Chapter 12. Sex: Evolutionary, Hormonal, and Neural Bases

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By Natasha Gilbert In May of 2018, Tabitha Bird spent a memorable day with her eldest son at a comic book convention in London. Later that evening, after she made sure that her two younger kids were safely tucked up in bed, Bird gathered every sleeping tablet, antidepressant, anti-anxiety med and ibuprofen pill she could find and walked out of the house. She drove to a nearby store where she bought a big bottle of water and some acetaminophen. Then she stopped in an empty industrial park and began to take the lot. Bird woke up from a coma four days later. The 47-year-old, from a town in West Sussex in the UK, now attributes her suicide attempt and the depression leading up to it to perimenopause — the time in most women’s lives when menstrual cycles become irregular and fertility wanes. During this transition, many women experience a suite of changes, including hot flashes, disrupted sleep and mood swings. Some breeze through perimenopause with little difficulty, but many — about 45 percent to 68 percent — experience depression, symptoms of which can include low mood, a loss of interest in things and even thoughts of suicide. Women with a history of depression, like Bird — who also suffered with it while pregnant — are the most vulnerable. During perimenopause, they are twice as likely to experience debilitating full-blown depressive disorder than women who haven’t had past episodes. As researchers probe for reasons why some women fall prey to depression at this time and others don’t, a leading candidate has emerged: widely fluctuating levels of the sex hormone estrogen. Estrogen directs fertility, but mounting research shows that it also holds sway on parts of the brain involved in regulating emotion and stress. © 2022 Annual Reviews

Keyword: Depression; Hormones & Behavior
Link ID: 28329 - Posted: 05.18.2022

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

Keyword: Sexual Behavior; Emotions
Link ID: 28302 - Posted: 04.27.2022

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

Keyword: Sexual Behavior; Epigenetics
Link ID: 28299 - Posted: 04.23.2022

By Gina Kolata Are you a man worried about your testosterone levels? Hoping to give them a boost? Tucker Carlson, the Fox News host, has a solution. A promotional video for a new installment in a video series by Mr. Carlson describes a “total collapse of testosterone levels in American men,” positing an explanation for what he and many conservatives see as a creeping loss of masculinity in today’s society. Chock-full of oiled, shirtless men performing vaguely masculine tasks, like turning over giant tires and throwing a javelin, the video has already been widely remarked upon on social media for its bizarre erotic imagery. But one shot in particular stands out: a naked man atop a rock pile, limbs outflung, exposing his genitals to the red light issuing from what appears to be a waist-high air purifier. Something very like the theme from “2001: A Space Odyssey” plays in the background. This is the treatment proposed by Mr. Carlson’s “documentary”: Revive your underperforming testicles with red light, in particular a device made by a little known company called Joovv. A leading endocrinologist says — no surprise — the whole thing is ridiculous, and not just because of the man receiving light therapy atop a pile of stone slabs in the dead of night. First, there is precious little evidence that testosterone “levels are declining by roughly 10 percent per decade, completely changing the way people are at the most fundamental level,” as Mr. Carlson has said. Studies examining changes in testosterone over time are challenging for several reasons, including difficulties in recruiting large populations of normal subjects, daily circadian changes in testosterone, and differences in testing methods over time, noted Dr. John Amory, an expert on male reproductive health at the University of Washington. © 2022 The New York Times Company

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 28298 - Posted: 04.23.2022

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.

Keyword: Sexual Behavior; Evolution
Link ID: 28280 - Posted: 04.13.2022

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

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28235 - Posted: 03.11.2022

Megan Lim Any parents out there will be familiar with the unique sort of misery that results when your kid has a new favorite song. They ask to hear it over and over, without regard for the rest of us. Well, it turns out that song sparrows might be better than children (and many adults, for that matter) when it comes to curating their playlists. Male sparrows, which attract females by singing, avoid tormenting their listeners with the same old tune. Instead they woo potential mates with a selection of 6 to 12 different songs. The song sparrow medley It might be hard to tell, but that audio clip contains three distinctive sparrow songs, each containing a unique signature of trills and notes. Even more impressive than the execution, though, is the way sparrows string their songs together. William Searcy, an ornithologist at the University of Miami, recently published a study in The Royal Society that analyzed patterns of song sparrow serenades. He said it would be easy for the birds to sing the first song, then the second, then the third and fourth. "But that's not what song sparrows are doing. They're not going through in a set order. They're varying the order from cycle to cycle, and that's more complicated," he said. In other words, rather than sing the same playlist every time, they hit shuffle. "What we're arguing is what they do is keep in memory the whole past cycle so they know what to sing next," Searcy said. The researchers are not sure why male sparrows shuffle their songs. But past work has shown that females prefer hearing a wider range of tunes, so maybe a new setlist keeps females interested. © 2022 npr

Keyword: Animal Communication; Sexual Behavior
Link ID: 28181 - Posted: 02.02.2022

By Azeen Ghorayshi An upsurge in teenagers requesting hormones or surgeries to better align their bodies with their gender identities has ignited a debate among doctors over when to provide these treatments. An international group of experts focused on transgender health last month released a draft of new guidelines, the gold standard of the field that informs what insurers will reimburse for care. Many doctors and activists praised the 350-page document, which was updated for the first time in nearly a decade, for including transgender people in its drafting and for removing language requiring adults to have psychological assessments before getting access to hormone therapy. But the guidelines take a more cautious stance on teens. A new chapter dedicated to adolescents says that they must undergo mental health assessments and must have questioned their gender identity for “several years” before receiving drugs or surgeries. Experts in transgender health are divided on these adolescent recommendations, reflecting a fraught debate over how to weigh conflicting risks for young people, who typically can’t give full legal consent until they are 18 and who may be in emotional distress or more vulnerable to peer influence than adults are. Some of the drug regimens bring long-term risks, such as irreversible fertility loss. And in some cases, thought to be quite rare, transgender people later “detransition” to the gender they were assigned at birth. Given these risks, as well as the increasing number of adolescents seeking these treatments, some clinicians say that teens need more psychological assessment than adults do. “They absolutely have to be treated differently,” said Laura Edwards-Leeper, a child clinical psychologist in Beaverton, Ore., who works with transgender adolescents. Dr. Edwards-Leeper was one of seven authors of the new adolescent chapter, but the organization that publishes the guidelines, the World Professional Association for Transgender Health, did not authorize her to comment publicly on the draft’s proposed wording. © 2022 The New York Times Company

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28156 - Posted: 01.15.2022

By Sabrina Imbler Common bottlenose dolphins have sex frequently — very likely multiple times in a day. Copulation lasts only a few seconds, but social sex, which is used to maintain social bonds, can last much longer, happen more frequently and involve myriad heterosexual and homosexual pairings of dolphins and their body parts. Anything is possible, and, as new research suggests, probably pleasurable for swimmers of both sexes. According to a paper published on Monday in the journal Current Biology, female bottlenose dolphins most likely experience pleasure through their clitorises. The findings come as little surprise to scientists who research these dolphins. “The only thing that surprises me is how long it has taken us as scientists to look at the basic reproductive anatomy,” Sarah Mesnick, an ecologist at NOAA Fisheries who was not involved with the research, said, speaking of the clitoris. She added, “It took a team of brilliant women,” referring to two of the authors. “A lot of people assume that humans are unique in having sex for pleasure,” Justa Heinen-Kay, a researcher at the University of Minnesota who was not involved with the paper, wrote in an email. “This research challenges that notion.” And learning more about the anatomy of marine mammals’ genitalia has clear implications for their survival, Dr. Mesnick said: “The more we know about the social behavior of these animals, the better we’re able to understand their evolution and help use that to manage and conserve them.” Historically, researchers have focused on male genitalia, driven by prejudice toward male subjects, prejudice against female choice in sexual selection and the fact that it can be easier to study something that sticks out. “Female genitalia were assumed to be simple and uninteresting,” Dr. Heinen-Kay said. “But the more that researchers study female genitalia, the more we’re learning that this isn’t the case at all.” She added that this shift may be driven in part by the increasing number of women researchers. © 2022 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 28147 - Posted: 01.12.2022

Jon Hamilton When baby mice cry, they do it to a beat that is synchronized to the rise and fall of their own breath. It's a pattern that researchers say could help explain why human infants can cry at birth — and how they learn to speak. Mice are born with a cluster of cells in the brainstem that appears to coordinate the rhythms of breathing and vocalizations, a team reports in the journal Neuron. If similar cells exist in human newborns, they could serve as an important building block for speech: the ability to produce one or many syllables between each breath. The cells also could explain why so many human languages are spoken at roughly the same tempo. "This suggests that there is a hardwired network of neurons that is fundamental to speech," says Dr. Kevin Yackle, the study's senior author and a researcher at the University of California, San Francisco. Scientists who study human speech have spent decades debating how much of our ability is innate and how much is learned. The research adds to the evidence that human speech relies — at least in part — on biological "building blocks" that are present from birth, says David Poeppel, a professor of psychology and neural science at New York University who was not involved in the study. But "there is just a big difference between a mouse brain and a human brain," Poeppel says. So the human version of this building block may not look the same. © 2022 npr

Keyword: Language; Evolution
Link ID: 28144 - Posted: 01.08.2022

By Bruce Bower Evidence that cross-continental Stone Age networking events powered human evolution ramped up in 2021. A long-standing argument that Homo sapiens originated in East Africa before moving elsewhere and replacing Eurasian Homo species such as Neandertals has come under increasing fire over the last decade. Research this year supported an alternative scenario in which H. sapiens evolved across vast geographic expanses, first within Africa and later outside it. The process would have worked as follows: Many Homo groups lived during a period known as the Middle Pleistocene, about 789,000 to 130,000 years ago, and were too closely related to have been distinct species. These groups would have occasionally mated with each other while traveling through Africa, Asia and Europe. A variety of skeletal variations on a human theme emerged among far-flung communities. Human anatomy and DNA today include remnants of that complex networking legacy, proponents of this scenario say. It’s not clear precisely how often or when during this period groups may have mixed and mingled. But in this framework, no clear genetic or physical dividing line separated Middle Pleistocene folks usually classed as H. sapiens from Neandertals, Denisovans and other ancient Homo populations. “Middle Pleistocene Homo groups were humans,” says paleoanthropologist John Hawks of the University of Wisconsin–Madison. “Today’s humans are a remix of those ancient ancestors.” © Society for Science & the Public 2000–2021.

Keyword: Evolution; Sexual Behavior
Link ID: 28111 - Posted: 12.15.2021

By Elizabeth Preston A person trying to learn the way around a new neighborhood might spend time studying a map. You would probably not benefit from being carried rapidly through the air, upside-down in the dark. Yet that’s how some baby bats learn to navigate, according to a study published last month in Current Biology. As their mothers tote them on nightly trips between caves and certain trees, the bat pups gain the skills they need to get around when they grow up. Mothers of many bat species carry their young while flying, said Aya Goldshtein, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany. Egyptian fruit bats, for example, are attached to their mothers continuously for the first three weeks of life. While a mother searches for food, her pup clings to her body with two feet and its jaw, latching its teeth around her nipple. Mothers can still be seen flying with older pups that weigh 40 percent of what they do. It hadn’t been clear why the moms go to this length, instead of leaving pups in the cave where they roost, as some other species do. Dr. Goldshtein worked with Lee Harten, a behavioral ecologist at Tel Aviv University in Israel, where both she and Dr. Goldshtein were graduate students at the time in the lab of Yossi Yovel, a study co-author, to make sense of this maternal mystery. The researchers captured Egyptian fruit bat mothers and pups from a cave just outside Tel Aviv. They attached a tag holding a radio transmitter and miniature GPS device to each bat’s fur that would drop off after a couple of weeks. Then, the researchers brought the bats back to their cave. To track the bats, Dr. Harten held an antenna while standing on the roof of a 10-story building with a view of the cave. She directed Dr. Goldshtein, who was on foot or in a car with her own antenna, to follow the radio signals of bat pairs as they flew out at night. But again and again, there was a problem: The pup’s movement would suddenly stop, while the mother’s signal disappeared. “At the beginning we thought that we were doing our job wrong, and just losing the bats,” Dr. Harten said. © 2021 The New York Times Company

Keyword: Learning & Memory; Animal Migration
Link ID: 28102 - Posted: 12.08.2021

By Sabrina Imbler The male Bornean rock frog cannot scream over the sound of a waterfall. Instead, he threatens other frogs with his feet. The frog intimidates his male competitors with a can-can-like gesture: kicking his leg up into the air, fully extending his splayed foot, and dragging it down toward the ground. This foot-flagging display may not sound threatening to a human, but its effect has to do with a frog’s visual perception. To a frog, the world contains two kinds of objects: things that are worms, and things that are not worms. If a frog sees a skinny object moving parallel to its long axis — like how a worm travels along the ground — it sees dinner. But if a frog sees a similar shape moving perpendicular its long axis — very unlike a worm — it sees a threat to flee from. Scientists call this latter movement the anti-worm stimulus, and it strikes fear into the hearts of frogs. Frogs likely evolved this visual system to hunt worms and stay safe from larger predators. Now, researchers suggest some male frogs have evolved to take advantage of their froggy brethren’s fears by kicking and lowering their legs in a gesture that looks a lot like an anti-worm signal, as a way to frighten their competition. In a paper published Wednesday in Proceedings of the Royal Society B, researchers reveal that they could amplify the foot-flagging behavior of Bornean rock frogs by giving the frogs a dose of testosterone. The hormone acts on the muscles in the frog’s leg to exaggerate the gesture, meaning the more testosterone coursing through the frog, the bigger the foot-flagging display. This flamboyant foot display, intensified by the sex hormone, suggests the frogs evolved a way to exploit their competitors’ unusual visual system to appear more dangerous to other frogs. © 2021 The New York Times Company

Keyword: Aggression; Hormones & Behavior
Link ID: 28087 - Posted: 11.20.2021

By Jamie Friedlander Serrano My dad was planning a trip to Cannon Beach, a small coastal town in Oregon that I love. Yet when I sat down to email him some recommendations, I drew a blank. I couldn’t remember the name of the state park we visited or the breakfast spot we adored. Even the name of the hotel we stayed at eluded me. U.S. coronavirus cases tracker and map Since giving birth to my year-old daughter, I’ve had countless moments like this. I have trouble recalling words, forget to respond to text messages, and even missed an appointment. What I’m experiencing is often called “mommy brain”— the forgetful, foggy and scatterbrained feeling many pregnant women and new mothers experience. But is mommy brain real? Anecdotally, yes. Ask any new mom if she has felt the above, and she'll likely say she has — as many as 80 percent of new moms report feelings of mommy brain. Scientifically, it also appears the answer is yes: A growing body of research supports the argument that moms' brains change during pregnancy and after giving birth. A clear explanation for the phenomenon still remains somewhat elusive, however. There are countless variables that experts say contribute to mommy brain, such as fluctuating hormones postpartum, sleep deprivation in dealing with a new baby, anxiety over new parenthood, elevated stress levels, and a general of lives that having a baby forces. Put together, it’s only natural that changes in mental processing would occur, says Moriah Thomason, Barakett associate professor of child and adolescent psychiatry at New York University School of Medicine. When our brain needs to make space for a new priority — keeping a baby alive — remembering a grocery list takes a back seat. “Does it mean that you literally cannot do those things that you used to do as well? Probably not,” she says. “It’s just not the most important thing for you to be accessing.” © 1996-2021 The Washington Post

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 28033 - Posted: 10.13.2021

Allison Aubrey The "diet" in diet drinks may be a false promise for some soda lovers. True, they deliver the fizz and taste of a soda experience, without the calories. Yet, new research shows they also can leave people with increased food cravings. A study published recently in JAMA Network Open adds to the evidence that drinks made with sucralose may stimulate the appetite, at least among some people, and the study gives some clues as to why. "We found that females and people with obesity had greater brain reward activity" after consuming the artificial sweetener, says study author Katie Page, a physician specializing in obesity at the University of Southern California. Both groups also had a reduction in the hormone that inhibits appetite, and they ate more food after they consumed drinks with sucralose, compared with after regular sugar-sweetened drinks. In contrast, the study found males and people of healthy weight did not have an increase in either brain reward activity or hunger response, suggesting they're not affected in the same way. The study notes that most earlier research focused on males and people of normal weight. But this finding suggests that diet drinks sweetened with sucralose could be disadvantageous to the people who could benefit most from an effective diet strategy. © 2021 npr

Keyword: Obesity; Sexual Behavior
Link ID: 28027 - Posted: 10.09.2021

By Tara Ellison As menopause hit, I found I wasn’t as interested in intimacy as I used to be. Sex started to feel like a box that needed to be checked a couple of times a week, and that was causing problems in my marriage. But it wasn’t just sex. I felt was slowing down in many areas. After hot flashes in my 40s had sent me running to the gynecologist for help, I’d been using bioidentical creams to balance my declining hormones. When, at 51, I confided to a friend that I’d had limited success with what my doctor prescribed, she said that she was thriving on something called hormonal “pellets.” I grilled her about them and then made an appointment with her practitioner, an internal medicine doctor. He ordered extensive lab work, which showed that my testosterone levels were very low, which can happen with aging. The doctor said I had two options: do nothing, which he said would eventually likely lead to loss of muscle, decreased bone density and a host of other health complications. Or up my testosterone. Testosterone therapy for women is a hotly debated subject. Studies suggest that testosterone can heighten libido in women with hypoactive sexual desire disorder (HSDD), at least in the short term. A recent statement by a group of international medical societies involved with women’s health endorsed the use of testosterone therapy in women for HSDD, and specifically excluded pellets and injectables as “not recommended.” It also cautioned there was not enough data to support the use of testosterone therapy for cognitive performance.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 28009 - Posted: 09.29.2021

By Kimberly Hickok Seahorses are some of the most dazzling fish in the sea. They’re also the only group of animals in which the males, not the females, go through pregnancy and give birth. Now, new research finds the male’s brood pouch—which can hold up to 1000 baby seahorses at a time—develops and functions like a human placenta. “Evolution is just mind boggling,” says Camilla Whittington, an evolutionary biologist at the University of Sydney who led the new work. The study is the first to thoroughly examine how males nurture their young brood while they’re still in the pouch, says Mari Kawaguchi, an evolutionary biologist at Sophia University in Tokyo. Kawaguchi, who has studied seahorses for some 2 decades, has long suspected pregnant seahorses develop something resembling a placenta. Now, at last, there’s proof. Male seahorses start their path toward fatherhood with a dance. They twirl together with their chosen female under the water, changing colors and linking tails as they pirouette around a shared holdfast. Next, they align the female’s ovipositor with the male’s pouch opening so the female can deposit her eggs. Once the deed is done, the male gently sways to settle the eggs. Ten days to 6 weeks later, depending on the species, the male spends hours in labor, pumping and thrusting to force hundreds of tiny babies out into the water. There, they drift until they are grown. As for dad, he is ready for another round of courtship within hours after birth. But during pregnancy, males have one goal: Provide the embryos with everything they need, from oxygen to nutrients to antibodies. “One of the biggest challenges that all pregnant parents have is getting oxygen to their embryos and carbon dioxide away from the embryos,” Whittington says. “That’s really what motivated our study–how do those baby seahorses actually breathe, if you will, inside the brood pouch?” © 2021 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 28004 - Posted: 09.25.2021

By Leigh Weingus I’ve struggled with sleep since I was a teenager, and have spent almost as long trying to fix it. I’ve absorbed countless books and articles on getting better sleep that instructed me to go blue-light free at least two hours before bedtime, take nightly baths to lower my body temperature, keep my phone far from my bedroom and avoid caffeine after 12 p.m. In between all my diligent sleep hygiene work, I couldn’t help but feel like there was a larger force at play. My sleep seemed to change throughout my menstrual cycle, for example, getting worse in the days before my period and significantly better afterward. When I was pregnant, I experienced the best sleep of my life, and when I stopped breastfeeding, I didn’t sleep for days. I finally started to ask myself: When we talk about getting better sleep, why aren’t we talking more about hormones? According to the National Sleep Foundation, the lifetime risk of insomnia is 40 percent higher for women than it is for men. Blaming this discrepancy entirely on hormones oversimplifies it — women also tend to take on the bulk of household worrying and emotional labor, and they tend to experience higher levels of anxiety. But according to Mary Jane Minkin, an obstetrician-gynecologist and clinical professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale School of Medicine, anecdotal evidence and studies suggest that hormones likely play a role.

Keyword: Sleep; Hormones & Behavior
Link ID: 28000 - Posted: 09.22.2021

By Joshua Rapp Learn Giraffes don’t fight much, says Jessica Granweiler, a master’s student at the University of Manchester in England who studies nature’s tallest mammals. When they do, look out. “Fighting is extremely rare because it’s extremely violent,” Ms. Granweiler said. When older adult males joust for territory or mating rights, their hornlike pairs of ossicones thrust with the force of their long necks and can cut into their opponents’ flesh, wounding and sometimes even killing a combatant. But some forms of giraffe dueling serve other purposes. In a study published last month in the journal Ethology, Ms. Granweiler and her colleagues reported some discoveries about sparring behavior that help giraffes establish social hierarchies. They showed that the animals didn’t take advantage of smaller members of their herds, but rather practiced their head butts with males of similar stature in ways that to a human might even appear fair or honorable. Such findings could aid in the conservation of the dwindling populations of the animals. Ms. Granweiler and her colleagues observed social behavior in giraffes at the small Mogalakwena River Reserve in South Africa from November 2016 to May 2017. They began to record the details of these fights — basically a who-fought-who, and how in the giraffe world. They were surprised to find that giraffes, like humans, can be righties or southpaws when it comes to sparring. Even the youngest animals showed a clear preference, although unlike humans it seemed they were evenly split between lefties and righties. The researchers also noticed that the younger males sparred more with each other, and nearly always chose opponents similar in size to themselves — there wasn’t a lot of bullying going on. A bar brawl effect went on as well, where one sparring match seemed to infect the crowd and prompt more fights around them. © 2021 The New York Times Company

Keyword: Aggression; Sexual Behavior
Link ID: 27997 - Posted: 09.18.2021

by Rachel Zamzow The X chromosome holds stronger-than-expected genetic sway over the structure of several brain regions, a new study finds. The X-linked genes that may underlie this oversized influence have ties to autism and intellectual disability. “There were already hints that the X chromosome was likely to be conspicuous, with how involved it is with the brain,” says lead investigator Armin Raznahan, chief of the section on developmental neurogenomics at the U.S. National Institute of Mental Health. Many X chromosome genes — including those at the root of several autism-related conditions, such as fragile X syndrome and Rett syndrome — are expressed in the brain, for example. But the new findings suggest that the X chromosome, despite containing only 5 percent of the human genome, has a privileged role in shaping the brain — one that may be particularly relevant to developmental conditions. What’s more, this influence may be stronger in men than in women, the study shows. “What they’re showing is X is fundamentally different,” says David Glahn, professor of psychology at Harvard University, who was not involved in the new study. “It’s off the scale.” Research over the past decade has linked genetic variation to shifts in brain features, such as overall size or patterns of connectivity between regions, Glahn says. But “the X chromosome and the Y chromosome are fundamentally understudied,” because including them requires extra analytical legwork, he says. © 2021 Simons Foundation

Keyword: Development of the Brain; Genes & Behavior
Link ID: 27992 - Posted: 09.15.2021