Chapter 8. Hormones and Sex

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By Meghan Rosen An experimental weight loss procedure cranks up the heat to dial down hunger. Blasting a patch of patients’ stomach lining with thermal energy curbed hunger and cut pounds, researchers reported in a small pilot study to be presented at the annual Digestive Disease Week meeting on May 19 in Washington, D.C. Called gastric fundus mucosal ablation, the procedure relies on an endoscope, a thin tube that can be threaded down the throat. It takes less than an hour and doesn’t require hospitalization. “The advantage of this is that it’s a relatively straightforward procedure,” says Cleveland Clinic surgical endoscopist Matthew Kroh, who was not involved with the work. Side effects, which included mild nausea and cramping, are minimal, one study author said in a news conference on May 8. That’s a big difference from bariatric surgery, considered the gold standard treatment for obesity, which includes many techniques to restrict stomach size or affect food absorption. Patients can be hospitalized for days and take weeks to recover. Obese people often avoid these treatments because they don’t want to endure surgery, Kroh says. The new procedure could one day offer an easier option — if the results hold up in larger groups of patients. “There’s potential,” Kroh says, “but I think we have to be cautious.” The trial included 10 women, so the method is still at the proof-of-concept stage. On average, the women lost nearly 8 percent of their body weight, some 19 pounds, over six months. That’s less than patients typically see from bariatric surgery or pharmaceutical treatments like the anti-obesity drug Wegovy (SN 12/13/23). © Society for Science & the Public 2000–2024.

Keyword: Obesity; Hormones & Behavior
Link ID: 29311 - Posted: 05.18.2024

By Clay Risen Academic conferences are usually staid affairs, but the 1973 International Symposium on Gender Identity, held in Dubrovnik, Yugoslavia, was an exception. Everything was peaceful until a psychologist named John Money stood and yelled, “Mickey Diamond, I hate your guts!” Milton Diamond, a sexologist who had gone by Mickey since childhood, was sitting on the other side of the room. Dr. Money and Dr. Diamond were bitter rivals: Dr. Money, a nationally recognized researcher at Johns Hopkins University, had long argued that sexual and gender identity are neutral at birth and shaped primarily by an infant’s surroundings. Dr. Diamond, who was just beginning his career at the University of Hawaii, strongly disagreed, and had said so repeatedly — including in a widely read 1965 critique of Dr. Money’s work. He took particular issue with Dr. Money’s recommendation that intersex infants have surgery to “correct” their genitals. Dr. Money rushed over to Dr. Diamond, getting in his face, furiously insisting he was right. Dr. Diamond only replied, “The data is not there.” At one point, eyewitnesses reported that Dr. Money slugged Dr. Diamond, though Dr. Diamond later said he didn’t remember it. The incident, reported by the journalist John Colapinto in Rolling Stone magazine and in a subsequent book, “As Nature Made Him: The Boy Who Was Raised as a Girl” (2000), was especially heated because of a recent announcement by Dr. Money. He had been working with a child who in 1965, after his penis was irreparably damaged during a circumcision, had undergone further surgery to remove his male genitalia. The child was then raised as a girl, taking on all the conventional physical and emotional characteristics of a female adolescent — happily, Dr. Money said. Though the child was not born intersex, Dr. Money claimed that the case proved that gender and sexual identity were malleable and that intersex children should indeed receive surgery. © 2024 The New York Times Company

Keyword: Sexual Behavior
Link ID: 29297 - Posted: 05.09.2024

By Gillian Dohrn “Puppy-dog eyes didn’t just evolve for us, in domestic dogs,” says comparative anatomist Heather Smith. Her team’s work has thrown a 2019 finding1 that the muscles in dogs’ eyebrows evolved to communicate with humans in the doghouse by showing that African wild dogs also have the muscles to make the infamous pleading expression. The study was published on 10 April in The Anatomical Record2. Now, one of the researchers who described the evolution of puppy-dog eyebrow muscles is considering what the African dog discovery means for canine evolution. “It opens a door to thinking about where dogs come from, and what they are,” says Anne Burrows, a biological anthropologist at the Duquesne University in Pittsburgh, Pennsylvania, and author of the earlier paper. The 2019 study garnered headlines around the world when it found that the two muscles responsible for creating the sad–sweet puppy-dog stare are pronounced in several domestic breeds (Canis familiaris), but almost absent in wolves (Canis lupus). If the social dynamic between humans and dogs drove eyebrow evolution, Smith wondered whether the highly social African wild dog might also have expressive brows. African wild dogs (Lycaon pictus) are native to sub-Saharan Africa. Between 1997 and 2012, their numbers dropped by half in some areas. With only 8,000 or so remaining in the wild, studying them is difficult but crucial for conservation efforts. Smith, who is based at Midwestern University in Glendale, Arizona, and her colleagues dissected a recently deceased African wild dog from Phoenix Zoo. They found that both the levator anguli oculi medalis (LAOM) and the retractor anguli oculi lateralis (RAOL) muscles, credited with creating the puppy-dog expression, were similar in size to those of domestic dog breeds.

Keyword: Emotions; Sexual Behavior
Link ID: 29295 - Posted: 05.07.2024

By Elizabeth Anne Brown The beluga whale wears its heart on its sleeve — or rather, its forehead. Researchers have created a visual encyclopedia of the different expressions that belugas (Delphinapterus leucas) in captivity seem to make with their highly mobile “melon,” a squishy deposit of fat on the forehead that helps direct sound waves for echolocation. Using muscles and connective tissue, belugas can extend the melon forward until it juts over their lips like the bill of a cap; mush it down until it’s flattened against their skull; lift it vertically to create an impressive fleshy top hat; and shake it with such force that it jiggles like Jell-O. “If that doesn’t scream ‘pay attention to me,’ I don’t know what does,” says animal behaviorist Justin Richard of the University of Rhode Island in Kingston. “It’s like watching a peacock spread their feathers.” Before Richard became a scientist, he spent a decade as a beluga trainer at the Mystic Aquarium in Connecticut, working closely with the enigmatic animals. “Even as a trainer, I knew the shapes meant something,” Richard says. “But nobody had been able to put together enough observations to make sense of it.” Over the course of a year, from 2014 to 2015, Richard and colleagues recorded interactions between four belugas at the Mystic Aquarium. Analyzing the footage revealed that the belugas make five distinct melon shapes the scientists dubbed flat, lift, press, push and shake. The belugas sported an average of nearly two shapes per minute during social interaction, the team reports March 2 in Animal Cognition. © Society for Science & the Public 2000–2024

Keyword: Animal Communication; Evolution
Link ID: 29291 - Posted: 05.03.2024

By Michael S. Rosenwald Prairie voles are stocky rodents and Olympian tunnellers that surface in grassy areas to feast on grass, roots and seeds with their chisel-shaped teeth, sprouting migraines in farmers and gardeners. But to Larry Young, they were the secret to understanding romance and love. Professor Young, a neuroscientist at Emory University in Atlanta, used prairie voles in a series of experiments that revealed the chemical process for the pirouette of heart-fluttering emotions that poets have tried to put into words for centuries. He died on March 21 in Tsukuba, Japan, where he was helping to organize a scientific conference. He was 56. The cause was a heart attack, his wife, Anne Murphy, said. With their beady eyes, thick tails and sharp claws, prairie voles are not exactly cuddly. But among rodents, they are uniquely domestic: They are monogamous, and the males and females form a family unit to raise their offspring together. “Prairie voles, if you take away their partner, they show behavior similar to depression,” Professor Young told The Atlanta-Journal Constitution in 2009. “It’s almost as if there’s withdrawal from their partner.” That made them ideal for laboratory studies examining the chemistry of love. In a study published in 1999, Professor Young and his colleagues exploited the gene in prairie voles associated with the signaling of vasopressin, a hormone that modulates social behavior. They boosted vasopressin signaling in mice, which are highly promiscuous. Headline writers were amused. “Gene Swap Turns Lecherous Mice Into Devoted Mates,” The Ottawa Citizen declared. The Fort Worth Star-Telegram: “Genetic Science Makes Mice More Romantic.” The Independent in London: “‘Perfect Husband’ Gene Discovered.” © 2024 The New York Times Company

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 29288 - Posted: 05.03.2024

By Joshua Cohen In the U.S., 23 states have passed legislation to ban medicalized care for minors with gender dysphoria, or the experience of distress that can occur when a person’s gender identity does not match the sex they were assigned at birth. On the other hand, 12 state legislatures have introduced laws to protect access to youth transgender care. Such care can include puberty blockers, which are medications that suppress the body’s production of sex hormones, and cross-sex hormones like testosterone or estrogen that alter secondary sex characteristics. It also may include sexual reassignment surgery in rare instances. U.S. policies on both ends of the spectrum are not science-driven but rather emanate from polar-opposite ideologies. Unlike in Europe, there doesn’t appear to be room for a non-ideological process for determining what the best care is that weighs the emerging clinical evidence and adjusts policies accordingly. As reported in Axios, state efforts to restrict various forms of transgender medicine are being fueled by religious groups that aim to shape policy based on their strongly held beliefs around the immutability of gender and family. Faith-based objections to transgender care come from a worldview in which God created humans as male or female. Here, the role of parents’ rights features prominently, as well as a conviction that adolescents are insufficiently mature to decide on trans alterations to their bodies. Moreover, lawmakers point out that some young people later regret having had irreversible body-altering treatment. The bans on care can be driven by extreme religious views. In one example, The Associated Press reported last year that Oklahoma state Sen. David Bullard introduced what he called the “Millstone Act” — a bill that would make the act of providing gender transition procedures to anyone under the age of 26 a felony — by citing a Bible passage that suggests those who cause children to sin should be drowned. The age limit was later lowered to 18.

Keyword: Sexual Behavior
Link ID: 29287 - Posted: 05.03.2024

In 2023, students protested against a new policy in Texas, where parents would be notified if their child asks to be identified as transgender.Credit: Brett Coomer/Houston Chronicle/Getty This week, Nature is launching a collection of opinion articles on sex and gender in research. Further articles will be published in the coming months. The series will highlight the necessity and challenges of studying a topic that is both hugely under-researched and, increasingly, the focus of arguments worldwide — many of which are neither healthy nor constructive. Some scientists have been warned off studying sex differences by colleagues. Others, who are already working on sex or gender-related topics, are hesitant to publish their views. Such a climate of fear and reticence serves no one. To find a way forward we need more knowledge, not less. Nearly 20 researchers from diverse fields, including neuroscience, psychology, immunology and cancer, have contributed to the series, which provides a snapshot of where scholars studying sex and gender are aligned — and where they are not. In time, we hope this collection will help to shape research, and provide a reference point for moderating often-intemperate debates. In practice, people use sex and gender to mean different things. But researchers studying animals typically use sex to refer to male and female individuals, as defined by various anatomical and other biological features. In studies involving humans, participants are generally asked to identify their own sex and/or gender category. Here, gender usually encompasses social and environmental factors, including gender roles, expectations and identity. © 2024 Springer Nature Limited

Keyword: Sexual Behavior
Link ID: 29281 - Posted: 05.02.2024

By Tim Vernimmen Most amphibians aren’t exactly doting parents — they just find a partner and release as many eggs or sperm as possible, in hopes that viable larvae will hatch from at least some fertilized eggs, and at least some of those larvae will survive to adulthood. Yet in as many as one in five amphibian species, one or both parents stick around to care for their offspring, using a staggering variety of strategies. The most well-known amphibian parents are the brightly colored poison frogs, a group of around 200 species that will repeatedly be leaping into view in this article. Yet their parenting skills may not be as exceptional as once thought, says biologist Jennifer Stynoski of the University of Costa Rica, who decided to study this group when she spotted them on a field trip as a student years ago. “I think they’ve just received a lot of attention because they’re so beautiful. They’re very cute to study.” So — what makes an exemplary amphibian parent? Much remains to be discovered, but some common principles have emerged. Stay away from the water Unlike reptiles and the birds that evolved from them, the ancestors of today’s amphibians never developed eggs with tough, watertight shells. This means their eggs need water to survive, as do the gilled larvae that usually come wriggling out. Yet the ponds in which many amphibians deposit their eggs are full of other animals, many eager to supplement their diet by slurping up a mouthful of eggs. “This must be one reason why so many species have evolved ways to lay their eggs away from the water,” says behavioral ecologist Eva Ringler of the University of Bern in Switzerland. © 2024 Annual Reviews

Keyword: Sexual Behavior; Evolution
Link ID: 29279 - Posted: 04.30.2024

By Angie Voyles Askham Larry Young, a neuroscientist known for illuminating oxytocin’s outsized role in social bonding, died of a heart attack last month at the age of 57. In his 30-year career at Emory University, Young teased apart the neurobiology of love and relationships—from the receptors that make voles monogamous to the hormones that shape sociability in psychiatric disorders. He founded and directed both the Center for Translational Social Neuroscience and the Silvio O. Conte Center for Oxytocin and Social Cognition at Emory, and he helped establish the Laboratory of Social Neural Networks in Tsukuba, Japan. “His impact has been enormous,” says Steven Phelps, professor of integrative biology at the University of Texas at Austin, who was Young’s first postdoctoral researcher at Emory. “He brought molecular biology to what we would call non-model organisms, the species that are normally neglected by mainstream science.” Young also fostered collaborations through the many international conferences he organized, and he raised the public profile of neuroscience research through his dedication to science communication. He served as a hub within the field of social neuroscience—someone who connected others across continents and research modalities—says Steve Chang, associate professor of psychology and neuroscience at Yale University. “Everyone feels there is now a giant hole.” Young grew up on a farm in Sylvester, Georgia, a small town that claims the title of “Peanut Capital of the World.” As a child, he loved animals and kept many pets—including, for a time, a possum that he carried around on his head, Young recalled on a podcast in 2022. He had thoughts of becoming a veterinarian but pivoted to medicine when, in his biochemistry classes at the University of Georgia, he became fascinated with genetics and how nature manages to translate a string of letters to the behaviors necessary for survival. © 2024 Simons Foundation

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 29257 - Posted: 04.16.2024

Jon Hamilton A sibling can change your life — even before you're born. That's because when males and females share a womb, sex hormones from one fetus can cause lasting changes in the others. It's called the intrauterine position phenomenon, or intrauterine position effects, and different versions of it have been observed in rodents, pigs, sheep — and, probably, humans. "It's really kind of strange to think something so random as who you develop next to in utero can absolutely change the trajectory of your development," says Bryce Ryan, a professor of biology at the University of Redlands. The phenomenon is more than a scientific oddity. It helped establish that even tiny amounts of hormone-like chemicals, like those found in some plastics, could affect a fetus. Cattle breeders in ancient Rome may have been the first people to recognize the importance of a sibling's sex. They realized that when a cow gives birth to male-female twins, the female is usually sterile. These females, known as freemartins, also act more like males when they grow up. Scientists began to understand why in the early 1900s. They found evidence that hormones from the male twin were affecting the female's development. The effect is less obvious in other mammals, Ryan says. Female offspring in rodents, for example, can still reproduce, but they have measurable differences in sexual development and tend to be more aggressive. © 2024 npr

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 29250 - Posted: 04.11.2024

By Catherine Offord Bone marrow transplants between mice can transmit symptoms and pathology associated with Alzheimer’s disease, according to a controversial study published today in Stem Cell Reports. Its authors found that healthy mice injected with marrow from a mouse strain carrying an extremely rare, Alzheimer’s-linked genetic mutation later developed cognitive problems and abnormal clumping of proteins in the brain. In claims that other scientists in the field have criticized as overstated, the team says its findings demonstrate “Alzheimer’s disease transmission” and support screening of human bone marrow, organ, and blood donors for mutations related to neurodegeneration. “The findings are not by any means conclusive,” says Lary Walker, a neuroscientist at Emory University. Although the team’s approach offers an interesting way to study potential causes of neurodegeneration, he says, “the mice do not have Alzheimer’s disease,” only certain symptoms that mimic those of the disorder and require further study. He and other scientists stress that the new findings should not deter people who medically need bone marrow or other transplants. Alzheimer’s is partly characterized by so-called plaques of beta amyloid, a fragment of a larger protein called APP, around cells in the brain. Although there are rare, early-onset versions of the disease driven by specific mutations in the gene coding for APP or related proteins, most cases arise in people over age 65 and don’t have a single known cause. Some research hints that in very unusual scenarios, Alzheimer’s could be transmitted via human tissue or medical equipment contaminated with disease-causing proteins. Earlier this year, for example, U.K. scientists described dementia and beta amyloid buildup in several people who had received injections of growth hormone from the brains of deceased donors. (The procedure was once a medical treatment for certain childhood disorders but was abandoned in the 1980s.)

Keyword: Alzheimers; Hormones & Behavior
Link ID: 29225 - Posted: 03.30.2024

By Gina Jiménez Being pregnant and giving birth changes a person’s brain, but the brain looks different depending on whether it’s examined during pregnancy or after a person gives birth, a recent study found. The research is helping disentangle some of the mysteries in the long-ignored field of maternal neuroscience. The study, published in January in Nature Neuroscience, followed more than 100 new mothers from near the end of their pregnancy until about three weeks on average after they had their baby. Previous research had examined birthing parents’ brain before they gave birth or during the postpartum period, but this study observed them both before and after birth, and it also took into account whether they had a vaginal birth or C-section. The findings reveal temporary changes in some brain regions and more permanent ones in a brain circuit that activates when people are not engaged in an active task and that is also involved in self-reflection and empathizing with others. The study has “ordered” some of the scientific disagreements in the field, says its senior author Susana Carmona, a neuroscience researcher now at Gregorio Marañón General University Hospital in Spain.* “It fills important gaps—that is why it’s novel,” says Joe Lonstein, a neuroscientist who studies animal parenting behaviors at Michigan State University but was not involved with the new paper. “There were things we just didn’t know about the timing of events.” Much of the scientific literature on pregnancy and postpartum neuroscience is only around a decade old. A 2016 study found that gray matter decreased in women after they had a baby for the first time, and the reductions persisted for at least six years after pregnancy. In contrast, other studies have observed that gray matter increases in the first weeks after people give birth. The new paper helps reconcile these results: the researchers found that women indeed lost gray matter during pregnancy and childbirth but got it back in most brain areas after they had their baby. © 2024 SCIENTIFIC AMERICAN,

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 29197 - Posted: 03.19.2024

By Jake Buehler In the middle of the night in a humid coastal rainforest, a litter of pink, hairless babies snuggle with their mother. They stir and squeak for milk, their mother obliges, and they are sated. But these are no puppies or cubs. They are snake-shaped amphibians, far closer to frogs than foxes. These ringed caecilian moms feed their hatchlings a kind of “milk” brewed in the reproductive tract, researchers report in the March 8 Science. The long, cylindrical creatures are the first egg-laying amphibians known to feed hatchlings this way. The discovery suggests the evolution of parental care across animal life is more diverse than researchers thought. For an animal with so few discernable external features, caecilians are a fount of strange biology. Caecilians are elusive, legless, burrowing amphibians that are nearly blind (SN: 6/19/17). Some species, like the ringed caecilian (Siphonops annulatus) in the new study, have poisonous slime, may be venomous and feed their own skin to their young (SN: 7/3/20). Herpetologist Carlos Jared of the Instituto Butantan in São Paulo and his colleagues have been studying these eccentric animals for years. In previous studies, the team noticed that ringed caecilian hatchlings, which live their first two months out of the egg in their mother’s care, spent much of their time around the end of her body near the shared opening of the reproductive, digestive and urinary systems — an anatomical part called the vent. The female would periodically expel a thick fluid from the vent, which the young would enthusiastically feed on. “Some [young] even stuck their heads inside this opening,” Jared says. In the new work, the team collected 16 females and their newly hatched litters from Bahia state in Brazil, bringing them into the lab for observation. There, the researchers recorded the amphibians’ interactions, accumulating over 240 hours of video footage. The team recorded 36 feedings, which often involved the babies wriggling and nibbling at their mother’s vent while making high-pitched noises. Mom would then raise that end of her body and release the fluid. This happened up to six times per day and appeared to be in response to the babies’ pleas. © Society for Science & the Public 2000–2024.

Keyword: Sexual Behavior
Link ID: 29188 - Posted: 03.09.2024

By Emily Anthes Colombia is a bird watcher’s paradise. Its stunningly diverse ecosystems — which include mountain ranges, mangrove swamps, Caribbean beaches and Amazonian rainforests — are home to more avian species than any other country on Earth. So when Hamish Spencer, an evolutionary biologist at the University of Otago in New Zealand, booked a bird-watching vacation in Colombia, he was hoping to spot some interesting and unusual creatures. He got more than he bargained for. During one outing, in early January 2023, the proprietor of a local farm drew his attention to a green honeycreeper, a small songbird that is common in forests ranging from southern Mexico to Brazil. But this particular green honeycreeper had highly unusual plumage. The left side of its body was covered in shimmering spring-green feathers, the classic coloring for females. Its right side, however, was iridescent blue, the telltale marker of a male. The bird appeared to be a bilateral gynandromorph: female on one side and male on the other. “It was just incredible,” Dr. Spencer said. “We were lucky to see it.” Gynandromorphism has been documented in a variety of birds, as well as insects, crustaceans and other organisms. But it’s a relatively rare and poorly understood phenomenon. The bird Dr. Spencer saw in Colombia is only the second known case of bilateral gynandromorphism in a green honeycreeper — and the first documented in the wild. © 2024 The New York Times Compan

Keyword: Sexual Behavior
Link ID: 29180 - Posted: 03.07.2024

Philip Hoare Whales are extraordinarily sensuous creatures. Those blubbery bodies are highly sensitive, and sensitised. At social meetings, pods of sperm, humpback and right whales will roll around one another’s bodies for hours at a time. I’ve seen a group of right whales engaged in foreplay and penetration lasting an entire morning. I have also watched a male-female couple so blissfully conjoined that they appeared unbothered by our little fishing boat as they passed underneath it. And in what may sound like a career of cetacean voyeurism, I have also been caught up in a fast-moving superpod of dusky dolphins continually penetrating each other at speed, regardless of the gender of their partner. That’s why this week’s report of the first scientifically documented male-to-male sexual interactions between two humpback whales off the coast of Hawaii is not surprising. The remarkable image of a two-metre whale penis entering another male “leaves little room for discussion that there is a sexual component to such behaviour”, as one whale scientist, Jeroen Hoekendijk at the Wageningen Marine Research institute in the Netherlands, notes drily. In fact, one of the whales was ailing and there has been speculation that the encounter may not have been consensual or that the healthy whale was actually giving comfort to the other. Whatever the truth, such “flagrant” acts also expose many of our human presumptions about sexuality, gender and identity. Off the north-west Pacific coast of the US, male orcas often leave family pods to rub their erections against each other’s bellies. But females have also reportedly been seen engaging in sexual contact with one another, too. © 2024 Guardian News & Media Limited

Keyword: Sexual Behavior
Link ID: 29173 - Posted: 03.02.2024

NIH-funded study shows prenatal mental health support is effective for women living in low-resource settings. Results from a large clinical trial funded by the National Institutes of Health show that an intervention for anxiety provided to pregnant women living in Pakistan significantly reduced the likelihood of the women developing moderate-to-severe anxiety, depression, or both six weeks after birth. The unique intervention was administered by non-specialized providers who had the equivalent of a bachelor’s degree in psychology—but no clinical experience. The results suggest this intervention could be an effective way to prevent the development of postpartum mental health challenges in women living in low-resource settings. “In low resource settings, it can be challenging for women to access mental health care due to a global shortage of trained mental health specialists,” said Joshua A. Gordon, M.D., Ph.D., Director of the National Institute of Mental Health, part of NIH. “This study shows that non-specialists could help to fill this gap, providing care to more women during this critical period." Led by Pamela J. Surkan, Ph.D., Sc.D.(link is external), of Johns Hopkins Bloomberg School of Public Health, Baltimore, the study was conducted in the Punjab Province of Pakistan between April 2019 and January 2022. Pregnant women with symptoms of at least mild anxiety were randomly assigned to receive either routine pregnancy care or a cognitive behavioral therapy (CBT)-based intervention called Happy Mother-Healthy Baby. The researchers assessed the participants (380 women in the CBT group and 375 women in the routine care group) for anxiety and depression six weeks after the birth of their child.

Keyword: Depression; Sexual Behavior
Link ID: 29165 - Posted: 02.27.2024

By Jackie Rocheleau Every day about 60,000 people have surgery under general anesthesia in the United States. Often casually compared to falling into a deep sleep, going under is in fact wildly different from your everyday nocturnal slumber. Not only does a person lose the ability to feel pain, form memories, or move—they can’t simply be nudged back into conscious awareness. But occasionally, people do wake unexpectedly—in about 1 out of every 1,000 to 2,000 surgeries, patients emerge from the fog of anesthesia into the harsh light of the operating room while still under the knife. One question that has dogged researchers over the past several decades is whether women are more likely to find themselves in these unfortunate circumstances. A number of recent studies, including a 2023 meta-analysis, suggest that the answer is yes. But the findings are controversial: Other studies have found no differences in waking frequency between the sexes and most of the studies were not designed specifically to identify sex differences. It’s also difficult to know whether other factors might have influenced the results: rates of metabolization of drugs by male and female bodies, as well as variation in kinds of surgeries and anesthetic regimens among study participants. No causal link had been established. Now, a new study published in the Proceedings of the National Academy of Sciences helps untangle some of the mystery. In a series of experiments in mice and in humans, the researchers found that females do wake more easily from anesthesia and that testosterone plays an important role in how quickly and deeply we go under, and how easily we wake up. “There seems to be something hardwired into the female brain that biases it more toward a state of wakefulness,” says University of Pennsylvania anesthesiologist Max Kelz, co-author of the study. © 2024 NautilusNext Inc., All rights reserved.

Keyword: Sexual Behavior; Sleep
Link ID: 29156 - Posted: 02.22.2024

By Christine Dell'Amore Thunderclouds rolled across Kenya’s Masai Mara savanna as the spotted hyena cubs played, tumbling over each other in the wet grass. The cubs’ mother lounged nearby, rising occasionally to discourage a bigger one-year-old from joining the little play group. When the older animal approached again, one of the pluckier cubs took a cue from its high-ranking mom and stood tall, trying its best to look intimidating. That action seemed comical, but both animals knew their place. The larger, lower ranking hyena stopped short, then bowed its head and slunk off. Photographer Jen Guyton recorded this scene with an infrared camera, allowing an intimate look into hyenas’ nocturnal behaviors. In doing so, she provided a small window into the intriguing structure of hyena society, where all members inherit their place in the pecking order from their mother. Females are in charge, and rank means everything—a matrilineal system that has fueled the spotted hyena’s rise as the most abundant large carnivore in Africa. These and other insights into hyena behavior wouldn’t be possible were it not for 35 years of on-the-ground research by Kay Holekamp, founder of the Mara Hyena Project. Her efforts have helped reveal a creature noted for its advanced society, cognition, and ability to adjust to new surroundings. Holekamp, a biologist at Michigan State University, has been studying the African species in the Masai Mara since 1988—one of the longest running investigations of any mammal ever. “I thought I’d be there for two years,” she says, “but I got hooked.” Hooked on hyenas? Mention their name, and most people grimace. Aristotle described them as “exceedingly fond of putrefied flesh.” Theodore Roosevelt called them a “singular mixture of abject cowardice and the utmost ferocity.” Across Africa, hyenas are seen as evil, greedy, and associated with witchcraft and sexual deviance. Even the 1994 movie The Lion King portrayed them as cunning and malicious. © 1996-2015 National Geographic Society

Keyword: Sexual Behavior; Evolution
Link ID: 29149 - Posted: 02.13.2024

By Matt Richtel For decades, eating disorders were thought to afflict mostly, if not exclusively, women and girls. In fact, until 2013, the loss of menstruation had long been considered an official symptom of anorexia nervosa. Over the last decade, however, health experts have increasingly recognized that boys and men also suffer from eating disorders, and they have gained a better understanding of how differently the illness presents in that group. A small but growing body of scientists and physicians have dedicated themselves to identifying the problem, assessing its scope and developing treatments. Recently, two of these experts spoke to The New York Times about how the disease is affecting adolescent boys, what symptoms and behaviors parents should look for, and which treatments to consider. Dr. Jason Nagata is a pediatrician at the University of California, San Francisco, who specializes in eating disorders; he is senior editor of the Journal of Eating Disorders and editor of the book “Eating Disorders in Boys and Men.” Dr. Sarah Smith is a child and adolescent psychiatrist at the University of Toronto who specializes in eating disorders; she was the lead author on a study published in JAMA Open Network in December that showed sharp increases in the rates of hospitalizations for boys with eating disorders. The medical and scientific understanding of eating disorders is changing and expanding. What happened? Dr. Smith: Historically, eating disorders have been conceptualized mostly as anorexia, which has been portrayed as an illness of adolescent females who want to lose weight for aesthetic reasons. Dr. Nagata: There’s increasing recognition, particularly in the last decade or so, that some people with body image dissatisfaction are not trying to lose weight at all. Some men and boys are trying to become large and muscular. In fact, one-third of teenage boys across the United States report that they’re trying to bulk up and get more muscular. And a subset of those may develop eating disorders or muscle dysmorphia that can lead to significant psychological distress and physical health complications. © 2024 The New York Times Company

Keyword: Anorexia & Bulimia; Sexual Behavior
Link ID: 29140 - Posted: 02.08.2024

By Sabrina Malhi Researchers have found a possible link between the common hormone disorder PCOS and cognitive decline later in life. PCOS, which stands for polycystic ovary syndrome, is the most common endocrine disorder among women ages 15 to 44. However, it is often underdiagnosed because many of its symptoms, including abnormal menstrual cycles and excess hair, can be attributed to other causes. The syndrome was first described in 1935 by American gynecologists Irving F. Stein and Michael L. Leventhal. They published a paper documenting a group of women with lack of periods, excess body hair and enlarged ovaries with multiple cysts. Their work helped identify and characterize PCOS as it is known today. Health experts hypothesize that genetic factors could contribute to the development of the condition, but the exact causes are still unknown. Here’s what to know about PCOS and its potential link to cognitive health. PCOS is a chronic hormonal disorder characterized by overproduction of androgens, which are typically considered male hormones. High androgen levels can lead to irregular menstrual cycles and fertility issues when excessively produced in women. In the United States, 6 to 12 percent of people assigned female at birth who are of reproductive age are affected by PCOS, according to data from the Centers for Disease Control and Prevention. The condition is associated with an increased risk of obesity, high blood pressure, high cholesterol and endometrial cancer. PCOS is also often linked to insulin resistance, which can result in elevated blood sugar levels and an escalated risk of Type 2 diabetes. The condition can contribute to various metabolic issues, including high blood pressure, excess abdominal fat, and abnormal cholesterol or triglyceride levels. People with PCOS face an elevated risk of developing cardiovascular problems, such as high blood pressure, high cholesterol levels and an increased risk of heart disease. A recent study in the journal Neurology found that people with PCOS performed lower than normal on a suite of cognitive tests.

Keyword: Hormones & Behavior; Learning & Memory
Link ID: 29132 - Posted: 02.06.2024