Links for Keyword: Sexual Behavior

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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

Related chapters from BN8e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 25341 - Posted: 08.17.2018

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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25304 - Posted: 08.07.2018

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.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 25266 - Posted: 07.28.2018

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.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 25217 - Posted: 07.17.2018

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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 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.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25195 - Posted: 07.12.2018

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.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25150 - Posted: 06.28.2018

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

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25131 - Posted: 06.23.2018

By Elizabeth Pennisi What if you could flip a single DNA switch and make a world of only women? That sci-fi vision is unlikely to become reality anytime soon, yet such a switch—one near the gene that prompts the development of male body parts in embryos—has just been discovered in mice. The finding could help explain why some human babies with a male chromosome are born female, and the “groundbreaking” method used to unearth this so-called enhancer might one day identify similar DNA switches that are key to a variety of diseases. “This is pinpointing a region that was a needle in a haystack,” says Vincent Harley, a molecular geneticist at the Hudson Institute of Medical Research in Clayton, Australia, who was not involved in the new study. “[The switch] seems alone to be able to do the job” of making a man. If left to their own devices, all human embryos would develop into girls. But a gene on the Y chromosome, named SRY, brings about a change in early development, causing testes, a penis, and other male traits to form. This gene indirectly turns on another gene called Sox9, which kick-starts the construction of the testes. Although developmental biologists have long known that one or more enhancers flips on Sox9 early in this process, they were at a loss to figure out exactly which ones were most important. Across the genome about 1 million enhancers control nearly 21,000 genes. These short pieces of DNA lie outside a gene but serve as landing spots for the proteins that turn that gene on or off. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25091 - Posted: 06.15.2018

By Natalie Angier In advance of Father’s Day, let’s take a moment to sort out the differences and similarities between “Dad jeans” and “Dad genes.” Dad jeans are articles of sex-specific leisure clothing, long mocked for being comfy, dumpy and elastic-waisted but lately reinvented as a fashion trend, suitable for male bodies of all shapes and ages. Dad genes are particles on the sex-specific Y chromosome, long mocked for being a stunted clump of mostly useless nucleic waste but lately revealed as man’s fastest friend, essential to the health of male bodies and brains no matter the age. Yes, dear fathers and others born with the appurtenances generally designated male. We live in exciting times, and that includes novel insights into the sole chromosomal distinction between you and the women now prowling the aisles at the hardware store. (“Didn’t he say he could use a new bow saw? Or some halogen light bulbs?”) Researchers have discovered that, contrary to longstanding assumptions, the Y chromosome is not limited to a handful of masculine tasks, like specifying male body parts in a developing embryo or replenishing the sperm supply in an adult man. New evidence indicates that the Y chromosome participates in an array of essential, general-interest tasks in men, like stanching cancerous growth, keeping arteries clear and blocking the buildup of amyloid plaque in the brain. As a sizable percentage of men age, their blood and other body cells begin to spontaneously jettison copies of the Y chromosome, sometimes quickly, sometimes slowly. That unfortunate act of chromosomal decluttering appears to put the men at a heightened risk of Alzheimer’s disease, leukemia and other disorders. “I’m quite certain,” said Lars Forsberg, an associate professor of medical genetics at Uppsala University in Sweden, “that the loss of the Y chromosome with age explains a very large proportion of the increased mortality in men, compared to women.” Other researchers are tracing the evolution of the Y chromosome and comparing the version found in modern men with those of our close relatives, both living and extinct. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25075 - Posted: 06.11.2018

By Jeremy Rehm A man may be attractive because of his curly, blond hair or slick pin-striped suit, but strip everything away and one luring—maybe evolutionary—piece remains, a new study finds: how proportional his body is, especially his legs. Women prefer a man with legs that are about half his height, according to previous research; scientists believe that is an evolutionary result of women wanting to choose only healthy men. Legs that are too short, for example, have been linked to type 2 diabetes. But other proportions, such as arm length to body height or whether the elbow and knee divide a limb in half, can also relate to a person’s health. Do they influence women’s views as well? To answer this, researchers collected average body proportions from roughly 9000 men in the U.S. military and used them to create computer-generated images of male models (pictured). The scientists made the model’s arms and legs slightly longer or shorter, and then asked more than 800 heterosexual U.S. women to rank each model’s attractiveness. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24986 - Posted: 05.17.2018

By Alexandra Sacks, M.D. A new mother finally gets her fussy baby to sleep and steps into a relaxing hot shower — with her glasses on. At a family barbecue she can’t recall the name of a relative she rarely sees. It’s easy to laugh off such lapses as “mommy brain,” but there remains a cultural belief that pregnancy and child care impact a woman’s cognition and mental life, long after a baby is born. Women have often chalked up these changes to hormones, fatigue and the intoxicating love for a new baby. Hormones do affect cognition, and, as anyone who has ever done shift work or had jet lag knows, sleep deprivation saps our mental abilities. And the current evidence in scientific literature suggests that pregnancy changes the brain on a physical, cellular level in ways that we are only beginning to understand. However, there is no convincing scientific evidence that pregnancy causes an overall decline in cognitive performance or memory. Instead, most experts believe that pregnant women’s brain changes are an example of neuroplasticity, the process in which the brain changes throughout life by reorganizing connections in response to the stimulation of new experiences, and neurogenesis, the process of growth that allows for new learning. A 2016 study in Nature Neuroscience found that even two years after pregnancy, women had gray matter brain changes in regions involved in social cognition or the ability to empathically understand what is going on in the mind of another person, to put yourself in their shoes. It may be that some subtle aspects of memory are sacrificed to enhance other areas of cognition. A 2010 study in Psychoneuroendocrinology showed that pregnant women experienced some impairment in the ability to remember words, but did not show changes in other memory functions such as recognition or working memory. This means that these women might forget the name of a character in their favorite TV show, for example, but would have no trouble in the type of memory that involves learning, reasoning and comprehension. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 24969 - Posted: 05.12.2018

Laurel Hamers Toastier nest temperatures, rather than sex chromosomes, turn baby turtles female. Now, a genetic explanation for how temperature determines turtles’ sex is emerging: Scientists have identified a temperature-responsive gene that sets turtle embryos on a path to being either male or female. When researchers dialed down that gene early in development, turtle embryos incubating at the cooler climes that would normally yield males turned out female instead, researchers report in the May 11 Science. Scientists have struggled since the 1960s to explain how a temperature cue can flip the sex switch for turtles and other reptiles (SN Online: 1/8/18). That’s partly because gene-manipulating techniques that are well-established in mice don’t work in reptiles, says study coauthor Blanche Capel, a developmental biologist at Duke University School of Medicine. Previous studies showed certain genes, including one called Kdm6b, behaving differently in developing male and female turtles. But until recently, nobody had been able to tweak those genes to directly test which ones controlled sex. “This is the first venture down that path,” says Clare Holleley, an evolutionary geneticist at the Australian National Wildlife Collection in Canberra who wasn’t part of the study. “It's really quite a breakthrough.” In the new study, Capel’s lab collaborated with a group of Chinese researchers led by Chutian Ge of Zhejiang Wanli University in Ningbo. Ge’s team recently developed a way to lessen the activity of particular reptilian genes by injecting viruses bearing snippets of artificial RNA into developing eggs. |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 24963 - Posted: 05.11.2018

/ By Cathleen O'Grady Growing up in Saudi Arabia, Aciel Eshky didn’t get the memo that science was for boys. When she was around 10 years old, her aunt started to teach her basic computer programming. From there, going on to a degree in computer science seemed like a natural fit. So when a classmate in her master’s program abroad told her that women were weaker than men at math, it came as a shock. “I was really annoyed,” Eshky says. “I felt like I was being bullied.” “If that means that you get fewer women in certain subjects, and more women in other subjects like psychology, it’s not necessarily a catastrophe.” Despite its dismal reputation for gender equality, Saudi Arabia has a surprising level of female graduates in the so-called STEM fields (science, technology, engineering, and mathematics). Ranked among the bottom 20 countries in the World Economic Forum’s Global Gender Gap Index in 2015, women nonetheless made up 39 percent of graduates in a cluster of “core” STEM subjects. This number is higher than Iceland’s 35 percent, even though the Nordic country ranks number one for gender equality. Norway, which has the second-highest level of gender equity, sees only 26 percent of women graduating with STEM degrees. Taken together with these numbers, Eshky’s experience is illustrative of the so-called “gender-equality paradox” reported in a recent headline-grabbing paper: Countries ranking higher on measures of gender equality, the study found, tend to have fewer women pursuing a STEM education than those further down the gender equality ranks. Copyright 2018 Undark

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 1: An Introduction to Brain and Behavior
Link ID: 24910 - Posted: 04.27.2018

By Jim Daley Male fruit flies enjoy ejaculating, according to research published yesterday (April 20) in Current Biology. The study also found that when fruit flies are denied sex, they consume more alcohol than usual. It is the first study to demonstrate that insects find sex pleasurable. “We wanted to know which part of the mating process entails the rewarding value for flies,” says Galit Shohat-Ophir, a neurobiologist at Bar-Ilan University in Israel, in a statement. “The actions that males perform during courtship? A female’s pheromones? The last step of mating which is sperm and seminal fluid release?” To test if the latter is pleasurable, Shohat-Ophi and her colleagues used genetically engineered male fruit flies whose neurons controlling ejaculation can be activated by red light. These flies spent more time near the red light, presumably because they found ejaculation pleasurable, the authors say in the statement. David Anderson, a neurobiologist at Caltech who was not part of the study, tells National Geographic that it’s possible the pleasure the flies experienced wasn’t from ejaculation, but other reward systems in the brain that the stimulated neurons act upon. Next, the researchers plied the flies with alcoholic and nonalcoholic drinks and observed their response. The flies that had ejaculated preferred nonalcoholic drinks, while those that had not been exposed to the red light chose the alcoholic ones. “Male flies that are sexually deprived have increased motivation to consume alcohol as an alternative reward,” says Shohat-Ophi in the statement. © 1986-2018 The Scientist

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24890 - Posted: 04.21.2018

Jason Bittel In most North American hummingbirds, males court females by diving at them head on — but Costa’s hummingbirds (Calypte costae) perform their courtship dives off to the side. Researchers now find that this strategy allows the males to aim sounds at potential mates as if they were using a megaphone. During high-speed courtship dives, males fan their tails at the last second to create a high-pitched chirp. The faster the dive, the more those tail feathers vibrate and the higher the pitch created by the would-be Romeos. Researchers suspect that females prefer higher-pitched dives, which results in various strategies to boost the frequency of the noise a male makes. A study1 published on 12 April in Current Biology finds that male Costa’s hummingbirds can twist half of their tail feathers in the direction of the female, manipulating the volume and pitch of their chirps (see video). The researchers suspect that the targeted noise also masks audio cues that the females can use to judge how fast the males are diving. “You can think of the feather as being like a flashlight,” says Chris Clark, an ornithologist at the University of California, Riverside. “If you point the flashlight straight at something, the light is much brighter. And if you look at it from the side, at a 90-degree angle, there’s still some light but not nearly as much.” © 2018 Macmillan Publishers Limited

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24866 - Posted: 04.14.2018

By Lydia Denworth The demands of parenthood are so considerable that it’s fair to wonder why any adult takes on the challenge. Mammalian babies are especially helpless—and among mammals, only humans can see beyond individual sacrifice to understand a species’s survival depends on caring for its young. Yet there is remarkable consistency in the way all mammals change their behavior upon becoming parents. Suddenly they are motivated to care for their young, and know how to feed and shelter, nurture and protect new babies. Parents also give up a lot of adult social interaction, whether it is mating with other mice or going barhopping with friends. “What this means is that there is this instinctive or genetically programmed aspect to the drive to take care of offspring,” says neuroscientist Catherine Dulac of Harvard University. But if a complicated and variable behavior like parenting is hardwired, how would that work? Reporting in Nature this week, Dulac, also a Howard Hughes Medical Institute investigator, and her colleagues have provided a wiring diagram of the brain-wide circuit that coordinates parenting behavior in mice. The study marks the first deconstruction of the architecture of a brain circuit underlying a complex social behavior. The circuit they describe resembles the hub-and-spoke flight-routing system used by airlines and relies on a type of neuron that expresses the signaling molecule galanin. A relatively small number of these galanin neurons form a parenting command center—the medial preoptic area (MPOA)—in the hypothalamus, a brain structure responsible for controlling everything from appetite to sex drive. Responding to sensory input received from all over the brain, the neurons at the hub send distinct messages to at least 20 downstream subsets of galanin neurons. Like an airport terminal serving passengers according to their destinations, these subsets of cells, which the researchers dub “pools,” handle different facets of parenting behavior such as motor control of grooming or the motivation to parent at all. © 2018 Scientific American

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24859 - Posted: 04.12.2018

By Shawna Williams In recent years, US society has seen a sea change in the perception of transgender people, with celebrities such as Caitlyn Jenner and Laverne Cox becoming the recognizable faces of a marginalized population. Transgender rights have also become a mainstream political issue, and the idea that people should be referred to by the names and pronouns they find most fitting—whether or not these designations match those on their birth certificates, or align with the categories of male and female—is gaining acceptance. Yet a biological understanding of the contrast between the natal sex and the gender identity of transgender people remains elusive. In recent years, techniques such as functional magnetic resonance imaging (fMRI) have begun to yield clues to possible biological underpinnings of the condition known as gender dysphoria. In particular, researchers are identifying similarities and differences between aspects of the structure and function of the brains of trans- and cisgender individuals that could help explain the conviction that one’s gender and natal sex don’t match. The results may not have much effect on how gender dysphoria is diagnosed and treated, notes Baudewijntje Kreukels, who studies gender incongruence at VU University Medical Center in Amsterdam. “It’s really important that it will not be seen as, ‘When you see [gender dysphoria] in the brain, then it’s true.’” But the insights from such research could go a long way toward satisfying the desire of some transgender people to understand the roots of their condition, she adds. “In that way, it is good to find out if these differences between them and their sex assigned at birth are reflected by measures in the brain.” © 1986-2018 The Scientist

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 24724 - Posted: 03.06.2018

by Amy Ellis Nutt In the first broad demographic study of trends in gender-affirming surgeries in the United States, researchers found that the number of operations increased fourfold from 2000 to 2014. Some of the dramatic rise, according to a study published Wednesday in the journal JAMA Surgery, may be related to an increase in insurance coverage for the procedures. “Early on we recognized there’s been a lot of work on health disparities having to do with age, race and so on that get collected in health-care settings,” said Brandyn Lau, an assistant professor of surgery and health sciences informatics at Johns Hopkins University School of Medicine. “One of the things we need to know is whether [lesbian, gay and transgender] patients are getting the same care.” Lau and other researchers from Johns Hopkins Medicine and Harvard University analyzed 15 years of data from the National Inpatient Sample, a collection of hospital inpatient information from across the country, and found a total of 4,118 gender-affirming surgeries. The surgeries took place as LGBTQ people are finding increasing acceptance, especially among younger generations. The majority of the surgeries that occurred between 2000 and 2011 involved patients not covered by health insurance. About half of the transgender patients in the study paid out of pocket between 2000 and 2005. That number rose to 65 percent between 2006 and 2011. However, the trend reversed between 2012 and 2014, with the number plummeting to 39 percent. Much of that decrease, say the study's authors, is due to Medicare and Medicaid. In May 2014, Medicare ended its 33-year ban on transgender surgeries. Loren Schechter, who specializes in transgender surgeries, says he does about 300 procedures a year, whereas it was only about 50 in 2000. The plastic surgeon also accepts Medicare, which others do not. © 1996-2018 The Washington Post

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24708 - Posted: 02.28.2018