Chapter 8. Hormones and Sex

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


Links 1 - 20 of 3073

By Matt Richtel The number of women drinking dangerous amounts of alcohol is rising sharply in the United States. That finding was among several troubling conclusions in an analysis of death certificates published Friday by the National Institute on Alcohol Abuse and Alcoholism. The analysis looked at deaths nationwide each year from 1999 through 2017 that were reported as being caused at least partly by alcohol, including acute overdose, its chronic use, or in combination with other drugs. The death rate tied to alcohol rose 51 percent overall in that time period, taking into account population growth. Most noteworthy to researchers was that the rate of deaths among women rose much more sharply, up 85 percent. In sheer numbers, 18,072 women died from alcohol in 2017, according to death certificates, compared with 7,662 in 1999. “More women are drinking and they are drinking more,” said Patricia Powell, deputy director of the alcohol institute, which is a division of the National Institutes of Health. Still, far more men than women die from alcohol-related illnesses, the study showed. In 2017, alcohol played a role in the deaths of 72,558 men, compared to 35,914 in 1999, a 35 percent increase when population growth is factored in. Like much research of its kind, the findings do not alone offer the reasons behind the increase in alcohol deaths. In fact, the data is confounding in some respects, notably because teenage drinking overall has been dropping for years, a shift that researchers have heralded as a sign that alcohol has been successfully demonized as a serious health risk. Experts said that the new findings could partly reflect the fact that baby boomers are aging and the health effects of chronic alcohol use have become more apparent. The increase in deaths might also reflect the increase in opioid-related deaths, which in many cases can involve alcohol as well, and that would be reflected on death certificates. © 2020 The New York Times Company

Keyword: Drug Abuse; Sexual Behavior
Link ID: 26955 - Posted: 01.13.2020

Emily Makowski Bruce McEwen, a neuroendocrinologist at Rockefeller University, died January 2 after a brief illness. He was 81 years old. McEwen is best known for his research on how stress hormones can reconfigure neural connections in the brain, according to a university statement. In 1968, McEwen and his colleagues discovered that the rat hippocampus is affected by the hormone cortisol, sparking further research into how hormones can enter the brain and affect mental functioning and mood. At the time, most scientists believed that the brain was not malleable after becoming fully developed, a line of thinking that McEwen’s research findings contradicted. In 1993, he coined the term allostatic load, which describes the physiological effects of chronic stress. With his wife, Karen Bulloch, a Rockefeller professor, he studied how immune cells in the brain increase during a person’s lifespan and can contribute to neurodegenerative disease. He also researched how sex hormones affect the central nervous system. Over the course of his career, which spanned six decades, McEwen received many accolades including the Pasarow Foundation award in neuropsychiatry, the Fondation Ipsen Neuronal Plasticity and Endocrine Regulation prizes, the Scolnick Prize in Neuroscience, and the William James Lifetime Achievement Award for Basic Research. He was a member of the National Academy of Sciences, the National Academy of Medicine, and the American Society of Arts and Sciences. “Bruce was a giant in the field of neuroendocrinology,” McEwen’s colleague Leslie Vosshall, a neuroscientist at Rockefeller, says in the statement. “He was a world leader in studying the impact of stress hormones on the brain, and led by example to show that great scientists can also be humble, gentle, and generous human beings.” © 1986–2020 The Scientist

Keyword: Stress; Hormones & Behavior
Link ID: 26942 - Posted: 01.09.2020

Nell Greenfieldboyce Shepherds in Christmas Nativity scenes that were painted, carved or sculpted hundreds of years ago sometimes have throats with large, abnormal growths. These are realistic depictions of goiter, an enlargement of the thyroid gland caused by iodine deficiency. The condition was common in those days in northern Italy, where the soil and water are depleted of iodine. "Goiter is more often seen in poor people," says retired surgeon Renzo Dionigi of the University of Insubria in Varese, Italy, who notes that the working classes in this region would historically not have a varied diet that might supply this vital nutrient. "That's why, probably, the poor shepherds are depicted with goiters," he says. He and his son, an endocrine surgeon named Gianlorenzo Dionigi, have for years enjoyed studying art and looking for signs of medical conditions. In the Sacri Monti ("Sacred Mountains") of Piedmont and Lombardy, they have visited chapels and churches created in the 16th and 17th centuries. "In all the Sacri Monti that I and my son visited, we have been able to observe representations of goiters very, very often," says the elder Dionigi. In one Nativity tableau from 1694, for example, a young horn player with a large goiter plays for the Holy Family. And in one fresco over the main door of the Aosta Cathedral, a shepherd with goiter plays his bagpipe for the newborn Jesus. © 2019 npr

Keyword: Hormones & Behavior
Link ID: 26913 - Posted: 12.26.2019

Nicola Slawson When Lynn Enright had a hysteroscopy to examine the inside of the womb, her searing pain was dismissed by medical professionals. She only understood why when she started working on her book on female anatomy, Vagina: A Re-education. She was looking for research on pain and women’s health, only to be shocked by how little data she found. It wasn’t just the topic of pain that was poorly researched. The lack of evidence was a problem she encountered time and time again, which is no surprise when you look at the research gap: less than 2.5% of publicly funded research is dedicated solely to reproductive health, despite the fact that one in three women in the UK will suffer from a reproductive or gynaecological health problem. There is five times more research into erectile dysfunction, which affects 19% of men, than into premenstrual syndrome, which affects 90% of women. “Women have been woefully neglected in studies on pain. Most of our understanding of ailments comes from the perspective of men; it is overwhelmingly based on studies of men, carried out by men,” Enright says. Her book is one of several in the past year about the female body and the impact a lack of knowledge can have on diagnosis and treatment. They include Emma Barnett’s Period, Eleanor Morgan’s Hormonal, and Gabrielle Jackson’s Pain and Prejudice, which draws on her experience of being diagnosed with endometriosis, a chronically underfunded condition. Given that in the US, which produces a lot of medical research, research trials weren’t required by the National Institutes of Health to include women until 1993, the lack of knowledge is perhaps no surprise. Traditionally this was justified by the idea that women’s bodies were seen to be too complex due to fluctuating hormones, so clinical trials often excluded them. © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 26898 - Posted: 12.18.2019

By Rachel E. Gross In the 1960s, manufacturers of the new birth-control pill imagined their ideal user as feminine, maternal and forgetful. She wanted discretion. She was married. And she wanted visible proof that her monthly cycle was normal and that she wasn’t pregnant. In 2019, the user of the pill is perceived as an altogether different person. She’s unwed, probably would prefer to skip her period and is more forthright about when it’s that time of the month. As such, many birth-control brands now come in brightly colored rectangular packs that make no effort to be concealed. But one part of the equation remains: the week of placebo pills, in which hormones are abruptly withdrawn and a woman experiences what looks and feels a lot like her regular period — blood, cramps and all — but isn’t. Physicians have widely described this pseudoperiod as medically unnecessary. So why do millions still endure it? That’s largely the legacy of two men: John Rock and David Wagner. First there’s Rock, a Harvard fertility expert and a developer of the pill. There’s a longstanding myth that Rock, a Catholic, designed the pill in the 1950s with the church in mind and included a week of hormonal withdrawal — and therefore bleeding — to make his invention seem more natural. In fact, the thought never crossed his mind, the Rutgers University historian Margaret Marsh says. Instead, it was Gregory (Goody) Pincus, the other developer of the pill, who suggested that the pill be given as a 20-days-on, 5-days-off regimen. Pincus wanted to provide women in his trials with reassurance that they weren’t pregnant, and to know himself that the pill was working as a contraceptive. Rock agreed. After the F.D.A. approved the pill in 1960, however, those few days of light bleeding took on a new significance. Anticipating the church’s opposition, Rock became not just a researcher but also an advocate. In his 1963 book “The Time Has Come: A Catholic Doctor’s Proposals to End the Battle Over Birth Control,” he argued that the pill was merely a scientific extension of the church-sanctioned “rhythm method.” It “completely mimics” the body’s own hormones, he wrote, to extend the “safe period” in which a woman could have intercourse and not become pregnant. © 2019 The New York Times Company

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 26892 - Posted: 12.12.2019

By Eva Frederick Many human grandmothers love to spoil their grandchildren with attention and treats, and for good reason: Studies have shown that having a living grandmother increases a child’s chance of survival. Now, new research shows the same may be true for killer whales. By providing young animals with some freshly caught salmon now and then—or perhaps with knowledge on where to find it—grannies increase their grand-offspring’s chance of survival. The new study is the first direct evidence in nonhuman animals of the “grandmother hypothesis.” The idea posits that females of some species live long after they stop reproducing to provide extra care for their grandchildren. “It’s very cool that these long-lived cetaceans have what looks like a postfertile life stage,” says Kristen Hawkes, an anthropologist at the University of Utah in Salt Lake City who has dedicated much of her career to studying the grandmother effect; she was not involved in the new study. Women usually go through menopause between ages 45 and 55, even though they may live to age 80, 90, or older. Studies in modern-day hunter-gatherer communities as well as in populations in Finland and Canada show that older women can help increase the number of children their daughters have, and boost the survival rates of their grandchildren. Dan Franks, a computer scientist and biologist at the University of York in the United Kingdom, wanted to know whether this grandmother effect occurs in other species as well. © 2019 American Association for the Advancement of Science

Keyword: Sexual Behavior; Evolution
Link ID: 26887 - Posted: 12.10.2019

Andrew Anthony Katrina Karkazis, a senior research fellow at Yale University, is a cultural anthropologist working at the intersection of science, technology, gender studies and bioethics. With Rebecca Jordan-Young, a sociomedical scientist, she has written Testosterone: An Unauthorised Biography. It is a critique of both popular and scientific understandings of the hormone, and how they have been used to explain, or even defend, inequalities of power. You suggest that testosterone is understood as an exclusively male hormone, even though it’s also found in women. But surely no scientist believes this. No, what we’re saying is that the hormone has a century-long biography and identity that continues to be that of a male sex hormone. That language is used by authoritative sources in the US like the National Library of Medicine, but also in many media articles. It’s an argument that has to do with how the hormone is understood, which then shapes the kinds of research questions that get asked, what kinds of research get done or not done. There’s actually almost no research on the relationship between testosterone and aggression in women. That is a consequence of the framing of the hormone as having to do with men, masculinity, behaviours understood and framed as masculine. It’s the idea that because men generally have more testosterone, somehow that makes it more relevant in men. But the truth is we know very little about it. You write that testosterone’s authorised biography is about libido, aggression and masculinity. Does this mean that testosterone is not about these things? I think that it’s still very widely understood as the driver of all things masculine. When people think about testosterone, aggression is one of the first things that comes to mind. But when you look at the evidence, there’s not good evidence at all. In fact, it’s very weak regarding the relationship between endogenous testosterone [ie testosterone that originates within an organism] and aggression. So it’s an artefact of the ideology of testosterone that we continue to believe that it drives aggression, because aggression has been framed as a masculine behaviour and testosterone has been framed as a masculine hormone. © 2019 Guardian News & Media Limited

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 26883 - Posted: 12.09.2019

By Laura Sanders “Does the pill cause depression?” the news headline asked. Prompted by a recent study that described a link between taking birth control pills as a teenager and depression in adulthood, the news got some doctors hopping mad. Early research hints that there are reasons to look more closely at hormonal birth control’s side effects. But so far, the link is less than certain. “This is a premature connection,” says pediatrician Cora Breuner of Seattle Children’s Hospital. Putting too much stock in preliminary evidence may lead to fewer teenagers getting birth control and, in turn, more unwanted pregnancies among teens — a situation that can upend young lives, Breuner says. Headlines that frighten teens, their families and doctors are “yet another barrier in place for accessing a completely effective way to prevent unplanned pregnancies.” Ob-gyn and contraception researcher Katharine O’Connell White agrees. “Birth control gets all of the worry and concern,” says White, of Boston University School of Medicine. “But we know that other things are much more dangerous.” Teen pregnancy, for instance. Access to effective birth control is vital for sexually active teenagers, the doctors say. “I don’t think the evidence is there right now to say that this is a threat,” adds epidemiologist and public health researcher Sarah McKetta of Columbia University, who has studied birth control use in teens. Still, she sees value in more research on the issue. “Women deserve good medication … that’s not giving them problems.” If there are risks that come with the pill, then scientists ought to get a handle on them. © Society for Science & the Public 2000–2019

Keyword: Depression; Hormones & Behavior
Link ID: 26864 - Posted: 12.02.2019

By James Gorman TEMPE, Ariz. — Xephos is not the author of “Dog Is Love: Why and How Your Dog Loves You,” one of the latest books to plumb the nature of dogs, but she helped inspire it. And as I scratched behind her ears, it was easy to see why. First, she fixed on me with imploring doggy eyes, asking for my attention. Then, every time I stopped scratching she nudged her nose under my hand and flipped it up. I speak a little dog, but the message would have been clear even if I didn’t: Don’t stop. We were in the home office of Clive Wynne, a psychologist at Arizona State University who specializes in dog behavior. He belongs to Xephos, a mixed breed that the Wynne family found in a shelter in 2012. Dr. Wynne’s book is an extended argument about what makes dogs special — not how smart they are, but how friendly they are. Xephos’ shameless and undiscriminating affection affected both his heart and his thinking. As Xephos nose-nudged me again, Dr. Wynne was describing genetic changes that occurred at some point in dog evolution that he says explain why dogs are so sociable with members of other species. “Hey,” Dr. Wynne said to her as she tilted her head to get the maximum payoff from my efforts, “how long have you had these genes?” No one disputes the sociability of dogs. But Dr. Wynne doesn’t agree with the scientific point of view that dogs have a unique ability to understand and communicate with humans. He thinks they have a unique capacity for interspecies love, a word that he has decided to use, throwing aside decades of immersion in scientific jargon. © 2019 The New York Times Company

Keyword: Sexual Behavior; Language
Link ID: 26848 - Posted: 11.23.2019

Ruth Williams After copulation, Drosophila melanogaster females are able to create long-term memories of unpleasant events—electric shocks—that virgin females cannot, according to a study published today in Science Advances (November 20). The authors suspect the memory boost may improve the chance of survival of the female during the subsequent egg-laying period as well as guide her choice of laying sites. Whatever the reason, the enhanced memory joins a list of physiological and behavioral effects on female flies that result from sex. “It’s quite impressive and convincing [data],” says entomologist Elwyn Isaac of the University of Leeds who was not involved in the research. “They propose that the sex peptide gets into the [female’s] circulation and somehow gets across the blood brain barrier [to activate memory].” It’s “very interesting,” Isaac continues, because until now, sex peptide—a protein produced in the male reproductive system and found in ejaculate—was thought to act on sensory neurons in the female’s uterus. These neurons produce a receptor protein to which sex peptide binds and are thought to be necessary for the peptide’s many effects on females, which include ramping up ovulation, increasing egg-laying behavior, changing food preference to a high-protein diet, and causing the female to reject other males. But, the authors of the new study, “show definitely that those neurons are not required for this [long-term memory] effect,” Isaac says. Indeed, deletion of the receptor in these neurons made no difference to the flies’ long-term memory formation after sex. © 1986–2019 The Scientist

Keyword: Learning & Memory; Sexual Behavior
Link ID: 26843 - Posted: 11.22.2019

Jef Akst From a small inflatable boat in the Rangiroa atoll in French Polynesia, Pamela Carzon got her first glimpse of the “strange” trio of marine mammals she’d been told about: a bottlenose dolphin mother (Tursiops truncatus), her seven-month-old calf, and another young cetacean that was slightly smaller and looked to be not a bottlenose dolphin at all, but a melon-headed whale (Peponocephala electra). It was April 2015, and Carzon and a colleague at the Marine Mammal Study Group of French Polynesia, a nongovernmental organization dedicated to whale and dolphin conservation, were out for the NGO’s annual photo-ID survey, very much hoping to find animals that a former collaborator had seen while diving in the region the previous November. “[T]he sea was very calm, and there were many dolphins around,” Carzon, also a PhD student at the Center for Island Research and Environmental Observatory (CRIOBE) in French Polynesia and the École Pratique des Hautes Études in Paris, recalls in an email to The Scientist. “It took us maybe two minutes to spot them: the dark calf was easy to spot among the bottlenose dolphins.” The mother, dubbed ID#TP25 by the researchers, was known to tolerate divers and boats, and that April day she approached the inflatable with both calves. Carzon grabbed her underwater camera and slipped into the water. “I was able to get good underwater footage and to sex both calves,” she says. ID#TP25’s natural calf was a female; the second calf was male. “I also noticed that both were ‘gently’ pushing each other [in order] to remain under the adult female’s abdomen” in so-called infant position. Continued observation over the following months revealed that the dolphin mom was nursing the foreign calf, whose species ID remains to be confirmed with genetic testing, and otherwise treated him as one of her own. © 1986–2019 The Scientist.

Keyword: Sexual Behavior
Link ID: 26836 - Posted: 11.20.2019

Jon Hamilton There's new evidence that girls start out with the same math abilities as boys. A study of 104 children from ages 3 to 10 found similar patterns of brain activity in boys and girls as they engaged in basic math tasks, researchers reported Friday in the journal Science of Learning. "They are indistinguishable," says Jessica Cantlon, an author of the study and professor of developmental neuroscience at Carnegie Mellon University. The finding challenges the idea that more boys than girls end up in STEM fields (science, technology, engineering, and mathematics) because they are inherently better at the sort of thinking those fields require. It also backs other studies that found similar math abilities in males and females early in life. "The results of this study are not too surprising because typically we don't see sex differences at the ages assessed in this study or for the types of math tasks they did, which were fairly simple," says David Geary, a psychologist and curator's distinguished professor at the University of Missouri who was not involved in the research. But there is evidence of sex differences in some exceptional older students, Geary says. For example, boys outnumber girls by about three to one when researchers identify adolescents who achieve "very, very high-end performance in mathematics," Geary says, adding that scientists are still trying to understand why that gap exists. © 2019 npr

Keyword: Sexual Behavior; Learning & Memory
Link ID: 26803 - Posted: 11.08.2019

By David Z. Hambrick, Daisuke S. Katsumata Disagreements are virtually inevitable in a romantic relationship. More than 90 percent of couples argue, according to a survey by the University of Michigan’s Institute for Social Research, with nearly half quarreling at least once a month. Common topics of marital disagreement are money, sex and time spent together. None of this will surprise anyone who has been in a long-term relationship. But a new study indicates that a cognitive ability may help to explain why some couples are more successful in resolving their differences. University of North Carolina Greensboro psychologist Levi Baker and his colleagues report that spouses who were high in working memory capacity had better memory for each other’s statements in discussions about problems. In turn, these couples showed greater progress in resolving their problems over time. The study suggests that it’s not just dogged commitment that gets couples through rough spots, but a cognitive factor that directly affects the quality of partners’ communication with each other. The sample included 101 couples (93 heterosexual, 7 lesbian and 1 gay) that had been married for less than three months. Working individually, the newlyweds first completed tests of working memory capacity, which is the ability to hold information in the focus of attention over a short period, as when following what someone is saying to you in a conversation. In one of the tests used by Baker and his colleagues, called “operation span,” the test-taker sees an arithmetic problem on the screen and attempts to solve it, after which a letter appears. After some number of these trials, the person is prompted to recall the letters in the order in which they were presented. © 2019 Scientific American

Keyword: Learning & Memory; Intelligence
Link ID: 26790 - Posted: 11.05.2019

By Lisa Sanders, M.D. “Please find something wrong with me,” the 28-year-old woman pleaded. For nearly a year, she’d been looking for a reason for the strange symptoms that now dominated her life. Dr. Raphael Sung, a cardiologist specializing in finding and fixing abnormal heart rhythms at National Jewish Health hospital in Denver, was surprised by her reaction to the news that her heart was normal. Most patients are happy to get that report. For this patient, it seemed like just one more dead end. The patient’s symptoms started right after her baby was born 10 months earlier. Out of nowhere, her heart would start beating like crazy. At first, she assumed that these were anxiety attacks, triggered by the stress of bringing her premature daughter home. Her baby spent her first week of life in the newborn intensive care unit. When she was big enough to come home, she still weighed only four pounds, nine ounces. The new mother worried that without the doctors and nurses and equipment that had kept her alive, her tiny baby might die. But she didn’t. She seemed to thrive at home. Despite that, her mother’s heart continued to take off like a spooked horse several times a day. After a couple of weeks, her symptoms worsened. Sometimes her racing heart would set off terrible headaches, the worst she’d ever had. It was as if someone had thrust a sharp stick deep into her brain. The knife of pain quickly turned into a sense of pressure so intense it felt as if the back of her skull would blow off. Minutes later, she would feel the blood drain from her face; she’d be suddenly drenched in sweat. Her hands would curl into tight fists, and vomit would shoot out of her mouth like a geyser. Her husband joked (though only once) that she looked like the girl in “The Exorcist.” © 2019 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 26767 - Posted: 10.30.2019

By Sofie Bates Make some noise for the white bellbirds of the Brazilian Amazon, now the bird species with the loudest known mating call. The birds (Procnias albus) reach about 125 decibels on average at the loudest point in one of their songs, researchers report October 21 in Current Biology. Calls of the previous record-holder — another Amazonian bird called the screaming piha (Lipaugus vociferans) — maxed out around 116 decibels on average. This difference means that bellbirds can generate a soundwave with triple the pressure of that made by pihas, says Jeff Podos, a behavioral ecologist at the University of Massachusetts Amherst, who did the research along with ornithologist Mario Cohn-Haft, of the National Institute of Amazon Research in Manaus, Brazil. The team measured sound intensity from three pihas and eight bellbirds. Each sounded off at different distances from the scientists. So to make an accurate comparison, the researchers used rangefinder binoculars, with lasers to measure distance, to determine how far away each bird was. Then, they calculated how loud the sound would be a meter from each bird to crown a winner. The small white bellbird, which weighs less than 250 grams, appears to be built for creating loud sounds, with thick abdominal muscles and a beak that opens extra wide. “Having this really wide beak helps their anatomy be like a musical instrument,” Podos says. Being the loudest may come with a cost: White bellbirds can’t hold a note for long because they run out of air in their lungs. Their loudest call sounds like two staccato beats of an air horn while the calls of screaming pihas gradually build to the highest point. © Society for Science & the Public 2000–2019

Keyword: Sexual Behavior; Hearing
Link ID: 26733 - Posted: 10.22.2019

Zoë Corbyn At a time when women’s reproductive freedoms are under attack, any suggestion that the birth control pill could be problematic feels explosive. But Sarah E Hill, a professor of social psychology at the Texas Christian University in Fort Worth, Texas argues we need to talk about how oral contraceptives are affecting women’s thinking, emotions and behaviour. How the Pill Changes Everything: Your Brain on Birth Control is her new book about the science behind a delicate subject. Some US states have recently made it harder to get an abortion and the Trump administration is doing its best to chisel away at access to birth control. Is your book trying to dissuade women from using the pill? My institution was founded as a Christian school, but it doesn’t have a particular religious bent now. My goal with this book is not to take the pill away or alarm women. It is to give them information they haven’t had up until now so they can make informed decisions. The pill, along with safe, legalised abortions, are the two biggest keys to women’s rights. But we also have a blind spot when it comes to thinking about how changing women’s sex hormones – which is what the pill does – influences their brains. For a long time, women have been experiencing “psychological” side-effects on the pill but nobody was telling them why. The backlash we are seeing against the pill, particularly with millennial women walking away from it, I think is because women haven’t felt right on it and have grown weary of doctors patting them on their heads and telling them they are wrong. The more information women have, the more it will bring them back to the pill. © 2019 Guardian News & Media Limited

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 26723 - Posted: 10.19.2019

Hannah Devlin Science correspondent Boosting testosterone levels significantly improves female athletic performance, according to one of the first randomised controlled trials. The findings come as the International Association of Athletics Federations (IAAF) announced on Monday it would impose an upper limit for testosterone levels on trans female athletes competing in middle-distance events. Testosterone was assumed to be performance-enhancing and a factor in explaining differences in strength and endurance between men and women. However, there was a surprising lack of evidence on the impact of testosterone in women and the question had become mired in controversy following a series of rulings in professional sport. The latest research confirmed that testosterone significantly increases endurance and lean muscle mass among young women, even when given for a relatively short period. Angelica Hirschberg, a gynaecologist for the Swedish Olympic Committee based at Karolinska University Hospital and the study’s first author, said the results were the first to show a causal effect of testosterone on physical performance in women. “This has not been demonstrated previously because most studies have been performed in men,” she said. “Furthermore, the study shows the magnitude of performance enhancement by testosterone. Testosterone levels increased more than four times but were still much below the male range. The improvement in endurance performance by the increased testosterone levels was more than 8% – this is a huge effect in sports.” © 2019 Guardian News & Media Limited

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 26706 - Posted: 10.16.2019

Nicola Davis A possible explanation for one of biology’s greatest mysteries, the female orgasm, has been bolstered by research showing that rabbits given antidepressants release fewer eggs during sex. The human female orgasm has long proved curious, having no obvious purpose besides being pleasurable. The scientists behind the study have previously proposed it might have its evolutionary roots in a reflex linked to the release of eggs during sex – a mechanism that exists today in several animal species, including rabbits. Since humans have spontaneous ovulation, the theory goes that female orgasm may be an evolutionary hangover. They say the new experiment supports the idea. “We know there is a reflex [in rabbits], but the question [is] could this be the same one that has lost the function in humans?” said Dr Mihaela Pavličev a researcher at the University of Cincinnati who co-authored the study. To explore the question the team gave 12 female rabbits a two-week course of fluoxetine (trade name Prozac) – an antidepressant known to reduce the capacity for women to orgasm – and looked at the number of eggs released after the animals had sex with a male rabbit called Frank. The results, published in the Proceedings of the National Academy of Sciences, showed that rabbits given the antidepressants released 30% fewer eggs than nine rabbits that were not given Prozac but still mated with Frank. © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 26659 - Posted: 10.01.2019

Alison Flood Caroline Criado Perez’s exposé of the gender data gap that has created a world biased against women has won her the Royal Society science book prize. Criado Perez’s Invisible Women, which explores how everything from speech-recognition software to bulletproof vests, from medical tests to office temperature controls are designed for men as a default, was called a brilliant exposé by chair of judges and Oxford professor Nigel Shadbolt. He said the book had made him, as an AI researcher and data scientist, look at his field afresh. “[Criado Perez] writes with energy and style, every page full of facts and data that support her fundamental contention that in a world built for and by men gender data gaps, biases and blind spots are everywhere,” he said. The author and feminist campaigner who successfully pushed for Jane Austen to be featured on the UK’s £10 note, called her £25,000 win on Monday night a huge relief. “Obviously it’s a huge honour, but mainly because it has the official endorsement of scientists and so it can’t be dismissed now, and that’s so important,” she said. “Writing this book was hellish. It really tested my mental strength to its limits, partly because it was a really emotional book to write because of the impact this is having on women’s lives and how angry and upsetting it was to keep coming across this gap in the data. But also it was very challenging because it was a book about the whole world and everything in it, and I had to work out how to synthesise that into something manageable.” © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior
Link ID: 26646 - Posted: 09.25.2019

Daniel Pfau I came out to a Christian counselor during a therapy session in 2001 when I was 14. He convinced me to engage in conversion therapy, a pseudoscientific practice to change an individual’s sexual orientation based in the assumption that such behaviors are “unnatural.” He produced an article describing a talk at that year’s American Psychological Association conference that indicated the therapy worked. This painful experience encouraged me, when I started my scientific career, to examine queerness in biology. The queer community, 25 million years (or more) in the making Understanding how complex human relationships developed requires a complete picture of our social behavior during evolution. I believe leaving out important behaviors, like same-sex sexual behavior, can bias the models we use to explain social evolution. Many researchers have postulated how queer behaviors, like same-sex sexual behavior, may have developed or how they are expressed. Recently, scientists at the Broad Institute of Harvard and MIT published a paper suggesting a genetic component to same-sex sexual behavior expression in modern humans. However, no studies provide an argument of when queer behavior may have arisen during humans’ evolution. Such research would push back against the assertions I encountered during my youth, that queerness is a modern aberration. © 2010–2019, The Conversation US, Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 26632 - Posted: 09.21.2019