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

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Tina Hesman Saey Add a new ingredient to the sugar, spice and everything nice needed to make girls. A protein called COUP-TFII is necessary to eliminate male reproductive tissue from female mouse embryos, researchers report in the Aug. 18 Science. For decades, females have been considered the “default” sex in mammals. The new research overturns that idea, showing that making female reproductive organs is an active process that involves dismantling a primitive male tissue called the Wolffian duct. In males, the Wolffian duct develops into the parts needed to ejaculate sperm, including the epididymis, vas deferens and seminal vesicles. In females, a similar embryonic tissue called the Müllerian duct develops into the fallopian tubes, uterus and vagina. Both duct tissues are present in early embryos. A study by French endocrinologist Alfred Jost 70 years ago indicated that the testes make testosterone and an anti-Müllerian hormone to maintain the Wolffian duct and suppress female tissue development. If those hormones are missing, the Wolffian duct degrades and an embryo by default develops as female, Jost proposed. That’s the story written in textbooks, says Amanda Swain, a developmental biologist at the Institute of Cancer Research in London. But the new study “demonstrates that females also have a pathway to make sure you don’t get the wrong ducts,” says Swain, who wrote a commentary in the same issue of Science. |© Society for Science & the Public 2000 - 2017.

Keyword: Sexual Behavior
Link ID: 23976 - Posted: 08.19.2017

By Jenna Gallegos Pathogens are real jerks. As if infecting and killing plants and animals isn’t bad enough, they can also turn their hosts into zombies that spread the pathogens to their next victim. Now scientists report that bacteria make some victims summon other victims as their dying act. The bacteria hijack the chemical signaling pathway of insects, making them release a burst of hormones that serve as a beacon to attract friends and potential mates right before the bacteria kill off the host. Like malware marauding as an enticing link, the bacteria attract and then infect. Fruit flies are generally pretty good at avoiding hazards. They can detect when food is infected with a dangerous mold or when a parasitic wasp is nearby, said Markus Knaden, a researcher at the Max Planck Institute for Chemical Ecology in Jena, Germany, who was involved in the study. In both cases, the flies won’t lay their eggs near the infectious agent. That’s why Knaden and colleagues at Cornell University were so surprised when they found that flies were actually attracted to other insects with a certain bacterial infection. “If you’re sitting in a theater and someone next to you is coughing, you move to another chair,” said Bill Hansson, one of the Max Planck authors of the study, published Wednesday in the journal Nature Communications. They expected flies to behave the same way, but instead, healthy flies found their sick friends to be extremely attractive. © 1996-2017 The Washington Post

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 23964 - Posted: 08.16.2017

Alice H. Eagly It’s no secret that Silicon Valley employs many more men than women in tech jobs. What’s much harder to agree on is why. The recent anti-diversity memo by a now former Google engineer has pushed this topic into the spotlight. The writer argued there are ways to explain the gender gap in tech that don’t rely on bias and discrimination – specifically, biological sex differences. Setting aside how this assertion would affect questions about how to move toward greater equity in tech fields, how well does his wrap-up represent what researchers know about the science of sex and gender? As a social scientist who’s been conducting psychological research about sex and gender for almost 50 years, I agree that biological differences between the sexes likely are part of the reason we see fewer women than men in the ranks of Silicon Valley’s tech workers. But the road between biology and employment is long and bumpy, and any causal connection does not rule out the relevance of nonbiological causes. Here’s what the research actually says. There is no direct causal evidence that biology causes the lack of women in tech jobs. But many, if not most, psychologists do give credence to the general idea that prenatal and early postnatal exposure to hormones such as testosterone and other androgens affect human psychology. In humans, testosterone is ordinarily elevated in males from about weeks eight to 24 of gestation and also during early postnatal development. © 2010–2017, The Conversation US, Inc.

Keyword: Sexual Behavior; Development of the Brain
Link ID: 23963 - Posted: 08.16.2017

Allison Aubrey What we eat can influence more than our waistlines. It turns out, our diets also help determine what we smell like. A recent study found that women preferred the body odor of men who ate a lot of fruits and vegetables, whereas men who ate a lot of refined carbohydrates (think bread, pasta) gave off a smell that was less appealing. Skeptical? At first, I was, too. I thought this line of inquiry must have been dreamed up by the produce industry. (Makes a good marketing campaign, right?) But it's legit. "We've known for a while that odor is an important component of attractiveness, especially for women," says Ian Stephen of Macquarie University in Australia. He studies evolution, genetics and psychology and is an author of the study. From an evolutionary perspective, scientists say our sweat can help signal our health status and could possibly play a role in helping to attract a mate. How did scientists evaluate the link between diet and the attractiveness of body odor? They began by recruiting a bunch of healthy, young men. They assessed the men's skin using an instrument called a spectrophotometer. When people eat a lot of colorful veggies, their skin takes on the hue of carotenoids, the plant pigments that are responsible for bright red, yellow and orange foods. "The carotenoids get deposited in our skin," explains Stephen. © 2017 npr

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 23961 - Posted: 08.15.2017

Conor Friedersdorf This week, headlines across a diverse array of media outlets proclaimed that at least one Google employee was so antagonistic to women that he circulated a 10-page “anti-diversity screed.” That is how Gizmodo characterized the now infamous internal memo when publishing it Saturday. Similar language was used in headlines at Fox News, CNN, ABC News, the BBC, NBC News, Time, Slate, Engadget, The Huffington Post, PBS, Fast Company, and beyond (including a fleeting appearance in a headline here at The Atlantic). But love or hate the memo, which makes a number of substantive claims, some of which I regard as wrongheaded (and which would’ve benefitted greatly from an editor with more emotional intelligence than the author to help him avoid alienating his audience, even if he was determined to raise all of the same arguments), the many characterizations of the memo as “anti-diversity” are inaccurate. Using that shorthand is highly misleading. As many who read past the headlines would later observe, its author, who was later fired, began, “I value diversity and inclusion, am not denying that sexism exists, and don’t endorse using stereotypes. When addressing the gap in representation in the population, we need to look at population level differences in distributions. If we can’t have an honest discussion about this, then we can never truly solve the problem.” The balance of his memo argues that he is not against pursuing greater gender diversity at Google; he says it is against the current means Google is using to pursue that end and the way the company conceives of tradeoffs between the good of diversity and other goods. (c) 2017 by The Atlantic Monthly Group.

Keyword: Sexual Behavior
Link ID: 23941 - Posted: 08.10.2017

By NICHOLAS BAKALAR The incidence of stroke has declined in recent years, but only in men. Researchers studied stroke incidence in four periods from 1993 to 2010 in five counties in Ohio and Kentucky. There were 7,710 strokes all together, 57.2 percent of them in women. After adjusting for age and race, they found that stroke incidence in men had decreased to 192 per hundred thousand men in 2010, down from 263 in 1993–94. But for women the incidence was 198 per hundred thousand in 2010, down from 217 in 1993–94, a statistically insignificant change. The study is in Neurology. Most of the difference was in ischemic stroke, the most common cause, resulting from a blocked blood vessel supplying blood to the brain. No one knows why there has been no improvement in women, but the lead author, Dr. Tracy E. Madsen, an assistant professor of emergency medicine at Brown, said that some risk factors have a stronger effect in women than in men. Risk factors for stroke include high blood pressure, heart disease, diabetes and smoking. “Maybe we’re not controlling risk factors to the same extent in women. Or maybe there’s a biological difference in the way these risk factors cause strokes in men versus women.” In any case, Dr. Madsen said, “It’s important for women to know they are at risk. Stroke has been considered a male disease, but we know that it is very prevalent in women and has a high risk of disability and death.” © 2017 The New York Times Company

Keyword: Stroke; Sexual Behavior
Link ID: 23939 - Posted: 08.10.2017

By Jamie Strashin, The look on Melissa Bishop's face said it all. The Canadian 800-metre star had just run the race of her life, at the best possible moment, on the world's biggest stage. "I have never run faster in my life. It's the smartest race I have ever put down on a track," Bishop said of her performance in the final at the Rio Olympics last summer. But it still wasn't enough. Despite setting a new Canadian record (which she has since broken by running a 1:57.01), Bishop finished fourth in the Rio final, missing a bronze medal by 13 hundredths of a second. Perhaps more distressingly, she crossed the line close to two seconds slower than gold medallist Caster Semenya. "I remember seeing my agent and just falling into his arms, thinking, I can't believe this just happened. What just happened?" Bishop recalled. "And then I saw my dad, and my dad is a very emotional man and he was livid. Not because of how I raced, but because of the scenario we were in. And he just kept telling me, 'You have nothing to be ashamed of.'" The "scenario" of finishing well behind Semenya is a familiar one for competitors since the South African burst onto the scene at the 2009 world track and field championships. As an 18-year-old in Berlin, Semenya blasted away her competition, winning by almost two and a half seconds and clocking the fastest time of the year. Caster Semenya dominates 800m at 2009 world championships ©2017 CBC/Radio-Canada.

Keyword: Sexual Behavior
Link ID: 23933 - Posted: 08.09.2017

/ By Florence Williams The 17th century ushered in an astonishing age of scientific discovery, from Galileo’s positioning of the sun in the heavens to Newton’s Laws of Motion to Francis Bacon’s empiricism. Armed with new swagger and understanding, the scientific rationalists of the day figured the pivot from astronomy and physics to biology would be a piece of cake. The workings of the universe had been proved to adhere to laws and formulas. All would be properly unveiled in due time. “The bold men of science,” Edward Dolnick writes, “raced off to take on the mystery of life and promptly face-planted.” How mistaken they were. As Edward Dolnick writes in his amusing and informative “The Seeds of Life,” “The bold men of science raced off to take on the mystery of life and promptly face-planted.” In fact, they were fairly undone, partly by their own pigheaded biases and partly by the truly mystifying matters of genes and heredity, for which they were woefully ill prepared. It was not until 1875 that a German scientist finally put the sperm and the egg together conceptually. The journey to that insight was sometimes comical, sometimes misguided, and usually revealing of cultural mores, gender politics, and societal blind spots. Consider, for example, the common scientific belief that a woman’s contribution to baby-making must surely be minimal. Copyright 2017 Undark

Keyword: Sexual Behavior; Development of the Brain
Link ID: 23921 - Posted: 08.07.2017

Daniel Trotta NEW YORK (Reuters) - While President Donald Trump has thrust transgender people back into the conflict between conservative and liberal values in the United States, geneticists are quietly working on a major research effort to unlock the secrets of gender identity. A consortium of five research institutions in Europe and the United States, including Vanderbilt University Medical Center, George Washington University and Boston Children's Hospital, is looking to the genome, a person's complete set of DNA, for clues about whether transgender people are born that way. Two decades of brain research have provided hints of a biological origin to being transgender, but no irrefutable conclusions. Now scientists in the consortium have embarked on what they call the largest-ever study of its kind, searching for a genetic component to explain why people assigned one gender at birth so persistently identify as the other, often from very early childhood. (reut.rs/2w3Ozg9) Researchers have extracted DNA from the blood samples of 10,000 people, 3,000 of them transgender and the rest non-transgender, or cisgender. The project is awaiting grant funding to begin the next phase: testing about 3 million markers, or variations, across the genome for all of the samples.

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 23919 - Posted: 08.05.2017

/ By Deborah Blum I’m hesitating over this one question I want to ask the scientist on the phone, a federal researcher studying the health effects of soy formula on infants. I worry that it’s going to sound slightly Dr. Frankenstein-esque. Finally, I spill it out anyway: “Are we talking about a kind of accidental experiment in altering child development?” The line goes briefly silent. “I’m a little worried about the word ‘experiment,’” replies Jack Taylor, a senior investigator at the National Institute of Environmental Health Sciences, a division of the National Institutes of Health. Taylor and his colleagues in North Carolina have been comparing developmental changes in babies fed soy formula, cow-milk formula, and breastmilk. His group’s most recent paper, “Soy Formula and Epigenetic Modifications,” reported that soy-fed infant girls show some distinct genetic changes in vaginal cells, possibly “associated with decreased expression of an estrogen-responsive gene.” But his first reaction is that my phrasing would, incorrectly, “make it sound like we were giving children a bad drug on purpose.” The research group, he emphasizes, is merely comparing the health of infants after their parents independently choose a preferred feeding method. No one is forcing soy formula on innocent infants. “No, no, that’s not what I meant,” I explain with some hurry. “I wasn’t suggesting that you were experimenting on children.” Rather, I was wondering whether we as a culture, with our fondness for all things soy, have created a kind of inadvertent national study. Soy accounts for about 12 percent of the U.S. formula market and I’ve become increasingly curious about what this means. Because the science does seem to suggest that we are rather casually testing the effect of plant hormones on human development, most effectively by feeding infants a constant diet of a food rich in such compounds. Copyright 2017 Undark

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 23912 - Posted: 08.03.2017

Jon Hamilton Professional fighter Gina Mazany practices during a training session at Xtreme Couture Mixed Martial Arts in Las Vegas. She well remembers her first concussion — which came in her first fight. "I was throwing up that night, Mazany says. Bridget Bennett for NPR Gina Mazany grew up in Anchorage, Alaska. And that's where she had her first fight. "It was right after I turned 18," she recalls. A local bar had a boxing ring, and Mazany decided to give it a shot. Her opponent was an older woman with a "mom haircut." "She beat the crap out of me," Mazany says. "Like she didn't knock me out, she didn't finish me. But she just knocked me around for three rounds. And I remember, later that night I was very, very nauseous. I was throwing up that night." It was her first concussion. Concussions are just part of her sport, Mazany figures, but says she tries to protect herself, and to not give anyone else a head injury--at least in training. Bridget Bennett for NPR Thanks to research on boxers and football players, both athletes and the public are becoming more aware of the dangers of sports-related head injuries. Yet there is little data on participants like Mazany. That's because, unlike the vast majority of athletes studied, she is a woman. "We classically have always known the male response to brain injury," says Mark Burns, at Georgetown University. But there have been remarkably few studies of females. The bias runs throughout the scientific literature, even in studies of mice. © 2017 npr

Keyword: Brain Injury/Concussion
Link ID: 23865 - Posted: 07.24.2017

by Laurel Hamers The tempo of a male elephant seal’s call broadcasts his identity to rival males, a new study finds. Every male elephant seal has a distinct vocalization that sounds something like a sputtering lawnmower — pulses of sound in a pattern and at a pace that stays the same over time. At a California state park where elephant seals breed each year, researchers played different variations of an alpha male’s threat call to subordinate males who knew him. The seals weren’t as responsive when the tempo of that call was modified substantially, suggesting they didn’t recognize it as a threat. Modifying the call’s timbre — the acoustic quality of the sound — had the same effect, researchers report August 7 in Current Biology. Unlike dolphins and songbirds, elephant seals don’t seem to vary pitch to communicate. Those vocal name tags serve a purpose. During breeding season, male elephant seals spend three months on land without food or water, competing with rivals for social status and mating rights. Fights between two blubbery car-sized animals can be brutal. “We’ve seen males lose their noses,” says Caroline Casey, a biologist at the University of California, Santa Cruz. For lower-ranking males, identifying an alpha male by his call and then backing off might prevent a beach brawl. |© Society for Science & the Public 2000 - 2017

Keyword: Animal Communication; Sexual Behavior
Link ID: 23859 - Posted: 07.21.2017

Xiaomeng (Mona) Xu, assistant professor of experimental psychology, and Ariana Tart-Zelvin, If you have experienced the evolution from having a crush to falling in love, it may seem like the transition happens naturally. But have you ever wondered how we make such a huge emotional leap? In other words, what changes take place in our brains that allow us to fall deeply in love? Stephanie Cacioppo, a psychologist at the University of Chicago who has studied the neuroscience of romantic love for the past decade, explains that the process involves several complex changes, particularly in the brain’s reward system. More specifically, in a 2012 review of the love research literature Lisa Diamond and Janna Dickenson, psychologists at the University of Utah, found romantic love is most consistently associated with activity in two brain regions—the ventral tegmental area (VTA) and the caudate nucleus. These areas play an essential role in our reward pathway and regulate the “feel good” neurotransmitter dopamine. In other words, during the early stages of love you crave the person because he or she makes you feel so good. And over time these feelings persist. Our neuroimaging research and that of others suggests that once you are in love—as long as the relationship remains satisfying—simply thinking about your partner not only makes you feel good but can also buffer against pain, stress and other negative feelings. © 2017 Scientific American,

Keyword: Emotions; Sexual Behavior
Link ID: 23852 - Posted: 07.20.2017

Hannah Devlin Science correspondent Brash, brawny and keen to impose their will on anyone who enters their sphere of existence: the alpha male in action is unmistakable. Now scientists claim to have pinpointed the biological root of domineering behaviour. New research has located a brain circuit that, when activated in mice, transformed timid individuals into bold alpha mice that almost always prevailed in aggressive social encounters. In some cases, the social ranking of the subordinate mice soared after the scientists’ intervention, hinting that it might be possible to acquire “alphaness” simply by adopting the appropriate mental attitude. Or as Donald Trump might put it: “My whole life is about winning. I almost never lose.” Prof Hailan Hu, a neuroscientist at Zhejiang University in Hangzhou, China, who led the work said: “We stimulate this brain region and we can make lower ranked mice move up the social ladder.” The brain region, called the dorsal medial prefrontal cortex (dmPFC), was already known to light up during social interactions involving decisions about whether to be assertive or submissive with others. But brain imaging alone could not determine whether the circuit was ultimately controlling how people behave. The latest findings answer the question, showing that when the circuit was artificially switched on, low-ranking mice were immediately emboldened. “It’s not aggressiveness per se,” Hu said. “It increases their perseverance, motivational drive, grit.” © 2017 Guardian News and Media Limited

Keyword: Aggression; Sexual Behavior
Link ID: 23836 - Posted: 07.14.2017

By Giorgia Guglielmi Semen has something in common with the brains of Alzheimer’s sufferers: Both contain bundles of protein filaments called amyloid fibrils. But although amyloid accumulation appears to damage brain cells, these fibrils may be critical for reproduction. A new study suggests that semen fibrils immobilize subpar sperm, ensuring that only the fittest ones make it to the egg. “I’m sure that from the very first time scientists described semen fibrils, they must have been speculating what their natural function was,” says Daniel Otzen, an expert in protein aggregates at Aarhus University in Denmark, who did not participate in the research. “This seems to be the smoking gun.” Researchers discovered semen fibrils in 2007. At first, they seemed like mostly bad news. Scientists showed that the fibrils, found in the seminal fluid together with sperm cells and other components, can bind to HIV, helping it get inside cells. But the fibrils are found in most primates, notes Nadia Roan, a mucosal biologist at the University of California, San Francisco. “If fibrils didn’t serve some beneficial purpose, they would have been eliminated over evolutionary time.” Because the way HIV fuses to cells is reminiscent of the way a sperm fuses to the egg, she wondered whether the fibrils facilitated fertilization. © 2017 American Association for the Advancement of Science.

Keyword: Alzheimers; Sexual Behavior
Link ID: 23828 - Posted: 07.12.2017

By Abby Olena For more than 50 years, scientists have taken for granted that all snakes share a ZW sex determination system, in which males have two Z chromosomes and females have one Z and one W. But a study, published today (July 6) in Current Biology, reveals that the Central American boa (Boa imperator) and the Burmese python (Python bivittatus) use an XY sex determination system, which evolved independently in the two species. “This work is a culmination of a lot of questions that we’ve had about pythons and boas for a long time,” says Jenny Marshall Graves, a geneticist at La Trobe Univeristy in Melbourne, Australia, who did not participate in the study. Some of these questions came up for Warren Booth, a geneticist and ecologist at the University of Tulsa, as he studied parthenogenesis—the growth and development of offspring in the absence of fertilization. He noticed a pattern for organisms undergoing parthenogenesis: animal species that use a ZW system have only male (ZZ) offspring, and the organisms that use an XY system have only female (XX) offspring. Except this pattern doesn’t hold true for boas and pythons, who consistently produce female offspring by parthenogenesis. Booth contacted Tony Gamble, a geneticist at Marquette University in Milwaukee, Wisconsin, who studies sex chromosomes, to begin a collaboration to investigate whether boas and pythons might actually have X and Y chromosomes. Spurred by Booth’s questions, “I went back and reread some of the early papers” on snake sex chromosomes, says Gamble. “What became clear is that they didn’t show that boas and pythons had a ZW sex chromosome system. They just said it without any evidence.” © 1986-2017 The Scientist

Keyword: Sexual Behavior; Evolution
Link ID: 23815 - Posted: 07.09.2017

By Michael Price Male baboons that harass and assault females are more likely to mate with them, according to a new study, adding evidence that sexual intimidation may be a common mating strategy among promiscuous mammals. The study’s authors even argue that the findings could shed light on the evolutionary origins of our own species’ behavior, although others aren’t convinced the results imply anything about people. “I think the data and analyses in this study are first-rate,” says Susan Alberts, a biologist who studies primate behavior at Duke University in Durham, North Carolina. “[But] I also think it’s a big stretch to infer something about the origins of human male aggression towards women.” To conduct the research, Elise Huchard, a zoologist at the National Center for Scientific Research in Montpellier, France, and colleagues examined a group of chacma baboons (Papio ursinus) living in Tsaobis Nature Park in Namibia over a 9-year period. These brownish, dog-sized primates live in troops of dozens of males and females. Females will mate with multiple males throughout the year. The male chacma are about twice the size of females and aggressively fight one another and engage in howling competitions to establish dominance. The more dominant a male is, the more likely he is both to succeed in finding a mate and to sire offspring. Males rarely force females to mate, but after years spent observing the animals in the wild, Huchard noticed that a subtler form of sexual coercion appeared to be going on. “Males often chase and attack some females of their own group when meeting another group, and they generally target sexually receptive females on such occasions,” she says. “I spent a great deal of time studying female mate choice, and my main impression … was that females don't have much room to express any preference.” © 2017 American Association for the Advancement of Science

Keyword: Sexual Behavior; Aggression
Link ID: 23813 - Posted: 07.07.2017

By STEPH YIN Whales and songbirds produce sounds resembling human music, and chimpanzees and crows use tools. But only one nonhuman animal is known to marry these two skills. Palm cockatoos from northern Australia modify sticks and pods and use them to drum regular rhythms, according to new research published in Science Advances on Wednesday. In most cases, males drop beats in the presence of females, suggesting they perform the skill to show off to mates. The birds even have their own signature cadences, not unlike human musicians. This example is “the closest we have so far to musical instrument use and rhythm in humans,” said Robert Heinsohn, a professor of evolutionary and conservation biology at the Australian National University and an author of the paper. A palm cockatoo drumming performance starts with instrument fashioning — an opportunity to show off beak strength and cleverness (the birds are incredibly intelligent). Often, as a female is watching, a male will ostentatiously break a hefty stick off a tree and trim it to about the length of a pencil. Holding the stick, or occasionally a hard seedpod, with his left foot (parrots are typically left-footed), the male taps a beat on his tree perch. Occasionally he mixes in a whistle or other sounds from an impressive repertoire of around 20 syllables. As he grows more aroused, the crest feathers on his head become erect. Spreading his wings, he pirouettes and bobs his head deeply, like an expressive pianist. He uncovers his red cheek patches — the only swaths of color on his otherwise black body — and they fill with blood, brightening like a blush. Over seven years, Dr. Heinsohn and his collaborators collected audio and video recordings of 18 male palm cockatoos exhibiting such behaviors in Australia’s Cape York Peninsula, where the birds are considered vulnerable because of aluminum ore mining. © 2017 The New York Times Company

Keyword: Animal Communication; Sexual Behavior
Link ID: 23790 - Posted: 06.29.2017

By Debra W. Soh If there was a way of telling who in our society is sexually attracted to children, are we entitled to know? A recent study from Georg-August-University Göttingen in Germany suggests that we may need to grapple with this question. Phallometric testing, also known as penile plethysmography, is considered the gold standard in measuring male sexual arousal, and particularly, deviant sexual interests such as pedophilia, which is the sexual interest in prepubescent children, roughly aged 3 to 10. The test involves measuring the volume of blood in the test-taker’s penis using an airtight glass tube (or conversely, measuring penile circumference with a mercury strain gauge) while he is presented with a series of images of children and adults, and audio stories describing a corresponding sexual encounter. Phallometry is commonly used in forensic settings to assess the sexual interests of sex offenders, in order to determine their risk of re-offending. As one can imagine, sex offenders tend not to be forthright about their sexual preferences, which makes phallometry all the more important. It has, however, been criticized because the test can become easier for individuals to fool with each successive assessment. Brain scanning using fMRI holds much promise as a diagnostic tool in evaluating sexual interests, as research has documented a reliable network of brain regions involved in sexual arousal. The current study took this another step by testing whether brain functional activation could be used to infer what someone finds sexually interesting without them knowing. © 2017 Scientific American,

Keyword: Sexual Behavior; Brain imaging
Link ID: 23783 - Posted: 06.28.2017

By Alice Klein Women are missing out on optimum medical treatment because most pre-clinical drug research is done in male animals, a new study suggests. New drugs must be evaluated in animals before being considered for human trials. Over three-quarters of these studies use only male animals because of concerns that female hormone cycles will affect experiments. It is also widely assumed that what works for males will work for females. However, research by Natasha Karp at the Wellcome Trust Sanger Institute in Cambridge and her colleagues casts doubt on this assumption. They compared 234 physical traits in 14,000 male and female lab mice. Sex differences were identified for 57 per cent of quantifiable traits – like cholesterol level and bone mass – and for 10 per cent of qualitative traits, like head shape. In another 40,000 mice, they found that when they switched off specific genes, the effects varied according to sex. This suggests that genetic diseases may manifest themselves differently in males and females and require different treatments, says Karp. These sex nuances mean that drugs optimised for male animals may be less effective in females, or even cause harm, says Karp. Between 1997 and 2001, 8 of the 10 drugs that were pulled from the market in the US posed greater health risks for women – possibly as a result of male-biased animal research, she says. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior
Link ID: 23780 - Posted: 06.27.2017