Chapter 8. Hormones and Sex

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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

Keyword: Sexual Behavior; Evolution
Link ID: 28662 - Posted: 02.11.2023

By Susan Dominus For the past two or three years, many of my friends, women mostly in their early 50s, have found themselves in an unexpected state of suffering. The cause of their suffering was something they had in common, but that did not make it easier for them to figure out what to do about it, even though they knew it was coming: It was menopause. The symptoms they experienced were varied and intrusive. Some lost hours of sleep every night, disruptions that chipped away at their mood, their energy, the vast resources of good will that it takes to parent and to partner. One friend endured weeklong stretches of menstrual bleeding so heavy that she had to miss work. Another friend was plagued by as many as 10 hot flashes a day; a third was so troubled by her flights of anger, their intensity new to her, that she sat her 12-year-old son down to explain that she was not feeling right — that there was this thing called menopause and that she was going through it. Another felt a pervasive dryness in her skin, her nails, her throat, even her eyes — as if she were slowly calcifying. Then last year, I reached the same state of transition. Technically, it is known as perimenopause, the biologically chaotic phase leading up to a woman’s last period, when her reproductive cycle makes its final, faltering runs. The shift, which lasts, on average, four years, typically starts when women reach their late 40s, the point at which the egg-producing sacs of the ovaries start to plummet in number. In response, some hormones — among them estrogen and progesterone — spike and dip erratically, their usual signaling systems failing. During this time, a woman’s period may be much heavier or lighter than usual. As levels of estrogen, a crucial chemical messenger, trend downward, women are at higher risk for severe depressive symptoms. Bone loss accelerates. In women who have a genetic risk for Alzheimer’s disease, the first plaques are thought to form in the brain during this period. Women often gain weight quickly, or see it shift to their middles, as the body fights to hold onto the estrogen that abdominal fat cells produce. The body is in a temporary state of adjustment, even reinvention, like a machine that once ran on gas trying to adjust to solar power, challenged to find workarounds. © 2023 The New York Times Company

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 28658 - Posted: 02.08.2023

By McKenzie Prillaman A newfound species of frog doesn’t ribbit. In fact, it doesn’t make any sound at all. Many frogs have unusual characteristics, from turning translucent to being clumsy jumpers (SN: 12/22/22; 6/15/22). The recently discovered amphibian lacks a voice. It joins a group of seven other voiceless frog species called spiny-throated reed frogs that reside in East Africa. Instead of croaking, the spines on male frogs’ throats might help their female counterparts recognize potential mates via touch, sort of like braille, says conservation biologist Lucinda Lawson of the University of Cincinnati. Lawson and colleagues spotted the little frog, only about 25 millimeters long, in 2019 while surveying wildlife in Tanzania’s Ukaguru Mountains. The team immediately recognized the animal, now named Hyperolius ukaguruensis, as a spiny-throated reed frog. But something seemed off. “It [was] the wrong color,” Lawson says. Most frogs from this group are green and silver, but this one was gold and brown. Some quick measurements to check if the peculiar frog simply had trivial color variations or if it could be a new species revealed that its eyes were smaller than other spiny-throated reed frogs. The researchers agreed: “Let’s do some genetics,” Lawson says. They ran DNA tests on two frogs that looked like they belonged to the suspected new species, as well as 10 individuals belonging to known spiny-throated species. Comparing the golden frogs’ genetic makeup with that of the others revealed the oddballs were genetically distinct, Lawson and colleagues report February 2 in PLOS ONE. © Society for Science & the Public 2000–2023.

Keyword: Animal Communication; Sexual Behavior
Link ID: 28655 - Posted: 02.04.2023

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

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28653 - Posted: 02.01.2023

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.

Keyword: Sexual Behavior; Evolution
Link ID: 28594 - Posted: 12.15.2022

By Bonnie Berkowitz and  William Neff Creating a physique that can win at the highest level of professional bodybuilding requires superhuman self-discipline, intense training and genetic good fortune. Increasingly, say the people familiar with the culture and its consequences, it cannot be done without illicit drugs and a willingness to push a body to — or past — its limits. More than a dozen scientists, trainers, judges and competitors interviewed for this report said that just earning a pro card, an amateur’s ticket to the pro ranks, is very difficult without anabolic steroids. Winning a marquee title drug-free? Several people laughed at the question. “Impossible,” said Harrison Pope, one of the country’s leading anabolic-steroid researchers. The behemoths who win the best-known and most lucrative titles barely resemble the iconic, classically muscled champions of the past, such as Arnold Schwarzenegger, who won the sport’s premiere title, Mr. Olympia, seven times between 1970 and 1980. “Arnold Schwarzenegger would not win today,” said Brad Schoenfeld, a professor at Lehman College in New York and author of several books on bodybuilding and muscle growth. “He would not even get a pro card.” Although bodybuilders spend years lifting weights and honing each muscle, they don’t need to demonstrate strength for the judges beyond the ability to hold poses onstage. They only need to look strong. Some competitors — and a growing legion of young, mostly male admirers — chase that look by diving into a reckless pharmacological game of whack-a-mole that insiders say has grown more intense and dangerous as sheer size has trumped the “Greek god” ideal of previous generations.

Keyword: Hormones & Behavior; Drug Abuse
Link ID: 28588 - Posted: 12.10.2022

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