Links for Keyword: Sexual Behavior

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By Emily Willingham When a male sand-sifting sea star in the coastal waters of Australia reaches out a mating arm to its nearest neighbor, sometimes that neighbor is also male. Undaunted, the pair assume their species’ pseudocopulation position and forge ahead with spawning. Mating, pseudo or otherwise, with a same-sex neighbor obviously does not transfer a set of genes to the next generation—yet several sea star and other echinoderm species persist with the practice. They are not alone. From butterflies to birds to beetles, many animals exhibit same-sex sexual behaviors despite their offering zero chance of reproductive success. Given the energy expense and risk of being eaten that mating attempts can involve, why do these behaviors persist? One hypothesis, hotly debated among biologists, suggests this represents an ancient evolutionary strategy that could ultimately enhance an organism’s chances to reproduce. In results published recently in Nature Ecology & Evolution, Brian Lerch and Maria R. Servedio, from the University of North Carolina, Chapel Hill, offer theoretical support for this proposed explanation. They created a mathematical model that calculated scenarios in which mating attempts, regardless of partner sex, might be worth it. The results predicted that, depending on life span and mating chances, indiscriminate mating with any available candidates could in fact yield a better reproductive payoff than spending precious time and energy sorting out one sex from the other. Although this study does not address sexual orientation or attraction, both of which are common among vertebrate species, it does get at some persistent evolutionary questions: when did animals start distinguishing mates by sex, based on specific cues, and why do some animals apparently remain indiscriminate in their choices? © 2020 Scientific American

Related chapters from BN: 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: 27603 - Posted: 12.05.2020

By Sabrina Imbler In the spring of 2018 at the Montreal Insectarium, Stéphane Le Tirant received a clutch of 13 eggs that he hoped would hatch into leaves. The eggs were not ovals but prisms, brown paper lanterns scarcely bigger than chia seeds. They were laid by a wild-caught female Phyllium asekiense, a leaf insect from Papua New Guinea belonging to a group called frondosum, which was known only from female specimens. Phyllium asekiense is a stunning leaf insect, occurring both in summery greens and autumnal browns. As Royce Cumming, a graduate student at the City University of New York, puts it, “Dead leaf, live leaf, semi-dried leaf.” Mr. Le Tirant, the collections manager of the insectarium since 1989, specializes in scarab beetles; he estimates that he has 25,000 beetles in his private collection at home. But he had always harbored a passion for leaf insects and had successfully bred two species, a small one from the Philippines and a larger one from Malaysia. A Phyllium asekiense — rare, beautiful and, most important, living — would be a treasure in any insectarium. In the insect-rearing laboratory, Mario Bonneau and other technicians nestled the 13 eggs on a mesh screen on a bed of coconut fibers and spritzed them often with water. In the fall, and over the course of several months, five eggs hatched into spindly black nymphs. The technicians treated the baby nymphs with utmost care, moving them from one tree to another without touching the insects, only whatever leaf they clung to. “Other insects, we just grab them,” Mr. Le Tirant said. “But these small leaf insects were so precious, like jewels in our laboratory.” The technicians offered the nymphs a buffet of fragrant guava, bramble and salal leaves. Two nymphs refused to eat and soon died. The remaining three munched on bramble, molted, munched, molted, and molted some more. One nymph grew green and broad, just like her mother. © 2020 The New York Times Company

Related chapters from BN: 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: 27601 - Posted: 12.05.2020

Moles have a pretty tough life. They live underground, in the dark, burrowing through heavy dirt. And when faced with an enemy, there's nowhere to turn — they have to fight. In most mammals, females tend to be at a disadvantage when it comes to face-to-face combat, because they tend to be smaller and less aggressive than males. But female moles have evolved a secret weapon: a hybrid organ made up of both ovarian and testicular tissue. This effectively makes them intersex, giving them an extra dose of testosterone to make them just as muscular and aggressive as male moles. "As a consequence, basically the whole body of the female, they get masculinized," geneticist Darío Lupiáñez told Quirks & Quarks host Bob McDonald. "They become the body builders of nature." Lupiáñez co-led a study to understand how the moles' genes facilitated this advantage, which was recently published in the journal Science. The research was part of a collaboration between the Max Planck Institute for Molecular Genetics and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association in Germany. Same genes, different instructions The team worked with Iberian moles, commonly found in Spain and Portugal, however this intersex adaptation has been documented in at least six mole species. "We know that intersexuality happens in species like humans, dogs or cats. But the difference actually in moles, it happens all the time, so all the females are intersexual. And this is really something unique among mammals," said Lupiáñez. To understand how moles evolved these intersexual traits, researchers fully mapped the genome of the Iberian mole, commonly found in Spain and Portugal. (David Carmona, Department of Genetics, University of Granada, Spain ) ©2020 CBC/Radio-Canada.

Related chapters from BN: 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: 27530 - Posted: 10.19.2020

By Aayushi Pratap In Rector, Pa., researchers have spotted one strange bird. This rose-breasted grosbeak has a pink breast spot and a pink “wing pit” and black feathers on its right wing — telltale shades of males. But on its left side, the songbird displays yellow and brown plumage, hues typical of females. Annie Lindsay had been out capturing and banding birds with identification tags with her colleagues at Powdermill Nature Reserve in Rector on September 24 when a teammate hailed her on her walkie-talkie to alert her of the bird’s discovery. Lindsay, who is banding program manager at Powdermill, immediately knew what she was looking at: a half-male, half-female creature known as a gynandromorph. “It was spectacular. This bird is in its nonbreeding [plumage], so in the spring when it’s in its breeding plumage, it’s going to be even more starkly male, female,” Lindsay says. The bird’s colors will become even more vibrant, and “the line between the male and female side will be even more obvious.” Gynandromorphs are found in many species of birds, insects and crustaceans such as crabs and lobsters. This bird is likely the result of an unusual event when two sperm fertilize an egg that has two nuclei instead of one. The egg can then develop male sex chromosomes on one side and female sex chromosomes on the other, ultimately leading to a bird with a testis and other male characteristics on one half of its body and an ovary and other female qualities on the other half. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27506 - Posted: 10.07.2020

By Cara Giaimo Last year, Katie Goldin was walking in her Los Angeles neighborhood when she saw, in the middle of the sidewalk, two lizards interlocked. The male, flecked like a pebble and about a foot long, had his jaws fully around the slightly smaller female’s head. “He was tenderly clasping her neck in his mouth,” said Ms. Goldin, host of a podcast called “Creature Feature.” “She seemed like she was in a trance.” Even in a world absolutely full of bizarre reproductive strategies, southern alligator lizards are up there. The pair Ms. Goldin spotted were engaged in what’s known as “mate-holding,” a part of the copulatory process in which a male grips a female’s head in his mouth for hours or even days at a time. It’s not clear why the lizards do this. But recently, two research projects have looked into the animals’ ecology and anatomy to better understand where, when and how this strange behavior happens. By approaching the same subject from these very different vantage points, scientists can inform each other’s research, and get a clearer picture of what’s really going on. Spying on lizard sex, for science After Ms. Goldin saw the happy couple, she sent pictures to the Natural History Museum of Los Angeles County. Since 2015, the museum has put out a yearly call for photos and videos of alligator lizards getting it on, which it collects through emails, social media and the platform iNaturalist. The species is the most widespread reptile in Los Angeles. But because the city is a “jigsaw puzzle of private property,” it’s difficult to do traditional wildlife surveys, said Greg Pauly, the museum’s herpetology curator. There are only a handful of published accounts of the lizard’s mating behavior in the scientific literature. © 2020 The New York Times Company

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 27500 - Posted: 09.30.2020

By Ann Gibbons Neanderthals have long been seen as uber-masculine hunks, at least compared with their lightweight human cousins, with whom they competed for food, territory, and mates. But a new study finds Homo sapiens men essentially emasculated their brawny brethren when they mated with Neanderthal women more than 100,000 years ago. Those unions caused the modern Y chromosomes to sweep through future generations of Neanderthal boys, eventually replacing the Neanderthal Y. The new finding may solve the decade-old mystery of why researchers have been unable to find a Neanderthal Y chromosome. Part of the problem was the dearth of DNA from men: Of the dozen Neanderthals whose DNA has been sequenced so far, most is from women, as the DNA in male Neanderthal fossils happened to be poorly preserved or contaminated with bacteria. “We began to wonder if there were any male Neanderthals,” jokes Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology and senior author of the new study. But in a technical breakthrough, Max Planck graduate student Martin Petr designed a set of probes that used the DNA sequence from small chunks of modern men’s Y chromosomes to “fish out” and bind with DNA from archaic men’s Y chromosomes. The new method works because the Neanderthal and modern human chromosomes are mostly similar; the DNA probes also reel in the few basepairs that differ. The researchers probed the fragmentary Y chromosomes of three Neanderthal men from Belgium, Spain, and Russia who lived about 38,000 to 53,000 years ago, and two male Denisovans, close cousins of Neanderthals who lived in Siberia’s Denisova Cave about 46,000 to 130,000 ago. When the researchers sequenced the DNA, they got a surprise: The Neanderthal Y “looked more like modern humans’ than Denisovans’,” Kelso says. © 2020 American Association for the Advancement of Science.

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27484 - Posted: 09.25.2020

Zeeya Merali Discovering the “on-and-off switch” for good parenting in male and female mouse brains has earned Catherine Dulac, a molecular biologist at Harvard University in Cambridge, Massachusetts, one of this year’s US$3-million Breakthrough prizes — the most lucrative awards in science and mathematics. Three other major prizes in biology, plus two in physics and one in mathematics, were also announced on 10 September, together with a number of smaller prizes. “Catherine Dulac has done amazing work that has really transformed the field,” says biologist Lauren O’Connell at Stanford University, California. Dulac’s team provided the first evidence that male and female mouse brains have the same neural circuitry associated with parenting, which is just triggered differently in each sex1. “It went against the dogma that for decades said that male and female brains are organized differently,” says O’Connell. Dulac says she was stunned to learn that she had won the award. “My brain froze, then I began to tear up,” she says, adding that it had been a long road to acceptance, because others had initially been sceptical of her work. In the 1990s, Dulac isolated the pheromone receptors in mice that govern sex-specific social behaviours. Virgin male mice usually attack other males and kill pups. But Dulac found that if their pheromone receptors were blocked, they would attempt to mate with both males and females, and virgin males would even care for pups. Pheromone-blind females, by contrast, would attempt to mount males. © 2020 Springer Nature Limited

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27467 - Posted: 09.12.2020

By Katharine Q. Seelye Shere Hite, who startled the world in the 1970s with her groundbreaking reports on female sexuality and her conclusion that women did not need conventional sexual intercourse — or men, for that matter — to achieve sexual satisfaction, died on Wednesday at her home in London. She was 77. Her husband, Paul Sullivan, confirmed the death to The Guardian. The newspaper quoted a friend of Ms. Hite’s as saying that she had been treated for Alzheimer’s and Parkinson’s diseases. Her most famous work, “The Hite Report: A Nationwide Study of Female Sexuality” (1976), challenged societal and Freudian assumptions about how women achieved orgasm: It was not necessarily through intercourse, Ms. Hite wrote; women, she found, were quite capable of finding sexual pleasure on their own. However obvious her conclusions might seem today, they were seismic at the time and “sparked a revolution in the bedroom,” as Ms. magazine reported. For all the women who had faked orgasm during intercourse, the Hite Report helped awaken their sexual power and was seen as advancing the liberation of women that was rapidly underway. The book became an instant best seller and has been translated into a dozen languages. More than 48 million copies have been sold worldwide. What set the Hite Report apart from other studies were the questionnaires at the heart of it. More than 3,000 women were given anonymity in answering the queries, allowing them to write candidly and open-endedly — not in response to multiple-choice questions — about their experiences. “Researchers should stop telling women what they should feel sexually and start asking them what they do feel sexually,” Ms. Hite wrote. She described her questionnaires as a “giant rap session on paper.” In revelatory first-person testimonials, more than 70 percent of the respondents shattered the notion that women received sufficient stimulation during basic intercourse to reach climax. Rather, they said, they needed stimulation of the clitoris but often felt guilty and inadequate about it and were too embarrassed to tell their sexual partners. © 2020 The New York Times Company

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27464 - Posted: 09.12.2020

Sean Ingle The double Olympic 800m champion Caster Semenya appears to have lost her long-running legal battle against regulations requiring women with high testosterone to take medication to compete internationally between 400m and a mile. A Swiss federal tribunal said on Tuesday that it supported a decision by the court of arbitration for sport last year that track and field’s policy for athletes with differences in sex development (DSD) was “necessary, reasonable and proportionate” to ensure fair competition in women’s sport. Charley Hull withdraws from ANA Inspiration after positive Covid-19 test Read more “Based on these findings, the Cas decision cannot be challenged,” the tribunal said. “Fairness in sport is a legitimate concern and forms a central principle of sporting competition. It is one of the pillars on which competition is based.” It now looks impossible for Semenya, the London 2012 and Rio 2016 gold medallist, to defend her title in Tokyo. She responded to the news by accusing World Athletics of being on the “wrong side of history”. “I am very disappointed by this ruling, but refuse to let World Athletics drug me or stop me from being who I am,” she said. “Excluding female athletes or endangering our health solely because of our natural abilities puts World Athletics on the wrong side of history. I will continue to fight for the human rights of female athletes, both on the track and off the track, until we can all run free the way we were born.” The South African was almost unstoppable until World Athletics implemented a new policy for DSD athletes, including Semenya, that compelled them to reduce their testosterone levels to less than 5 nmol/L if they wanted to compete in elite events between 400m and a mile. © 2020 Guardian News & Media Limited

Related chapters from BN: 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: 27462 - Posted: 09.09.2020

A line of elephants trundles across a dusty landscape in northern Botswana, ears flapping and trunks occasionally brushing the ground. As they pass a motion-activated camera hidden in low shrubbery, photos record the presence of each elephant. What's special about this group? It's only males. Female elephants are known to form tight family groups led by experienced matriarchs. Males were long assumed to be loners, because they leave their mother's herd when they reach 10 to 20 years of age. A new study shows that teenage males aren't anti-social after all. Younger male elephants were seen tagging along behind older males as they travel from place to place. It's more evidence in an emerging body of research that shows older males — like their female counterparts — play an important role in elephants' complex society. For the study published Thursday in the journal Scientific Reports, researchers analyzed photos of 1,264 sightings of male African savannah elephants travelling toward the Boteti River in 2017 and 2018. They found that younger males seldom travelled alone and older males most often led groups of mixed ages. "Mature male elephants often take a position at the front of the line when they are leading the group" to streams or seasonal grazing grounds, said Diana Reiss, director of the Animal Behavior and Conservation Program at Hunter College, who was not involved in the new study. "In human societies, grandparents are valued because they make really important contributions — helping with childcare and passing down knowledge gained over decades," she said. "We're now learning this pattern is also true for some other long-lived mammals, including dolphins, whales and elephants." Photos of 1,264 sightings of male African savannah elephants travelling toward the Boteti River in 2017 and 2018 showed that younger males seldom travelled alone and older males most often led groups of mixed ages. (Connie Allen) ©2020 CBC/Radio-Canada

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 27452 - Posted: 09.05.2020

For Armin Raznahan, publishing research on sex differences is a fraught proposition. Now chief of the section on developmental neurogenomics at the National Institutes of Health, Raznahan learned early that searching for dissimilarities between men’s and women’s brains can have unintended effects. “I got my fingers burned when I first started,” Raznahan says. As a PhD student, he published a study that examined structural differences between men’s and women’s brains and how they changed with age. “We observed a particular pattern, and we were very cautious about just describing it, as one should be, not jumping to functional interpretations,” he says. Despite his efforts, The Wall Street Journal soon published an article that cited his study in a defense of single-sex schooling, under the assumption that boys and girls must learn in distinct ways because their brain anatomy is slightly different. “That really threw me,” he says. “The experience has stayed with me.” Nevertheless, Raznahan has continued to study sex differences, in the hope that they could help us better understand neurodevelopmental disorders. He focuses on people with sex chromosome aneuploidy, or any variation other than XX (typically female) and XY (typically male). People with genetic variations (such as XXY) have an inflated risk of autism spectrum disorder, ADHD, and anxiety, among other ailments. Raznahan’s hope is that uncovering if and how men’s and women’s brains differ—for example, in the sizes of regions or the strengths of the connections among them—could help us figure out why people with aneuploidy are more likely to experience neurodevelopmental and psychiatric concerns. Solving this puzzle could be a step toward unlocking the perplexing mystery of psychiatric illness. © 2020 Condé Nast

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 27451 - Posted: 09.05.2020

By Apoorva Mandavilli The coronavirus may infect anyone, young or old, but older men are up to twice as likely to become severely sick and to die as women of the same age. Why? The first study to look at immune response by sex has turned up a clue: Men produce a weaker immune response to the virus than do women, the researchers concluded. The findings, published on Wednesday in Nature, suggest that men, particularly those over age 60, may need to depend more on vaccines to protect against the infection. “Natural infection is clearly failing” to spark adequate immune responses in men, said Akiko Iwasaki, an immunologist at Yale University who led the work. The results are consistent with what’s known about sex differences following various challenges to the immune system. Women mount faster and stronger immune responses, perhaps because their bodies are rigged to fight pathogens that threaten unborn or newborn children. But over time, an immune system in a constant state of high alert can be harmful. Most autoimmune diseases — characterized by an overly strong immune response — are much more prevalent in women than in men, for example. “We are looking at two sides of the same coin,” said Dr. Marcus Altfeld, an immunologist at the Heinrich Pette Institute and at the University Medical Center Hamburg-Eppendorf in Germany. The findings underscore the need for companies pursing coronavirus vaccines to parse their data by sex and may influence decisions about dosing, Dr. Altfeld and other experts said. © 2020 The New York Times Company

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 27435 - Posted: 08.26.2020

By Gillian R. Brassil and Jeré Longman A restrictive Idaho law — temporarily blocked by a federal judge Monday night — has amplified a charged debate about who should be allowed to compete in women’s sports, as transgender athletes have become increasingly accepted on the playing field while still facing strong resistance from some competitors and lawmakers. While scientific and societal views of sex and gender identity have changed significantly in recent decades, a vexing question persists regarding athletes who transition from male to female: how to balance inclusivity, competitive fairness and safety. There are no uniform guidelines — in fact the existing rules that govern sports often conflict — to determine the eligibility of transgender women and girls (policy battles have so far primarily centered on regulating women’s sports). And there is scant research on elite transgender athletes to guide sports officials as they attempt to provide equitable access to sports while reconciling any residual physiological advantages that may carry on from puberty. Dr. Eric Vilain, a geneticist specializing in sexual development who has advised the N.C.A.A. and the International Olympic Committee on policies for transgender athletes, said that sports leaders were confronted with “two almost irreconcilable positions” in setting eligibility standards — one relying on an athlete’s declared gender and the other on biological litmus tests. Politics, too, have entered the debate in a divided United States. While transgender people have broadly been more accepted across the country, the Trump administration and some states have sought to roll back protections for transgender people in health care, the military and other areas of civil rights, fueling a rise in hate crimes, according to the Human Rights Campaign. In March, Idaho became the first state to bar transgender girls and women from participating in women’s sports. © 2020 The New York Times Company

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 5: The Sensorimotor System
Link ID: 27426 - Posted: 08.20.2020

By Hannah Thomasy Some 2 percent of men in the U.S. identify as bisexual. But, for decades, some sexuality researchers have questioned whether true bisexual orientation exists in men. In 2005, J. Michael Bailey, a sexuality researcher at Northwestern University, and two colleagues showed men who identify as bisexual brief pornographic clips featuring men or women, while measuring their subjects’ self-reported arousal and change in penis circumference. The results, when compared to men who identified as straight or gay, led them to conclude that the men identifying as bisexual did not actually have “strong genital arousal to both male and female sexual stimuli.” This was in contrast to work on sexual arousal in women, which showed that they — whether identifying as straight or gay — were physically aroused by both male and female stimuli. A New York Times headline covering Bailey’s 2005 study on men declared: “Straight, Gay, or Lying? Bisexuality Revisited.” But the paper also spurred more research into the subject — some of which has now led Bailey to revise his conclusions. In a paper published last month in the Proceedings of the National Academy of Sciences (PNAS), Bailey and 12 colleagues reanalyzed data from eight previously published studies of bisexual-identified men, including the 2005 paper. The new review finds that men who reported attraction to both men and women do in fact show genital arousal towards both male and female stimuli. The data, the authors conclude, offers “robust evidence for bisexual orientation among men.” The PNAS study has drawn positive coverage and received praise from some activists, who see it as valuable confirmation for an often-marginalized sexual identity. But it has also received backlash from other scientists and many bisexual people, some of whom argue that in attempting to prove, based on genital arousal, that bisexuality exists, researchers are discounting bisexual people’s lived experiences. It has also reignited a broader debate over the ethics of human sexuality research — and about what role, if any, scientists should play in validating the experiences of queer people.

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27422 - Posted: 08.18.2020

A scientific analysis of more than 2,000 brain scans found evidence for highly reproducible sex differences in the volume of certain regions in the human brain. This pattern of sex-based differences in brain volume corresponds with patterns of sex-chromosome gene expression observed in postmortem samples from the brain’s cortex, suggesting that sex chromosomes may play a role in the development or maintenance of sex differences in brain anatomy. The study, led by researchers at the National Institute of Mental Health (NIMH), part of the National Institutes of Health, is published in Proceedings of the National Academy of Sciences. “Developing a clearer understanding of sex differences in human brain organization has great importance for how we think about well-established sex differences in cognition, behavior, and risk for psychiatric illness. We were inspired by new findings on sex differences in animal models and wanted to try to close the gap between these animal data and our models of sex differences in the human brain,” said Armin Raznahan, M.D., Ph.D., study co-author and chief of the NIMH Section on Developmental Neurogenomics. Researchers have long observed consistent sex-based differences in subcortical brain structures in mice. Some studies have suggested these anatomical differences are largely due to the effects of sex hormones, lending weight to a “gonad-centric” explanation for sex-based differences in brain development. However, more recent mouse studies have revealed consistent sex differences in cortical structures, as well, and gene-expression data suggest that sex chromosomes may play a role in shaping these anatomical sex differences. Although the mouse brain shares many similarities with the human brain, it is not clear whether these key findings in mice also apply to humans.

Related chapters from BN: 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 and Learning
Link ID: 27377 - Posted: 07.21.2020

Ruairi J MacKenzie Research into developing treatments for psychiatric illness is missing out vital data from female animals, producing drugs that aren’t optimized for women and contributing to the failure of clinical trials, said a panel of neuroscientists today at FENS Virtual Forum of Neuroscience. In a press conference, Professor Christina Dalla from the National and Kapodistrian University of Athens, Dr Debra Bangasser from Temple University and Professor Mohammed Milad at New York University Grossman School of Medicine spoke of the impacts of the inequitable use of female animals on their research areas. Dalla reviewed the targeting of the hypothalamic–pituitary–adrenal (HPA) axis using antidepressants. The HPA axis is a major neuroendocrine system that regulates responses to stress and many other bodily processes. Dysfunctions in the HPA axis have long thought to be a factor in the onset of depression, but drugs targeting this axis have roundly failed in clinical trials. Dalla proposed that this failure may partly be the result of pre-clinical studies using male animals, followed by clinical trials that often recruit more women than men. Bangasser and Milad respectively showed how responses to stress and fear also vary between male and female mice. The Forum, held online for the first time, has extensively addressed the representation of women in the field in its program, opening with a Mini-Conference led by the Cajal Club that celebrated the impact of women in the development of neuroscience.

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27376 - Posted: 07.21.2020

By Elizabeth Preston A clown fish uses his fins to fan water across a glistening mass of eggs, keeping them aerated. A silver arowana scoops up his fertilized eggs with his mouth and holds them gently for two months, until a host of miniature adults swims free from his jaws. A seahorse drifts through coral, his belly pouch swollen with unborn young. Most fish are uninvolved parents. They dump their eggs and sperm, then swim off and let nature take its course. But some species of fish take their parental duties more seriously — and among them, the majority of caring parents are dads. Care from mothers, or from both parents at once, is much less common. In a study published last fall in Evolution, researchers found evidence that paternal care, the system in which dads are the sole caretakers, has evolved dozens of times in fish. These fish aren’t exactly helicopter dads. Their most common parenting style is simply guarding eggs after they’re fertilized. “Some people are surprised this is considered care,” said Frieda Benun Sutton, an evolutionary biologist at the City University of New York. But it does count. To learn more about why this type of care in fish usually comes from dads, Dr. Benun Sutton and her co-author, Anthony Wilson, of Brooklyn College, took a deep dive into the family history of fish parents. They started with an evolutionary tree, built by other researchers in 2017 using genetic data, that shows how almost 2,000 fish species are related. Then they mapped onto the tree all the information they could find about parental care in those species: Were young cared for by fathers, mothers, both or nobody? They also added other factors including the size and number of each fish’s eggs and how they’re fertilized. The completed tree showed that care by fathers is no evolutionary accident: It has arisen at least 30 separate times. Hundreds of the species in this sample have absent mothers and caring fathers. But why? © 2020 The New York Times Company

Related chapters from BN: 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: 27316 - Posted: 06.22.2020

By Bethany Brookshire Biomedical science has historically been a male-dominated world — not just for the scientists, but also for their research subjects. Even most lab mice were male (SN: 6/18/19). But now, a new study shows that researchers are starting to include more females — from mice to humans — in their work. In 2019, 49 percent of articles surveyed in biomedical science used both male and female subjects, almost twice as many as a decade before, according to findings published June 9 in eLife. A study of articles published in 2009 across 10 biomedical disciplines showed a dismal picture. Only 28 percent of 841 research studies included both males and female subjects. The results were published in 2011 in Neuroscience and Biobehavioral Reviews. The scientific world took note. In 2016, the U.S. National Institutes of Health instituted the Sex as a Biological Variable policy in an effort to correct the imbalance. Scientists had to use both males and females in NIH-funded research unless they could present a “strong justification” otherwise. Annaliese Beery, a neuroscientist at Smith College in Northhampton, Mass., conducted the original study showing the extent of sex bias in research. In 2019, she and Nicole Woitowich, a chemist at Northwestern University in Evanston, Ill., wanted to see if sex bias was still as strong as it was in 2009. Have things improved? After scanning another 720 articles across nine of the 10 original disciplines, the researchers have shown that yes, they have, with nearly half of all journal articles including both males and females. Behavioral research was the most inclusive, with both sexes in 81 percent of studies. Overall, six out of nine fields surveyed showed a significant increase in studies that included both sexes. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 27297 - Posted: 06.10.2020

By Yasmin Anwar, Media Relations Stephen Glickman, a pioneer in behavioral endocrinology and founder of the world’s first colony of captive spotted hyenas — he raised generations of them in a UC Berkeley research facility — died at his home in Berkeley on May 22 from pancreatic cancer. He was 87. A professor emeritus of psychology and of integrative biology, whose lifelong bond with animals began during his boyhood near the Bronx Zoo in New York, Glickman joined the UC Berkeley faculty in 1968. Over the next five decades, he conducted studies of creatures great and small, authoring more than 100 research papers. His sharp intellect, warm wit and overall lovability engaged peers and protégés in scientific and social justice pursuits, colleagues said. “Steve was a giant in the field of animal behavior,” said UC Berkeley psychology chair Ann Kring. “He studied a wide variety of species in the wild, at the zoo and, perhaps most famously, at the field station where he conducted work with hyenas for more than 30 years.” Glickman’s standout legacy is his ardent stewardship of a colony of spotted hyenas at UC Berkeley’s Field Station for the Study of Behavior, Ecology and Reproduction. The hyena compound in the Berkeley hills, above the campus, closed in 2014 when funding dried up, but not before yielding seminal discoveries about endocrinology, fertility and other medical conditions that affect humans. Hormone-driven matriarchy By studying female hyenas, who use a long, phallic clitoris, instead of a vagina, for mating and giving birth, Glickman and fellow researchers found that high levels of androgens produced in their ovaries masculinized their sex organs and boosted their aggression and dominance in the pack. Copyright © 2020 UC Regents; all rights reserved

Related chapters from BN: 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: 27292 - Posted: 06.09.2020

by Marcus A. Banks Brain structures differ in volume depending on a person’s social environment and socioeconomic status, and between men and women, according to a new analysis1. The findings could help explain differences seen in the brains of autistic women and men, many of whom find social communication challenging. Researchers analyzed brain scans from about 10,000 people enrolled in the UK Biobank, a large-scale initiative to understand health trends in the United Kingdom. The participants were 55 years old, on average. They completed surveys, answering questions about their income level, satisfaction with friends and family, participation in social activities and feelings of loneliness. The researchers found that associations between the survey responses and the volume of brain regions linked to social contact differ by sex. For example, women who live with two or more people have a larger amygdala — a brain region involved in decision-making and emotional responses — than do women from smaller households. By contrast, household size has little effect on the size variation of amygdalae among men. The study appeared 18 March in Science Advances. The scans also showed that men who say they lack social support from siblings and friends tend to have a larger nucleus accumbens, part of the brain’s reward circuitry, than men who reported having more social support. The researchers did not see this difference in women. Other differences between men and women appeared in networks involving multiple brain regions, such as those involved with visual processing. © 2020 Simons Foundation

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 27260 - Posted: 05.21.2020