Chapter 8. Hormones and Sex

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


Links 1 - 20 of 3203

Darby Saxbe The time fathers devote to child care every week has tripled over the past 50 years in the United States. The increase in fathers’ involvement in child rearing is even steeper in countries that have expanded paid paternity leave or created incentives for fathers to take leave, such as Germany, Spain, Sweden and Iceland. And a growing body of research finds that children with engaged fathers do better on a range of outcomes, including physical health and cognitive performance. Despite dads’ rising participation in child care and their importance in the lives of their kids, there is surprisingly little research about how fatherhood affects men. Even fewer studies focus on the brain and biological changes that might support fathering. It is no surprise that the transition to parenthood can be transformative for anyone with a new baby. For women who become biological mothers, pregnancy-related hormonal changes help to explain why a new mother’s brain might change. But does fatherhood reshape the brains and bodies of men – who don’t experience pregnancy directly – in ways that motivate their parenting? We set out to investigate this question in our recent study of first-time fathers in two countries. Recent research has found compelling evidence that pregnancy can enhance neuroplasticity, or remodeling, in the structures of a woman’s brain. Using magnetic resonance imaging, researchers have identified large-scale changes in the anatomy of women’s brains from before to after pregnancy. In one study, researchers in Spain scanned first-time mothers before conceiving, and again at two months after they gave birth. Compared with childless women, the new mothers’ brain volume was smaller, suggesting that key brain structures actually shrank in size across pregnancy and the early postpartum period. The brain changes were so pronounced that an algorithm could easily differentiate the brain of a woman who had gone through a pregnancy from that of a woman with no children. Copyright © 2010–2022, The Conversation US, Inc.

Keyword: Sexual Behavior; Brain imaging
Link ID: 28576 - Posted: 12.03.2022

By Ingrid Wickelgren  Science has largely neglected pregnancy’s effect on the brain, even though it involves dramatic surges in steroid hormones, which are known to alter the organ. A decade ago neuroscientist Elseline Hoekzema, then a young postdoctoral fellow thinking about having her first child, and two of her female colleagues set out to bridge the knowledge gap. “There’s this enormous event involving such strong hormone changes,” says Hoekzema, now at Amsterdam University Medical Center. “It’s really weird that so little was known about this.” Their initial study, published in 2016, revealed for the first time that pregnancy produced significant structural changes in a woman’s brain that endured for at least two years after birth. Now in a new seven-year study, Hoekzema and her colleagues have seen the same structural changes in different women and have shown that pregnancy also alters the function of a key brain network involved in self-reflection. According to the work, which appeared on Nov. 22 in Nature Communications, the brain changes correlate with a mother’s enhanced bonding with her baby. The findings were derived from examining the female participants’ physiology and using questionnaires to assess their behavior and mental state. And for the first time in humans, the researchers found strong evidence that female hormones are behind it all. The biggest changes occur in a brain network that is active when the brain is idling—that is, when it is not engaged in any particular task—suggesting that pregnancy alters the organ’s baseline state. “[The researchers] are seeing these functional connectivity changes even at rest,” says Jodi Pawluski, a neuroscientist at the University of Rennes 1 in France, who studies the maternal brain and perinatal mental illness but was not involved in the study. “That speaks to the significance of this stage in a birthing person’s life and how it really is transformative in the brain.”

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 28566 - Posted: 11.23.2022

By Megan Twohey and Christina Jewett The medical guidance was direct. Eleven-year-old Emma Basques had identified as a girl since toddlerhood. Now, as she worried about male puberty starting, a Phoenix pediatrician advised: Take a drug to stop it. At 13, Jacy Chavira felt increasingly uncomfortable with her maturing body and was beginning to believe she was a boy. Use the drug, her endocrinologist in Southern California recommended, and puberty would be suspended. An 11-year-old in New York with deepening depression expressed a desire to no longer be a girl. A therapist told the family the drug was the preteen’s best option, and a local doctor agreed. “‘Puberty blockers really help kids like this,’” the child’s mother recalled the therapist saying. “It was presented as a tourniquet that would stop the hemorrhaging.” As the number of adolescents who identify as transgender grows, drugs known as puberty blockers have become the first line of intervention for the youngest ones seeking medical treatment. Their use is typically framed as a safe — and reversible — way to buy time to weigh a medical transition and avoid the anguish of growing into a body that feels wrong. Transgender adolescents suffer from disproportionately high rates of depression and other mental health issues. Studies show that the drugs have eased some patients’ gender dysphoria — a distress over the mismatch of their birth sex and gender identity. “Anxiety drains away,” said Dr. Norman Spack, who pioneered the use of puberty blockers for trans youth in the United States and is one of many physicians who believe the drugs can be lifesaving. “You can see these kids being so relieved.” But as an increasing number of adolescents identify as transgender — in the United States, an estimated 300,000 ages 13 to 17 and an untold number who are younger — concerns are growing among some medical professionals about the consequences of the drugs, a New York Times examination found. The questions are fueling government reviews in Europe, prompting a push for more research and leading some prominent specialists to reconsider at what age to prescribe them and for how long. A small number of doctors won’t recommend them at all. © 2022 The New York Times Company

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28555 - Posted: 11.16.2022

By Hannah Thomasy Ned and Sunny stretch out together on the warm sand. He rests his head on her back, and every so often he might give her an affectionate nudge with his nose. The pair is quiet and, like many long-term couples, they seem perfectly content just to be in each other’s presence. The couple are monogamous, which is quite rare in the animal kingdom. But Sunny and Ned are a bit scalier that your typical lifelong mates — they are shingleback lizards that live at Melbourne Museum in Australia. In the wild, shinglebacks regularly form long-term bonds, returning to the same partner during mating season year after year. One lizard couple in a long-term study had been pairing up for 27 years and were still going strong when the study ended. In this way, the reptiles are more like some of the animal kingdom’s most famous long-term couplers, such as albatrosses, prairie voles and owl monkeys, and they confound expectations many people have about the personalities of lizards. “There’s more socially going on with reptiles than we give them credit for,” said Sean Doody, a conservation biologist at the University of South Florida. Social behavior in reptiles has been largely overlooked for decades, but a handful of dedicated scientists have begun unraveling reptiles’ cryptic social structures. With the help of camera traps and genetic testing, scientists have discovered reptiles living in family groups, caring for their young and communicating with each other in covert ways. And they aren’t only doing this because they love lizards. Currently, one in five reptile species are threatened with extinction; researchers say learning more about reptile sociality could be crucial for conservation. Humans have a long history of animosity toward reptiles, and influential twentieth century scientists added to the idea of reptiles as cold, unintelligent beasts. In the mid-1900s, Paul MacLean, a neuroscientist at Yale and then the National Institute of Mental Health, began developing the triune brain hypothesis. He theorized that the human brain contained three parts: the reptilian R-complex, which governed survival and basic instinctual behaviors; the paleomammalian complex, which controlled emotional behavior; and the neomammalian cortex, which was responsible for higher functions like problem-solving and language. © 2022 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 28528 - Posted: 10.26.2022

By Rodrigo Pérez Ortega There’s clear evidence that racial discrimination negatively affects the health of people of color over the course of their lives. It’s associated with depression, anxiety, and psychological stress; it increases blood pressure; and it has been shown to weaken the immune system. However, few studies have linked single discriminatory events to immediate health effects. Now, data from a first-of-its-kind study suggest a racist attack could raise a person’s stress biomarkers almost immediately. “The big question mark, for me, has always been, how does this happen? What’s the black box that’s in the middle of discrimination, stress, and health disparities?” says Tiffany Yip, a developmental psychologist at Fordham University who was not involved with the study. “I think that this paper addresses that mechanistic question.” For the proof-of-concept study, Soohyun Nam at Yale University’s School of Nursing and her team collaborated with Black churches and their communities to recruit 12 Black people between the ages of 30 and 55 living in the northeastern United States. After accounting for the participants’ baseline stress levels, the research team adapted standardized survey questions about discrimination and microaggressions—such as whether they believed they had been mistaken for a service worker because of their race—and asked participants to share any occurrences of these experiences through a smartphone app. The method, known as ecological momentary assessment (EMA), has previously been used to study physical activity and behavior—such as alcohol intake reduction or smoking frequency. But this is one of the first studies correlating stress biomarkers and racist experiences using this precise monitoring technique. Researchers also asked the participants to describe their mood five times a day over the course of a week using the same phone app. To measure their biological response, participants spat into a tube four times a day over 4 days and froze the samples until research staff collected them. The researchers then had the samples analyzed in the lab to measure levels of cortisol, a hormone released during emotional distress, and alpha amylase, an enzyme that breaks down sugars and is secreted in stressful situations.

Keyword: Stress; Hormones & Behavior
Link ID: 28481 - Posted: 09.17.2022

Emily Willingham In 2016, pharmacologist Susan Howlett wrote up a study on how hormone levels during pregnancy affect heart function and sent it off to a journal. When the reviewers’ comments came back, two of the three had asked an unexpected question: where were the tissues from male mice? Because they were studying high hormone levels related to pregnancy, Howlett, at Dalhousie University in Halifax, Canada, and her team had used only female animals. “I was really surprised that they wanted us to repeat everything in males,” she said. Nonetheless, they obliged, and their findings were published in 2017. As expected, they found no effect of the hormone progesterone on heart function in males; in females, it influenced the activity of cardiac cells1. Howlett had mixed feelings about the request to add males. “It was a big ask and it was a lot more research.” But in general, she adds, it’s really important to factor sex into studies. “I’m a big proponent of doing experiments in both males and females.” Many of science’s gatekeepers — granting agencies and academic journals — feel the same way. Over the past decade or so, a growing list of funders and publishers, including the US National Institutes of Health (NIH) and the European Union, have been asking researchers to include two sexes in their work with cells and animal models. Two major catalysts motivated these policies. One was a growing recognition that sex-based differences, often related to hormone profiles or genes on sex chromosomes, can influence responses to drugs and other treatments. The other was the realization that including two sexes can increase the rigour of scientific inquiry, enhance reproducibility and open up questions for scientific pursuit. © 2022 Springer Nature Limited

Keyword: Sexual Behavior
Link ID: 28473 - Posted: 09.14.2022

Short ribs glazed in a sweet sticky sauce and slow-cooked to perfection, potato chips hand-fried and tossed with a generous coating of sour cream, chicken wings battered and double-fried so that they stay crispy for hours. What is it about these, and other, mouth-watering — but incredibly fatty — foods that makes us reach out, and keep coming back for more? How they taste on the tongue is one part of the story, but to really understand what drives “our insatiable appetite for fat,” we have to examine what happens after fat is consumed, says Columbia University’s Charles Zuker, a neuroscientist and molecular geneticist who has been a Howard Hughes Medical Institute (HHMI) Investigator since 1989. Two years ago, Zuker and his team reported how sugar, upon reaching the gut, triggers signals that are sent to the brain, thus fueling cravings for sweet treats. Now, in an article published in Nature on September 7, 2022, they describe a similar gut-to-brain circuit that underlies a preference for fat. “The gut is the source of our great desire for fat and sugar,” says Zuker. The topic in question is an incredibly timely one, given the current global obesity epidemic. An estimated 13 percent of adults worldwide are obese — thrice that in 1975. In the US, that figure is even higher — at a staggering 42 percent. “It’s a very significant and important health problem,” says Zuker. Having a high body-mass index is a risk factor for stroke, diabetes, and several other diseases. “It’s clear that if we want to help make a difference here, we need to understand the biological basis for our strong appetite for fat and sugar,” he says. Doing so will help us design interventions in the future to “suppress this strong drive to consume” and combat obesity.

Keyword: Obesity; Hormones & Behavior
Link ID: 28468 - Posted: 09.10.2022

Nicola Davis Regular doses of a hormone may help to boost cognitive skills in people with Down’s syndrome, a pilot study has suggested. Researchers fitted seven men who have Down’s syndrome with a pump that provided a dose of GnRH, a gonadotropin-releasing hormone, every two hours for six months. Six out of the seven men showed moderate cognitive improvements after the treatment, including in attention and being able to understand instructions, compared with a control group who were not given the hormone. However, experts raised concerns about the methods used in the study, urging caution over the findings. The team behind the work said brain scans of the participants, who were aged between 20 and 37, given the hormone suggest they underwent changes in neural connectivity in areas involved in cognition. “[People] with Down’s syndrome have cognitive decline which starts in the 30s,” said Prof Nelly Pitteloud, co-author of the study from the University of Lausanne. “I think if we can delay that, this would be great, if the therapy is well tolerated [and] without side effects.” Writing in the journal Science, Pitteloud and colleagues said they previously found mice with an extra copy of chromosome 16 experienced an age-related decline in cognition and sense of smell, similar to that seen in people with Down’s syndrome – who have an extra copy of chromosome 21. In a series of experiments, the team found regular doses of gonadotropin-releasing hormone boosted both the sense of smell and cognitive performance of these mice. Pitteloud said no side effects were seen in the participants and that the hormone is already used to induce puberty in patients with certain disorders. “I think these data are of course very exciting, but we have to remain cautious,” said Pitteloud. She said larger, randomised control studies are now needed to confirm that the improvements were not driven by patients becoming less stressed during assessments and thus performing better. Prof Michael Thomas of Birkbeck, University of London, who studies cognitive development across the lifespan in Down’s syndrome, said the results were exciting. “For parents, this is good news: interventions can still yield benefits across the lifespan,” he said, although he noted it is not clear how applicable the hormone therapy would be for children. © 2022 Guardian News & Media Limited

Keyword: Hormones & Behavior; Development of the Brain
Link ID: 28462 - Posted: 09.03.2022

Sofia Quaglia Dolphins form decade-long social bonds, and cooperate among and between cliques, to help one another find mates and fight off competitors, new research has found – behaviour not previously confirmed among animals. “These dolphins have long-term stable alliances, and they have intergroup alliances. Alliances of alliances of alliances, really,” said Dr Richard Connor, a behavioural ecologist at the University of Massachusetts Dartmouth and one of the lead authors of the paper. “But before our study, it had been thought that cooperative alliances between groups were unique to humans.” The findings, published on Monday in the journal Proceedings of the National Academy of Sciences, appear to support the “social brain” hypothesis: that mammals’ brains evolved to be larger in size for animals that keep track of their social interactions and networks. Humans and dolphins are the two animals with the largest brains relative to body size. “It’s not a coincidence,” Connor said. Connor’s team of researchers collected data between 2001 and 2006 by conducting intensive boat-based surveys in Shark Bay, Western Australia. The researchers tracked the dolphins by watching and listening to them, using their unique identifying whistles to tell them apart. They observed 202 Indo-Pacific bottlenose dolphins (Tursiops aduncus), including during the peak mating season between September and November. Back in the lab, they pored over data focusing on 121 of these adult male dolphins to observe patterns in their social networks. And for the next decade they continued to analyse the animals’ alliances. Dolphins’ social structures are fluid and complex. The researchers found alliances among two or three male dolphins – like best friends. Then the groups expanded to up to 14 members. Together, they helped each other find females to herd and mate with, and they help steal females from other dolphins as well as defend against any “theft” attempts from rivals. © 2022 Guardian News & Media Limited

Keyword: Sexual Behavior; Evolution
Link ID: 28457 - Posted: 08.31.2022

By Erin Blakemore There’s growing consensus on the danger of sport-related concussion — and how to treat athletes after head injuries. But the research at the heart of those recommendations has a fatal flaw, a new study suggests: It relies almost exclusively on male athletes. In a review in the British Journal of Sports Medicine, a national team of medical and concussion experts looked at 171 concussion studies cited by the three most influential consensus and position statements on sport-related concussion. These documents update professionals on how to treat athletes with concussions, providing important protocols for clinicians and setting the agenda for future research. Although the statements define the standard of care, the study suggests, they are based on data that largely excludes female athletes. Participants in the underlying studies were 80.1 percent male. Among the studies, 40.3 percent didn’t look at female athletes at all; only 25 percent of them had roughly equal male and female participation. Researchers said there could be several reasons for the disparity such as women’s historic exclusion from sports and professional sports organizations with no female counterpart. Women’s sports are underrepresented among groups that sponsor concussion research, they write. Bias in the sciences could have an effect, too: women are still underrepresented in both university faculties and scientific research. Because of the research gap, it isn’t yet clear whether females respond to concussions differently than males. Both sex and gender can cause medical conditions to develop — and be experienced, reported and treated — differently.

Keyword: Brain Injury/Concussion; Sexual Behavior
Link ID: 28432 - Posted: 08.13.2022

By Sara Goudarzi Life isn’t always easy for little mouse pups: Hours to days after they are born, the squirmy babies, who can’t hear or see, can roll or stumble away from their nest. Cold and lonely, they call out to their mother. Luckily, Mom snaps into action to ensure the adventures of the little ones are short-lived. Grabbing each pup by the skin on their backs, Mama mouse brings each baby back home to safety. The mom’s behavior is innate, burnt into the mouse brain, and requires no training. But where in the brain does it happen and how does the brain process or execute it? And what happens in those rare cases when the animal brain doesn’t properly execute such behavior? That’s what Stephen Shea is trying to answer in mice, with hopes that it may someday be applicable to humans. Shea, an associate professor at Cold Spring Harbor Laboratory, discovered that this innate mothering behavior corresponds to the firing of cells in a region of the brain called locus coeruleus, a cluster of cells that can be found in the brainstem of all vertebrates. Locus coeruleus is also the source of noradrenaline, a chemical that affects some key brain functions. Shea’s work has greater implications. He hopes that understanding the brain circuits that facilitate this very simple action could be a window into how disruptions in wiring affect social behavior, and a key into understanding inappropriate social interactions, such as those observed in people with autism spectrum disorders. And it may even shed some light on the iconic debate about whether creatures are shaped by nature or nurture. © 2022 NautilusThink Inc,

Keyword: Sexual Behavior
Link ID: 28424 - Posted: 08.06.2022

By Virginia Morell In the summer of 2013, dolphin researcher Nicole Danaher-Garcia spotted something rare and remarkable in the animal world. As she stood on top of the bridge of a sport fishing yacht near Bimini in the Bahamas, she spied 10 adult Atlantic spotted dolphins she had never seen before—speeding into the waters of another group of dolphins. Most mammals attack intruders, but war wasn’t on the menu that day. Instead, the newcomers—eventually 46 in all—joined up with the resident dolphins, some 120 in number. Today, the two groups of Atlantic spotted dolphins (Stenella frontalis) have partially integrated, diving and swimming together, forming fast friendships, and likely even mating. It’s a “striking” display of tranquility between animals scientists usually consider rivals, says Richard Wrangham, a primatologist at Harvard University who was not involved with the study. Most mammals fight to protect mates and other resources if they encounter strangers entering their territory, he notes. This research, he says, may ultimately lead to a better understanding of the evolution of peacefulness. Danaher-Garcia, a behavioral ecologist, and her colleagues at the Dolphin Communication Project observed the two groups of dolphins in Bimini for 5 years, carrying out nearly 300 surveys. At first, the scientists only saw one small group of mixed Bimini and newcomer dolphins. But the next year, the scientists spotted a larger group of males and females of all ages from both communities mixing without “any signs of aggression,” she says. The dolphins continued their friendly behaviors through 2018, leading the team to suspect the two groups were merging. (Because of COVID-19 concerns, the scientists put their studies on hold in 2020.) The scientists discovered the newcomers had migrated from Little Bahama Bank, an area some 160 kilometers to the north known for its shallow seas, coral reefs, and sand banks. They were part of the White Sand Ridge (WSR) spotted dolphin community that another scientific team has been studying since the mid-1980s. © 2022 American Association for the Advancement of Science.

Keyword: Aggression; Sexual Behavior
Link ID: 28419 - Posted: 08.03.2022

By Gina Kolata It’s been known for more than half a century that many men lose their Y chromosomes as they age. But no one knew if it really mattered. The loss of Y could just be a sign of aging, like gray hair, with no clinical relevance. Now, though, researchers report that it can matter. Very much. A new study using male mice genetically engineered to lose their Y chromosomes provides insight. The paper, published on Thursday in the journal Science, found that when the Y chromosome was gone from blood cells in those mice, scar tissue built up in the heart, leading to heart failure and a shortened life span. Because there was a direct cause-and-effect relationship between the loss of Y and ailments of aging in the mice, the study bolsters the notion that the same thing can happen in human males. Researchers have documented an increase in risk for chronic diseases like heart disease and cancer related to loss of the Y chromosome in many studies over the years, including the new one, which used data from a large genetic study of the British population. The loss of Y could even account for some of the difference between the life spans of men and women, the authors of the Science study say. Other investigators not associated with the work were impressed. “The authors really nailed it here,” said Dr. Ross Levine, the deputy physician in chief for translational research at Memorial Sloan Kettering Cancer Center. “It’s super important work.” The inspiration for the new research came when Lars Forsberg, a researcher at Uppsala University, ran into a former professor on a bus in Uppsala, Sweden, in 2013. They began talking, and the professor told Dr. Forsberg that the Y chromosomes in fruit flies were more important than previously appreciated. Dr. Forsberg was intrigued. He had never paid much attention to the loss of Y chromosomes. Males have one X and one Y (females have two X’s), and nearly all the genes used by male cells are genes on the X. Dr. Forsberg had shared the common view that the Y chromosome was pretty much a genetic wasteland. © 2022 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 28400 - Posted: 07.16.2022

By Veronique Greenwood Human beings maintain the polite fiction that we’re not constantly smelling one another. Despite our efforts to the contrary, we all have our own odors, pleasant and less so, and if we are like other land mammals, our particular perfume might mean something to our fellow humans. Some of these, like the reek of someone who hasn’t bathed all month, or the distinctive whiff of a toddler who is pretending they didn’t just fill their diaper, are self-explanatory. But scientists who study human olfaction, or your sense of smell, wonder if the molecules wafting off our skin may be registering at some subconscious level in the noses and brains of people around us. Are they bearing messages that we use in decisions without realizing it? Might they even be shaping whom we do and don’t like to spend time around? Indeed, in a small study published Wednesday in the journal Science Advances, researchers investigating pairs of friends whose friendship “clicked” from the beginning found intriguing evidence that each person’s body odor was closer to their friend’s than expected by chance. And when the researchers got pairs of strangers to play a game together, their body odors predicted whether they felt they had a good connection. There are many factors that shape whom people become friends with, including how, when or where we meet a new person. But perhaps one thing we pick up on, the researchers suggest, is how they smell. Scientists who study friendship have found that friends have more in common than strangers — not just things like age and hobbies, but also genetics, patterns of brain activity and appearance. Inbal Ravreby, a graduate student in the lab of Noam Sobel, an olfaction researcher at the Weizmann Institute of Science in Israel, was curious whether particularly swift friendships, the kind that seem to form in an instant, had an olfactory component — whether people might be picking up on similarities in their smells. © 2022 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28382 - Posted: 06.25.2022

By Emily Bazelon Scott Leibowitz is a pioneer in the field of transgender health care. He has directed or worked at three gender clinics on the East Coast and the Midwest, where he provides gender-affirming care, the approach the medical community has largely adopted for embracing children and teenagers who come out as transgender. He also helps shape policy on L.G.B.T. issues for the American Academy of Child and Adolescent Psychiatry. As a child and adolescent psychiatrist who is gay, he found it felt natural to work under the L.G.B.T. “umbrella,” as he put it, aware of the overlap as well as the differences between gay and trans identity. It was for all these reasons that Leibowitz was selected, in 2017, to be a leader of a working group of seven clinicians and researchers drafting a chapter on adolescents for a new version of guidelines called the Standards of Care to be issued by the World Professional Association for Transgender Health (WPATH). The guidelines are meant to set a gold standard for the field of transgender health care, and this would be the first update since 2012. What Leibowitz and his co-authors didn’t foresee, when they began, was that their work would be engulfed by two intersecting forces: a significant rise in the number of teenagers openly identifying as transgender and seeking gender care, and a right-wing backlash in the United States against allowing them to medically transition, including state-by-state efforts to ban it. During the last decade, the field of transgender care for youth has greatly shifted. A decade ago, there were a handful of pediatric gender clinics in the United States and a dozen or so more in other countries. The few doctors and therapists who worked in them knew one another, and the big debate was whether kids in preschool or elementary school should be allowed to live fully as the gender they identified as when they strongly and consistently asserted their wishes. Now there are more than 60 comprehensive gender clinics in the United States, along with countless therapists and doctors in private practice who are also seeing young patients with gender-identity issues. The number of young people who identify as transgender nationally is about 300,000, according to a new report by the Williams Institute, a research center at U.C.L.A.’s law school, which is much higher than previous estimates. In countries that collect national data, like the Netherlands and Britain, the number of 13-to-17-year-olds seeking treatment for gender-identity issues has also increased, from dozens to hundreds or thousands a year. © 2022 The New York Times Company

Keyword: Sexual Behavior; Development of the Brain
Link ID: 28375 - Posted: 06.15.2022

By Erika Engelhaupt To Charles Darwin, nature had a certain order. And in that order, males always came out on top. They were the leaders, the innovators, the wooers and the doers. “The males of almost all animals have stronger passions than the females,” Darwin wrote in 1871. “The female, on the other hand, with the rarest of exceptions, is less eager.” The founder of evolutionary theory posited that throughout the animal kingdom, males are active, females are passive, and that’s pretty much that. Females, in sum, are boring. That’s poppycock, Lucy Cooke writes in her latest book, Bitch. This blinkered view of nature as a man’s world was conceived and promulgated by Victorian men who imposed their values and world view on animals, she says. Cooke, a documentary filmmaker and the author of The Truth About Animals and two children’s books (SN: 4/14/18, p. 26), has traveled the world and met scientists who are exposing the truth about the sexes. She takes readers on a wild ride as she observes the ridiculous mating rituals of sage grouse, searches for orca poop (to monitor sex hormones) and watches female lemurs boss around males. Through such adventures, Cooke learns that females are anything but boring. “Female animals are just as promiscuous, competitive, aggressive, dominant and dynamic as males,” she writes. That may not sound radical to today’s feminists, but in the field of evolutionary biology, such a pronouncement has long bordered on the heretical. Generations of biologists have focused on male behavior and physiology, on the assumption that females are little more than baby-making machines to be won over by the strongest, showiest males. © Society for Science & the Public 2000–2022.

Keyword: Sexual Behavior; Evolution
Link ID: 28372 - Posted: 06.15.2022

Meghan Hoyer and Tim Meko When Vanderbilt University psychiatrist Jonathan Metzl learned that the perpetrator of the Uvalde, Tex., school massacre was a young man barely out of adolescence, it was hard not to think about the peculiarities of the maturing male brain. Salvador Rolando Ramos had just turned 18, eerily close in age to Nikolas Cruz, who had been 19 when he shot up a school in Parkland, Fla. And to Adam Lanza, 20, when he did the same in Newtown, Conn. To Seung-Hui Cho, 23, at Virginia Tech. And to Eric Harris, 18, and Dylan Klebold, 17, in Columbine, Colo. Teen and young adult males have long stood out from other subgroups for their impulsive behavior. They are far more reckless and prone to violence than their counterparts in other age groups, and their leading causes of death includes fights, accidents, driving too fast, or, as Metzl put it, “other impulsive kinds of acts.” “There’s a lot of research about how their brains are not fully developed in terms of regulation,” he said. Perhaps most significantly, studies show, the prefrontal cortex, which is critical to understanding the consequences of one’s actions and controlling impulses, does not fully develop until about age 25. In that context, Metzl said, a shooting “certainly feels like another kind of performance of young masculinity.” In coming weeks and months, investigators will dissect Ramos’s life to try to figure out what led him to that horrific moment at 11:40 a.m. Tuesday, May 24 when he opened fire on a classroom full of 9- and-10-year-olds at Robb Elementary School. Although clear answers are unlikely, the patterns that have emerged about mass shooters in the growing databases, school reports, medical notes and interview transcripts show a disturbing confluence between angry young men, easy access to weapons and reinforcement of violence by social media. © 1996-2022 The Washington Post

Keyword: Aggression; Hormones & Behavior
Link ID: 28352 - Posted: 06.04.2022

By Jack Tamisiea Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. Since the days of Charles Darwin, the long necks of giraffes have been a textbook example of evolution. The theory goes that as giraffe ancestors competed for food, those with longer necks were able to reach higher leaves, getting a leg — or neck — up over shorter animals. But a bizarre prehistoric giraffe relative reveals that fighting may have driven early neck evolution in addition to foraging. In a study published Thursday in Science, a team of paleontologists described Discokeryx xiezhi, a giraffe ancestor, as having helmet-like headgear and bulky neck vertebrae. Discokeryx was adapted to absorb and deliver skull-cracking collisions to woo mates and vanquish rivals. “It shows that giraffe evolution is not just elongating the neck,” said Jin Meng, a paleontologist at the American Museum of Natural History and co-author of the new study. “Discokeryx goes in a totally different direction.” Dr. Meng and his colleagues discovered the fossils in an outcrop of rock in northwestern China called the Junggar Basin. Around 17 million years ago, this area was an expanse of savannas and forests home to an array of large mammals like shovel-tusked elephants, short-horned rhinoceroses and burly bear dogs. While exploring this bonebed in 1996, Dr. Meng stumbled across a hunk of skull. He could tell it was a mammalian braincase, but the top was flattened like an iron press. Without more of the animal’s skeleton, Dr. Meng and his colleagues referred to it as the “strange beast.” © 2022 The New York Times Company

Keyword: Evolution; Aggression
Link ID: 28350 - Posted: 06.04.2022

By Amber Dance Suppose a couple has two children, a boy and a girl. Chances are, they’ll both grow up with typical, healthy brains. But should either diverge from the usual route of brain development, or suffer mental health issues, their paths are likely to be different. The son’s differences might show up first. All else being equal, he’s four times more likely than his sister to be diagnosed with autism. Rates of other neurodevelopmental conditions and disabilities are also higher in boys. As he grows into a young man, his chances of developing schizophrenia will be two to three times higher than hers. When the siblings hit puberty, those relative risks will flip. The sister will be almost twice as likely to experience depression or an anxiety disorder. Much later in life, she’ll be at higher risk of developing Alzheimer’s disease. Those trends are not hard and fast rules, of course: Men can and do suffer from depression and Alzheimer’s; some girls develop autism; women aren’t immune to schizophrenia. Male and female brains are more alike than they are different. But scientists are learning that there’s more to these different risk profiles than, say, the pressures women face in a patriarchal society or the fact that women tend to live longer, giving diseases of aging time to develop. Subtle biological differences between male and female brains, and bodies, are important contributors. To explain these sex differences, there are some obvious places to look. The female’s two X chromosomes, to the male’s single copy, is one. Differing sex hormones — primarily testosterone in males and estrogen in females — is another. But a steadily growing body of research points to a less obvious influence: the cells and molecules of the immune system. © 2022 Annual Reviews

Keyword: Sexual Behavior; Neuroimmunology
Link ID: 28345 - Posted: 06.01.2022

NPR's Sacha Pfeiffer talks with Eliot Schrefer, author of Queer Ducks (And Other Animals): The Natural World of Animal Sexuality. It's about how "natural sex" may not be as binary as some think. SACHA PFEIFFER, HOST: At its worst, a nonfiction science book about animal sexuality could read like a dry biology textbook. But that's not the kind of book Eliot Schrefer wrote. His book, called "Queer Ducks (And Other Animals): The Natural World Of Animal Sexuality," is designed to be teenager-friendly, for one thing. It's a young adult book filled with comics and humor and accessible science, and it's filled with research on the diversity of sexual behavior in the animal world. Eliot Schrefer is with us to explain more. Welcome, Eliot. ELIOT SCHREFER: Hi. I'm really happy to be here. PFEIFFER: We're glad to have you. I really liked the way you structured your book. It's basically an animal per chapter, in a way. But you also have these wonderful illustrations. You have interviews with scientists. Tell us a little bit about how you decided to make it accessible because, again, you're aiming for adolescents, as I understand it, in a nonfiction way, and they might be inclined to think nonfiction equals boring, dry textbook. SCHREFER: Right. I sort of imagine, like, we're kind of sitting in the science classroom, passing notes back and forth, and it even comes down to the doodles. There's an artist, Jules Zuckerberg, who did a one-page comic for each of the animal species that we discuss. So it's - the premise is that it's an animal GSA. PFEIFFER: A gender sexuality alliance meeting. SCHREFER: That's right. And so they're each taking a turn introducing themselves. And so the bonobo takes a turn introducing how her family works, and then the doodlebug and the dolphin and so on. PFEIFFER: Yeah, they're really great. They make the book really accessible. As we said, every chapter basically tackles an animal and something about the sexuality of that animal. Do you have a favorite or one of your favorites that you could tell us about? © 2022 npr

Keyword: Sexual Behavior
Link ID: 28335 - Posted: 05.25.2022