Chapter 8. Hormones and Sex

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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

By Kim Tingley Men have a far greater appetite for sex and are more attracted to pornography than women are. This is the timeworn stereotype that science has long reinforced. Alfred Kinsey, America’s first prominent sexologist, published in the late 1940s and early 1950s his survey results confirming that men are aroused more easily and often by sexual imagery than women. It made sense, evolutionary psychologists theorized, that women’s erotic pleasure might be tempered by the potential burdens of pregnancy, birth and child rearing — that they would require a deeper emotional connection with a partner to feel turned on than men, whose primal urge is simply procreation. Modern statistics showing that men are still the dominant consumers of online porn seem to support this thinking, as does the fact that men are more prone to hypersexuality, whereas a lack of desire and anorgasmia are more prevalent in women. So it was somewhat surprising when a paper in the prestigious journal P.N.A.S. reported in July that what happens in the brains of female study subjects when they look at sexual imagery is pretty much the same as what happens in the brains of their male counterparts. The researchers, led by Hamid Noori at the Max Planck Institute for Biological Cybernetics in Germany, weren’t initially interested in exploring sexual behavior. They were trying to find ways to standardize experiments that use functional magnetic resonance imaging (fM.R.I.) to observe how the brain responds to visual stimuli. In order to do that, they needed to compare past studies that used similar methods but returned diverse results. They happened to choose studies in which male and female volunteers looked at sexual imagery, both because doing so tends to generate strong signals in the brain, which would make findings easier to analyze, and because this sort of research has long produced “inconsistent and even contradictory” results, as they note in their paper. Identifying the reasons for such discrepancies might help researchers design better experiments. © 2019 The New York Times Company

Keyword: Sexual Behavior; Brain imaging
Link ID: 26622 - Posted: 09.18.2019

By Emily Underwood Adrenaline. The word is synonymous with any activity that gets our blood racing, whether it be encountering a rattlesnake or watching the latest horror movie. But a new study reveals that when it comes with our body’s stress response, adrenaline may be less important than another hormone, one that seeps out of our bones. Our skeleton is much more than a rigid scaffold for the body, says geneticist Gérard Karsenty of Columbia University. Our bones secrete a protein called osteocalcin, discovered in the 1970s, that rebuilds the skeleton. In 2007, Karsenty and colleagues discovered that this protein acts as a hormone to keep blood sugar levels in check and burn fat. Later, his group showed that the hormone is important for maintaining brain function and physical fitness, restoring memory in aged mice and boosting performance during exercise in old mice and people. The findings led Karsenty to hypothesize that animals evolved bony skeletons to escape danger. The new study furthers that argument. Karsenty and colleagues exposed mice to several stressors, including a mild electric shock to the foot and a whiff of fox urine, a scent that triggers an innate fear response. Then, the researchers measured the osteocalcin in the animals’ blood. Within 2 to 3 minutes of being exposed to a stressor, levels of osteocalcin in the mice quadrupled, the team reports today in Cell Metabolism. A classic stressor in people had a similar effect: When the researchers asked volunteers to speak in front of an audience, osteocalcin levels also spiked. © 2019 American Association for the Advancement of Science

Keyword: Hormones & Behavior; Stress
Link ID: 26609 - Posted: 09.13.2019

By Roni Dengler | Testosterone often gets a bad rap. The hormone responsible for male sexual development has been linked in studies to aggression and a lack of empathy. People with autism – a developmental condition that can lead to anxiety and trouble interacting with others – also have a hard time empathizing. Since the condition is four times more common in boys than girls, scientists once thought testosterone might reduce our ability to tell how others are feeling. But now, researchers find that’s not the case. “Of course, the primary suspect when we have something that is sharply differentiated by sex is testosterone,” University of Pennsylvania marketing professor Gideon Nave, who led the work, said in a press release. In the new study, Nave and colleagues report men given extra testosterone were able to read emotions just as well as those with typical hormone levels. The findings contrast a prevailing hypothesis that testosterone challenges men’s ability to empathize. Emotional Eyes In previous studies, other scientists tested whether testosterone influences empathy. They gave a few dozen women testosterone and then tested their ability to infer emotions by looking at pictures of people’s eyes. The studies concluded the testosterone lowered the women’s ability to empathize. The findings lent support for what’s known as the “extreme male brain hypothesis.” The hypothesis posits that men and women process and experience the world differently – women empathize and men systemize. Another study linking prenatal testosterone levels to autism added weight to the hypothesis.

Keyword: Hormones & Behavior; Emotions
Link ID: 26603 - Posted: 09.12.2019

By Emily Oster At some point or another, most books about the brain come back to the story of Phineas Gage. Gage was a railroad worker in the 19th century. In an unfortunate 1848 accident, a large steel spike was driven through his eye and out the other side of his head, taking some of his brain with him (this is the point in the story where my 8-year-old told me to please stop telling it). Amazingly, Gage survived the accident with much of his faculties intact. What did change was his personality, which, by many reports, became more aggressive and belligerent. Gage’s doctor wrote up his case, arguing that it suggested “civilized conduct” was localized in a particular part of the brain — specifically, the part he had lost. Science was off in search of where in the brain various skills were kept, with the idea that the brain was a kind of map, with little areas for, say, walking or talking or hearing or smelling. This proceeded, albeit slowly; for a while, there wasn’t much of a way to study this other than by looking at people with traumatic brain injuries. So it’s understandable that the development of technologies to study intact brains caused a lot of excitement. Generating the most discussion in recent years has been functional magnetic resonance imaging (or fMRI), which allows researchers to measure oxygen flow to the brain and identify which parts activate in response to varying stimuli. These technologies have not always lived up to the hype. The mechanics and statistics of processing fMRI imaging data have turned out to be far more complex than initially imagined. As a result there were many false claims made about which parts of the brain “controlled” different aspects of behavior or actions. The best, or at least funniest, example of this was a paper that showed how cutting-edge statistical analysis of fMRI made it possible to identify parts of the brain that responded differently to happy or sad faces. Sounds good, until you learn that the subject for this experiment was a dead fish. © 2019 The New York Times Company

Keyword: Sexual Behavior; Brain imaging
Link ID: 26594 - Posted: 09.10.2019

/ By Hope Reese In her new book “Gender and Our Brains,” cognitive neuroimaging professor Gina Rippon explains that brains aren’t gendered, but research can be. The differences among women as a group, or men as a group, are greater than the differences between men and women, Rippon says. Rippon sifts through centuries of research into supposed differences in areas such as behavior, skills, and personality, and shows that external factors like gender stereotypes and real-world experiences are the likely cause of any detectable differences in mental processing. And she demonstrates that the differences among women as a group, or among men as a group, are much greater than the differences between men and women. She cites a 2015 study looking at 1,400 brain scans as an example. Comparing 160 brain structures in the scans — identifying areas that were, on average, larger in men or in women — researchers could not find any scans that had all “male” traits, or all “female” traits — physical attributes such as weight or tissue thickness. “The images were, literally, of a mosaic,” she says. “We’re trying to force a difference into data that doesn’t exist.” Rippon teaches cognitive neuroimaging — the study of behavior through brain images — at Aston University in England. For this installment of the Undark Five, I spoke with her about how neuroimages are misinterpreted and whether PMS is real, among other topics. Here is our conversation, edited for length and clarity. Undark: Scientists have been trying to find differences in the brains of men and women for years. What are some examples of how the cherry-picking approach is problematic? Gina Rippon: It’s what I call the “hunt the differences” agenda, which started about 200 years ago when scientists were starting to understand the importance of the brain in explaining human behavior and human ability. Copyright 2019 Undark

Keyword: Sexual Behavior; Brain imaging
Link ID: 26584 - Posted: 09.07.2019

By Emily Underwood Of the many proposed triggers for autism, one of the most controversial is the “extreme male brain” hypothesis. The idea posits that exposure to excess testosterone in the womb wires both men and women to have a hypermasculine view of the world, prioritizing stereotypically male behaviors like building machines over stereotypically female behaviors like empathizing with a friend. Now, a study is raising new doubts about this theory, finding no effect of testosterone on empathy in adult men. The work does not directly address whether high levels of prenatal testosterone cause autism or lack of empathy. That would require directly sampling the hormone in utero, which can endanger a developing fetus. But the new study’s large size—more than 600 men—makes it more convincing than similar research in the past, which included no more than a few dozen participants, experts say. The extreme male brain hypothesis was first proposed by psychologist Simon Baron-Cohen at the University of Cambridge in the United Kingdom. In 2001, he and colleagues found that women given a single hefty dose of testosterone fared significantly worse at the Reading the Mind in the Eyes test (RMET), which asked them to gauge the emotional states of others based on their facial expressions. The women’s performance seemed to track with a controversial metric called the 2D:4D ratio, the relative lengths of the second and fourth fingers. Men—and people with autism—tend to have a longer ring finger than index finger, and some researchers believe that is due to higher prenatal exposure to testosterone. (Others are skeptical.) © 2019 American Association for the Advancement of Science

Keyword: Autism; Sexual Behavior
Link ID: 26571 - Posted: 09.04.2019

By Pam Belluck How do genes influence our sexuality? The question has long been fraught with controversy. An ambitious new study — the largest ever to analyze the genetics of same-sex sexual behavior — found that genetics does play a role, responsible for perhaps a third of the influence on whether someone has same-sex sex. The influence comes not from one gene but many, each with a tiny effect — and the rest of the explanation includes social or environmental factors — making it impossible to use genes to predict someone’s sexuality. “I hope that the science can be used to educate people a little bit more about how natural and normal same-sex behavior is,” said Benjamin Neale, a geneticist at the Broad Institute of M.I.T. and Harvard and one of the lead researchers on the international team. “It’s written into our genes and it’s part of our environment. This is part of our species and it’s part of who we are.” The study of nearly half a million people, funded by the National Institutes of Health and other agencies, found differences in the genetic details of same-sex behavior in men and women. The research also suggests the genetics of same-sex sexual behavior shares some correlation with genes involved in some mental health issues and personality traits — although the authors said that overlap could simply reflect the stress of enduring societal prejudice. Even before its publication Thursday in the journal Science, the study has generated debate and concern, including within the renowned Broad Institute itself. Several scientists who are part of the L.G.B.T.Q. community there said they were worried the findings could give ammunition to people who seek to use science to bolster biases and discrimination against gay people. One concern is that evidence that genes influence same-sex behavior could cause anti-gay activists to call for gene editing or embryo selection, even if that would be technically impossible. Another fear is that evidence that genes play only a partial role could embolden people who insist being gay is a choice and who advocate tactics like conversion therapy. © 2019 The New York Times Company

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 26555 - Posted: 08.30.2019

By Lindsey Bever There is no one gene that determines a person’s sexual orientation, but genetics — along with environment — play a part in shaping sexuality, a massive new study shows. Researchers analyzed DNA from hundreds of thousands of people and found that there are a handful of genes clearly connected with same-sex sexual behavior. The researchers say that, although variations in these genes cannot predict whether a person is gay, these variants may partly influence sexual behavior. Andrea Ganna, lead author and European Molecular Biology Laboratory group leader at the Institute of Molecular Medicine in Finland, said the research reinforces the understanding that same-sex sexual behavior is simply “a natural part of our diversity as a species.” The new study, published Thursday in the journal Science, is not the first to explore the link between genetics and same-sex behavior, but it is the largest of its kind, and experts say it provides one of the clearest pictures of genes and sexuality. Ganna, who is also an instructor at Massachusetts General and Harvard, and an international team of scientists examined data from more than 470,000 people in the United States and the United Kingdom to see whether certain genetic markers in their DNA were linked to their sexual behavior. Specifically, the researchers used data from the UK Biobank study and from the private genomics company 23andMe, which included their DNA data and responses to questions about sexual behaviors, sexual attraction and sexual identity. More than 26,000 participants reported at least one sexual encounter with someone of the same sex. Earlier studies, the researchers said, weren’t large enough to reveal the subtle effects of individual genes. © 1996-2019 The Washington Post

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 26554 - Posted: 08.30.2019

By Annie Roth Kalutas live fast and die young — or, at least, the males do. Male kalutas, small mouselike marsupials found in the arid regions of Northwestern Australia, are semelparous, meaning that shortly after they mate, they drop dead. This extreme reproductive strategy is rare in the animal kingdom. Only a few dozen species are known to reproduce in this fashion, and most of them are invertebrates. Kalutas are dasyurids, the only group of mammals known to contain semelparous species. Only around a fifth of the species in this group of carnivorous marsupials — which includes Tasmanian devils, quolls and pouched mice — are semelparous and, until recently, scientists were not sure if kalutas were among them. Now there is no doubt that, for male kalutas, sex is suicide. In a study, published in April in the Journal of Zoology, researchers from the University of Western Australia and the University of Queensland confirmed that kalutas exhibit what is known as obligate male semelparity. “We found that males only mate during one highly synchronized breeding season and then they all die,” said Genevieve Hayes, a vertebrate ecologist and the lead author of the study. Dr. Hayes and her colleagues monitored the breeding habits of a population of kalutas in Millstream Chichester National Park in Western Australia during the 2013 and 2014 breeding seasons. In both seasons, the researchers observed a complete die-off of males. Although male kalutas have exhibited semelparity in captivity, this was the first time it had been seen in the wild. Kalutas evolved independently of other semelparous dasyurids, so the confirmation that male kalutas die after mating suggests that this unorthodox reproductive strategy has evolved not once, but twice in dasyurids.

Keyword: Sexual Behavior
Link ID: 26552 - Posted: 08.29.2019

Patti Neighmond The pathway to opioid abuse for women often starts with a prescription from the doctor's office. One reason is that women are more likely than men to seek help for pain. Pain researchers say that not only do women suffer more painful conditions, they actually perceive pain more intensely than men do. "The burden of pain is substantially greater for women than men," says researcher and psychologist Roger Fillingim, "and that led pain researchers like myself to wonder if the pain perception system is different in women than in men." For more than two decades, Fillingim has been studying gender differences and pain, most recently at the University of Florida's Pain Research and Intervention Center of Excellence, where he is director. He recruits healthy male and female volunteers to take part in experimental pain sessions using various painful stimuli, including pressure, heat, cold and electrical stimulation. Probes are typically applied to the hand or arm. As intensity of the stimuli is increased, volunteers are asked to rate their pain on a scale of zero to 10, where zero is no pain and 10 is the most intense pain one can imagine. If volunteers report pain levels at 10, Fillingim stops the experiment immediately. "On average, women report the same stimuli to be more painful than men," Fillingim says, emphasizing that the same stimulus is applied to everybody, so if there are differences in how painful the experience is, it can't be because of the stimulus because it's calibrated to be the same for all. © 2019 npr

Keyword: Pain & Touch; Sexual Behavior
Link ID: 26546 - Posted: 08.27.2019