divorce in couples in which there is discordant drinking,” says Andrey Ryabinin at Oregon Health and Science University. Money is thought to play a role, but nobody knows the precise causes because a randomised study in people would be unethical. “You can’t tell people to start drinking,” he says. To explore the question in animals, Ryabinin and his colleague Andre Walcott turned to prairie voles: the only rodents known to form lasting, monogamous relationships. “They maintain the same pair bond for their entire lives,” says Ryabinin. Unlike other rodents, both partners take care of offspring. And rather than leaving the nest as soon as they reach adolescence, the young stay and look after their younger siblings. Prairie voles are also the only rodents known to willingly drink alcohol. While mice and rats avoid the stuff, prairie voles prefer it to water, says Ryabinin. Voles on the sauce Ryabinin has previously shown that alcohol consumption affects prairie vole relationships. When given a choice between their partner and a new female, male voles that drank more alcohol were more likely to go and mate with the new female than those that abstained. Alcohol seemed to have the opposite effect in females – those that drank more alcohol more strongly preferred their original partner. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 8: Hormones and Sex
Link ID: 24325 - Posted: 11.15.2017

By Giorgia Guglielmi The popular claim that women in their fertile days prefer men with more masculine faces may not be true. That’s the conclusion of the largest study to analyze how sex hormones influence women’s preference for men’s faces. Researchers first created 10 prototype male faces by averaging 50 photos of young white men. Then, they tweaked the prototype faces to create a more masculine and a more feminine version of each (pictured, masculine version on the left, feminine version on the right). Finally, the scientists asked nearly 600 heterosexual women to look at these photos and rate men’s attractiveness for either a fling or a long-term relationship. The women also provided saliva samples, which the researchers tested for sex hormones such as estradiol and testosterone. Hormone levels were not significantly related to women’s preference for manly faces, the team reports on the preprint server bioRxiv. The researchers also didn’t find evidence that women using the birth control pill prefer more feminine faces, as had been suggested. However, women did prefer masculine faces over feminine ones, especially for short-term relationships. This could be because manly traits, like a large jaw and jutting cheekbones, signal good heritable characteristics, such as a strong immune system, but have also been linked to people that are less willing to invest time in personal relationships, the scientists say. © 2017 American Association for the Advancement of Scien

Related chapters from BN8e: 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: 24286 - Posted: 11.04.2017

By NICHOLAS ST. FLEUR Swallowed by a sinkhole. Washed away by a mudflow. Drowned after falling through thin ice. These are the fates that many unlucky mammoths suffered in Siberia thousands of years ago. Their well-preserved fossils have provided paleobiologists with insight into their prehistoric lives. Now, after performing a genetic analysis on the remains from the furry victims of natural traps, a team of scientists made a striking discovery: Most were male. “In many species, males tend to do somewhat stupid things that end up getting them killed in silly ways, and it appears that may have been true for mammoths also,” said Love Dalén, an evolutionary biologist from the Swedish Museum of Natural History. In a study published Thursday in the journal Current Biology, he and his colleagues analyzed DNA from nearly 100 mammoth bones, teeth and tusks, and found that about two-thirds came from males. They speculate the reason for the skewed sex-ratio may have to do with the risky behavior that young males take after leaving the protection of their mothers to live on their own. “Old females are very knowledgeable, they know best,” he said. The finding was an accident, according to Patrícia Pečnerová, a doctoral student at Stockholm University and lead author on the study. It came while she was entering data for a different project on mammoth genetics. “While filling this in on the spreadsheet we saw that there were too many males, more than there should be,” she said. “We were really surprised to see there were more than twice as many males as females because there was no previous research or indication that that should be the case.” The 98 specimens that the team had analyzed came from across the northern part of Siberia and had been collected over the course of four decades. The oldest were more than 60,000 years old, and the youngest, a specimen known as “Lonely Boy,” was about 4,000 years old. The genetic data did not provide insight into how old the mammoths were when they died, only their sex. © 2017 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24285 - Posted: 11.03.2017

By Andy Coghlan For the first time, female dark-eyed juncos have been found to burst into song in the wild. Although many female tropical birds sing, singing females are rare among northern, temperate songbirds. However, the behaviour is now becoming more common, and climate change may mean it becomes even more widespread. Dustin Reichard of Ohio Wesleyan University knew that female dark-eyed juncos (Junco hyemalis) sometimes sang in captivity, but only after being injected with testosterone. To find out if they sang in the wild, he and his colleagues goaded them by placing a live, caged female in their territories. The researchers also played recordings of a soft trill that females make when they are receptive to mating. In all, 17 females, along with 25 males, interacted with the caged females. Half the females dived and lunged at them, and a minority also performed aggressive tail-spreads not normally seen in females. Three of the females sang songs similar to those of males. “The context in which the songs were observed – responding to a female intruder – suggests these songs have an aggressive, territorial function,” says Reichard. “But we can’t say whether female song is specific to female intruders without also measuring their response to male intruders.” The females also reacted badly to attempts by males to woo the intruder female, both with song and other courtship behaviours such as puffing up their feathers and spreading their tails. Dark-eyed juncos are monogamous, and the females sought to keep their mates faithful by aggressively chasing them away from the rival female. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 24255 - Posted: 10.28.2017

By Aylin Woodward Not in my backyard. Territorial songbirds in New Zealand reacted more aggressively towards males encroaching on their territory if those rivals sang more complicated songs. The tui birds perceived these snappy singers as greater territorial threats than their simpler singing counterparts. Birdsong has two main functions: defending a territory and attracting a mate, says Samuel Hill at Massey University in Auckland, New Zealand. For tui (Prosthemadera novaeseelandiae), territory defence is a key concern. “There are flowering and fruiting trees year round in New Zealand, so the tui always have resources to defend,” says Hill. This explains why “they natter all year round”. Warbling away takes lots of energy, so males may be showing off their physical endurance to females. Long and complicated songs may also be a sign of skill, as to sing them birds must use superfast vocal muscles to control rapid acoustic changes. In other songbirds, like zebra finches, females prefer males that sing harder songs. This hasn’t been tested in tui, but Hill says the complexity of a male’s song is probably a proxy for more relevant measures of his quality, like body condition and cognitive ability. If that is so, Hill reasoned, breeding male tui would take umbrage at potential rivals singing at the edge of their territory, particularly if their songs were complex and they were therefore strong competitors. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 24227 - Posted: 10.21.2017

By Helen Thomson THE most detailed study ever of brain activity during orgasm has discovered why climaxing makes women feel less pain, and shown that “switching off” isn’t necessary. Nan Wise at Rutgers University, New Jersey, and her colleagues recruited 10 women to lie in a functional MRI scanner and stimulate themselves to orgasm. They then repeated the experiment but had the volunteers’ partners stimulate them. The team was able to follow brain activity in 20-second intervals to see what happens just before, during and after orgasm. Back in 1985, Wise’s colleagues Beverly Whipple and Barry Komisaruk, both at Rutgers, discovered that during self-stimulation and orgasm, women’s ability to withstand painful finger squeezing increased by 75 per cent, and the level of squeezing at which women noticed the pain more than doubled. Now Wise’s team has explained why. At the point of orgasm, the brain’s dorsal raphe nucleus area becomes more active. This region plays a role in controlling the release of serotonin, which can act as an analgesic, dampening the sensation of pain. Her team also saw a burst of activity in the nucleus cuneiformis, which is a part of systems thought to help us control pain through thought alone. “Together, this activity – at least in part – seems to account for the pain attenuating effect of the female orgasm,” says Wise. It’s not yet clear why pain sensation decreases during orgasm, or if men experience the same phenomenon. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 14: Attention and Consciousness
Link ID: 24221 - Posted: 10.20.2017

By Karen Weintraub Each time health care workers grab a pint of blood for an emergency transfusion, they make sure the donor and recipient have compatible blood types. But they do not pay attention to the donor’s sex. A new study raises questions as to whether that should change. In the first large study to look at how blood transfusions from previously pregnant women affect recipients’ health, researchers discovered men under 50 were 1.5 times more likely to die in the three years following a transfusion if they received a red blood cell transfusion from a woman donor who had ever been pregnant. This amounts to a 2 percent increase in overall mortality each year. Female recipients, however, did not appear to face an elevated risk. The study of more than 42,000 transfusion patients in the Netherlands was published Tuesday in JAMA The Journal of the American Medical Association. The American Red Cross and the researchers themselves were quick to say the study is not definitive enough to change the current practice of matching red blood cell donors to recipients. But if this explosive finding is confirmed with future studies, it could transform the way blood is matched—and it would suggest millions of transfusion patients worldwide have died prematurely. “If this turns out to be the truth, it’s both biologically interesting and extremely clinically relevant,” says Gustaf Edgren, an expert who was not involved in the study but co-wrote an editorial about it. “We certainly need to find out what’s going on.” Edgren, an associate professor of epidemiology at the Karolinska Institute and a hematologist at Karolinska University Hospital in Stockholm, says his own research suggests the donor’s sex makes no difference to the transfused patient. “Our data is really not compatible with this finding,” he says. © 2017 Scientific American

Related chapters from BN8e: 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: 24214 - Posted: 10.19.2017

By John Horgan To help my students appreciate how science reflects cultural prejudices, I often cite examples from psychiatry. The Diagnostic and Statistical Manual of Mental Disorders, or DSM, which the American Psychiatric Association compiles as a guide to diagnosis and treatment of illness, listed homosexuality as a "sociopathic personality disturbance” in the DSM-I, published in 1952, and as a “sexual deviation” in the DSM-II, published in 1968 (see Further Reading). Homosexuality has been treated with lobotomies, chemical castration, electrical shocks and nausea-inducing drugs as well as psychotherapy. I then tell my students about a bizarre gay-conversion experiment carried out in 1970 by a leading brain-implant researcher, Dr. Robert G. Heath of Tulane University in New Orleans. I mentioned Heath in my recent profile of Jose Delgado, a pioneer in the use of brain implants to manipulate patients’ minds and behavior. Heath was arguably even more ambitious than Delgado in his experiments, and he was not a fringe figure. He had degrees in psychiatry and neurology from Columbia and the University of Pennsylvania. n 1949 he founded Tulane’s department of psychiatry and neurology. He oversaw the department until 1980 but continued working into the 1990s. In his 1996 book Exploring the Mind-Brain Relationship, he reviews his career and speculates that someday “biological methods” might make it possible “for man to live in harmony with his fellow man.” © 2017 Scientific American,

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24198 - Posted: 10.16.2017

Jo Marchant Male scientists are more likely to share their published work than are women — but only with other men, a study of hundreds of researchers has found. Humans are generally considered to be a highly cooperative species, says Jorg Massen, a cognitive biologist at the University of Vienna. But most of the evidence for that assumption comes from artificial situations such as computerized cooperation tasks. “I wanted to test human prosociality in an everyday situation,” he says. So he chose one of the most competitive situations he could think of: his own field of research psychology. To investigate cooperation among psychologists, Massen turned his fellow researchers into guinea pigs. He and his colleagues e-mailed nearly 300 researchers and asked them to share either a PDF of one of their latest papers, or some raw data (pretending that they wanted to include it in a meta-analysis). The results were published in Scientific Reports on 10 October1. In general, the scientists contacted were highly cooperative, with almost 80% willing to share a PDF and almost 60% willing to send raw data. “I was surprised,” says Massen. “Humans are prosocial even in this competitive field.” Even more unexpected, however, was a strong gender difference in how the scientists responded to the request for help. Massen and his colleagues had wondered whether men might respond more favourably to women, or vice versa. In fact, men were more likely to share, but only with other men. A male–male request was 15% more likely to be granted than any other gender combination. © 2017 Macmillan Publishers Limited,

Related chapters from BN8e: 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: 24188 - Posted: 10.13.2017

By Helen Thomson The most detailed study yet of orgasm brain activity has discovered why climaxing makes women feel less pain and shown that ‘switching off’ isn’t necessary. It’s not easy to study the brain during orgasm. “A brain scanner like fMRI is the least sexy place in the world,” says Nan Wise at Rutgers University in Newark, New Jersey. “It’s noisy, claustrophobic and cold.” There is also the problem of keeping your head still – movement of little more than the width of a pound coin can render data useless. Despite these hurdles, Wise and her colleagues recruited 10 heterosexual women to lay in a fMRI scanner and stimulate themselves to orgasm. They then repeated the experiment but had their partners stimulate them. Wise’s custom-fitted head stabiliser allowed the team to follow brain activity in 20 second intervals to see what happens just before, during, and after an orgasm. Pain relief Back in 1985, Wise’s colleagues Beverly Whipple and Barry Komisaruk, both at Rutgers, discovered that, during self-stimulation and orgasm, women are less likely to notice painful squeezing of a finger, and can tolerate more of this pain. They found that women’s ability to withstand pain increased by 75 per cent during stimulation, while the level of squeezing at which women noticed the pain more than doubled. Now Wise’s team has explained why. At the point of orgasm, the dorsal raphe nucleus area of the brain becomes more active. This region plays a role in controlling the release of the brain chemical serotonin, which can act as an analgesic, dampening the sensation of pain. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 14: Attention and Consciousness
Link ID: 24187 - Posted: 10.13.2017

Dean Burnett Another day, another powerful man embroiled in a sinister sexual scandal decades in the making. This time it’s powerful Hollywood figure Harvey Weinstein. The moral, ethical and political aspects of this whole mess have been covered extensively elsewhere, and will no doubt continue to be so over the coming days and weeks. However, recent reports suggest that Weinstein has checked himself into a European rehab clinic for sex addiction. This has been met with some not-inconsiderable cynicism, but, even if it is true, wondering whether Weinstein is a sex addict overlooks a more fundamental question: is anyone a sex addict? Because that diagnosis, as commonplace as it may seem, is far from established psychiatric fact. Many people do believe sex addiction is real and serious problem, while others dismiss it outright. Despite it being a widely-used term, it doesn’t feature in either the DSM-V or ICD-10, the two main sources for officially-recognised psychiatric disorders the world over (although that’s not a guarantee of consensus either). How can something that seems, to many, to be so straightforward be the subject of so wide a debate? We all know what sex is, we all know what addiction is, what’s the issue? First, sex is a fundamental drive inherent in practically every human. A large percentage of our brain’s systems are responsible for or at least involved in it. An underlying need to seek out sex and an ability to engage in it as and when we like is a remarkably human trait (well, maybe bonobos too). This has many significant consequences for how our societies and cultures work, but one relevant problem is, at what point do you want sex too much? Because that’s not an easy thing to pin down. Those who don’t support the idea of sex addiction often argue that it’s another attempt to pin a clinical diagnosis on “normal” human behaviour (like the dispute around grief in the DSM-V). Some even compare it to gay conversion therapy, in how it medicalises and tries to undo what is an expression of human sexuality. © 2017 Guardian News and Media Limited

Related chapters from BN8e: 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: 24185 - Posted: 10.12.2017

Hannah Devlin Forget negotiations over who takes out the bin, new research suggests that the ideal home temperature is the vexed question most likely to split households down gender lines. A study found that one third of couples dispute this issue and that four in 10 women covertly turn up the heating behind their partner’s back. The research, which was sponsored by Corgi Homeplan, a company that installs and maintains boilers and thermostats, probably falls short of the rigours of peer-reviewed science. However, there is strong evidence to back up the idea that women are more sensitive to the cold. A 2015 study by Dutch scientists, for instance, found that women are comfortable at a temperature 2.5C warmer than men, typically between 24-25C. Men and women have roughly the same core body temperature, at over 37C; in fact, some studies have found the female core body temperature is slightly higher. However, our perception of temperature depends more on skin temperature, which, for women, tends to be lower. One study reported that the average temperature of women’s hands exposed to cold was nearly 3C degrees lower than that observed in men. The female hormone oestrogen contributes to this because it slightly thickens the blood, reducing the flow to capillaries that supply the body’s extremities. This means that, in women, blood flow to the tips of fingers and toes tends to shut off more readily when it is cold. Research has shown that women tend to feel colder around ovulation, when estrogen levels are high. © 2017 Guardian News and Media Limited

Related chapters from BN8e: 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: 24181 - Posted: 10.12.2017

By Lise Eliot As efforts to improve diversity in science, technology, engineering and maths accelerate, so the voices of those who question those efforts seem to get louder. They say the STEM gender gap has its roots in innate biology, that men are inherently better at or more interested in these subjects. One of their favourite supporting arguments is that differences in male and female brains are clearly influenced by prenatal testosterone. Is there any truth in this claim? As a biologist, I appreciate that genes and hormones are important in brain and behavioural development. But my research over the past 20 years indicates that the differences between boys’ and girls’ brains are subtle, and that testosterone isn’t a key determinant of interest in or aptitude for STEM subjects. First, in spite of decades of MRI studies, there is little evidence that boys’ higher prenatal exposure to testosterone affects their brain structure or function. Most recently, the two largest studies of the brains of newborns found no difference between boys’ and girls’ functional brain networks and that prenatal testosterone exposure had a surprisingly weak effect on specific neural structures. Even the most clear-cut gender difference in infant behaviour – verbal ability, which develops more slowly in boys – hasn’t been linked to prenatal testosterone. Of course, male and female brains are different, but not in the way the diversity critics claim. At birth, boys’ brains are 6 per cent larger on average than those of girls, but boys’ birthweight is also typically about 7 per cent heavier. This difference in brain size has long been known to parallel sex differences in height and weight across the lifespan. Every other organ, such as the heart and kidneys, is also some 15 per cent larger in males. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24172 - Posted: 10.11.2017

By Josh Gabbatiss Some female dolphins have evolved a secret weapon in their sexual arms race with males: vaginas that protect them from fertilisation by unwelcome partners. Penises come in a wide variety of shapes and sizes, especially in dolphins and other cetaceans. That seems to imply a similar diversity in vaginas, but Dara Orbach of Dalhousie University, Canada, says there is “a huge lag” in our understanding of female genitalia. That is partly because it is tricky to visualise vaginal structure. To overcome this problem, Orbach has created silicone moulds of cetaceans’ vaginas, revealing complex folds and spirals. “There’s this unparalleled level of vaginal diversity that we had no idea existed before,” Orbach says. Similarly complex vaginal structures are found in several species of duck. Orbach’s collaborator Patricia Brennan of Mount Holyoke College, Massachusetts, has previously found evidence that duck vaginas have evolved to make it harder for males to force copulation. So Orbach wondered if female cetaceans’ unusual vaginas had also evolved to keep out unwanted sperm. Orbach, Brennan and their colleagues obtained genitals from marine mammals that had died of natural causes: common and bottlenose dolphins, common porpoises and common seals. They inflated the males’ penises with saline to see how they looked when they were erect, and compared them with the vaginal moulds. They also took CT scans of penises inserted into the corresponding vaginas, to determine whether they fitted in easily and the best positions. © Copyright New Scientist Ltd.

Related chapters from BN8e: 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: 24170 - Posted: 10.11.2017

Nicola Davis “Woman seems to differ from man in mental disposition, chiefly in her greater tenderness and less selfishness,” wrote Charles Darwin in The Descent of Man. Now scientists claim that the stereotype is supported by evidence that the brain’s reward system may be geared towards more “prosocial” behaviour in women. “It was known that women and men behave differently, but it was not known why, or how this comes about in the brain,” said Philippe Tobler, associate professor of neuroeconomics and social neuroscience at the University of Zurich, and co-author of the research. The team note it is not clear whether the gender differences they see in the brain’s reward system are in any way “innate”, or whether they are the result of social pressures, but in short: women seem to get more of a chemical reward for being generous than men do. “It is known that girls receive different kinds of feedback than boys for being prosocial,” said Tobler. “It is perfectly conceivable that [the root of the differences here are] only cultural – we simply don’t know.” Writing in the journal Nature Human Behaviour, Tobler and colleagues from Germany, Switzerland and the Netherlands carried out two studies looking at whether dopamine, a neurotransmitter that plays a crucial role in the brain’s reward system, is linked to different social behaviours in men and women. In the first, a group of 56 men and women were randomly allocated to two groups, and either given a placebo or amisulpride – a drug that blocks the action of dopamine in the brain. Neither the scientists nor the participants knew which pill was taken. © 2017 Guardian News and Media Limited

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24169 - Posted: 10.10.2017

By HEATHER MURPHY Michal Kosinski felt he had good reason to teach a machine to detect sexual orientation. An Israeli start-up had started hawking a service that predicted terrorist proclivities based on facial analysis. Chinese companies were developing facial recognition software not only to catch known criminals — but also to help the government predict who might break the law next. And all around Silicon Valley, where Dr. Kosinski works as a professor at Stanford Graduate School of Business, entrepreneurs were talking about faces as if they were gold waiting to be mined. Few seemed concerned. So to call attention to the privacy risks, he decided to show that it was possible to use facial recognition analysis to detect something intimate, something “people should have full rights to keep private.” After considering atheism, he settled on sexual orientation. Whether he has now created “A.I. gaydar,” and whether that’s even an ethical line of inquiry, has been hotly debated over the past several weeks, ever since a draft of his study was posted online. Presented with photos of gay men and straight men, a computer program was able to determine which of the two was gay with 81 percent accuracy, according to Dr. Kosinski and co-author Yilun Wang’s paper. The backlash has been fierce. “I imagined I’d raise the alarm,” Dr. Kosinski said in an interview. “Now I’m paying the price.” He’d just had a meeting with campus police “because of the number of death threats.” © 2017 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24167 - Posted: 10.10.2017

Josh Dehaas: Earlier this month, Stanford University researchers released a study that showed artificial intelligence can be used to predict whether a person is gay. Given a single image, computers used an algorithm to correctly distinguish between gay and heterosexual men in 81 per cent of cases, and in 71 per cent of cases for women. Humans could also pick out gay people more often then not: 61 per cent for men, and 54 per cent for women. The researchers said their results offer support for the theory that prenatal hormones, which influence how we look, also influence sexual orientation. For gay people like me, the study simply seemed to confirm what we already know: sexual orientation is fixed at birth. You might think that LGBT activists would embrace this new study as yet more evidence that could be used to persuade religious conservatives or other skeptics that being gay isn’t a moral failing. Their response was, in fact, the opposite. The Human Rights Campaign (HRC), a huge lobby group in the U.S., called the study “junk science.” The Gay & Lesbian Alliance Against Defamation (GLAAD) chided the few media outlets who dared to write about it, criticizing the methodology, including the researchers’ decision to use all Caucasian photos (which they presumably did to ensure the computers were detecting facial differences related to sexuality rather than race), and their exclusion of transgender and bisexual people (a flaw, but not a huge one). A couple of professors joined the pile on, suggesting that it is unethical to so much as study whether machines can predict a person’s sexuality, because it could be used by anti-gay governments to further target and oppress people. That is a frightening concern in a world where being gay is illegal in more than 70 countries, but it ignores the possibility that this kind of research might actually change how oppressive regimes think about these issues in the long term. As University of Lethbridge sexuality researcher Paul Vasey points out, “the more people think homosexuality is biological the more tolerant they are.” And intolerance persists, even here in North America. Roy Moore, the man who just won a primary runoff to become the Republican nominee for senator in Alabama, wrote in 2002 (when he was the chief justice of that state’s Supreme Court) that “homosexual behavior is a crime against nature, an inherent evil, and an act so heinous that it defies one’s ability to describe it.” In 2005, he said that “homosexuality should be © 2017 National Post,

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24128 - Posted: 09.30.2017

Robin Dunbar, Angela Saini, Ben Garrod, Adam Rutherford We were all gearing up for the summer of love when, in 1967, Desmond Morris’s The Naked Ape took us by storm. Its pitch was that humans really were just apes, and much of our behaviour could be understood in terms of animal behaviour and its evolution. Yes, we were naked and bipedal, but beneath the veneer of culture lurked an ancestral avatar. With his zoologist’s training (he had had a distinguished career studying the behaviour of fishes and birds at Oxford University as part of the leading international group in this field), he gave us a picture of who we really are. In the laid-back, blue-smoke atmosphere of the hippy era, the book struck a chord with the wider public – if for no other reason than that, in the decade of free love, it asserted that humans had the largest penis for body size of all the primates. The early 1960s had seen the first field studies of monkeys and apes, and a corresponding interest in human evolution and the biology of contemporary hunter-gatherers. Morris latched on to the fact that the sexual division of labour (the men away hunting, the women at home gathering) necessitated some mechanism to ensure the sexual loyalty of one’s mate – this was the era of free love, after all. He suggested that becoming naked and developing new erogenous zones (notably, ear lobes and breasts), not to mention face-to-face copulation (all but unknown among animals), helped to maintain the couple’s loyalty to each other. Morris’s central claim, that much of our behaviour can be understood in the context of animal behaviour, has surely stood the test of time, even if some of the details haven’t. Our hairlessness (at around 2m years ago) long predates the rise of pair bonds (a mere 200,000 years ago). It owes its origins to the capacity to sweat copiously (another uniquely human trait) in order to allow us to travel longer distances across sunny savannahs. But he is probably still right that those bits of human behaviour that enhance sexual experience function to promote pair bonds – even if pair bonds are not lifelong in the way that many then assumed. © 2017 Guardian News and Media Limited

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24107 - Posted: 09.25.2017

Bruce Y. Lee , Contributor Sorry SpongeBob Square Pants. You too Yoda. Some people are on to your wandering eyes. According to a new study published in the journal Archives of Sexual Behavior, men with a high facial width-to-height ratio (FWHR) may have higher sex drives and be more likely to cheat. So if you believe this study, watch out for those partners with wide, microwave oven-shaped faces...right? Before you start bringing a tape measure to your dates or blaming your partner for having such a wide face, let's take a closer look at the study, which was actually a combination of two studies. Researchers from Nipissing University (Steven Arnocky, Justin M. Carré, Triana Ortiz, and Nicole Marley), Simon Fraser University (Brian M. Bird), Northern Ontario School of Medicine (Benjamin J. P. Moreau), and the University of Ottawa (Tracy Vaillancourt) conducted the studies. The first study recruited 145 heterosexual students, 69 men and 76 females, who were currently in romantic relationships, from a mid-sized Canadian university, measured the dimensions of their faces from facial photographs, and had them complete sexual drive questionnaires. The researchers calculated the FWHR by dividing the bi-zygomatic width of the face by the height of the upper face (i.e., the distance between the upper lip and brow) and found that both men and women who had higher FWHR's were more likely to report higher sex drives. The second study recruited 314 students (43% men) from a different small Canadian university, which was about 350 km away from the university where the first study was conducted. In addition to measuring the participant's FWHRs on facial photographs and sex drive via questionnaires, the researchers also had the participants complete questionnaires designed to measure attitudes towards and likelihood of infidelity or cheating.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24106 - Posted: 09.25.2017