Chapter 8. Hormones and Sex

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By Elizabeth Pennisi For a glimpse of the power of sexual selection, the dance of the golden-collared manakin is hard to beat. Each June in the rainforests of Panama, the sparrow-size male birds gather to fluff their brilliant yellow throats, lift their wings, and clap them together in rapid fire, up to 60 times a second. When a female favors a male with her attention, he follows up with acrobatic leaps, more wing snaps, and perhaps a split-second, twisting backflip. “If manakins were human, they would be among the greatest artists, athletes, and socialites in our society,” says Ignacio Moore, an integrative organismal biologist at Virginia Polytechnic Institute and State University. As biologists have understood since Charles Darwin, such exhibitionism evolves when females choose to mate with males that have the most extravagant appearances and displays—a proxy for fitness. And now, by studying the genomes of the golden-collared manakin (Manacus vitellinus) and its relatives, researchers are exploring the genes that drive these elaborate behaviors and traits. Last month at the virtual meeting of the Society for Integrative and Comparative Biology, Moore and other researchers introduced four manakin genomes, adding to two already published, and singled out genes at work in the birds’ muscles and brains that may make the displays possible. © 2021 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 27716 - Posted: 03.06.2021

By Jake Buehler You might be able to do a mean celebrity impression or two, but can you imitate an entire film’s cast at the same time? A male superb lyrebird (Menura novaehollandiae) can, well almost. During courtship and even while mating, the birds pull off a similar feat, mimicking the calls and wingbeat noises of many bird species at once, a new study shows. The lyrebirds appear to be attempting to recreate the specific ecological soundscape associated with the arrival of a predator, researchers report February 25 in Current Biology. Why lyrebirds do this isn’t yet clear, but the finding is the first time that an individual bird has been observed mimicking the sounds of multiple bird species simultaneously. The uncanny acoustic imitation of multispecies flocks adds a layer of complexity to the male lyrebird’s courtship song yet unseen in birds and raises questions about why its remarkable vocal mimicry skills, which include sounds like chainsaws and camera shutters, evolved in the first place. Superb lyrebirds — native to forested parts of southeastern Australia — have a flair for theatrics. The males have exceptionally long, showy tail feathers that are shaken extensively in elaborate mating dances (SN: 6/6/13). The musical accompaniment to the dance is predominantly a medley of greatest hits of the songs of other bird species, the function of which behavioral ecologist Anastasia Dalziell was studying via audio and video recordings of the rituals.

Keyword: Sexual Behavior; Animal Communication
Link ID: 27715 - Posted: 02.28.2021

By Brooke N. Dulka Think back to years past. When you were a kid, you most likely had more friends than you do now. There were probably a lot of children on the playground you considered a friend, but not all of these friendships were very deep. As you grew up, your friendship circle most likely grew smaller. Instead of having many superficial relationships, you now have just a few really important friendships. This is normal. When we are older, we tend to focus on maintaining positive, meaningful relationships. One idea suggests that we become more selective about our friends because we become increasingly aware of our own mortality. In other words, we have future-oriented cognition. However, a recent study published in Science on the wild chimpanzees living in Uganda’s Kibale National Park suggests that our friendships may not actually be tied to thinking about the future. Alexandra Rosati, an evolutionary psychologist at the University of Michigan and one of the study’s lead investigators, had heard about this long-term field study in Uganda. “It seemed like it all could sort of fit together, in this cool way, this primatology data to actually test this idea about human cognition,” she says. Advertisement In this study, a team of researchers analyzed 78,000 hours of observations of 21 male chimpanzees made between 1995 and 2016 at the Kibale National Park. According to Rosati, a unique feature of this study is the value that exists in the long-term collection of data. “We used 20 years of data for this paper. [It] lets us look at this really detailed information about what's going on in these chimpanzees’ social lives,” she says. The findings surprised her. © 2021 Scientific American

Keyword: Stress; Development of the Brain
Link ID: 27681 - Posted: 02.08.2021

by Peter Hess Mice missing a copy of the autism-linked gene MAGEL2 have trouble discerning between a familiar mouse and an unfamiliar one, but treating them with the social hormone vasopressin reverses this deficit, according to a new study. Mutations in or deletions of MAGEL2 are linked to autism and several related conditions, including Prader-Willi syndrome, which is characterized by intellectual disability, poor muscle tone, difficulty feeding and problems with social interactions. The new findings suggest that these social issues in people stem from impairments in vasopressin’s function in a brain region called the lateral septum, which relays signals between the hippocampus and the ventral tegmental area. They also hint that vasopressin treatment could remedy those issues, says Elizabeth Hammock, assistant professor of psychology and neuroscience at Florida State University in Tallahassee, who was not involved with the study. A 2020 study showed that low levels of vasopressin in cerebrospinal fluid can flag many infants who are later diagnosed with autism. But clinical trials have shown that either providing vasopressin or blocking its effects can improve social communication in autistic children. Because of these seemingly contradictory results, “a better understanding of how alterations in the vasopressinergic system leads to social deficits and how vasopressin administration could resolve some of these problems was needed,” says co-lead researcher Freddy Jeanneteau, professor of neuroscience at Montpellier University in Montpellier, France. © 2021 Simons Foundation

Keyword: Autism; Hormones & Behavior
Link ID: 27665 - Posted: 01.27.2021

Catherine S. Woolley, Ph.D. Sex differences in the brain are real, but they are not what you might think. They’re not about who is better at math, reading a map, or playing chess. They’re not about being sensitive or good at multi-tasking, either. Sex differences in the brain are about medicine and about making sure that the benefits of biomedical research are relevant for everyone, both men and women. You may be surprised to learn that most animal research is done in males. This is based on an erroneous view that hormonal cycles complicate studies in female research animals, and an assumption that the sexes are essentially the same down at cellular and molecular levels. But these beliefs are starting to change in neuroscience. New research shows that some fundamental molecular pathways in the brain operate differently in males and females, and not just by a little. In some cases, molecular sex differences are all-or-nothing. Recognition that male and female brains differ at a molecular level has the potential to transform biomedical research. Drugs act on molecular pathways. If those pathways differ between the sexes, we need to know how they differ as early as possible in the long (and expensive) process of developing new medicines and treatments for disease. The bulk of public attention to brain sex differences is focused on structural differences and their purported relationship to behavior or cognition. Yet structural sex differences are actually quite small, and their interpretation is often based on gender stereotypes with little to no scientific justification. © 2021 The Dana Foundation

Keyword: Sexual Behavior; Brain imaging
Link ID: 27650 - Posted: 01.15.2021

by Peter Hess Two types of neurons process social information, a new mouse study suggests, but only one is disrupted in mice missing the autism-linked gene FMR1. The neurons reside in a brain region called the hypothalamus, and both send signals via the hormone oxytocin. The deletion of FMR1, however, affects these cells differently: The loss of FMR1 in the smaller, ‘parvocellular’ neurons diminishes the mice’s interest in social interactions — but only those involving peers, the new work shows. The gene’s loss from the larger, ‘magnocellular’ neurons, by contrast, does not disrupt the animals’ interactions with either peers or parents. “There are a lot of different types of social behaviors, and not all of them are impaired in autism,” says lead investigator Gül Dölen, assistant professor of neuroscience at Johns Hopkins University in Baltimore, Maryland. Whereas peer-to-peer social interactions are troublesome for many autistic people, other social interactions — such as parental connections — are on par with those seen in non-autistic people, she says. This new understanding of the different neurons’ functions could help explain why clinical trials of oxytocin for treating autism traits have shown mixed results. It could also help scientists develop more effective treatments, experts say. “There are these two different kinds of neurons that we’ve known about for a really long time, and each of their contributions to social behavior has never really been dissected out,” says Larry Young, chief of behavioral neuroscience and psychiatric disorders at Emory University in Atlanta, Georgia, who was not involved with the study. “It’s really important for the future of drug development.” © 2020 Simons Foundation

Keyword: Autism; Hormones & Behavior
Link ID: 27632 - Posted: 12.19.2020

Mercedes Burns An Asian water dragon hatched from an egg at the Smithsonian National Zoo, and her keepers were shocked. Why? Her mother had never been with a male water dragon. Through genetic testing, zoo scientists discovered the newly hatched female, born on Aug. 24, 2016, had been produced through a reproductive mode called parthenogenesis. Parthenogenesis is a Greek word meaning “virgin creation,” but specifically refers to female asexual reproduction. While many people may assume this behavior is the domain of science fiction or religious texts, parthenogenesis is surprisingly common throughout the tree of life and is found in a variety of organisms, including plants, insects, fish, reptiles and even birds. Because mammals, including human beings, require certain genes to come from sperm, mammals are incapable of parthenogenesis. Creating offspring without sperm Sexual reproduction involves a female and a male, each contributing genetic material in the form of eggs or sperm, to create a unique offspring. The vast majority of animal species reproduce sexually, but females of some species are able to produce eggs containing all the genetic material required for reproduction. Females of these species, which include some wasps, crustaceans and lizards, reproduce only through parthenogenesis and are called obligate parthenogens. A larger number of species experience spontaneous parthenogenesis, best documented in animals kept in zoo settings, like the Asian water dragon at the National Zoo or a blacktip shark at the Virginia Aquarium. Spontaneous parthenogens typically reproduce sexually, but may have occasional cycles that produce developmentally ready eggs. © 2010–2020, The Conversation US, Inc.

Keyword: Sexual Behavior
Link ID: 27630 - Posted: 12.19.2020

Claudia Dreifus Questions like “why do men and women act differently?” are age-old, with tangled, deeply buried answers. But that is why Catherine Dulac, a Howard Hughes Medical Investigator and a professor of molecular and cellular biology at Harvard University, has become so well respected by her neuroscientist colleagues for the originality and creativity with which she has brought important answers to light. Though she is trained as a developmental biologist, Dulac takes her research into territory usually explored by social scientists by trying to discern the balance of genetic determination and environmental influence that shapes vital behaviors in mammals. Moreover, she deploys the genetic tools of modern biology to discover the mechanisms that activate these behaviors. Relatively early in her career, Dulac’s investigations into how animals detect pheromones changed our understanding of what those airborne chemicals may signify to the brain. More recently, her experiments identified how the brain circuitry that regulates crucial mating and parenting behaviors works — at least in her model animals, which are mice. She found astonishing evidence that although certain of these behaviors are often described as “male” or “female,” both types of circuitry are present and potentially active in both sexes. As a result, the right combination of triggers can switch an individual creature’s behavior to that of the opposite sex. Scientists are still exploring the full implications of her findings, but Dulac and others are hopeful that they might yield useful insights into conditions like postpartum behavioral disorders. Because of her work’s relevance, in September Dulac, just age 57, was awarded the $3 million Breakthrough Prize in Life Sciences, the richest single personal award in the scientific world. The citation for the prize hailed the success of her work, which connected behaviors to specific neural mechanisms and “overturned decades-old dogma in behavioral science.” Simons Foundation © 2020

Keyword: Sexual Behavior
Link ID: 27625 - Posted: 12.15.2020

By Jason Castro To be an expectant mother, or the anxious partner of one, is to be keenly, even agonizingly aware of how chemicals affect a developing life. The basic advice is well known, and obsessively followed: Alcohol in strict moderation, and no nicotine at all. Don’t mess with mercury. Folic acid is your friend. More protein and less caffeine. Stay away from BPA, PBCs and PFA, and generally make an enemy of the unpronounceable. But, if we take the results of a provocative recent paper seriously, there may be another important, and deeply underappreciated chemical influence at work: a man’s odor. The research, by a team headed by Noam Sobel of the Weizmann Institute of Science, suggests that there is a relationship between women’s response to “social odors” contained in male sweat and the heartbreaking condition of unexplained repeated pregnancy loss (uRPL). Specifically, in blind smell-tests, these scientists observed that women who had experienced uRPL were significantly better at identifying their spouse’s odor than age-matched controls. Additionally, their brains responded differently to nonspouse odors and they displayed unique olfactory neuroanatomy. Taken in the context of a large body of literature on chemosignaling in nonhuman animals, these results make it conceivable that the human nose could also communicate with the womb and may even influence a pregnancy. So far, the results are strictly correlative, and in no way point to male odor as some kind of pheromonal smoking gun that explains pregnancy loss. Hypothetically, it could also be true that women experiencing uRPL have, on average, larger middle toes, larger whites of their eyes, thinner wrists and a proclivity for wearing purple socks. None of these would give one pause or prompt a serious search for some kind of causal link to pregnancy loss. Yet this particular link between smell and pregnancy loss is intriguing because of how prevalent and robust it is in other mammals, including primates. Many miscarriages still have unexplained causes, which makes any lead, correlative or not, a particularly interesting and worthwhile area of research. © 2020 Scientific American

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 27619 - Posted: 12.09.2020

By Sally Satel For over a half-century, steroid drugs have been a mainstay of medical care, widely used to treat inflammatory illness such as asthma, skin conditions and autoimmune diseases. Less is known about their dramatic and sometimes frightening long-term effects on mood, personality and thinking. I took steroids years ago, and the side effects changed my life. Steroid medications mimic a natural hormone in the body called glucocorticoid, which suppresses immune system processes that trigger inflammation, the sources of many autoimmune and chronic disease. In 1948, glucocorticoid was first used for a chronic inflammatory disease, rheumatoid arthritis, which causes joint deformity and chronic pain. Two years later, the American physician behind the breakthrough therapy was one of the winners of the Nobel Prize. Steroids have been prescribed for many other conditions since then. One steroid, dexamethasone, has been used for people with severe cases of covid-19 and President Trump was given it when he was hospitalized for the disease in October. My story starts in 1977. I was finishing my senior year as a biology major at Cornell University when I was diagnosed with Crohn’s disease, a form of inflammatory disease in which the body’s immune system attacks the gastrointestinal tract. I had a relatively mild case — transient pain, causing me to rush to the nearest ladies’ room, and find some blood in the bowl — and so I was able to finish my final year on time and begin a PhD program in evolutionary biology that summer. My predoctoral project entailed measuring the jaw muscles of tadpoles using jewelers’ tools and a dissecting microscope. Within weeks, though, I had a “flare” in the parlance of gastroenterology — I felt weak and was having increased bouts of blood-streaked diarrhea. In mid-October, I spent five days at the hospital where my symptoms resolved on a daily regimen of 60 mg of the potent steroid prednisone. I was discharged on 60 mg per day and felt fine for a week. But soon my brain began to feel like cotton wrapped in yards of gauze. I tried to study for an upcoming quiz but I couldn’t concentrate. © 1996-2020 The Washington Post

Keyword: Hormones & Behavior
Link ID: 27609 - Posted: 12.07.2020

By Emily Willingham When a male sand-sifting sea star in the coastal waters of Australia reaches out a mating arm to its nearest neighbor, sometimes that neighbor is also male. Undaunted, the pair assume their species’ pseudocopulation position and forge ahead with spawning. Mating, pseudo or otherwise, with a same-sex neighbor obviously does not transfer a set of genes to the next generation—yet several sea star and other echinoderm species persist with the practice. They are not alone. From butterflies to birds to beetles, many animals exhibit same-sex sexual behaviors despite their offering zero chance of reproductive success. Given the energy expense and risk of being eaten that mating attempts can involve, why do these behaviors persist? One hypothesis, hotly debated among biologists, suggests this represents an ancient evolutionary strategy that could ultimately enhance an organism’s chances to reproduce. In results published recently in Nature Ecology & Evolution, Brian Lerch and Maria R. Servedio, from the University of North Carolina, Chapel Hill, offer theoretical support for this proposed explanation. They created a mathematical model that calculated scenarios in which mating attempts, regardless of partner sex, might be worth it. The results predicted that, depending on life span and mating chances, indiscriminate mating with any available candidates could in fact yield a better reproductive payoff than spending precious time and energy sorting out one sex from the other. Although this study does not address sexual orientation or attraction, both of which are common among vertebrate species, it does get at some persistent evolutionary questions: when did animals start distinguishing mates by sex, based on specific cues, and why do some animals apparently remain indiscriminate in their choices? © 2020 Scientific American

Keyword: Sexual Behavior; Evolution
Link ID: 27603 - Posted: 12.05.2020

By Sabrina Imbler In the spring of 2018 at the Montreal Insectarium, Stéphane Le Tirant received a clutch of 13 eggs that he hoped would hatch into leaves. The eggs were not ovals but prisms, brown paper lanterns scarcely bigger than chia seeds. They were laid by a wild-caught female Phyllium asekiense, a leaf insect from Papua New Guinea belonging to a group called frondosum, which was known only from female specimens. Phyllium asekiense is a stunning leaf insect, occurring both in summery greens and autumnal browns. As Royce Cumming, a graduate student at the City University of New York, puts it, “Dead leaf, live leaf, semi-dried leaf.” Mr. Le Tirant, the collections manager of the insectarium since 1989, specializes in scarab beetles; he estimates that he has 25,000 beetles in his private collection at home. But he had always harbored a passion for leaf insects and had successfully bred two species, a small one from the Philippines and a larger one from Malaysia. A Phyllium asekiense — rare, beautiful and, most important, living — would be a treasure in any insectarium. In the insect-rearing laboratory, Mario Bonneau and other technicians nestled the 13 eggs on a mesh screen on a bed of coconut fibers and spritzed them often with water. In the fall, and over the course of several months, five eggs hatched into spindly black nymphs. The technicians treated the baby nymphs with utmost care, moving them from one tree to another without touching the insects, only whatever leaf they clung to. “Other insects, we just grab them,” Mr. Le Tirant said. “But these small leaf insects were so precious, like jewels in our laboratory.” The technicians offered the nymphs a buffet of fragrant guava, bramble and salal leaves. Two nymphs refused to eat and soon died. The remaining three munched on bramble, molted, munched, molted, and molted some more. One nymph grew green and broad, just like her mother. © 2020 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 27601 - Posted: 12.05.2020

By Jake Buehler Naked mole-rats — with their subterranean societies made up of a single breeding pair and an army of workers — seem like mammals trying their hardest to live like insects. Nearly 300 of the bald, bucktoothed, nearly blind rodents can scoot along a colony’s labyrinth of tunnels. New research suggests there’s brute power in those numbers: Like ants or termites, the mole-rats go to battle with rival colonies to conquer their lands. Wild naked mole-rats (Heterocephalus glaber) will invade nearby colonies to expand their territory, sometimes abducting pups to incorporate them into their own ranks, researchers report September 28 in the Journal of Zoology. This behavior may put smaller, less cohesive colonies at a disadvantage, potentially supporting the evolution of bigger colonies. Researchers stumbled across this phenomenon by accident while monitoring naked mole-rat colonies in Kenya’s Meru National Park. The team was studying the social structure of this extreme form of group living among mammals (SN: 6/20/06). Over more than a decade, the team trapped and marked thousands of mole-rats from dozens of colonies by either implanting small radio-frequency transponder chips under their skin, or clipping their toes. One day in 1994, while marking mole-rats in a new colony, researchers were surprised to find in its tunnels mole-rats from a neighboring colony that had already been marked. The queen in the new colony had wounds on her face from the ravages of battle. It looked like a war was playing out down in the soil. © Society for Science & the Public 2000–2020.

Keyword: Evolution; Sexual Behavior
Link ID: 27538 - Posted: 10.21.2020

Moles have a pretty tough life. They live underground, in the dark, burrowing through heavy dirt. And when faced with an enemy, there's nowhere to turn — they have to fight. In most mammals, females tend to be at a disadvantage when it comes to face-to-face combat, because they tend to be smaller and less aggressive than males. But female moles have evolved a secret weapon: a hybrid organ made up of both ovarian and testicular tissue. This effectively makes them intersex, giving them an extra dose of testosterone to make them just as muscular and aggressive as male moles. "As a consequence, basically the whole body of the female, they get masculinized," geneticist Darío Lupiáñez told Quirks & Quarks host Bob McDonald. "They become the body builders of nature." Lupiáñez co-led a study to understand how the moles' genes facilitated this advantage, which was recently published in the journal Science. The research was part of a collaboration between the Max Planck Institute for Molecular Genetics and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association in Germany. Same genes, different instructions The team worked with Iberian moles, commonly found in Spain and Portugal, however this intersex adaptation has been documented in at least six mole species. "We know that intersexuality happens in species like humans, dogs or cats. But the difference actually in moles, it happens all the time, so all the females are intersexual. And this is really something unique among mammals," said Lupiáñez. To understand how moles evolved these intersexual traits, researchers fully mapped the genome of the Iberian mole, commonly found in Spain and Portugal. (David Carmona, Department of Genetics, University of Granada, Spain ) ©2020 CBC/Radio-Canada.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 27530 - Posted: 10.19.2020

By Aayushi Pratap In Rector, Pa., researchers have spotted one strange bird. This rose-breasted grosbeak has a pink breast spot and a pink “wing pit” and black feathers on its right wing — telltale shades of males. But on its left side, the songbird displays yellow and brown plumage, hues typical of females. Annie Lindsay had been out capturing and banding birds with identification tags with her colleagues at Powdermill Nature Reserve in Rector on September 24 when a teammate hailed her on her walkie-talkie to alert her of the bird’s discovery. Lindsay, who is banding program manager at Powdermill, immediately knew what she was looking at: a half-male, half-female creature known as a gynandromorph. “It was spectacular. This bird is in its nonbreeding [plumage], so in the spring when it’s in its breeding plumage, it’s going to be even more starkly male, female,” Lindsay says. The bird’s colors will become even more vibrant, and “the line between the male and female side will be even more obvious.” Gynandromorphs are found in many species of birds, insects and crustaceans such as crabs and lobsters. This bird is likely the result of an unusual event when two sperm fertilize an egg that has two nuclei instead of one. The egg can then develop male sex chromosomes on one side and female sex chromosomes on the other, ultimately leading to a bird with a testis and other male characteristics on one half of its body and an ovary and other female qualities on the other half. © Society for Science & the Public 2000–2020

Keyword: Sexual Behavior
Link ID: 27506 - Posted: 10.07.2020

By Cara Giaimo Last year, Katie Goldin was walking in her Los Angeles neighborhood when she saw, in the middle of the sidewalk, two lizards interlocked. The male, flecked like a pebble and about a foot long, had his jaws fully around the slightly smaller female’s head. “He was tenderly clasping her neck in his mouth,” said Ms. Goldin, host of a podcast called “Creature Feature.” “She seemed like she was in a trance.” Even in a world absolutely full of bizarre reproductive strategies, southern alligator lizards are up there. The pair Ms. Goldin spotted were engaged in what’s known as “mate-holding,” a part of the copulatory process in which a male grips a female’s head in his mouth for hours or even days at a time. It’s not clear why the lizards do this. But recently, two research projects have looked into the animals’ ecology and anatomy to better understand where, when and how this strange behavior happens. By approaching the same subject from these very different vantage points, scientists can inform each other’s research, and get a clearer picture of what’s really going on. Spying on lizard sex, for science After Ms. Goldin saw the happy couple, she sent pictures to the Natural History Museum of Los Angeles County. Since 2015, the museum has put out a yearly call for photos and videos of alligator lizards getting it on, which it collects through emails, social media and the platform iNaturalist. The species is the most widespread reptile in Los Angeles. But because the city is a “jigsaw puzzle of private property,” it’s difficult to do traditional wildlife surveys, said Greg Pauly, the museum’s herpetology curator. There are only a handful of published accounts of the lizard’s mating behavior in the scientific literature. © 2020 The New York Times Company

Keyword: Sexual Behavior; Aggression
Link ID: 27500 - Posted: 09.30.2020

By Lisa Sanders, M.D. The waiter had barely put the plate in front of her when the 46-year-old woman felt the color drain from her face. She was in Fresno, Calif., on a work trip and had come to a restaurant to meet an old friend for dinner. But all of a sudden her stomach dropped — the way it might on a roller-coaster ride. A sudden coolness on her face told her she’d broken out in a sweat. She felt dizzy and a little confused. She saw the alarmed face of her friend and knew she looked as bad as she felt. She excused herself and carefully made her way to the bathroom. She sat in front of the vanity and supported her head on her arms. There was the now-familiar stabbing pain in her stomach. She wasn’t sure how long she stayed like that. Was it 10 minutes? 15? At last she felt as if she could get up. As she hurried to meet her friend at the entrance, she felt the contents of her stomach surging upward. She covered her mouth as vomit shot between her fingers. She lowered her head and bolted through the doorway, trying not to see the horrified faces of the diners. In the parking lot, the rush of stomach contents continued until she was completely empty. Exhausted, she sank into the seat of her friend’s car. She was too sick to go back to her hotel, her friend said. Instead the friend would take her to her house, until she felt better. The next thing the woman remembered was that she was sitting on the floor of her friend’s shower, hot water pounding her back. When she could, she crawled into bed. She slept until late the next morning. She thanked her friend, canceled her morning meetings and later that day headed home to Stockton, Calif. © 2020 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 27498 - Posted: 09.30.2020

By Lisa Grossman Clues from a chemical — Science News, October 3, 1970 An experimental drug’s effects on the sexual behavior of certain animals is arousing interest among investigators.… The drug, para-chlorophenylalanine … reduces the level of a naturally occurring neurochemical, serotonin, in the brain of rats, mice and dogs.… Little is known about how serotonin acts in the brain, and investigators quickly recognized that PCPA could be used to study this brain chemical. Update PCPA helped e­stablish serotonin’s role in regulating sexual desire, as well as sleep, appetite and mood. The chemical messenger has become key to one common class of antidepressant drugs called selective serotonin r­euptake inhibitors. Identified in 1974, SSRIs work by increasing the brain’s serotonin levels. But such drugs can hinder sexual desire. One SSRI that failed to relieve depression in humans found a second life as a treatment for sexual dysfunction. Approved by the U.S. Food and Drug Administration in 2015, this “little pink pill,” sold as Addyi, may boost sex drive in women by lowering serotonin in the brain’s reward centers. H.A. Croft. Understanding the role of serotonin in female hypoactive sexual desire disorder and treatment options. Journal of Sexual Medicine. Vol. 14, December 2017, p. 1575. Doi: 10.1016/j.jsxm.2017.10.068. © Society for Science & the Public 2000–2020.

Keyword: Depression; Sexual Behavior
Link ID: 27497 - Posted: 09.30.2020

The benefits of companionship for humans are well known, and they're not just confined to our mental health. Humans with strong social bonds with others live longer, healthier lives. Now a study looking at wild baboons in Africa has shown this is true for them as well. In particular, male baboons with non-sexual friendships with females live far longer than animals who lack these social bonds. Researchers have known for years that companionship is beneficial for the health and longevity of female baboons. But because of their social structure, male baboons are much harder to study over a long term than females. Female baboons stay with their birth troop for their entire lives, and so are easy to track and observe. Males, on the other hand, switch troops after they mature, and sometimes in adulthood as well, and so tracking them for their lifetime — which averages something like a decade and a half — can be a challenge. But a team led by Susan Alberts, a professor of biology and chair of the evolutionary anthropology department at Duke University, was able to master this problem. Friends with benefits Platonic friendship among baboons of the opposite sex is, it turns out, common. According to Alberts, male baboons will frequently form non-sexual friendship bonds with females and will protect them and their offspring from aggression within the troop and from predators. The benefits of this for the females are clear. What was less clear was the benefits of this kind of companionship for the males. The new study from Alberts and her team drew on data collected over many years from over 500 baboons at Amboseli National Park in Kenya to answer that question.. ©2020 CBC/Radio-Canada.

Keyword: Stress; Sexual Behavior
Link ID: 27492 - Posted: 09.28.2020

By Ann Gibbons Neanderthals have long been seen as uber-masculine hunks, at least compared with their lightweight human cousins, with whom they competed for food, territory, and mates. But a new study finds Homo sapiens men essentially emasculated their brawny brethren when they mated with Neanderthal women more than 100,000 years ago. Those unions caused the modern Y chromosomes to sweep through future generations of Neanderthal boys, eventually replacing the Neanderthal Y. The new finding may solve the decade-old mystery of why researchers have been unable to find a Neanderthal Y chromosome. Part of the problem was the dearth of DNA from men: Of the dozen Neanderthals whose DNA has been sequenced so far, most is from women, as the DNA in male Neanderthal fossils happened to be poorly preserved or contaminated with bacteria. “We began to wonder if there were any male Neanderthals,” jokes Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology and senior author of the new study. But in a technical breakthrough, Max Planck graduate student Martin Petr designed a set of probes that used the DNA sequence from small chunks of modern men’s Y chromosomes to “fish out” and bind with DNA from archaic men’s Y chromosomes. The new method works because the Neanderthal and modern human chromosomes are mostly similar; the DNA probes also reel in the few basepairs that differ. The researchers probed the fragmentary Y chromosomes of three Neanderthal men from Belgium, Spain, and Russia who lived about 38,000 to 53,000 years ago, and two male Denisovans, close cousins of Neanderthals who lived in Siberia’s Denisova Cave about 46,000 to 130,000 ago. When the researchers sequenced the DNA, they got a surprise: The Neanderthal Y “looked more like modern humans’ than Denisovans’,” Kelso says. © 2020 American Association for the Advancement of Science.

Keyword: Sexual Behavior
Link ID: 27484 - Posted: 09.25.2020