Links for Keyword: Sexual Behavior

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


Links 1 - 20 of 1592

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

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: 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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
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.

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: 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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 26622 - Posted: 09.18.2019

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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 26584 - Posted: 09.07.2019

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

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: 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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
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.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26552 - Posted: 08.29.2019

Ammar Kalia Three years ago, Paul (not his real name), now 31, went to the doctor with stomach pains. His blood test came back with low testosterone levels. “We went to see a urologist and he said bluntly that we wouldn’t have any options to have kids with my sperm – we would have to use a donor or adopt,” he says. “My wife immediately burst into tears.” The couple had been trying for a child since they married in 2015. Paul was also devastated. “It put so much stress on me, because I thought I couldn’t give my wife or my family what they so desperately wanted.” Eventually, Paul was diagnosed with Klinefelter syndrome. Affecting about one in 600 men, it is one of the most common genetic conditions in the UK, yet most people have never heard of it – including many who have it. Its symptoms – extra height, persistent tiredness, reduced bodily hair and small testes – can be difficult to identify, meaning it often goes unnoticed by patients and GPs. Untreated, however, it can lead to reduced testosterone and infertility, and even increased prevalence of testicular cancer. The non-hereditary syndrome was first discovered in 1942. It is caused by the presence of an extra X chromosome, resulting in XXY, as opposed to XY. With only one in six men who have Klinefelter’s ever diagnosed, even though symptoms often emerge during puberty, it may be one of the leading unexplored causes of infertility. Now, the first clinic in the UK to deal solely with Klinefelter’s has opened at Guy’s hospital in London – and its clinicians believe it could revolutionise its treatment and diagnosis. © 2019 Guardian News & 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: 26539 - Posted: 08.26.2019

By James Gorman Here are three good things about gulls: They are devoted parents. Males share child care equally with females. That includes sitting on the eggs during incubation. And they have figured out a way — actually many ways — to survive in a harsh and unforgiving world. Some eat clams, some eat fish, some are attracted to landfills. Of course, a few will divebomb you at the beach or boardwalk to steal a French fry, or the cheese on your cracker, or an entire slice of pizza. The beach pirate approach to survival is, of course, where humans and gulls clash. And the outcry from humans is almost as loud and outraged as the cries of the gulls themselves. Several recent news articles have chronicled the predations of gulls and some possible remedies. Ocean City, N.J., is bringing in hawks, and some scientists have suggested staring directly at gulls to fend them off. Though that is hard to do when the birds sneak up behind you as you are putting cheese on a cracker. There are some reports of more serious trouble. In England, a woman said a gull carried off her Chihuahua, and in Russia a pilot was hailed as a hero for safely landing his plane after a collision with a flock of gulls. In the New York area, thousands of birds, including gulls, have been killed in the decade since the Miracle on the Hudson crash to clear the skies for airplanes, without an apparent reduction in bird strikes. But it’s at the beach where tempers flare most predictably. And in times like these, with heightened human-gull tensions, very little has been written about the gulls’ point of view. Is there a Lorax who speaks for the gulls? Admittedly, gulls have quite a strong voice of their own, it’s just that it’s pretty unintelligible to most of us. An ornithologist would seem to be the obvious choice. They like birds. I called Christopher Elphick at the University of Connecticut. He spends a lot of time studying sparrows, but has a soft spot for gulls. © 2019 The New York Times Company

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: 26537 - Posted: 08.24.2019

By Katie Camero For humans, slight variations in temperature don’t mean much. But for some turtles, they mean the difference between whether embryos come out male or female. Now, scientists have evidence that these embryos have some power over their sexual destiny: By moving to slightly warmer or cooler spots inside their eggs, freshwater turtle embryos can help determine their own sex. Not everyone is convinced. But if the new finding holds, this behavior could potentially save some turtle species from extinction by balancing their sex ratios. A reptile’s sex depends on hormones produced during development. For crocodiles, many fish, some lizards, and most turtles, those hormones in turn depend on external temperatures. Cooler temperatures typically lead to more males, and warmer temperatures generally lead to more females. That means a shift of just 2°C can make all of the offspring one sex. As average global temperatures rise, such a strategy could doom some species, including the already-endangered Chinese pond turtle (Mauremys reevesii). As weather warms, warmer eggs produce more and more females—leaving them fewer males to mate with. Wondering whether turtle embryos could respond to rapidly changing temperatures, scientists from the Chinese Academy of Sciences in Beijing examined the behavior of the Chinese soft-shelled turtle (Pelodiscus sinensis). They discovered that the embryos could in fact move between cooler and warmer spots inside their paperclip-size eggs, they reported in 2011 in the Proceedings of the National Academy of Sciences. © 2019 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26477 - Posted: 08.02.2019

By Knvul Sheikh It’s a myth that black widow female spiders always kill and consume their mates. But courtship remains perilous for males, cannibalism or no. The terrain, navigated in the dark, is challenging. The female’s web releases come-hither pheromones, but only about 12 percent of prospective males manage to reach it. And once there, they can expect to face male rivals competing to pass their genes on to the next generation. Usually, this results in wild displays of machismo. The males slash the female’s webs to make them less enticing to others. They deposit “mating plugs” in the female’s body to block rival sperm. Why not simply avoid the competition and seek out females’ webs empty of other males? But male black widows actually seem to thrive on the competition, according to a study published Wednesday in the Proceedings of the Royal Society B: Biological Sciences. Researchers found that male black widows find potential mates faster by following the silk trails left behind by other males. “Males have to race to find females,” said Catherine Scott, an arachnologist at the University of Toronto Scarborough in Canada and the study’s lead author. “It makes sense for them to try to use all the tricks they can to find females as soon as possible, even if there are other males that have already found her.” If a male arrives an hour or two late at a female’s web, he still has a chance to interrupt the courting rituals of other males, and could still be the first to mate with the female, Ms. Scott said. Males typically make their way to a rendezvous by following female pheromones back to their source. But those signals must be at just the right distance, and uninterrupted by shifting winds and other factors. © 2019 The New York Times Company

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: 26476 - Posted: 08.01.2019

Carolyn Wilke Most frogs lay oodles of eggs and quickly hop away. But some poison dart frogs baby their offspring, cleaning and hydrating eggs laid on land and piggybacking hatched tadpoles to water. A peek inside the brains of these nurturing amphibians reveals that in males and females, two regions linked with caring for young are the same — a finding that may provide clues to the neural underpinnings of parental behavior, researchers report online July 17 in Proceedings of the Royal Society B. From humans to crocodiles, many creatures tend to their young. “But we actually understand very little about how the brain makes parental behaviors,” says Eva Fischer, a neuroethologist at Stanford University. To study how such care is wired into the amphibian brain, Fischer and her colleagues looked at neural activity in three poison dart frog species with different parenting strategies: Dendrobates tinctorius, among whom the males take care of the young; Oophaga sylvatica, whose females do the parenting; and Ranitomeya imitator, whose offspring are cared for by a monogamous male and female pair. The researchers collected and quickly killed 25 frogs while the amphibians were toting their tadpoles to water, in order to study the brain while it was still influenced by the parental task. Another 59 brains from non-caregiving frog species or caregivers’ partners were also included in the study. The researchers froze the frog brains and sliced them like loaves of bread. They stained the layers of tissue to pinpoint which nerve cells, or neurons, were turned on. In all three species, a brain region called the preoptic area was lit up with activity in caregiving frogs, but not in those of non-caregiving animals. |© Society for Science & the Public 2000 - 2019.

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: 26451 - Posted: 07.26.2019

Nicola Davis The belief that men are more likely to get turned on by sexual images than women may be something of a fantasy, according to a study suggesting brains respond to such images the same way regardless of biological sex. The idea that, when it comes to sex, men are more “visual creatures” than women has often been used to explain why men appear to be so much keener on pornography. But the study casts doubt on the notion. “We are challenging that idea with this paper,” said Hamid Noori, co-author of the research from the Max Planck Institute for Biological Cybernetics in Germany. “At least at the level of neural activity … the brains of men and women respond the same way to porn.” Writing in the Proceedings of the National Academy of Sciences, Noori and his colleagues report how they came to their conclusions by analysing the results of 61 published studies involving adults of different biological sex and sexual orientation. The subjects were shown everyday images of people as well as erotic images while they lay inside a brain-scanning machine. Noori said all participants rated the sexual images as arousing before being scanned. Previously studies based on self-reporting have suggested men are more aroused by images than women, and it has been proposed that these differences could be down to the way the brain processes the stimuli – but studies have returned different results. Now, looking at the whole body of research, Noori and his colleagues say they have found little sign of functional differences. For both biological sexes, a change in activity was seen in the same brain regions including the amygdala, insula and striatum when sexual images were shown. © 2019 Guardian News & 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: 26423 - Posted: 07.16.2019

By C. Claiborne Ray Q. When the chicks have just hatched, how do chicken farmers tell future hens from future roosters? A. Sexing hatchlings is important for the egg industry. Roosters do not lay eggs, obviously, and they are not needed in order for hens to lay eggs. But it is surprisingly difficult to tell hatchling males from females; there are no external genitalia, and the internal equipment is only subtly different. Though some breeds may show early differences in feather color, often it can take weeks for obvious signs of gender — like combs, wattles and behavioral traits — to emerge. An alternative to waiting was developed in the 1930s by two Japanese researchers, Kiyoshi Masui and Juro Hashimoto. It is called venting or vent sexing. Sign up for Science Times We’ll bring you stories that capture the wonders of the human body, nature and the cosmos. Ideally, about 12 hours after hatching, the chicken-sexer gently squeezes open the multipurpose vent under the tail called the cloaca and exposes a key area of the interior. Several folds of mucus membrane can be seen, and the male sex organ, if present, can be found visually or by touch in an indentation on the second fold. It is a tiny bump, about the size of a pinpoint. It takes a lot of skill and practice to use this method without harming the chicks, so it is mostly done by trained chicken-sexers — who are often well paid for their expertise. © 2019 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: 26352 - Posted: 06.25.2019

By Katie Thomas The Food and Drug Administration has approved a new drug to treat low sexual drive in women, the only one besides Addyi, which entered the market in 2015. The drug, to be called Vyleesi, will be sold by AMAG Pharmaceuticals and is intended to be used 45 minutes before sex, via an auto-injector pen that is administered in the thigh or abdomen. “We’re obviously thrilled about being able to bring another option to patients,” said Dr. Julie Krop, the chief medical officer of AMAG, which is based in Waltham, Mass. “These women have suffered significantly, pretty much in silence, for a stigmatized condition, and many of them have not known that it’s a treatable medical condition.” For years, the F.D.A. has been under pressure to encourage more treatments for women with low sexual drive — a condition known as hypoactive sexual desire disorder. Medications for men experiencing erectile dysfunction arrived on the market two decades ago. But these treatments for women have provoked controversy. The first product, Addyi, was approved amid an industry-backed publicity campaign painting detractors as sexist. But some opponents argued its risks outweighed its benefits. Addyi must be taken every day and cannot be taken with alcohol, which can cause fainting. Soon after it went on sale, Addyi was acquired by Valeant Pharmaceuticals for $1 billion, which then failed to promote it. Valeant sold it back to its original owners in 2017 and the drug’s sales have been tepid. Company officials declined to say how much Vyleesi would cost and said they would provide more details when the product goes on sale later this year. They said they expected insurance to cover Vyleesi on a scale similar to Addyi and to male erectile dysfunction drugs — coverage of those drugs by commercial health care plans is mixed. © 2019 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: 26347 - Posted: 06.22.2019

Bethany Brookshire When researchers release a new finding about the brain, it’s often mice or rats who have run the mazes and taken the tests for science. People might wonder: Are rodents good substitutes for humans? Maybe for men, but what about women? That’s less likely, because most neuroscience experiments don’t use female rodents — a fact one scientist says comes from outdated ideas that should go into the scientific dustbin. For years, many scientists have dismissed female rodents as too variable to use in the lab, with tricky hormone surges that can affect behavior and compromise study results. In 2009, male lab mammals in neuroscience studies outnumbered females 5.5 to 1, according to a 2011 study in Neuroscience & Biobehavioral Reviews. “The idea that women are primarily driven by ovarian hormones [was] a narrative put in place intentionally in the Victorian era,” says Rebecca Shansky, a neuroscientist at Northeastern University in Boston. “That has also infiltrated the way we think about female animals” in science. Male animals can be just as “hormonal” as their female counterparts, Shansky argues in an essay published May 31 in Science, and it’s time that both sexes got equal attention in the lab. Here are five things to know about the issue of sex in the study of rodent brains. In humans, reproductive hormones such as estrogen and progesterone ebb and flow over a roughly 28-day cycle. In rodents, that cycle is compressed to four or five days. Estrogen or progesterone levels on one day could be up to four times as much as on the day before. |© Society for Science & the Public 2000 - 2019

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: 26342 - Posted: 06.20.2019

By Mitch Leslie If papers published in the past 6 months are right, a single number is enough to show whether people are likely to suffer a premature heart attack, land first authorship on published papers, become dependent on alcohol, or put on fat around the middle. That magic number is the ratio between the lengths of the second and fourth fingers, known as the 2D:4D ratio. It tends to be lower in men—meaning their fourth fingers tend to be longer than their second—than in women. Researchers who believe in its predictive power say it reflects a fetus's exposure to testosterone and other hormones that guide development, including that of the brain. The idea that the lengths of human fingers reveal so much stems from the work of evolutionary biologist John Manning, now at Swansea University in the United Kingdom. But the field he inspired has ballooned beyond what he could have imagined. More than 1400 papers in just over 20 years have linked the finger ratio to attributes such as personality, cognitive abilities, and sexual orientation as well as to risk of illnesses such as cardiovascular disease, cancer, and amyotrophic lateral sclerosis. Researchers have even tried to use ratios gleaned from stenciled handprints on cave walls to determine whether the artists behind ancient paintings were men or women. But the notion has also riled plenty of critics, who argue that researchers who rely on the 2D:4D comparison have been seduced by a simplistic, faulty measure. Some doubters contend that the difference in ratios between the sexes is an illusion resulting from men's larger hands or that the measure itself is statistically problematic. "I'm skeptical about every single finding involving that ratio," says physiologist and biostatistician Douglas Curran-Everett of National Jewish Health in Denver. © 2019 American Association for the Advancement of Science

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: 26311 - Posted: 06.07.2019

By Marisa Iati A bill in Alabama awaiting the governor’s signature would require people convicted of certain sex offenses to undergo “chemical castration” as a condition of parole — a requirement meant to keep perpetrators from committing similar crimes. The proposed law, passed by the state legislature, says a judge must order anyone convicted of a sex offense involving a child under the age of 13 to start receiving testosterone-inhibiting medication a month before their release from prison. Most offenders would have to pay for their treatment, which would be administered by the Department of Public Health, until a judge decides the medication is no longer necessary. Under the proposed law, a judge — and not a doctor — would tell the offender about the effects of the treatment. An offender could choose to stop getting the medication and return to prison to serve the remainder of their term. Anyone who stopped receiving the castration treatment without approval would be considered guilty of a Class C felony, punishable under Alabama law by up to 10 years in prison and a fine of up to $15,000. “Chemical castration” is a misnomer, as the process leaves the testes intact, can be reversed and does not prevent a man from reproducing. It does not guarantee a man’s sexual urge will be eliminated. (There’s no consensus on whether chemical castration would be effective for women.) © 1996-2019 The Washington Post

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: 26304 - Posted: 06.06.2019