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Guess Which Sex Behaves More Erratically (at Least in Mice)

By Azeen Ghorayshi For decades, male mice have been the default in scientific experiments that test new drugs or examine the connections of the brain. The reason? Female mice, which experience a four- to five-day cycle of fluctuating ovarian hormones, were thought to be too complicated. Accounting for the hormonal changes was viewed as too cumbersome and too expensive. But the estrous cycle has little to do with how female mice behave, according to a new study that used machine-learning software to track the second-to-second behavior of animals exploring an open space. Male mice actually exhibited more erratic behavior than females did. The study, published in the journal Current Biology on Tuesday, challenges century-old stereotypes that kept female animals out of laboratory research — and, until the 1990s, barred women from clinical trials. The new research is “tipping all of these assumptions about sex differences and the influence of hormones on their head,” said Rebecca Shansky, a behavioral neuroscientist at Northeastern University and a co-author of the new study. The cost of excluding females — whether human or animal — from scientific research is high. Women are almost twice as likely as men to experience severe side effects from drugs, most of which have dosages based on the initial testing done in men. Women also may not derive the same benefits from the drugs. Women “capable of becoming pregnant,” as the federal government put it, were largely excluded from clinical trials of drugs until 1993, when a new law required researchers funded by the National Institutes of Health to include women and minority groups. In the decades since, women have made up close to half of clinical research participants, though they still lag behind in studies of certain drugs, like those used to treat cardiovascular disease and psychiatric disorders. But a large sex gap persisted in basic science research using lab animals, studies that pave the way to medical breakthroughs. In neuroscience, according to a review published in 2010, studies of male lab animals outnumbered female ones by a factor of five. © 2023 The New York Times Company

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: 28694 - Posted: 03.08.2023

Orca Moms Pay a High Price to Feed Large Adult Sons

By Elizabeth Preston A fully grown male orca is one of the planet’s fiercest hunters. He’s a wily, streamlined torpedo who can weigh as much as 11 tons. No other animal preys on him. Yet in at least one population, these apex predators struggle to survive without their moms, who catch their food and even cut it up for them. Scientists have previously seen that some killer whale mothers share food with their grown sons. In a study published Wednesday in Current Biology, researchers found that this prolonged feeding carries a huge reproductive cost for mothers. Killer whales, actually the largest members of the dolphin family, swim throughout the world’s oceans. Yet they live in discrete populations with their own territories, dialects and hunting customs. A group that spends much of the year off the coast of British Columbia, Washington and Oregon is known as the southern residents. They eat mainly Chinook salmon, which have been increasingly hard to find. “Killer whales worldwide are doing fine,” said Michael Weiss, research director at the Center for Whale Research in Friday Harbor, Wash. But the southern residents, with a population of just 73, are considered endangered. These whales stay with their birth family for their whole lives. The families are led by matriarchs who can live 80 to 90 years. Yet the females stop reproducing in midlife: Orcas and a few other whale species are the only mammals, besides humans, known to undergo menopause. To try to explain menopause, scientists have looked for ways that matriarchs encourage the survival of their children and grandchildren. A 2012 study of southern resident killer whales, along with their neighbors, the northern residents, showed that the presence of older moms helped adult offspring stay alive — especially sons. Males over age 30 were eight times more likely to die in the year following their own mothers’ deaths. © 2023 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 28662 - Posted: 02.11.2023

CRISPR voles can’t detect ‘love hormone’ oxytocin — but still mate for life

Heidi Ledford The humble prairie vole (Microtus ochrogaster) has long been revered for its unusual commitment to family. Pair-bonded couples huddle together, raise pups together and mate exclusively together — at least most of the time. Drop another couple’s pups into a cage with pair-bonded prairie voles and the adults will often foster those young as their own — highly unusual behaviour for a rodent. But a study published on 27 January in Neuron1 challenges decades of research that suggests a protein that detects the ‘love hormone’ oxytocin is responsible for the voles’ domestic bliss. Using CRISPR gene-editing, researchers found that prairie voles lacking the protein were still responsible parents and still formed monogamous relationships. These surprising results highlight the importance of revisiting accepted dogma when new scientific techniques emerge, says neuroscientist Bianca Jones Marlin at the Columbia University Zuckerman Institute in New York City. “Neuroscientists grew up in our field understanding that prairie voles pair bonded because of the distribution of oxytocin receptors and oxytocin,” she says. “That was canon.” For decades, neuroscientists interested in understanding the biological underpinnings of human social behaviours have been fascinated by prairie voles. “There’s a sort of eerie similarity between prairie vole social behaviours and human social behaviours,” says Nirao Shah, a neuroscientist at Stanford University in California. “Prairie voles are one of the few mammalian species that exhibit social attachment.” Social attachment The hormone oxytocin has long been thought to have a pivotal role in social behaviours. A protein that binds to oxytocin, called oxytocin receptor, is expressed differently in prairie vole brains than in the brains of other voles that do not form monogamous relationships. In humans, oxytocin levels rise in response to social interactions, and the hormone is important in stimulating uterine contractions during childbirth and the production of milk afterwards. © 2023 Springer Nature Limited

Scientists thought snakes didn’t have clitorises. They were wrong

By Jake Buehler Female snakes have clitorises too, a new study finds. The research raises the possibility that the sex lives of snakes are more complicated and diverse than previously understood, researchers report December 14 in Proceedings of the Royal Society B. Clitorises are found in a wide range of vertebrate life, from crocodiles to dolphins (SN: 1/10/22). One exception is birds, which lost their clitorises over the course of their evolution. Female snakes appeared to have lost the sex organ too, which was puzzling, since their close lizard relatives possess paired clitorises, called hemiclitorises. Male lizards and snakes have accompanying paired phalli, or hemipenises. This element of female snakes’ sexual anatomy went unexamined in detail for so long partly because hemiclitorises can be fragile and easy to miss, but also because female genitalia have historically been considered “quite taboo,” says evolutionary biologist Megan Folwell of the University of Adelaide in Australia. “Even in humans, the proper function and significance of the human clitoris was still being discussed in 2006,” she says. Conflicting accounts of snake hemiclitorises in some scientific papers led Folwell to take a detailed look. She first examined a euthanized female common death adder (Acanthophis antarcticus). “I just started with dissecting the tail and going into it with a really open mind of what I might find,” she says. She was “pleasantly surprised” to find dual organs within that were completely different from the hemipenises found in male snakes. Also, unlike lizard hemiclitorises, the snake’s couldn’t turn out externally. © Society for Science & the Public 2000–2022.

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: 28594 - Posted: 12.15.2022

Fatherhood changes men’s brains, according to before-and-after MRI scans

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.

The Gut Microbiome Helps Social Skills Develop in the Brain

By Joanna Thompson Two recent papers have shown that during a critical early period of brain development, the gut’s microbiome — the assortment of bacteria that grow within in it — helps to mold a brain system that’s important for social skills later in life. Scientists found this influence in fish, but molecular and neurological evidence plausibly suggests that some form of it could also occur in mammals, including humans. In a paper published in early November in PLOS Biology, researchers found that zebra fish who grew up lacking a gut microbiome were far less social than their peers with colonized colons, and the structure of their brains reflected the difference. In a related article in BMC Genomics in late September, they described molecular characteristics of the neurons affected by the gut bacteria. Equivalents of those neurons appear in rodents, and scientists can now look for them in other species, including humans. In recent decades, scientists have come to understand that the gut and the brain have powerful mutual influences. Certain types of intestinal ulcers, for example, have been linked to worsening symptoms in people with Parkinson’s disease. And clinicians have long known that gastrointestinal disorders are more common in people who also have neurodevelopmental disorders, such as ADHD and autism spectrum disorder. “Not only does the brain have an impact on the gut, but the gut can also profoundly affect the brain,” said Kara Margolis, a pediatric gastroenterologist at New York University’s Langone Health, who was not involved in the new research. How these anatomically separate organs exert their effects, however, is far less clear. Philip Washbourne, a molecular biologist at the University of Oregon and one of the principal co-authors of the new studies, has been studying genes implicated in autism and the development of social behaviors for over two decades. But he and his lab were looking for a new model organism, one that displayed social behavior but was quicker and easier to breed than their go-to, mice. “Can we do this in fish?” he recalls thinking, and then: “Let’s get really quantitative about it and see if we can measure how friendly the fish get.” All Rights Reserved © 2022

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory and Learning
Link ID: 28557 - Posted: 11.16.2022

They Paused Puberty, but Is There a Cost?

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

They May Have Love on Their Lizard Brains

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

The fraught quest to account for sex in biology research

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

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 28473 - Posted: 09.14.2022

Male dolphins form lifelong bonds that help them find mates

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

Unlocking Mom’s Brain

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,

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 28424 - Posted: 08.06.2022

As Y Chromosomes Vanish With Age, Heart Risks May Grow

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

The Battle Over Gender Therapy

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

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: 28375 - Posted: 06.15.2022

Lucy Cooke’s new book ‘Bitch’ busts myths about female animals

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.

Sex, immunity and the brain

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

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 28345 - Posted: 06.01.2022

Animal sexuality may not be as binary as we're led to believe

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

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 28335 - Posted: 05.25.2022

How Love Changes Your Brain

By Hope Reese Can we do without love? For many years, the neuroscientist Stephanie Ortigue believed that the answer was yes. Even though she researched the science of human connections, Dr. Ortigue — an only child and, in her 20s and 30s, contentedly single — couldn’t completely grasp its importance in her own life. “I told myself that being unattached made me a more objective researcher: I could investigate love without being under its spell,” she writes in her new book, “Wired for Love: A Neuroscientist’s Journey Through Romance, Loss and the Essence of Human Connection.” But then, in 2011, at age 37, she met John Cacioppo at a neuroscience conference in Shanghai. Dr. Cacioppo, who popularized the concept that prolonged loneliness can be as toxic to health as smoking, intrigued her. The two scientists fell hard for each other and married. She took his last name and they soon became colleagues at the University of Chicago’s Pritzker School of Medicine (where she now directs the Brain Dynamics Laboratory) — forming a team at home and in the lab. “Wired for Love” is the neurobiological story of how love rewires the brain. It’s also a personal love story — one that took a sad turn when John died of cancer in March 2018. Here, Dr. Cacioppo discusses what exactly love does to the brain, how to fight loneliness and how love is, literally, a product of the imagination. You went from being happily single, to coupled, to then losing your husband. How did meeting him bring your research on love to life? Sign Up for Love Letter Your weekly dose of real stories that examine the highs, lows and woes of relationships. This newsletter will include the best of Modern Love, weddings and love in the news. Get it sent to your inbox. When we first met, we spoke for three hours, but I couldn’t feel time go by. I felt euphoria — from the rush of dopamine. I blushed — a sign of adrenaline. We became closer, physically, and started imitating each other. This was from the activation of mirror neurons, a network of brain cells that are activated when you move or feel something, and when you see another person moving. When you have a strong connection with someone, the mirror neuron system is boosted. © 2022 The New York Times Company

In Sexy Worms, Inheritance Beyond Genes Can Help Evolution

Carrie Arnold Playing the mating game is risky. Organisms must cope with the existential risk that swiping right on the wrong choice could doom future generations to a lifetime of bad genes. They also have to contend with more immediate burdens and risks: Participants need to gather resources for courting and summon energy to pursue a potential partner. Animals engaged in amorous activities also make easy targets for predators. Small wonder, then, that when times are good, the roundworm Caenorhabditis elegans doesn’t bother with the process. As a mostly hermaphroditic species (with a few males thrown in for variety), a C. elegans worm usually self-fertilizes its eggs until its sperm stash is depleted late in life; only then does it produce a pheromone to attract males and stay in the reproductive game. But when environmental conditions become stressful, the worms become sexually attractive much sooner. For them, sex is the equivalent of a Hail Mary pass — a desperate gamble that if their offspring are more genetically diverse, some will fare better under the new, rougher conditions. Scientists thought this stress-induced shift was purely fleeting. But recently when scientists at Tel Aviv University raised C. elegans in too-warm conditions for more than 10 generations, they discovered that the worms continued to be sexually attractive for several more generations after they were moved to cooler surroundings. It’s an observation that highlights how inheritance does not always reduce to a simple accounting of the genes in organisms, and it may point to a mechanism that works in tandem with traditional natural selection in shaping the evolution of some organisms. As the new paper in Developmental Cell shows, the cause of this trait wasn’t a genetic change to the worm’s DNA but rather an inherited “epigenetic” change that influenced how the DNA was used. The researchers — senior author Oded Rechavi, a biologist at Tel Aviv University, first author Itai Toker (now a postdoctoral fellow at Columbia University) and their colleagues — identified a small RNA molecule that can be passed between generations to signal for production of the pheromone. In effect, this heritable RNA molecule improves the odds that the worms will evolve in stressful times. All Rights Reserved © 2022

How a mound-building bird shapes its Australian ecosystem

By Jake Buehler Earthen piles built by a chicken-like bird in Australia aren’t just egg incubators — they may also be crucial for the distribution of key nutrients throughout the ecosystem. In the dry woodlands of South Australia, sandy mounds rise between patches of many-stemmed “mallee” eucalyptus trees. These monuments — big enough to smother a parking space — are nests, painstakingly constructed by the malleefowl bird. By inadvertently engineering a patchwork of nutrients and churned soil, the industrious malleefowl may be molding surrounding plant and soil communities and even blunting the spread of fire, researchers report March 27 in the Journal of Ecology. Such ecosystem impacts suggest malleefowl conservation could benefit many species, says Heather Neilly, an ecologist at the Australian Landscape Trust in Calperum Station. The species is currently listed as “vulnerable” and declining by the International Union for Conservation of Nature. Some animals — termed “ecosystem engineers” — produce habitats for other species by shaping the environment around them. Beavers build dams that create homes for pond-dwelling lifeforms. In deserts, owls and giant lizards support plant and animal life with their burrows (SN: 10/8/19; SN: 1/19/21). “In Australia in particular, the focus has largely been on our array of digging mammals,” Neilly says. But malleefowl (Leipoa ocellata) — found throughout western and southern Australia — also perturb the soil. They and their close relatives are “megapodes,” a group of fowl native to Australasia and the South Pacific that have the unusual habit of incubating their eggs much like alligators do: in a massive pile of rotting compost. Heat from the decaying vegetation — locked in with an insulating sand layer on top — regulates the eggs’ temperature, and the young scratch their way to the surface upon hatching. © Society for Science & the Public 2000–2022.

Help! How Do I Get My Sex Drive Back?

By Christina Caron Q: Are there any proven treatments for low libido in women? “Proven” is a strong word — and one that makes scientists squeamish. But it is safe to say that there is “very strong evidence” for increasing sexual desire through certain types of psychological interventions like cognitive behavioral therapy and mindfulness meditation, said Lori A. Brotto, a psychologist and professor at the University of British Columbia in Vancouver and a renowned expert in women’s sexual health. When it comes to medications, however, it’s a different story. In recent years, two new medications for women with low libido have been approved by the U.S. Food and Drug Administration, “though their efficacy is marginally better than a placebo,” said Dr. Stacy Tessler Lindau, a gynecologist at the University of Chicago Medicine and the creator of WomanLab, a website about sexual health. These drugs, flibanserin (a pill) and bremelanotide (an injection that is self-administered about 40 minutes before sexual activity), were approved for the “very small subset of women” who are premenopausal, have low libidos and do not have any identifiable physical, mental or relationship problems, Dr. Lindau said. “They may have modest benefit, but they also come with side effects and cost,” she added. “So far, insurance coverage has been limited.” In the end, the most beneficial solution will depend on the reason you are experiencing low libido and why you consider your libido to be a problem. For older women, loss of estrogen during menopause is commonly associated with a change in libido because it can cause vaginal dryness and tightness that can make intercourse painful. Some women also find it more difficult to get aroused. And when menopause is accompanied by hot flashes and night sweats, that can make sex seem less appealing too. © 2022 The New York Times Company

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