Links for Keyword: Sexual Behavior

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By Ann Lukits Teens who baby-sit may not only gain confidence in caring for young children, they may also alter their brain chemistry in a way that could make them better parents, suggests an animal study in Developmental Psychobiology. Young female rats housed with various groups of unrelated rat pups had fully developed mothering skills as adults, compared with control rats without caregiving, or alloparenting, experience. The early caregivers had significantly higher concentrations of tryptophan hydroxylase-2 (TPH2) in the brain, an enzyme associated with increased production of serotonin, a chemical involved in mood and social behavior. Previous research has associated baby-sitting experience in humans with greater confidence in new mothers, researchers said. Experiments at Michigan State University involved two groups of juvenile or adolescent female rats from 16 litters. In one group, 24 rats were housed in separate cages with a different group of week-old pups each day. A second group of 24 controls were given pink pup-size pencil erasers. The experiments continued for 14 days. Eight mature rats from both groups were subsequently exposed to new groups of pups. Six rats with alloparenting experience acted maternally toward the pups, whereas none of the control rats exhibited maternal behavior. Rats with alloparenting experience also displayed less anxiety during behavioral testing. The animals were euthanized after testing and TPH2 levels measured in a section of the brain called the dorsal raphe nucleus. ©2016 Dow Jones & Company, Inc

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 22273 - Posted: 06.01.2016

Susan Milius Forget it, peacocks. Nice try, elk. Sure, sexy feathers and antlers are showy, but the sperm of a fruit fly could be the most over-the-top, exaggerated male ornamentation of all. In certain fruit fly species, such as Drosophila bifurca, males measuring just a few millimeters produce sperm with a tail as long as 5.8-centimeters, researchers report May 25 in Nature. Adjusted for body size, the disproportionately supersized sperm outdoes such exuberant body parts as pheasant display feathers, deer antlers, scarab beetle horns and the forward-grasping forceps of earwigs. Fruit flies’ giant sperm have been challenging to explain, says study coauthor Scott Pitnick of Syracuse University in New York. Now he and his colleagues propose that a complex interplay of male and female benefits has accelerated sperm length in a runaway-train scenario. Males with longer sperm deliver fewer sperm, bucking a more-is-better trend. Yet, they still manage to transfer a few dozen to a few hundred per mating. And as newly arrived sperm compete to displace those already waiting in a female’s storage organ, longer is better. Fewer sperm per mating means females tend to mate more often, intensifying the sperm-vs.-sperm competition. Females that have the longest storage organs, which favor the longest sperm, benefit too: Males producing megasperm, the researchers found, tend to be the ones with good genes likely to produce robust offspring. “Sex,” says Pitnick, “is a powerful force.” © Society for Science & the Public 2000 - 2016

Related chapters from BP7e: 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: 22249 - Posted: 05.26.2016

Sara Reardon As a medical student in Paris in the 1980s, Eric Vilain found himself pondering the differences between men and women. What causes them to develop differently, and what happens when the process goes awry? At the time, he was encountering babies that defied simple classification as a boy or girl. Born with disorders of sex development (DSDs), many had intermediate genitalia — an overlarge clitoris, an undersized penis or features of both sexes. Then, as now, the usual practice was to operate. And the decision of whether a child would be left with male or female genitalia was often made not on scientific evidence, says Vilain, but on practicality: an oft-repeated, if insensitive, line has it that “it's easier to dig a hole than build a pole”. Vilain found the approach disturbing. “I was fascinated and shocked by how the medical team was making decisions.” Vilain has spent the better part of his career studying the ambiguities of sex. Now a paediatrician and geneticist at the University of California, Los Angeles (UCLA), he is one of the world's foremost experts on the genetic determinants of DSDs. He has worked closely with intersex advocacy groups that campaign for recognition and better medical treatment — a movement that has recently gained momentum. And in 2011, he established a major longitudinal study to track the psychological and medical well-being of hundreds of children with DSDs. © 2016 Nature Publishing Group

Related chapters from BP7e: 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: 22206 - Posted: 05.11.2016

By Virginia Morell After defeating other males in boxing matches and winning a territorial roost—and a bevy of females—a male Seba’s short-tailed bat (Carollia perspicillata, pictured) might think his battles for reproductive rights are over. But the defeated males of this neotropical species have a trick up their sleeve: clandestine matings with willing females. The tactic works, and now researchers know why. Scientists studied bats in a captive colony in Switzerland, removing alpha males from their harems for 3 days, and examining their sperm—as well as that of their rivals. A previous study showed that the sneaky males have faster, longer lived sperm, which gives them a leg-up on the alpha male. Researchers had suspected this was because the sneakers produced this supersperm to compete. But the new study finds that after the 3 days of abstinence, the alpha male’s sperm is as agile and vigorous as that of his rivals. Thus, the team reports today in the Journal of Experimental Biology, the sneaky males aren’t generating special sperm—they just mate less, so their sperm is in better shape when it comes time to race to the egg. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: 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: 22180 - Posted: 05.05.2016

By Sarah Kaplan The ancient Greeks spoke of a mythological society composed entirely of warrior women. The medieval traveler John Mandeville wrote of a place whose female rulers "never would suffer man to dwell amongst them." "Paradise Island," home of Wonder Woman, was a feminist utopia where no one with a Y chromosome was allowed. Sadly, those places only exist in fiction. But something like them does exist in the real world. It's in a wetland in rural Ohio. And it's full of salamanders. "They’re pretty incredible," said Robert Denton, a biologist at Ohio State who studies an unusual group of salamander species that literally don't need men. These creatures – all female – reproduce by cloning themselves. To keep their gene pool diverse, they sometimes "steal" sperm left behind on trees and leaves by male salamanders of other species and incorporate that DNA into their offspring. Most sexually reproducing organisms have two sets of chromosomes to make up their genome – one from each parent. But one of these strange salamanders can have between two and five times that much genetic material lying in wait within her cells. It's as if they have multiple genomes to fall back on, and that's made them incredibly successful. "Polyploid" salamanders have been around some 6 million years, Denton said — far longer than most other animal species that reproduce asexually. Since a lack of diversity means having a smaller arsenal of genetic variation to fall back on when living conditions change, these groups usually go extinct relatively quickly. © 1996-2016 The Washington Post

Related chapters from BP7e: 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: 22176 - Posted: 05.04.2016

by Susan Milius There’s nothing like a guy doing all the child care to win female favor, even among giant water bugs. Thumbnail-sized Appasus water bugs have become an exemplar species for studying paternal care. After mating, females lay eggs on a male’s back and leave him to swim around for weeks tending his glued-on load. For an A. major water bug, lab tests show an egg burden can have the sweet side of attracting more females, researchers in Japan report May 4 in Royal Society Open Science. Given a choice of two males, females strongly favored, and laid more eggs on, the one already hauling around 10 eggs rather than the male that researchers had scraped eggless. Females still favored a well-egged male even when researchers offered two males that a female had already considered, but with their egg-carrying roles switched from the previous encounter. That formerly spurned suitor this time triumphed. A similar preference, though not as clear-cut, showed up in the slightly smaller and lighter A. japonicus giant water bug. “We conclude that sexual selection plays an important role in the maintenance of elaborate paternal care,” says study coauthor Shin-ya Ohba of Nagasaki University. © Society for Science & the Public 2000 - 2016

Related chapters from BP7e: 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: 22175 - Posted: 05.04.2016

Nicola Davis Benedict Cumberbatch’s deep and booming voice might have made him a hit among women, but a low pitch is more likely to have evolved to intimidate other men, new research suggests. When both heterosexual men and women were played recordings of male voices, the deeper tones were hailed by men as sounding more dominant. While the deeper voices were judged to be more attractive by female listeners, the effect was weaker, the researchers report. “If you look at what men’s traits look like they are designed for, they look much better designed for intimidating other males than for attracting females,” said David Puts of Pennsylvania State University, who led the study. Published in Proceedings of the Royal Society B: Biological Sciences, the three-part study by an international team of scientists explored the links between voice pitch and mating systems, attractiveness and, for males only, perceived dominance. A formula for the perfect voice? Read more In the first leg of the research, the scientists turned their attention to primates encompassing Old and New World monkeys, as well as humans and other apes, to explore differences in “fundamental frequency” between males and females of each species - the aspect of the voice that is perceived as pitch. After selecting 1721 recordings, they found large differences were more common in polygynous species - where males mate with more than one female - than monogamous ones. That, they say, could be because in polygynous species, competition between males is greater - hence a male with a lower-pitched voice deemed to be intimidating could have the edge in securing a mate. Intriguingly, the researchers found that among the apes humans showed the greatest difference in pitch between the sexes, suggesting our ancestors were not searching for “the one” but were polygynous - a situation Puts still believes to be the case. © 2016 Guardian News and Media Limited

Related chapters from BP7e: 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: 22152 - Posted: 04.27.2016

By Patrick Monahan You might have seen a video from David Attenborough’s The Life of Birds series where a male superb lyrebird (Menura novaehollandiae) attempts to lure a mate by imitating a smorgasbord of bird calls and even chainsaws. As nature’s show-offs, male animals tend to have more elaborate colors and courtship behaviors than their female counterparts, so it’s typical that the male would get the public’s attention. The same is true in science: Plenty of female birds sing songs, but researchers have in the past often dismissed them as simply being evolutionary tag-alongs of the males’ “come hither” calls. Now, by recording the calls of female superb lyrebirds, researchers have found that they can keep up with the boys just fine. According to a study published this week in Frontiers in Ecology and Evolution, the females collectively imitated 19 other species of birds, and also sang lyrebird-specific songs. And they changed their songs depending on context, using more lyrebird-specific “whistle” calls when out foraging and vying for territory, but more mimicking calls when defending their nests (as in the audio file below). The fact that the females change their type of call depending on the context makes it likely that these songs evolved in their own right—and the males’ calls aren’t so special after all. Plus, that part about the chainsaw? It probably doesn’t even happen in the wild. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 22127 - Posted: 04.23.2016

Medical research and new drugs to treat human illness usually start with studies on mice and rats. But that type of research has been traditionally sexist — using far more male than female rodents. Scientists warn that has already led to drugs and treatments that are potentially dangerous for women and say the approach slows down the development of treatments and drugs that are safe and effective for everyone. Cara Tannenbaum, scientific director of the Institute of Gender and Health at the Canadian Institutes of Health Research, cited a couple of examples on CBC's The Current of cases where drug side-effects turned out to be far more harmful in women: A stomach drug called cisapride that was sold in the 1990s under the name Prepulsid was withdrawn by Health Canada in 2000 because it sometimes caused irregular heartbeat and sudden death "in women only," Tannenbaum said. Among the victims was the 15-year-old daughter of former Ontario MP Terence Young. "It's not clear that the drug was ever tested in female animals or minors," Tannenbaum added. Health Canada has issued a warning about sleeping pills containing the drug zolpiclone, also known as Ambien, Tannenbaum said. Women are recommended to take half the dose that is prescribed to men. "It was recently discovered that the level of the drug was 45 per cent higher in women the next day, which can lead to car accidents," Tannenbaum said. Jeffrey Mogil, a neuroscientist and pain specialist at McGill University, said there are lots of reasons to suspect men and women respond differently to many different kinds of drugs, but very little actual data. "We actually don't know the scope of the problem," he told The Current. ©2016 CBC/Radio-Canada.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 5: The Sensorimotor System
Link ID: 22125 - Posted: 04.21.2016

Ian Sample Science editor The subtle impact of genetics on the age at which people lose their virginity has been teased apart by scientists and shown to have an effect on how well people fare at school. Though mostly driven by upbringing and peer behaviour, a person’s age when they first have sex is also shaped by biological factors where genes have a role to play. Researchers found that differences in DNA could account for a quarter of the variation in the age at which people lost their virginity, with other factors, among them religious beliefs, family background and peer pressure, making up the rest. Genes influence academic ability across all subjects, latest study shows Read more “We were able to calculate for the first time that there is a heritable component to age at first sex, and the heritability is about 25%, so one quarter nature, three quarters nurture,” said John Perry, an expert in reproductive ageing and related health conditions at Cambridge University. Among 38 sections of DNA found to affect the age at which people first had sex were genes that drive reproductive biology, such as the release of sex hormones and the age of puberty. Still others were found that appear to affect behaviour, personality and appearance. A variant of one of the genes, named CADM2, linked an early start to one’s sex life with risk-taking behaviour and having a large number of children. A version of another gene, MSRA, found in people who lost their virginity later than average, was linked to irritability. © 2016 Guardian News and Media Limited

Related chapters from BP7e: 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: 22116 - Posted: 04.19.2016

Scientists have outwitted the crafty rat with a stimulating new formula that puts sex on the brain. A team at Simon Fraser University in Burnaby, B.C., has developed a rat trap that combines synthetic sex pheromones, food scents and baby rat sounds to lure rodents to their deaths. The bait has proven 10 times more powerful than traditional traps and could be commercialized in about two years, said principal investigator Gerhard Gries. "Rats are really intelligent, and in order to manipulate them you have to be intelligent as well, and do that in a way that addresses their needs," said Gries, a communication ecologist in the department of biological sciences. "It smells delicious, it smells like rat and it sounds like rat." Research outlining the pheromone component of the control tactic was published last week in the international edition of the German peer-reviewed online journal Angewandte Chemie, which translates to "Applied Chemistry." The research on the use of baby rat sounds was published recently in the journal Pest Management Science. Gries worked for several years with research associates Stephen Takacs and Regine Gries, his wife, to develop the three-pronged extermination technique. Humans have waged war against the pests for more than 10,000 years, said Gerhard Gries, noting they spread disease, reduce agricultural crop yields and threaten endangered animal species. But rats are quick learners that have evolved to avoid traps, a behaviour called "neophobia," he said. ©2016 CBC/Radio-Canada.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22095 - Posted: 04.12.2016

Carl Zimmer Five days a week, you can tune into “Paternity Court,” a television show featuring couples embroiled in disputes over fatherhood. It’s entertainment with a very old theme: Uncertainty over paternity goes back a long way in literature. Even Shakespeare and Chaucer cracked wise about cuckolds, who were often depicted wearing horns. But in a number of recent studies, researchers have found that our obsession with cuckolded fathers is seriously overblown. A number of recent genetic studies challenge the notion that mistaken paternity is commonplace. “It’s absolutely ridiculous,” said Maarten H.D. Larmuseau, a geneticist at the University of Leuven in Belgium who has led much of this new research. The term cuckold traditionally refers to the husband of an adulteress, but Dr. Larmuseau and other researchers focus on those cases that produce a child, which scientists politely call “extra-pair paternity.” Until the 20th century, it was difficult to prove that a particular man was the biological father of a particular child. In 1304 a British husband went to court to dispute the paternity of his wife’s child, born while he was abroad for three years. Despite the obvious logistical challenges, the court rejected the husband’s objection. “The privity between a man and his wife cannot be known,” the judge ruled. Modern biology lifted the veil from this mystery, albeit slowly. In the early 1900s, researchers discovered that people have distinct blood types inherited from their parents. In a 1943 lawsuit, Charlie Chaplin relied on blood-type testing to prove that he was not the father of the actress Joan Barry’s child. (The court refused to accept the evidence and forced Chaplin to pay child support anyway.) © 2016 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 22089 - Posted: 04.09.2016

by Sarah Zielinski Spring has finally arrived, and birds’ nests all over the country will soon be filling up with eggs and then nestlings. Watch a nest long enough (the Science News staff is partial to the DC Eagle Cam) and you’ll see itty bitty baby birds begging for a meal. But mama birds don’t always reward that begging with food. In some species, like the tree swallow, birds that beg more will get more food. But in others, like the hoopoe, mom ignores who is begging and gives more food to the biggest chicks, researchers have found. This lack of an overall pattern has confounded ornithologists, but it seems that they may have been missing a key piece of the puzzle. A new study finds that the quality of the birds’ environment determines whether a mama bird can afford to feed all of her kids or if she has to ignore some to make sure the others survive. The study appears March 29 in Nature Communications. Stuart West of the University of Oxford and colleagues compiled data from 306 studies that looked at 143 bird species. When the birds were living in a good environment — one that had plenty of resources or a high amount of predictability — then mom would feed the chicks that beg the most, which were often the ones that needed the most help. But when the environment was poor in quality or unpredictable, then mama bird responded less to begging. |© Society for Science & the Public 2000 - 2016.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 22079 - Posted: 04.07.2016

By Elizabeth Pennisi The “brrreeet” you hear in the video above is not coming from this broadbill’s beak, but rather from its wings. Charles Darwin marveled at “instrumental music” of birds—from the rattled quills of peacocks to the wing-drumming of grouse and the wing “booming” of night-jars. But those percussive noises are no match for the definitive tones generated by the three Smithornis broadbills (S. rufolateralis, S. capensis, and S. sharpei) that live in remote forests in sub-Saharan Africa. One bird acoustics specialist was so intrigued in 1986 by a recording of this “song,” that he vowed to hear it for himself. More than 2 years ago, he and his colleagues tracked two of these species down in the wild. Synchronized high-speed video and acoustic recordings revealed the downstroke of the wings produces the tones as the bird flies in a meter-wide oval from its perch and back again. At first the researchers thought the outermost flight feathers flutter to make the sounds, but studies of a wing and of the feathers themselves in a wind tunnel showed that the inner flight feathers are “singing” the most, the team reports today in the Journal of Experimental Biology. The tones may scale with the species’ body and feather size, with the bigger ones producing deeper tones, the researchers suggest. The wing tones seemed to have replaced vocal singing, they note, and are likely unique to this group of birds. Audible 100 meters away in dense forest, they represent yet another innovation for communicating with one’s peers. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 22056 - Posted: 04.01.2016

by Sarah Zielinski There must be something wrong with the guy who never leaves home, right? Maybe not — at least if that guy is a male spotted hyena. Males that stay with their birth clan, instead of taking off to join a new group, may simply be making a good choice, a new study suggests. Spotted hyenas are a matriarchal society. Females are in charge. They rank higher than every male in the clan. And the females generally stay with the clan for their entire lives. But males face a choice when they reach two and a half years in age. They can stay with the clan, or they can leave and join a new clan. Each choice has its pros and cons. Staying with the clan means that a male hyena keeps a place at the top of the male pecking order. He’ll probably have his mother around to help. But he’ll be limited in the number of females he can mate with, because many of the female hyenas won’t mate with him because they might be related. If he joins a new clan, the male hyena might have access to more females — and they might even be better than the ones in his home clan — but he’ll start with the lowest social rank and have to spend years fighting his way to the top. Among most group-living mammal species, the guys that stay at home turn out to be losers, siring fewer offspring. But spotted hyenas, it appears, are an exception. Eve Davidian of the Leibniz Institute for Zoo and Wildlife Research in Berlin and colleagues tracked 254 male spotted hyenas that lived in eight clans in Ngorongoro Crater in Tanzania throughout their lives, a study lasting 20 years. When these males reached the age of maturity, they left their clans to take a look at the other options available to them. Forty-one hyenas returned to their home clans, and 213 settled with new ones. © Society for Science & the Public 2000 - 2016

Related chapters from BP7e: 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: 22045 - Posted: 03.29.2016

By Virginia Morell A fungal disease that has killed amphibians worldwide may be spreading by making the mating calls of infected males more attractive to females. The finding—one of the first—to show that the pathogen can alter a species’s reproductive behavior could explain why frogs and related animals continue to disappear across the globe. “If true—that the fungus is manipulating individuals’ behaviors to facilitate its spread—then this is extraordinary,” says Michael Ryan, a herpetologist at the University of Texas, Austin, who was not involved in the study. The pathogenic fungus, Batrachochytrium dendrobatidis (Bd), causes chytridiomycosis (also known as chytrid fungus disease, which kills amphibians by destroying their skin, disrupting their immune systems, and causing heart failure). Scientists first recognized its lethal effects in the 1990s when numerous species of frogs in Australia and Central and South America experienced massive die-offs; a related fungus attacks salamanders. Bd has been blamed for the extinction of hundreds of amphibian species, and poses a threat to up to one-third of the world’s frogs, salamanders, and other amphibians. There is no cure, but some frog species infected with the fungus are able to survive for years, indicating that they’ve adapted to the disease. Indeed, a recent study showed that Bd has been evolving with amphibians for some 40,000 years, although some species have only recently encountered it. But even amphibian populations adapted to Bd continue to suffer and decline from its effects, says Bruce Waldman, a behavioral ecologist at Seoul National University and one of the authors of the new paper. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21944 - Posted: 03.02.2016

By SABRINA TAVERNISE WASHINGTON — Half of one satisfying sexual encounter a month. That is the average benefit a woman gets when she takes the new female libido drug, sometimes called the “female Viagra,” researchers reported Monday. Last year the Food and Drug Administration approved the drug, flibanserin, making it the first drug available to treat low sexual desire in women. It was promoted by a group of women’s rights activists who argued it was unfair that men had numerous drugs to boost sexual function while women had nothing. But public health groups and some other women’s groups contended that the science did not justify its approval. The drug’s effects were modest, they said, and not worth side effects such as sleepiness, dizziness, fatigue and nausea. And the risk of some side effects increased with alcohol consumption. In the new study, published in JAMA Internal Medicine, researchers found benefits that were slightly more modest than those submitted to the F.D.A. during the approval process. The researchers analyzed eight studies of about 5,900 women, using a method that involved pooling the data. They concluded that treatment with flibanserin, now marketed as Addyi, resulted in “one-half of an additional sexually satisfying encounter per month.” (The study did not define what “one-half” of a sexually satisfying encounter was.) That result was not very different from original findings of three clinical trials submitted to the F.D.A. as support for the drug’s approval. Those trials found that once women started taking the drug, they had an average of about one additional satisfying sexual encounter a month, on top of the two to three they were having already. That result lifted the benefits above the bar of being scientifically meaningful, but barely. Still, it was enough for the agency’s approval. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21938 - Posted: 03.01.2016

By Michael Balter About 90% of bird species live in monogamous pairs, but that doesn’t mean they don’t fool around on the side. The females of most monogamous species breed with outside males at least occasionally. Male birds have evolved two main ways to combat such cuckoldry: They either aggressively drive away rival males, or they cement the pair bond by singing lovely duets with their partners. Which works better, making love or making war? Researchers working with the red-backed fairywren (Malurus melanocephalus), native to Australia, put the question to the test by conducting the experiment in the video above. The team mounted a taxidermically stuffed male fairywren on a branch (upper left) in a male-female pair’s territory and then observed what happened. In this case, the live male attacks its artificial rival once, but then spends most of the next minute duetting with its female partner (who is light gray and white). The researchers analyzed data from various trials involving up to 51 males, using parameters such as how long they delayed before attacking the artificial mount, how long before beginning a duet, and how many duets they sang with the females. These data were then correlated with genetic paternity tests of 186 offspring in the nests of the supposedly monogamous birds. Although the percentage of cuckoldry was high—47% of the offspring had been fathered by outside males—those males that quickly responded to the threat of a rival by repeatedly duetting with their partners were much more likely to be the fathers of the offspring in their nests, the team reports online today in Biology Letters. On the other hand, there was no correlation between how aggressive the males were to the artificial rival and the paternity rate, the researchers found. © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 21927 - Posted: 02.24.2016

By Julia Shaw The approach to Valentine's Day is a reminder that we humans are so intrigued by the idea of love that we have made it into something to celebrate in it’s own right. Love is something amazing. Love is something special. But what are the implications of love for our memories? Remember those “your brain on drugs” awareness posters? You can essentially substitute “love” for “drugs” and the same warnings apply. Scientists have found that being in love actually makes you activate some of the same brain regions as when you take addictive drugs, like ecstasy or cocaine. Neuroscientist Kayo Takahashi and his team have described passionate love as an “all-encompassing experience” which has “disorienting effects” and is generally considered “highly pleasurable”. While you probably don’t need a bunch of scientists to tell you that, you probably do need them to explain what that actually means in the brain. In 2015 Kayo and his team were keen on exploring the role of one particular culprit of the feel-good effects of love, the neurotransmitter dopamine. Among many other effects, dopamine generally makes us feel pleasure. Kayo and his team looked into the brains of people who were in the early stages of romantic relationships, and they found that when shown pictures of their romantic partners, participants experienced a flood of dopamine to parts of their brains. As it turns out, brains need to release dopamine in order to store long-term memories. © 2016 Scientific American

Related chapters from BP7e: 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: 21888 - Posted: 02.11.2016

Rae Ellen Bichell There's been a male tilt to biomedical research for a long time. The National Institutes of Health is trying to change that and is looking to bring gender balance all the way down to the earliest stages of research. As a condition of NIH funding, researchers will now have to include female and male animals in their biomedical studies. As late as the 1990s, researchers worried that testing drugs in women who could be pregnant or become pregnant might lead to birth defects, so experimental drugs were mainly tested in men. Research in animals followed the same pattern. "There was not the understanding that it really isn't scientifically appropriate to study men and apply your findings to women. We just didn't know that back then," says Dr. Janine Clayton, director of the Office of Research on Women's Health at the NIH. When the drugs this way finally went to market and women took them, sometimes things went wrong. To try to fix the problem, the NIH and Congress required that women and men be included in research involving human subjects. Now, there are more women than men participating in clinical trials, at least in studies funded by the NIH. But there's still a mystery: Why do women still report many more bad reactions to medications than men do? "Men and women respond to medications differently. In fact, one study looked at the drugs that have been taken off the market and 8 of the 10 drugs taken off the market in that particular time period had more severe effects in women," says Clayton. © 2016 npr

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21885 - Posted: 02.11.2016