Links for Keyword: Sexual Behavior

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By Katie Camero For humans, slight variations in temperature don’t mean much. But for some turtles, they mean the difference between whether embryos come out male or female. Now, scientists have evidence that these embryos have some power over their sexual destiny: By moving to slightly warmer or cooler spots inside their eggs, freshwater turtle embryos can help determine their own sex. Not everyone is convinced. But if the new finding holds, this behavior could potentially save some turtle species from extinction by balancing their sex ratios. A reptile’s sex depends on hormones produced during development. For crocodiles, many fish, some lizards, and most turtles, those hormones in turn depend on external temperatures. Cooler temperatures typically lead to more males, and warmer temperatures generally lead to more females. That means a shift of just 2°C can make all of the offspring one sex. As average global temperatures rise, such a strategy could doom some species, including the already-endangered Chinese pond turtle (Mauremys reevesii). As weather warms, warmer eggs produce more and more females—leaving them fewer males to mate with. Wondering whether turtle embryos could respond to rapidly changing temperatures, scientists from the Chinese Academy of Sciences in Beijing examined the behavior of the Chinese soft-shelled turtle (Pelodiscus sinensis). They discovered that the embryos could in fact move between cooler and warmer spots inside their paperclip-size eggs, they reported in 2011 in the Proceedings of the National Academy of Sciences. © 2019 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: 26477 - Posted: 08.02.2019

By Knvul Sheikh It’s a myth that black widow female spiders always kill and consume their mates. But courtship remains perilous for males, cannibalism or no. The terrain, navigated in the dark, is challenging. The female’s web releases come-hither pheromones, but only about 12 percent of prospective males manage to reach it. And once there, they can expect to face male rivals competing to pass their genes on to the next generation. Usually, this results in wild displays of machismo. The males slash the female’s webs to make them less enticing to others. They deposit “mating plugs” in the female’s body to block rival sperm. Why not simply avoid the competition and seek out females’ webs empty of other males? But male black widows actually seem to thrive on the competition, according to a study published Wednesday in the Proceedings of the Royal Society B: Biological Sciences. Researchers found that male black widows find potential mates faster by following the silk trails left behind by other males. “Males have to race to find females,” said Catherine Scott, an arachnologist at the University of Toronto Scarborough in Canada and the study’s lead author. “It makes sense for them to try to use all the tricks they can to find females as soon as possible, even if there are other males that have already found her.” If a male arrives an hour or two late at a female’s web, he still has a chance to interrupt the courting rituals of other males, and could still be the first to mate with the female, Ms. Scott said. Males typically make their way to a rendezvous by following female pheromones back to their source. But those signals must be at just the right distance, and uninterrupted by shifting winds and other factors. © 2019 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: 26476 - Posted: 08.01.2019

Carolyn Wilke Most frogs lay oodles of eggs and quickly hop away. But some poison dart frogs baby their offspring, cleaning and hydrating eggs laid on land and piggybacking hatched tadpoles to water. A peek inside the brains of these nurturing amphibians reveals that in males and females, two regions linked with caring for young are the same — a finding that may provide clues to the neural underpinnings of parental behavior, researchers report online July 17 in Proceedings of the Royal Society B. From humans to crocodiles, many creatures tend to their young. “But we actually understand very little about how the brain makes parental behaviors,” says Eva Fischer, a neuroethologist at Stanford University. To study how such care is wired into the amphibian brain, Fischer and her colleagues looked at neural activity in three poison dart frog species with different parenting strategies: Dendrobates tinctorius, among whom the males take care of the young; Oophaga sylvatica, whose females do the parenting; and Ranitomeya imitator, whose offspring are cared for by a monogamous male and female pair. The researchers collected and quickly killed 25 frogs while the amphibians were toting their tadpoles to water, in order to study the brain while it was still influenced by the parental task. Another 59 brains from non-caregiving frog species or caregivers’ partners were also included in the study. The researchers froze the frog brains and sliced them like loaves of bread. They stained the layers of tissue to pinpoint which nerve cells, or neurons, were turned on. In all three species, a brain region called the preoptic area was lit up with activity in caregiving frogs, but not in those of non-caregiving animals. |© Society for Science & the Public 2000 - 2019.

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: 26451 - Posted: 07.26.2019

Nicola Davis The belief that men are more likely to get turned on by sexual images than women may be something of a fantasy, according to a study suggesting brains respond to such images the same way regardless of biological sex. The idea that, when it comes to sex, men are more “visual creatures” than women has often been used to explain why men appear to be so much keener on pornography. But the study casts doubt on the notion. “We are challenging that idea with this paper,” said Hamid Noori, co-author of the research from the Max Planck Institute for Biological Cybernetics in Germany. “At least at the level of neural activity … the brains of men and women respond the same way to porn.” Writing in the Proceedings of the National Academy of Sciences, Noori and his colleagues report how they came to their conclusions by analysing the results of 61 published studies involving adults of different biological sex and sexual orientation. The subjects were shown everyday images of people as well as erotic images while they lay inside a brain-scanning machine. Noori said all participants rated the sexual images as arousing before being scanned. Previously studies based on self-reporting have suggested men are more aroused by images than women, and it has been proposed that these differences could be down to the way the brain processes the stimuli – but studies have returned different results. Now, looking at the whole body of research, Noori and his colleagues say they have found little sign of functional differences. For both biological sexes, a change in activity was seen in the same brain regions including the amygdala, insula and striatum when sexual images were shown. © 2019 Guardian News & Media Limited

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26423 - Posted: 07.16.2019

By C. Claiborne Ray Q. When the chicks have just hatched, how do chicken farmers tell future hens from future roosters? A. Sexing hatchlings is important for the egg industry. Roosters do not lay eggs, obviously, and they are not needed in order for hens to lay eggs. But it is surprisingly difficult to tell hatchling males from females; there are no external genitalia, and the internal equipment is only subtly different. Though some breeds may show early differences in feather color, often it can take weeks for obvious signs of gender — like combs, wattles and behavioral traits — to emerge. An alternative to waiting was developed in the 1930s by two Japanese researchers, Kiyoshi Masui and Juro Hashimoto. It is called venting or vent sexing. Sign up for Science Times We’ll bring you stories that capture the wonders of the human body, nature and the cosmos. Ideally, about 12 hours after hatching, the chicken-sexer gently squeezes open the multipurpose vent under the tail called the cloaca and exposes a key area of the interior. Several folds of mucus membrane can be seen, and the male sex organ, if present, can be found visually or by touch in an indentation on the second fold. It is a tiny bump, about the size of a pinpoint. It takes a lot of skill and practice to use this method without harming the chicks, so it is mostly done by trained chicken-sexers — who are often well paid for their expertise. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26352 - Posted: 06.25.2019

By Katie Thomas The Food and Drug Administration has approved a new drug to treat low sexual drive in women, the only one besides Addyi, which entered the market in 2015. The drug, to be called Vyleesi, will be sold by AMAG Pharmaceuticals and is intended to be used 45 minutes before sex, via an auto-injector pen that is administered in the thigh or abdomen. “We’re obviously thrilled about being able to bring another option to patients,” said Dr. Julie Krop, the chief medical officer of AMAG, which is based in Waltham, Mass. “These women have suffered significantly, pretty much in silence, for a stigmatized condition, and many of them have not known that it’s a treatable medical condition.” For years, the F.D.A. has been under pressure to encourage more treatments for women with low sexual drive — a condition known as hypoactive sexual desire disorder. Medications for men experiencing erectile dysfunction arrived on the market two decades ago. But these treatments for women have provoked controversy. The first product, Addyi, was approved amid an industry-backed publicity campaign painting detractors as sexist. But some opponents argued its risks outweighed its benefits. Addyi must be taken every day and cannot be taken with alcohol, which can cause fainting. Soon after it went on sale, Addyi was acquired by Valeant Pharmaceuticals for $1 billion, which then failed to promote it. Valeant sold it back to its original owners in 2017 and the drug’s sales have been tepid. Company officials declined to say how much Vyleesi would cost and said they would provide more details when the product goes on sale later this year. They said they expected insurance to cover Vyleesi on a scale similar to Addyi and to male erectile dysfunction drugs — coverage of those drugs by commercial health care plans is mixed. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26347 - Posted: 06.22.2019

Bethany Brookshire When researchers release a new finding about the brain, it’s often mice or rats who have run the mazes and taken the tests for science. People might wonder: Are rodents good substitutes for humans? Maybe for men, but what about women? That’s less likely, because most neuroscience experiments don’t use female rodents — a fact one scientist says comes from outdated ideas that should go into the scientific dustbin. For years, many scientists have dismissed female rodents as too variable to use in the lab, with tricky hormone surges that can affect behavior and compromise study results. In 2009, male lab mammals in neuroscience studies outnumbered females 5.5 to 1, according to a 2011 study in Neuroscience & Biobehavioral Reviews. “The idea that women are primarily driven by ovarian hormones [was] a narrative put in place intentionally in the Victorian era,” says Rebecca Shansky, a neuroscientist at Northeastern University in Boston. “That has also infiltrated the way we think about female animals” in science. Male animals can be just as “hormonal” as their female counterparts, Shansky argues in an essay published May 31 in Science, and it’s time that both sexes got equal attention in the lab. Here are five things to know about the issue of sex in the study of rodent brains. In humans, reproductive hormones such as estrogen and progesterone ebb and flow over a roughly 28-day cycle. In rodents, that cycle is compressed to four or five days. Estrogen or progesterone levels on one day could be up to four times as much as on the day before. |© Society for Science & the Public 2000 - 2019

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: 26342 - Posted: 06.20.2019

By Mitch Leslie If papers published in the past 6 months are right, a single number is enough to show whether people are likely to suffer a premature heart attack, land first authorship on published papers, become dependent on alcohol, or put on fat around the middle. That magic number is the ratio between the lengths of the second and fourth fingers, known as the 2D:4D ratio. It tends to be lower in men—meaning their fourth fingers tend to be longer than their second—than in women. Researchers who believe in its predictive power say it reflects a fetus's exposure to testosterone and other hormones that guide development, including that of the brain. The idea that the lengths of human fingers reveal so much stems from the work of evolutionary biologist John Manning, now at Swansea University in the United Kingdom. But the field he inspired has ballooned beyond what he could have imagined. More than 1400 papers in just over 20 years have linked the finger ratio to attributes such as personality, cognitive abilities, and sexual orientation as well as to risk of illnesses such as cardiovascular disease, cancer, and amyotrophic lateral sclerosis. Researchers have even tried to use ratios gleaned from stenciled handprints on cave walls to determine whether the artists behind ancient paintings were men or women. But the notion has also riled plenty of critics, who argue that researchers who rely on the 2D:4D comparison have been seduced by a simplistic, faulty measure. Some doubters contend that the difference in ratios between the sexes is an illusion resulting from men's larger hands or that the measure itself is statistically problematic. "I'm skeptical about every single finding involving that ratio," says physiologist and biostatistician Douglas Curran-Everett of National Jewish Health in Denver. © 2019 American Association for the Advancement of Science

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: 26311 - Posted: 06.07.2019

By Marisa Iati A bill in Alabama awaiting the governor’s signature would require people convicted of certain sex offenses to undergo “chemical castration” as a condition of parole — a requirement meant to keep perpetrators from committing similar crimes. The proposed law, passed by the state legislature, says a judge must order anyone convicted of a sex offense involving a child under the age of 13 to start receiving testosterone-inhibiting medication a month before their release from prison. Most offenders would have to pay for their treatment, which would be administered by the Department of Public Health, until a judge decides the medication is no longer necessary. Under the proposed law, a judge — and not a doctor — would tell the offender about the effects of the treatment. An offender could choose to stop getting the medication and return to prison to serve the remainder of their term. Anyone who stopped receiving the castration treatment without approval would be considered guilty of a Class C felony, punishable under Alabama law by up to 10 years in prison and a fine of up to $15,000. “Chemical castration” is a misnomer, as the process leaves the testes intact, can be reversed and does not prevent a man from reproducing. It does not guarantee a man’s sexual urge will be eliminated. (There’s no consensus on whether chemical castration would be effective for women.) © 1996-2019 The Washington Post

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: 26304 - Posted: 06.06.2019

By JoAnna Klein Say you are prescribed medication for depression, anxiety or even just to sleep. Would you want to take it if you knew that the drug had only been tested on men and male animals? Rebecca Shansky, a neuroscientist at Northeastern University in Boston, thinks you might not. When she tells nonscientific audiences that researchers “for the most part don’t study female animals, people are blown away,” she said. She added: “It seems like such an obvious thing to a normal person. But when you come up in the academic and science world, it’s like, ‘Oh no, females are so complicated, so we just don’t study them.’” In 2016, the National Institutes of Health and its Canadian counterpart mandated that all preclinical research they fund must include female subjects. Now, Dr. Shansky and other scientists wonder if that requirement will do enough to improve how research is conducted. In an essay published Thursday in Science, Dr. Shansky questions whether simply adding female organisms to experiments or looking for sex differences misses the point. She warns that this is a public health problem — with implications beyond neuroscience — and says scientists should design experiments better suited to both biological sexes. If scientists don’t stop looking through a male lens, outdated gender stereotypes will continue to foster dangerous assumptions about the brain and behavior, resulting in clinical studies and eventual treatments that don’t work equally for all people on the gender spectrum. Basic research is the foundation for clinical studies and practice, and that often begins with animals, which offer controlled settings for research of human diseases. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26284 - Posted: 05.31.2019

By Susan Rudnick I was a month shy of turning 16 when a red-faced man in a white coat told me I had been born without a uterus. With a huge dark desk between us, he told me I would never menstruate, and would need plastic surgery to correct the anomaly of my vaginal opening that was a mere dimple, so that one day I would to be able to have sexual intercourse. I have M.R.K.H. These four letters stand for Mayer, Rokitansky, Küster and Hauser, the names of the four doctors who discovered the syndrome over a hundred years ago. This anatomical condition occurs during the first trimester of pregnancy, when the duct that normally forms the uterus, cervix and vaginal canal fails to develop. Ovaries do develop, but there is no menstruation. Although the condition is rare, impacting just one in every 4,500 women, for over 40 years I thought I was like nobody else. At the time of the diagnosis, he described my symptoms but neglected to tell that the condition had a name. Without a name for my syndrome, I couldn’t connect with others like me. I was left to navigate my life feeling defective, marginalized and alone. I carried my difference as a secret shame, acting as if I were just like other people. In high school I learned to pretend I had my period. I even talked about having period cramps, which I never had. Even though swimming and water ballet club were my favorite activities, I didn’t go swimming a few times so that it would seem as if I had my period, like all the other girls. There was nothing I wouldn’t do to be like everybody else. One day in college I was lying in my dorm room bed with a gaggle of women, when the conversation turned to diaphragms, something I would never need, but which seemed a rite of passage. Birth control was way beyond my knowledge base. This was in the early 60s, when abortions were still illegal, but you could go to Planned Parenthood and get fitted for a diaphragm. While my girlfriends laughed about looking at condoms in the drugstore, I spaced out. I felt like such an outsider carrying the pain of my secret. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26268 - Posted: 05.28.2019

By Megan Schmidt “The women’s winter is here. The freeze is upon us,” warns a Game of Thrones parody about men and women’s office temperature preferences. If you have a Y chromosome, you probably haven’t experienced “women’s winter.” As the video explains, women’s winter is “when spring turns to summer and there’s blossom on the trees, the office air doth turns to ice and all the women freeze.” Although the skit is now a few years old, it perfectly captures women’s daily struggle with overly air-conditioned workplaces. To some people, thermostat complaints might seem trivial. But a new study has found that cold offices do more than make women shiver. Thermostat settings geared for men’s comfort — typically cooler temperatures — may actually disadvantage women by lowering their ability to perform some tasks. The study, published in PLOS One, found that women are better at math and word tests when room temperatures are warmer. The women in the study answered more questions correctly and submitted more answers overall during the timed tests. Men, on the other hand, performed marginally better on the same tests at cooler room temperatures, the researchers found. Temperature didn’t influence performance on the logic test for either gender. Study author Agne Kajackaite, a behavioral economics researcher at the WZB Berlin Social Science Center, said the research illustrates that “the battle for the thermostat is not just a complaint about comfort levels.” When it comes to women succeeding in the classroom or in the workplace, room temperatures may make a big difference.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 26266 - Posted: 05.24.2019

Ian Sample Science editor Male bonobos living with their mothers are three times more likely to father offspring, research suggests. Their mothers are so keen for them to father children that they usher them in front of promising partners, shield them from violent competitors and dash the chances of other males by charging them while they are at it. For a bonobo mother, it is all part of the parenting day, and analysis finds the hard work pays off. Males of the species that live with their mothers are three times more likely to father offspring than those whose mothers are absent. Martin Surbeck, a primatologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, said: “We wanted to see if the mothers’ behaviour changes the odds of their sons’ success, and it does. The mothers have a strong influence on the number of grandchildren they get.” Bonobo mothers seize every opportunity to give their sons a leg-up. In bonobo society, the lower ranks tend to be gender balanced, but females dominate the top ranks. Many mothers have social clout and chaperone their sons to huddles with fertile females, ensuring them better chances to mate. “The mothers tend to be a social passport for their sons,” said Surbeck. © 2019 Guardian News & Media 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: 26256 - Posted: 05.21.2019

Mitchel Daniel If you’re looking for love, it pays to stand out from the crowd. Or at least that’s how it works in some parts of the animal kingdom. Scientists have found that in several species – green swordtail fish, Trinidadian guppies, fruit flies, Poecilia parae fish – ladies overwhelmingly go for the guy that looks different from the rest. But the reason for this attraction to novelty has remained a mystery. So my colleagues and I used the Trinidadian guppy to investigate the psychology behind why many females have an affinity for the unusual. Male features that attract females The guppy has long been a workhorse for biologists like me who are interested in understanding the mating decisions that animals make and the evolutionary forces behind those decisions. Male guppies attempt to woo females using courtship dances that show off the elaborate color patterns adorning their bodies. The females of the species are color pattern connoisseurs, carefully choosing among their suitors based, in large part, on their visual appeal. This tendency has made the guppy an excellent model for studying mate choice. Male guppies showcase their colors during their courtship dances. Many types of animals exhibit what evolutionary biologists call directional preferences, an attraction to more of a certain thing – think bigger antlers, a longer tail or brighter color spots. And there are evolutionary theories that help make sense of these preferences. If a male can grow more extreme features, that can be a sign that he is in good physical condition, has good genes, or would make a good parent. What’s less clear, though, is why females should value unusualness in a mate. © 2010–2019,

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: 26233 - Posted: 05.15.2019

By Gina Kolata The Court of Arbitration for Sport in Zurich has ruled that women with very high testosterone levels — far above the normal range — cannot compete against other women in races from 400 meters to one mile unless they take drugs to suppress production of the hormone. The ruling prevents Caster Semenya, 28, an elite runner and Olympic champion from South Africa, from competing in those races because her testosterone levels are naturally very high. She had challenged attempts to disqualify her from racing as a woman. The science underpinning that decision is complicated, raising difficult questions about biology, fairness and gender identity. What is testosterone? Where does it come from in women? It’s a hormone, an androgen, that has a variety of effects on the body. Women and men produce testosterone, but women don’t make nearly as much In men, high levels of testosterone are made by the testes. Much lower levels are produced in the adrenal glands, which rest above the kidneys. Women also make testosterone in their adrenal glands, and in their ovaries. But testes produce much more: Testosterone levels in men are 295 to 1,150 nanograms per deciliter of blood, while the levels in the women are 12 to 61 nanograms per deciliter of blood. Testosterone “builds muscle,” said Dr. Benjamin D. Levine, who studies sex differences in athletic performance at the University of Texas Southwestern Medical Center. “It builds skeletal muscle, it builds cardiac muscle. It increases the number of red blood cells.” The effects are seen whether the hormone is naturally present or introduced with drugs. In one of the most infamous examples, women who represented East Germany at the Olympic Games in the ’70s and ’80s achieved astounding success after they were unknowingly doped with anabolic steroids including testosterone. “The science is quite clear,” said Dr. Aaron Baggish of Massachusetts General Hospital, who is an expert on testosterone’s effects. “An androgenized body has a performance advantage.” © 2019 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: 26196 - Posted: 05.02.2019

By Emily Oster In 1980, 8.6 percent of first births were to women over 30; by 2015 this was 31 percent. This is more than an interesting demographic fact. It means that many of us are having children much later than our parents did. By the time a baby arrives, many of us have been through school, spent time in the working world, developed friendships, hobbies. And through all of these activities, we have probably grown used to the idea that if we work harder — at our jobs, at school, at banking that personal record in the half marathon — we can achieve more. Babies, however, often do not respond to a diligent work ethic. Take, as an example, crying. When my daughter, Penelope, was an infant, she was typically inconsolable between 5 and 8 p.m. I’d walk her up and down the hall, sometimes just crying (me crying, that is — obviously she was crying). I once did this in a hotel — up and down, up and down, Penelope screaming at the top of her lungs. I hope no one else was staying there. I tried everything — bouncing her more, bouncing her less, bouncing with swinging, bouncing with nursing (difficult). Nothing worked; she would eventually just exhaust herself. I wondered whether this was normal. I’m an economist, someone who works with data. I wrote a book on using data to make better choices during pregnancy; it was natural for me to turn to the data again once the baby arrived. And here, faced with crying, I found that the data was helpful. We often say babies are “colicky,” but researchers have an actual definition of colic (three hours of crying, more than three days a week, for more than three weeks) and some estimates of what share of babies fit this description (about 2 percent). But the same data can also tell us that many babies cry just a bit less than that, and almost 20 percent of parents report their baby “cries a lot.” So I was not alone. The data also told me the crying would get better, which it eventually did. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26162 - Posted: 04.22.2019

Nicola Davis Philandering men have unfaithfulness written all over their faces, according to research that suggests men and women are able to spot cheating chaps just by looking at them. Experts found men with more “masculine” faces were more likely to be thought to be unfaithful, and such men also self-reported more cheating or “poaching” of other men’s partners. However, they stressed the results were modest, and said people should be wary of deciding whether someone is a love rat based on impressions of facial features alone. The team said being suspicious of men with masculine features – such as a strong browridge, strong jaw and thinner lips – might have offered an evolutionary advantage, allowing heterosexual women to spot a flaky partner and men to recognise a potential rival who might seduce their partner or leave them raising someone else’s child. Previous research has suggested women are able to spot unfaithful men from their mugshot, with the masculinity of the man’s face a key factor in the judgment, while weaker effects have been found for men weighing up images of women. However, it was unclear whether people could also spot a philanderer of the same sex. Writing in the journal Royal Society Open Science, researchers described how they asked heterosexual white participants to judge the facial features of 189 white adults who had been photographed and taken part in previous research. Overall, 293 men and 472 women rated pictures of women, while 299 men and 452 women judged images of men, rating on a scale of one to 10 how likely they thought each person was to be unfaithful. © 2019 Guardian News & Media Limited

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: 26147 - Posted: 04.17.2019

Robert J King Ph.D. Saying that people deserve to be treated decently is not a factual claim. You can’t look it up in a textbook, and no amount of brain-scanning is going to reveal why it’s true. People have been either succeeding (or more often failing) to treat each other kindly, fairly, and honorably, since before there was science, since before there were people really. And—they will continue to try (and often fail) far into the future, whatever science reveals about our natures. If I am trying to help a child understand why stealing from another child was wrong, or that they should share the sandpit, or apologize to that other annoying (and now crying) kid…yes…I know he took your dolly, but you still can’t hit him with that Lego dinosaur… Well, I don’t get out my copy of Eric Kandel's Principles of Neural Science, and start pointing meaningfully to the diagram of Brodmann area 11 in the prefrontal cortex. This seems blindingly obvious. However, the corollary: That you don’t need neurological backup to argue that you should treat people fairly, seems lost on writers like Cordelia Fine and Gina Rippon. Both are trying to argue that humans are neurological hermaphrodites, as if somehow admitting any sex differences in brains would mandate the unfair treatment of women. Gina Rippon is back to “debunk” neuroscience with her latest, The Gendered Brain: The New Neuroscience That Shatters The Myth Of The Female Brain. It is tempting to rebunk these debunkings but, if I am right in my guess about what is going on here, no amount of factual piling on is going to help. In fact—it may make things worse, because it’s going to convince writers like Fine and Rippon that some hideous conspiracy is occurring and, like some horrible feminist version of Alex Jones, that the whole of brain science is fake news. Let’s stop things before they get out of hand. © 2019 Sussex Publishers, LLC

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26135 - Posted: 04.13.2019

Rhonda Voskuhl & Sabra Klein We are concerned that Lise Eliot’s review of Gina Rippon’s book The Gendered Brain (Nature 566, 453–454; 2019) undermines the premise that sex is a biological variable with respect to many medical conditions and drug responses (see J. A. Clayton and F. S. Collins Nature 509, 282–283; 2014). As president-elect and president, respectively, of the Organization for the Study of Sex Differences, we disagree with Eliot’s claim that the brain is “no more gendered than the liver or kidneys or heart”. We also disagree that sex differences in behaviour are due to cultural effects on newborns, not to biological effects. In our view, these are not mutually exclusive. Sex disparities occur in animal models that are not subject to cultural bias. The brain, like many organs, shows differences attributable to sex, both during health (see, for example, E. Luders et al. J. Neurosci. 29, 14265–14270; 2009) and during disease. Two-thirds of people with Alzheimer’s disease are women; twice as many men as women have Parkinson’s disease (see, for example, L. J. Young and D. W. Pfaff Front. Neuroendocrinol. 35, 253–254; 2014). And multiple sclerosis affects three times more women than men, although men with the condition develop neurological disability more quickly (see, for example, R. R. Voskuhl and S. M. Gold Nature Rev. Neurol. 8, 255–263; 2012). Sex is a modifier of disease risk and progression. © 2019 Springer Nature Publishing AG

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26130 - Posted: 04.12.2019

By Sarah Mervosh He is called the “father of the American cavalry,” a Polish-born Revolutionary War hero who fought for American independence under George Washington and whose legend inspired the dedication of parades, schools, roads and bridges. But for more than 200 years, a mystery persisted about his final resting place. Historical accounts suggested the cavalryman, Casimir Pulaski, had been buried at sea, but others maintained he was buried in an unmarked grave in Savannah, Ga. Researchers believe they have found the answer — after coming to another significant discovery: The famed general was most likely intersex. New evidence suggests that although Pulaski identified and lived as a man, biologically, he did not fit into the binary definitions of male and female, a twist that helps explain why scientists could not previously identify his remains. The revelatory findings are detailed in a new documentary, “The General Was Female?,” which is showing on the Smithsonian Channel on Monday. The discovery offers historical representation to people who are intersex, a group that has often been stigmatized and overlooked throughout history. About one in 2,000 people is born with ambiguous genitalia, which can lead doctors to perform what advocates say are unnecessary and harmful surgeries, according to the Intersex Society of North America. But intersex includes a variety of conditions, and many more people have subtler variations in sex anatomy, which may manifest later in life — or not at all. Some estimates suggest that about 1.7 percent of the population has intersex traits, making such characteristics about as common as having red hair. Though Pulaski’s role in history has long been embraced in areas with strong Polish and Catholic ties — his birthday is an Illinois state holiday and he is celebrated with an annual Polish pride parade in New York City — the new findings now also place him alongside the few historical figures who are known to have had intersex traits. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 26120 - Posted: 04.08.2019