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

By Ruth Williams Contrary to the longstanding belief that puberty is largely controlled by hormones, new evidence shows that sexual touch is a powerful puberty promoter. Touching prepubescent female rats’ genitals can cause the brain region that responds to such tactile stimuli to double in size and their bodies to show signs of puberty up to three weeks earlier than non-stimulated females, according to a report in PLOS Biology today (September 21). The study reveals the hitherto unappreciated influence of physical sexual experience on the young brain and body. “The dominant idea has been that puberty is controlled in the brain and in behavior by the release of hormones . . . but there has been a smattering of findings over the years that additional environmental influences effect puberty and the onset of sexual behavior,” says Dan Feldman of the University of California, Berkeley, who was not involved in the study. This new work “suggests that maybe this is true and that actual tactile stimulation can be something that accelerates the onset of puberty,” he adds. Puberty in mammals is a period of dramatic changes not just to the body, but to behavior and brain function. Indeed, one of the most pronounced changes, recently observed in both male and female rats, is the doubling in size of the genital cortex, which is a part of the larger somatosensory cortex—the brain area associated with physical sensation. © 1986-2017 The Scientist

Related chapters from BN8e: 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: 24102 - Posted: 09.23.2017

Katherine Ellen Foley, Youyou Zhou, Christopher Groskopf One way to understand long-term trends in medical and health research is to analyze the language used in massive bodies of literature produced in the different fields. To better understand the shifting focus of sex research since the field was established, we downloaded (with permission) 4,545 articles published in the Journal of Sex Research and the Archives of Sexual Behavior from 1970 to 2017, and tracked just over 1,000 of the most-used words in these studies. You can use the tool below to explore all of these words, and see how their frequency in the literature has changed over time. Beneath it, we’ve pulled out some of the most interesting trends we noticed and investigated possible explanations for why they’ve occurred. Humans have been having sex since as long as we’ve been on the planet, but it wasn’t until recently that we really started studying it. Sexology became a serious field just after World War II, starting with the work of Alfred Kinsey, a biologist at Indiana University, and later founder of the school’s Kinsey Institute, which today studies love and sexuality. Kinsey published his first book, Sexual Behavior in the Human Male, in 1948, followed by Sexual Behavior in the Human Female in 1953. In the 1960s, the field was further advanced by the work of lab mates (and lovers) William Masters and Victoria Johnson, who published the seminal Human Sexual Response in 1966.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24094 - Posted: 09.22.2017

By Alla Katsnelson, Men and women both transmit an increasing number of new mutations to their children as they age, according to a study published today in Nature1. The finding is based on an analysis of whole genomes from nearly 5,000 people. The increase in these ‘de novo’ mutations may explain why older parents are more likely to have a child with a condition such as autism. Men accumulate de novo mutations four times faster than women, the researchers found. However, in about 10 percent of the genome, mutations accumulate twice as quickly as elsewhere, and appear at an equal rate in both women and men. “The majority of the contribution still comes from the father, particularly when the father is in an older age range,” says lead investigator Kári Stefánsson, chief executive of deCODE Genetics. “But the mutation rate is not equal across the genome, so we have to make sure we do not generalize too much.” The new study builds on earlier work by deCODE Genetics, a company based in Reykjavik, Iceland. In 2012, the researchers reported that the rate at which people acquire mutations and pass them down to their children increases sharply with age in men but stays level in women. Those findings were based on whole-genome sequences from just 78 individuals and their parents. The findings provide one possible explanation for the increased risk of autism among children born to older parents. © 2017 Scientific American

Related chapters from BN8e: 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: 24091 - Posted: 09.21.2017

Amy Maxmen Male ducks respond to sexual competition by growing either an extra-long penis or a nub of flesh, a new study finds. The unusual phenomena occurred in two species studied: the lesser scaup (Aythya affinis) and the ruddy duck (Oxyura jamaicensis). It suggests that penis size — in line with many traits and behaviours meant to impress or allow impregnation of the opposite sex — involves a trade-off between the potential to reproduce and to survive. Patricia Brennan, an evolutionary biologist at Mount Holyoke College in South Hadley, Massachusetts, compared the penises of ducks kept in male–female pairs to those housed with multiple males per female. The findings are published in a study on 20 September in The Auk: Ornithological Advances1. “If they were alone with a female, the males just grew a normal-sized penis, but if there were other males around, they had the ability to change dramatically,” Brennan says. “So evolution must be acting on the ability to be plastic — the ability to invest only in what is needed in your current circumstance.” Because evolutionary success relies on reproduction, genitals are adapted to meet the varied circumstances that every animal faces. Some male ducks, for example, have penises in the shape of corkscrews to navigate the labyrinth-like vaginas of their female counterparts. An earlier study by Brennan found that females’ anatomy evolved to prevent access to undesirable males who force copulation2. To mate successfully with their chosen partners, Brennan says, female ducks assume a posture that allows males to enter them fully and deposit sperm near eggs. © 2017 Macmillan Publishers Limited,

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: 24086 - Posted: 09.21.2017

Cordelia Fine argues no; Joe Herbert says yes. Cordelia Fine: A common assumption, which I refer to as the ‘Testosterone Rex’ view, is that testosterone is a proximal tool of distal evolutionary processes, acting via the brain (prenatally, then from pubescence) to shape sex differences in behaviour that would have been differentially reproductively advantageous for men versus women in our ancestral past. Joe, as you put it in your book Testosterone: Sex, power and the will to win, ‘for [male] reproduction to be successful, testosterone has to act on many parts of the male to make him fit for the competitive world of male sexuality’. So, for example, males’ greater testosterone exposure predisposes them to be more risk-taking and competitive than females – an idea sometimes called on to help explain gender gaps in risky and competitive occupations, a category which happens to include most high-status and well-remunerated roles. So what exactly does testosterone do? Testosterone acts directly on the brain, but the circulating level of testosterone in the blood is just one part of a highly complex, multi-faceted system. What’s more, different species appear to tweak those system dials in different ways, enabling cross-species differences in relations between hormones and behaviour. What do we need to try to explain when it comes to humans? One important feature of sex differences in behaviour is that these are much smaller than sex differences in testosterone exposure (a lot of overlap between female and male populations, and very little, respectively). This casts serious doubt on the assumption that more testosterone means more masculinity, and that men must inevitably be more masculine because they have higher absolute levels of testosterone on average. © Copyright 2000-2017 The British Psychological Society

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24085 - Posted: 09.20.2017

Grant Tomkinson and Makailah Dyer Examine your fingers. Which is longer? Is it the index finger (the finger you use to point with — technically the second digit, or 2D, counting the thumb), or the ring finger (the fourth digit, or 4D)? The relative length of the index and ring fingers is known as the digit ratio or the 2D:4D. For example, if your index finger is 2.9 inches (or 7.4 cm) long, and your ring finger is 3.1 inches (or 7.9 cm) long, your digit ratio is 0.935 (i.e., 2.9/3.1 or 7.4/7.9). Males typically have lower digit ratios (the ring finger in males is typically longer than the index finger) than females (the fingers are about the same length in females). The ratio does not change much with age. There is some indirect evidence that the digit ratio is determined during early fetal development — as early as the second trimester of pregnancy — by the balance between the steroid hormones testosterone and estrogen. The developing ring finger has a high number of receptors for testosterone: the more testosterone the fetus produces, the longer the ring finger, and so the lower the digit ratio. Our research team wanted to take this finger research a step further: could the differences predict athletic ability, and, if so, how?

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: 24062 - Posted: 09.14.2017

Reza Ziai In recent years, many individuals on the political left have been earnestly conveying the message that what a person is attracted to (i.e. mate preference) is entirely constructed by the environment. Their reasons for doing so seem sincere. Take for example, the oft-cited connection between the media’s portrayal of female standards of beauty and eating disorders like anorexia and bulimia. To postmodernists, since standards of attraction are seen as being environmentally produced, the media’s “stereotypical” portrayal of female beauty is also seen as being environmentally produced, sexist, and therefore, unjustifiable. Postmodernism (see also Critical Theory and The Frankfurt School) combats this perceived bigotry by attempting to justify the need to enforce changes in the status quo. Most notably in recent news, many liberal arts students have attempted to deplatform speakers like Charles Murray, Christina Hoff Sommers, and Ayaan Hirsi Ali from speaking on their campuses. Limiting free speech has been just one way that postmodernism and people on the far-left have tried to control the environment. Reforms (sometimes mandatory ones) have been seen in pronoun usage, soft drink sizes, the media, children’s toys, social attitudes, etc. Their idea is that since the environment (and not biology) affects our attitude, if you change the environment, you change the person, and thus, society is improved. By minimizing or ignoring the role that biology has on human nature, postmodernists can effectively blame all of the ills of the modern world on poorly designed laws, U.S. foreign policy, or Western cultural attitudes. Those who dissent from their view can be denounced as bigots and cast aside.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24061 - Posted: 09.14.2017