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

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


Links 1 - 20 of 2369

By Nicole M. Baran When Kathleen Morrison stepped onto the stage to present her research on the effects of stress on the brains of mothers and infants, she was nearly seven and a half months pregnant. The convergence was not lost on Morrison, a postdoctoral researcher at the University of Maryland School of Medicine, nor on her audience. If there ever was a group of scientists that would be both interested in her findings and unfazed by her late-stage pregnancy, it was this one. Nearly 90 percent were women. It is uncommon for any field of science to be dominated by women. In 2015, women received only 34.4 percent of all STEM degrees.1 Even though women now earn more than half of PhDs in biology-related disciplines, only 36 percent of assistant professors and 18 percent of full professors in biology-related fields are women.2 Yet, 70 percent of the speakers at this year’s meeting of the Organization for the Study of Sex Differences (OSSD), where Morrison spoke, were women. Women make up 67 percent of the regular members and 81 percent of trainee members of OSSD, which was founded by the Society for Women’s Health Research. Similarly, 68 percent of the speakers at the annual meeting of the Society for Behavioral Neuroendocrinology (SBN) in 2017 were women. In the field of behavioral neuroendocrinology, 58 percent of professors and 62 percent of student trainees are women. The leadership of both societies also skews female, and the current and recent past presidents of both societies are women. It wasn’t always this way. As Elizabeth Adkins-Regan, a professor emerita at Cornell University and the recent past president of the SBN puts it: “The whole field was founded by guys!” “It was not a women’s field in the beginning,” agrees C. Sue Carter, director of the Kinsey Institute and professor of biology at Indiana University. © 2018 NautilusThink Inc

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 25341 - Posted: 08.17.2018

By Dana G. Smith Postpartum depression afflicts 10 to 20 percent of the nearly four million women who give birth in the U.S. every year. The condition hits at a vulnerable moment when mother and infant normally begin to bond. Depressed moms pay less attention to their newborns, so the critical attachment between mother and baby does not occur. For some women, postpartum depression can last for years, and the lack of maternal bonding can interfere with children’s development through adolescence. “There's a real need to identify women and treat them, and treat them quickly,” says Samantha Meltzer-Brody, director of the Perinatal Psychiatry Program at the University of North Carolina at Chapel Hill Center for Women’s Mood Disorders. “When mom is not doing well, it becomes a crisis for the whole family at this vulnerable time. But like many issues related to mental health, and specifically women's mental health, it has been neglected.” Despite the frequency of postpartum depression, no treatments specifically target it. Many women who suffer from the condition receive standard antidepressants like SSRIs (selective serotonin reuptake inhibitors, such as Prozac) but it is unclear how well these drugs work because the neurochemical serotonin may play only a secondary role in postpartum depression or may not be involved at all. Instead, researchers hypothesize that a shift in female reproductive hormones during pregnancy is the main cause. Now a new drug that has gone through late-stage clinical trials aims to correct the consequences of these hormonal changes, and early results in human trials suggest it may be working. © 2018 Scientific American

Keyword: Depression; Sexual Behavior
Link ID: 25337 - Posted: 08.16.2018

Yao-Hua Law What can males wear to look sexier? For zebra finches, the trick seemed simple: add a dash of red to their legs. Research conducted in the 1980s found that slipping red bands onto the legs of male birds turned them into sex magnets. Those studies became iconic in sexual selection research because they provided something rare in the discipline: strong, consistent effects. But data accumulated in recent years question these influential findings. Zebra finches (Taeniopygia guttata) are native Australian birds with a bright red-orange beak. They form monogamous breeding pairs in which the male and female cooperate to raise young. Easy to rear in captivity, zebra finches are model organisms for research in cognition and sexual selection. In the 1980s, ornithologist Nancy Burley, then at the University of Illinois, found that placing plastic leg bands of different colors—used by scientists to identify individual birds—on the legs of zebra finches affected the birds’ chances of mating. Burley reported, first in Science and then in other leading journals, that females preferred red-banded males and disliked green-banded males. Females also spent more time caring for nestlings sired by red-banded males. Burley’s results inspired subsequent research in female choice and maternal effects. But results contradictory to Burley’s began to emerge in the late 1990s. And this March, Wolfgang Forstmeier of the Max Planck Institute for Ornithology and colleagues published the strongest disagreement yet. Forstmeier’s lab ran eight experiments and analyzed unpublished data from four other labs and found no effects of leg-band colors on the reproductive success of male or female zebra finches. The new study also included a meta-analysis of 39 published studies, including 22 that supported leg-band color effects. The meta-analysis found that effect sizes shrank as sample sizes increased—a sign of selective reporting. © 1986 - 2018 The Scientist

Keyword: Sexual Behavior; Evolution
Link ID: 25333 - Posted: 08.15.2018

By Bilal Choudhry Killifish are a family of freshwater fish that have evolved to survive in the most difficult of situations. Here in the United States, for instance, the Atlantic killifish is known for having adapted to live in heavily polluted places like the Lower Passaic River. But in small murky puddles that come after heavy rains in parts of East Africa, another killifish, called Nothobranchius furzeri, or the African annual fish, has developed its own unique adaptations to its environment. Its embryos are able to enter a state of diapause, similar to hibernation in bears, when conditions aren’t right. It turns out that entering dormancy isn’t the only thing that’s unusual about this African killifish. In a paper published on Monday in Current Biology, a team of Czech researchers report that N. furzeri has the quickest known rate of sexual maturity of any vertebrate — approximately two weeks. By studying the fish’s unusual life cycle, they hope to gain insights into the process of aging in other vertebrates, including us. Dr. Martin Reichard, a biologist who is studying the evolution of aging at the Czech Academy of Sciences’ Institute of Vertebrate Biology, led a team of colleagues to Mozambique to study the fish’s developmental stages in the wild. There, they were able to observe embryos buried in the sand that had entered a dormant state. They also documented their maturation after rainfall. When N. furzeri receive cues from their environment, they can be flexible in sexual development. Under these circumstances, their embryos enter a stage of dormancy called embryonic diapause, a reproductive strategy that extends their gestational period and helps them survive unfavorable conditions, like a dry season. But when it rains, they undergo rapid growth, going from juvenile fish to mature adults that are able to reproduce in about two weeks. © 2018 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 25304 - Posted: 08.07.2018

By Michael Erard , Catherine Matacic If you want a no-fuss, no-muss pet, consider the Bengalese finch. Dubbed the society finch for its friendliness, breeders often use it to foster unrelated chicks. But put the piebald songbird next to its wild ancestor, the white-rumped munia, and you can both see and hear the differences: The aggressive munia tends to be darker and whistles a scratchy, off-kilter tune, whereas the pet finch warbles a melody so complex that even nonmusicians may wonder how this caged bird learned to sing. All this makes the domesticated and wild birds a perfect natural experiment to help explore an upstart proposal about human evolution: that the building blocks of language are a byproduct of brain alterations that arose when natural selection favored cooperation among early humans. According to this hypothesis, skills such as learning complex calls, combining vocalizations, and simply knowing when another creature wants to communicate all came about as a consequence of pro-social traits like kindness. If so, domesticated animals, which are bred to be good-natured, might exhibit such communication skills too. The idea is rooted in a much older one: that humans tamed themselves. This self-domestication hypothesis, which got its start with Charles Darwin, says that when early humans started to prefer cooperative friends and mates to aggressive ones, they essentially domesticated themselves. Along with tameness came evolutionary changes seen in other domesticated mammals—smoother brows, shorter faces, and more feminized features—thanks in part to lower levels of circulating androgens (such as testosterone) that tend to promote aggression. © 2018 American Association for the Advancement of Science.

Keyword: Language; Evolution
Link ID: 25289 - Posted: 08.03.2018

Laura Sanders Among amateur players who headed a similar number of balls, women had more signs of microscopic damage in their brains’ white matter than men, scientists report July 31 in Radiology. Female athletes are known to have worse symptoms after brain injuries than male athletes, but a clear head-to-head comparison of post-heading brains hadn’t been done until now. From 2013 to 2016, study coauthor Michael Lipton of Albert Einstein College of Medicine in Bronx, N.Y., and colleagues recruited 98 soccer players from amateur teams, including from colleges. The researchers then compared male and female players who headed the ball a similar number of times over the past year. For men, that median estimate was 487 headers. Women had an estimated median of 469 headers. Despite those similar numbers of head knocks, women’s brains had more spots that showed signs of microscopic damage. A type of magnetic resonance imaging scan called diffusion tensor imaging identified brain regions with changes in white matter, bundles of message-sending fibers. In some cases, those altered spots indicated possible damage to nerve cell axons and myelin, a protective coating that speeds neural signals along. In men, only three brain regions showed potential damage associated with heading frequency. In women, eight regions showed signs of damage with frequent heading. These brain changes weren’t enough to cause symptoms in the amateur soccer players. But repeated blows to the brain can contribute to memory loss and chronic traumatic encephalopathy, a disorder found in professional football players, soldiers and others whose brains suffer repetitive trauma (SN: 7/13/13, p. 18). |© Society for Science & the Public 2000 - 2018.

Keyword: Brain Injury/Concussion; Sexual Behavior
Link ID: 25281 - Posted: 08.01.2018

Diana Kwon Bruce Baker, a geneticist who studied gene-behavior interactions in Drosophila melanogaster, died on July 1. He was 72 years old. “Bruce had enormous respect for the details of science, not only the science in his own lab but also that of his peers,” Deborah Andrew, a biologist at Johns Hopkins and one of Baker’s former graduate students, writes in an obituary posted by the Genetics Society of America. Baker was born in Swannanoa, North Carolina in 1945. After completing his undergraduate studies at Reed College in 1966 and receiving a PhD from the University of Washington in 1971, Baker joined the faculty at the University of California, San Diego. In 1986, he became a professor at Stanford University, where he remained for more than two decades before moving to the Howard Hughes Medical Institute’s Janelia Research Campus in 2008. Over the course of his career, Baker published more than 150 papers, primarily focused on the cellular and genetic mechanisms that determine the development of sex-specific characteristics in fruit flies. He also investigated dosage compensation, the strategies used by fruit flies to deal with having one X chromosome instead of two. Among Baker’s scientific contributions is the discovery that the gene encoding the transcription factor Fruitless plays a key role in male-specific courtship behaviors. Studies led by Baker and his colleague, neurobiologist Barry Dickson, revealed that Fruitless (fru) influenced male flies’ attraction to females and, when expressed in females, led them to court other female flies. © 1986 - 2018 The Scientist.

Keyword: Genes & Behavior; Sexual Behavior
Link ID: 25276 - Posted: 08.01.2018

Abby Olena To convince female Drosophila melanogaster flies to mate, males sing—that is, they vibrate their wings to serenade females. In more than 50 years of studying these songs, scientists thought there were only two song modes, known as pulse and sine. But in a study published today (July 26) in Current Biology, researchers found that there are actually two different types of pulse songs, lengthening the set list to three and paving the way for a greater understanding of how the brain generates behavior. “The beauty of the paper is that it demonstrates the hidden complexity in these fruit fly songs,” says David Stern, a biologist at the Howard Hughes Medical Institute’s Janelia Research Campus who did not participate in the work. “Even what we thought was one song type hides really interesting variation, and this is a beautiful quantitative description of that underlying complexity that most of us missed in the past.” In a 2014 Nature study, Princeton biologist Mala Murthy and colleagues used computational models to predict which song male flies would produce based on sensory cues they received during courtship. The researchers’ models accounted for much of the variability in the males’ choice of song modes, but not all of it. Murthy says that one reason the models didn’t account for all the variability could be that they were missing information about the song itself. © 1986 - 2018 The Scientist.

Keyword: Sexual Behavior; Animal Communication
Link ID: 25266 - Posted: 07.28.2018

Jon Hamilton There's new evidence that a woman's levels of female sex hormones, including estrogen and progesterone, can influence her risk of Alzheimer's and other forms of dementia. Women are less likely to develop dementia later in life if they begin to menstruate earlier, go through menopause later, and have more than one child, researchers reported Monday at the Alzheimer's Association International Conference in Chicago. And recent studies offer hints that hormone replacement therapy, which fell out of favor more than a decade ago, might offer a way to protect a woman's brain if it is given at the right time, the researchers said. The findings could help explain why women make up nearly two-thirds of people in the U.S. with Alzheimer's, says Maria Carrillo, the association's chief scientific officer. "It isn't just that women are living longer," Carrillo says. "There is some biological underpinning. And because of the large numbers of women that are affected, it is important to find out [what it is]." Scientists have long suspected that sex hormones such as estrogen and progesterone play a role in Alzheimer's. And two studies on dementia and what occurs during a women's reproductive years support that idea. One of the studies looked at nearly 15,000 women in California. And it found an association between a woman's reproductive history and her risk of memory problems later in life. © 2018 npr

Keyword: Alzheimers; Hormones & Behavior
Link ID: 25242 - Posted: 07.24.2018

Noise from oil and gas pumps can be a real mood-killer for a male sparrow trying to attract a mate, but a team of biologists in southern Alberta has discovered that songbirds are finding ways to cope. Their research involves high fidelity speakers, powerful microphones and many early morning hours spent on a patch of prairie near the small city of Brooks. They blast recordings of various types of oil and gas pumps through the speakers and then track and record the birds' response. The acoustic experiments are producing intriguing results. One songbird species, the Savannah sparrow, appears to be adapting its love songs with a high degree of complexity. "They're doing whatever they can to make the sound go further," said Nicola Koper, a conservation biologist from the University of Manitoba's Natural Resources Institute who is involved in the research. After all, the birds have flown all the way up from the southern U.S. on important business: to breed and raise their young. Fastest declining avian group in Canada The mixed grass prairies in southern Alberta serve as a bug buffet and a nursery for grassland birds, but their territory has shrunk. "We've converted so much of our grassland habitat to cropland, that grassland birds are declining more rapidly than birds of any other ecosystem across North America, including in Canada," said Koper. ©2018 CBC/Radio-Canada

Keyword: Animal Communication; Hearing
Link ID: 25233 - Posted: 07.21.2018

According to a new National Institutes of Health-funded study, it is not destiny that brings two fruit flies together, but an evolutionary matchmaker of sorts that made tiny adjustments to their brains’ mating circuits, so they would be attracted to one another while rejecting advances from other, even closely-related, species. The results, published in Nature, may help explain how a specific female scent triggers completely different responses in different male flies. “This study reveals how a very small tweak in brain wiring can result in large changes in very complex social behaviors, which can ultimately determine the fate of a species,” said Jim Gnadt, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), which supported the study. “Understanding how variation in brain circuits leads to changes in behavior is one of the primary goals of the NIH’s BRAIN Initiative and this study provides a piece of the puzzle.” Vanessa Ruta, Ph.D., professor at Rockefeller University in New York City, and her colleagues used cutting-edge genetic tools to compare the brain circuits behind courtship behavior in two closely related species of fruit fly, D. melanogaster and D. simulans. Previous studies showed that although males from both species could detect a specific pheromone, or scent, called 7,11-heptacosadiene (7,11-HD), their reactions to it were very different. Male D. melanogaster flies found it attractive while D. simulans males avoided females that carried it. In this study, Dr. Ruta and her team discovered that slight differences in the way the fly’s brains are wired may control these opposite reactions.

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 25217 - Posted: 07.17.2018

by Melissa Healy An extra shot of testosterone, it seems, makes a man act like an animal. You know the type: one of those male birds that unfurls some of its most spectacular feathers when the ladies are around, or the buck who uses his crown of antlers to advertise his virility. In short, an animal prone to making showy displays of his power, beauty or wealth to win mates, gain allies and intimidate competitors. But for humans — American men, at least — new research suggests that this testosterone-driven display of prowess finds its expression in a preference for status goods. Whether it’s in his choice of top-shelf alcohol at the club, the watch on his wrist or the clothes he wears, a man under the influence of the male sex hormone is going to reach for the product that says to potential mates (and to competitors for those mates), “U can’t touch this.” This pursuit of status in the choice of manufactured goods is called “positional consumption.” It’s been a hot topic among evolutionary psychologists and now is finding its way into the study of marketing. Researchers from the Wharton School of the University of Pennsylvania gave a supply of gel to 243 men, ages 18 to 55, and asked them to rub it all over their upper body. Some of the gels contained testosterone, others a placebo. Then the researchers asked the subjects to look at pictures and descriptions of five pairs of items — including watches, jeans and jackets — and judge which ones they preferred. © 1996-2018 The Washington Post

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 25210 - Posted: 07.16.2018

Laura Sanders Today’s young women are more likely to experience depression and anxiety during pregnancy than their mothers were, a generation-spanning survey finds. From 1990 to 1992, about 17 percent of young pregnant women in southwest England who participated in the study had signs of depressed mood. But the generation that followed, including these women’s daughters and sons’ partners, fared worse. Twenty-five percent of these young women, pregnant in 2012 to 2016, showed signs of depression, researchers report July 13 in JAMA Network Open. “We are talking about a lot of women,” says study coauthor Rebecca Pearson, a psychiatric epidemiologist at Bristol University in England. Earlier studies also had suggested that depression during and after pregnancy is relatively common (SN: 3/17/18, p. 16). But those studies are dated, Pearson says. “We know very little about the levels of depression and anxiety in new mums today,” she says. To measure symptoms of depression and anxiety, researchers used the Edinburgh Postnatal Depression Scale — 10 questions, each with a score of 0 to 3, written to reveal risk of depression during and after pregnancy. A combined score of 13 and above signals high levels of symptoms. From 1990 to 1992, 2,390 women between the ages of 19 and 24 took the survey while pregnant. Of these women, 408 — or 17 percent — scored 13 or higher, indicating worrisome levels of depression or anxiety. |© Society for Science & the Public 2000 - 2018.

Keyword: Depression; Hormones & Behavior
Link ID: 25207 - Posted: 07.14.2018

By Jeré Longman Researchers have found flaws in some of the data that track and field officials used to formulate regulations for the complicated cases of Caster Semenya of South Africa, the two-time Olympic champion at 800 meters, and other female athletes with naturally elevated testosterone levels. Three independent researchers said they believed the mistakes called into question the validity of a 2017 study commissioned by track and field’s world governing body, the International Federation of Athletics Associations, or I.A.A.F., according to interviews and a paper written by the researchers and provided to The New York Times. The 2017 study was used to help devise regulations that could require some runners to undergo medical treatment to lower their hormone levels to remain eligible for the sport’s most prominent international competitions, like the Summer Games. The researchers have called for a retraction of the study, published last year in the British Journal of Sports Medicine. The study served as an underpinning for rules, scheduled to be enacted in November, which would establish permitted testosterone levels for athletes participating in women’s events from 400 meters to the mile. “They cannot use this study as an excuse or a reason for setting a testosterone level because the data they have presented is not solid,” one of the independent researchers, Erik Boye of Norway, said Thursday. The I.A.A.F. has updated its research, which was published last week, again in the British Journal of Sports Medicine. “The I.A.A.F. will not be seeking a retraction of the 2017 study,” the governing body said in a statement on Thursday. “The conclusions remain the same.” But the statement did little to dampen criticism by the independent researchers. The I.A.A.F. seems “bound to lose” an intended challenge by Semenya to the Court of Arbitration for Sport, a kind of Supreme Court for international athletics, said Boye, a cancer researcher and an antidoping expert. © 2018 The New York Times Company

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 25200 - Posted: 07.13.2018

Yao-Hua Law It’s easy to tell a male from a female shark. Flip it over. If it has a pair of claspers — finger-like extensions jutting from the end of the pelvic fins — it is male; no claspers means female. Like a penis, claspers deliver sperm inside the female. That was marine biologist Alissa Barnes’ understanding until she dissected seven bigeye houndsharks (Iago omanesis) with claspers and found a complete female reproductive system in each. None of the seven sharks had any internal male sex organs. Six were pregnant. Barnes, of the Dakshin Foundation, shared her findings June 25 at the 5th International Marine Conservation Congress in Kuching, Sarawak, Malaysia. Barnes stumbled upon these hermaphrodite sharks at a port in Odhisa in eastern India in 2017. She was surveying local fishers to see if changes in their practices might explain a decline in hauls of sharks and rays. When she checked what the fishing vessels brought in, Barnes noticed two oddities. Male bigeye houndsharks greatly outnumbered females. And though males of this deepwater species are smaller than females, she saw immature males as large as female adults. Sensing something amiss, she took some sharks back to her lab for dissection. “I was amazed,” says Barnes, who admits she squealed during the dissections. Even before opening the fish, she had pressed on the bellies of the "male" sharks and felt the pups inside. |© Society for Science & the Public 2000 - 2018.

Keyword: Sexual Behavior
Link ID: 25195 - Posted: 07.12.2018

Laura Sanders I’m making my way through my third round of breastfeeding a newborn and taking stock of how things are going. Some aspects are definitely easier: My milk came in really quickly (a perk of being a repeat lactator), the fancy breastfeeding baby holds are no longer mysterious to me and I already own all of the weird pillows I need to prop up my tiny baby. But one thing isn’t easier this time around: the bone-crushing, mind-numbing exhaustion. Just like my other two, this sweet baby seems to eat all the time. All day. All night. Sometimes multiple times an hour, especially in the witching hours of the evening. This frequency got me curious about the biology of newborns’ stomachs. Just how small are they? Are they so microscopic that one can hold only enough sustenance to keep my newborn satisfied for a thousandth of a second? Birth educators and medical professionals often use a marble to illustrate the size of a newborn’s stomach, a tiny orb that holds about 5 to 7 milliliters of liquid. But that small estimate has come into question. A 2008 review published in the Journal of Human Lactation points out that there aren’t many solid studies on the size of the infant stomach, and some of the ones that do exist come to different conclusions. Another review of existing studies concluded that the average newborn stomach is slightly smaller than a Ping-Pong ball and can hold about 20 milliliters, or about two-thirds of an ounce. © Society for Science and the Public

Keyword: Development of the Brain; Sexual Behavior
Link ID: 25189 - Posted: 07.10.2018

NPR's Lulu Garcia-Navarro talks with Dr. Randi Hutter Epstein about her new book Aroused, which tells the story of the scientific quest to understand human hormones. LULU GARCIA-NAVARRO, HOST: What do sleep, sex, insulin, mood and hunger have in common? Well, they're all controlled by hormones. But just a century ago, the power of our chemical messengers was barely understood. A new book by Dr. Randi Hutter Epstein called "Aroused" tells the stories of the scientists who work to explore and explain our hormones. Dr. Epstein joins us now from our New York bureau. Welcome to the program. RANDI HUTTER EPSTEIN: Thanks for having me. GARCIA-NAVARRO: The book is organized around stories from key moments in hormone research. And I have to say, many of the studies they were doing in the early days were pretty gruesome. EPSTEIN: When we say study, we tend now to think of the randomised clinical controlled trial. You know, you have one sample here. You compare it to another. When they were doing studies, they were doing sort of weird experiments on people and dogs and all kind of things. So there was Harvey Cushing. He was one of the first people to talk about that pituitary tumors can really muck you up and like send a lot of hormones awry. But here's what he tried to do that didn't work out that's kind of a wacky experiment. He had a 48-year-old man that had a pituitary tumor that was making him have double vision and headaches and other endocrine issues. And Harvey Cushing thought, what if we take a nice, healthy pituitary of a baby that just died if there is a newborn that didn't make it and just implant that in this old man, and then we just revive him and he'd be back to normal. Newspapers got a hold of it, as media tends to do. And there were wonderful headlines like baby brain, you know, broken brain fixed by baby. And it went wild in terms of, wow, we can now cure broken, old brains. And, spoiler alert, let's just say that we don't replace baby pituitary glands into grownups when they have pituitary tumors anymore.

Keyword: Hormones & Behavior
Link ID: 25168 - Posted: 07.03.2018

By Alex Barasch Before “Love is love” became the rallying cry gracing protest signs and storefronts for Pride Month, the go-to gay slogan, by way of Lady Gaga, was “Born this way.” It was a succinct articulation of an argument some saw as essential to acceptance: Same-gender attraction was neither a choice nor a contagion, but rather an innate aspect of identity. This idea is not the straightforward civil rights argument its purveyors seem to believe. Lesbian, gay, bisexual and transgender people have long been the victims of bad science, and President Trump’s military ban is just the latest example. The American Medical Association promptly debunked claims that trans people are unfit to serve and that gender dysphoria — the distress that arises from a perceived mismatch between a person’s natal sex and gender identity — cannot be alleviated with access to transition-related care. But more insidious invocations of medical objectivity have continued to undermine trans rights: The so-called American College of Pediatricians, an anti-LGBTQ hate group that attempts to pass itself off as the (gender-affirmative) American Academy of Pediatrics, for instance, has been cited by GOP lawmakers to justify justify anti-trans “bathroom bills.” In this climate, the rush to fight pseudoscience with real scientific results is understandable. A study published in Nature in January and a presentation at the European Congress of Endocrinology in May each pointed toward potential anatomical markers of transness. They sparked a flurry of articles trumpeting a definitive “born this way” narrative and anticipating brain scans that “can tell kids if they’re transgender.” But this impulse to validate marginalized identities through medicine oversimplifies the science, overestimates its role in effecting social change and willfully ignores its more sinister applications. Even if a precise biological origin for same-gender attraction or trans identities could be found, it would be far from an assurance of equality — and opponents of LGBTQ rights could just as readily construe it as a defect in need of correction.

Keyword: Sexual Behavior
Link ID: 25150 - Posted: 06.28.2018

Erika Engelhaupt The first scientific experiment on hormones took an approach that sounds unscientific: lopping off roosters’ testicles. It was 1848, and Dr. Arnold Berthold castrated two of his backyard roosters. The cocks’ red combs faded and shrank, and the birds stopped chasing hens. Then things got really weird. The doctor castrated two more roosters and implanted a testicle from each into the other’s abdomen. As Randi Hutter Epstein writes in a new book, each rooster “had nothing between his drumsticks but a lone testicle in his gut — yet he turned back into a full-fledged hen-chaser, red comb and all.” It was the first glimpse that certain body parts must produce internal secretions, as hormones were first known, and that these substances — and not just nerves — were important to the body’s control systems. Today, we know that hormones are chemical messengers shaping everything from sex and development to sleep, stress, mood, metabolism and behavior. Yet few of us know much about these powerful substances coursing through our bodies. That ignorance makes Aroused — titled for the Greek meaning of the word hormone — an invaluable guide. Epstein, a medical writer and M.D., tells the history of hormone research from that first rooster experiment, but cleverly moves back and forth through time, avoiding any hint of dry recitation. She explores the scientists who discovered and deciphered the effects of important hormones, as well as the personal stories of how people’s lives have been profoundly changed by these chemicals. |© Society for Science & the Public 2000 - 2018

Keyword: Hormones & Behavior
Link ID: 25141 - Posted: 06.26.2018

by Katie Herzog • On Wednesday, Vox published an article entitled "How a Pseudopenis-packing Hyena Smashes the Patriarchy’s Assumptions: Lessons from Female Spotted Hyenas for the #MeToo Era." The piece, by Katherine J. Wu, a graduate student in microbiology and immunobiology, broadly explores how the spotted hyena could be used as a model for humankind. The bottom line: Humans get it wrong; hyenas get it right. "Unlike most other mammals," Wu writes, "spotted hyenas (Crocuta crocuta) live in matriarchal societies led by alpha females. In these clans throughout sub-Saharan Africa, females do the majority of the hunting, dictate the social structure, and raise cubs as single mothers. Even the highest-ranking male in the group is subservient to the most junior female. Accordingly, male spotted hyenas have evolved to be comparatively diminutive, weighing about 12 percent less than females—a feature uncommon even among matrilines." Sounds great. Unfortunately, it's not exactly true, according to Oliver Höner, a research scientist at the Leibniz Institute for Zoo and Wildlife and the co-founder of the Spotted Hyena Project, a research project based in Tanzania. A tweet by the Hyena Project was featured in Wu's article (much to Höner's chagrin), and when I saw him getting salty about Wu's work on Twitter, I reached out to ask what she got wrong. There was plenty in that paragraph alone. Höner says: © Index Newspapers LLC

Keyword: Sexual Behavior
Link ID: 25131 - Posted: 06.23.2018