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

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Sara Reardon When it comes to lab mice and antidepressants, it's complicated. Mouse experiments with the popular club drug ketamine may be skewed by the sex of the researcher performing them, a study suggests. The findings, presented on 14 November at the Society for Neuroscience (SfN) meeting in Washington DC, only deepen the mystery of how ketamine, which has powerful mood-lifting properties, interacts with the brain. They also raise questions about the reproducibility of behavioural experiments in mice. Ketamine is best known as a psychoactive recreational drug. But it has caught psychiatrists’ interest because of its potential to treat depression within hours. It’s unclear exactly how the drug works, however, and many researchers are using animal models to suss out the mechanism. Polymnia Georgiou, a neuroscientist at the University of Maryland in Baltimore, is one of them. In 2015, a male colleague asked her to run some experiments for him while he was out of town, including a standard way of testing antidepressants called the forced-swim test. In this assay, researchers inject healthy mice with a drug, place them into a tank of water and measure how long they swim before they give up and wait for someone to rescue them. Antidepressants can cause healthy mice to swim for longer than their untreated counterparts, which is what Georgiou’s male colleague found during his experiments using ketamine. © 2017 Macmillan Publishers Limited

Keyword: Sexual Behavior; Depression
Link ID: 24341 - Posted: 11.20.2017

By Jessica Hamzelou Heavy drinkers and abstainers don’t make the best couples. In humans, one partner that drinks more than the other is thought to be a recipe for a breakup. The same appears to be true for prairie voles, one of the only other mammals known to form long-term monogamous relationships. The finding suggests the link between alcohol consumption and relationship failure may have a biological basis, say the researchers. “There is an increase in divorce in couples in which there is discordant drinking,” says Andrey Ryabinin at Oregon Health and Science University. Money is thought to play a role, but nobody knows the precise causes because a randomised study in people would be unethical. “You can’t tell people to start drinking,” he says. To explore the question in animals, Ryabinin and his colleague Andre Walcott turned to prairie voles: the only rodents known to form lasting, monogamous relationships. “They maintain the same pair bond for their entire lives,” says Ryabinin. Unlike other rodents, both partners take care of offspring. And rather than leaving the nest as soon as they reach adolescence, the young stay and look after their younger siblings. Prairie voles are also the only rodents known to willingly drink alcohol. While mice and rats avoid the stuff, prairie voles prefer it to water, says Ryabinin. Voles on the sauce Ryabinin has previously shown that alcohol consumption affects prairie vole relationships. When given a choice between their partner and a new female, male voles that drank more alcohol were more likely to go and mate with the new female than those that abstained. Alcohol seemed to have the opposite effect in females – those that drank more alcohol more strongly preferred their original partner. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Drug Abuse
Link ID: 24325 - Posted: 11.15.2017

By STEPHEN HEYMAN “For years, science has relegated our love to this basic instinct, almost like an addiction that has no redeeming value.” These are not the words of some New Age evangelist preaching from the mount at a couples retreat in Arizona but of Stephanie Cacioppo, a neuroscientist at the University of Chicago who has spent much of her career mapping the dynamics of love in the brain. Her research and some of the theories she has developed put her at odds with other scientists who have described romantic love as an emotion, a primitive drive, even a drug. Using neuroimaging, Dr. Cacioppo has collected data that could suggest that this kind of love activates not only the emotional brain, but also regions that are involved in higher-level intellectual activities and cognition. “This means that it’s possible that love has a real function — not only to connect with people emotionally but also to improve our behavior,” she said. Dr. Cacioppo attributes all kinds of mental and physical benefits to being in love. She says it can help you think faster, to better anticipate other people’s thoughts and behavior, or to bounce back more quickly from an illness. “The empirical tests I’ve done in my lab suggest that, in many ways, when you’re in love, you can be a better person,” she said. Talk to Dr. Cacioppo for long enough and you will be struck by how optimistic her views on traditional romance seem, especially in a world where divorce is commonplace, marriage rates are down, and polyamory and other forms of unconventional relationships are in the news. While she acknowledges that many types of relationships can be healthy, she believes that we are all searching for a “true love” to complete us, that humans are hard-wired for monogamy and that there is indirect biological evidence for fairy-tale tropes like love at first sight. © 2017 The New York Times Company

Keyword: Emotions; Sexual Behavior
Link ID: 24308 - Posted: 11.09.2017

By Giorgia Guglielmi The popular claim that women in their fertile days prefer men with more masculine faces may not be true. That’s the conclusion of the largest study to analyze how sex hormones influence women’s preference for men’s faces. Researchers first created 10 prototype male faces by averaging 50 photos of young white men. Then, they tweaked the prototype faces to create a more masculine and a more feminine version of each (pictured, masculine version on the left, feminine version on the right). Finally, the scientists asked nearly 600 heterosexual women to look at these photos and rate men’s attractiveness for either a fling or a long-term relationship. The women also provided saliva samples, which the researchers tested for sex hormones such as estradiol and testosterone. Hormone levels were not significantly related to women’s preference for manly faces, the team reports on the preprint server bioRxiv. The researchers also didn’t find evidence that women using the birth control pill prefer more feminine faces, as had been suggested. However, women did prefer masculine faces over feminine ones, especially for short-term relationships. This could be because manly traits, like a large jaw and jutting cheekbones, signal good heritable characteristics, such as a strong immune system, but have also been linked to people that are less willing to invest time in personal relationships, the scientists say. © 2017 American Association for the Advancement of Scien

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 24286 - Posted: 11.04.2017

By NICHOLAS ST. FLEUR Swallowed by a sinkhole. Washed away by a mudflow. Drowned after falling through thin ice. These are the fates that many unlucky mammoths suffered in Siberia thousands of years ago. Their well-preserved fossils have provided paleobiologists with insight into their prehistoric lives. Now, after performing a genetic analysis on the remains from the furry victims of natural traps, a team of scientists made a striking discovery: Most were male. “In many species, males tend to do somewhat stupid things that end up getting them killed in silly ways, and it appears that may have been true for mammoths also,” said Love Dalén, an evolutionary biologist from the Swedish Museum of Natural History. In a study published Thursday in the journal Current Biology, he and his colleagues analyzed DNA from nearly 100 mammoth bones, teeth and tusks, and found that about two-thirds came from males. They speculate the reason for the skewed sex-ratio may have to do with the risky behavior that young males take after leaving the protection of their mothers to live on their own. “Old females are very knowledgeable, they know best,” he said. The finding was an accident, according to Patrícia Pečnerová, a doctoral student at Stockholm University and lead author on the study. It came while she was entering data for a different project on mammoth genetics. “While filling this in on the spreadsheet we saw that there were too many males, more than there should be,” she said. “We were really surprised to see there were more than twice as many males as females because there was no previous research or indication that that should be the case.” The 98 specimens that the team had analyzed came from across the northern part of Siberia and had been collected over the course of four decades. The oldest were more than 60,000 years old, and the youngest, a specimen known as “Lonely Boy,” was about 4,000 years old. The genetic data did not provide insight into how old the mammoths were when they died, only their sex. © 2017 The New York Times Company

Keyword: Sexual Behavior
Link ID: 24285 - Posted: 11.03.2017

By Andy Coghlan For the first time, female dark-eyed juncos have been found to burst into song in the wild. Although many female tropical birds sing, singing females are rare among northern, temperate songbirds. However, the behaviour is now becoming more common, and climate change may mean it becomes even more widespread. Dustin Reichard of Ohio Wesleyan University knew that female dark-eyed juncos (Junco hyemalis) sometimes sang in captivity, but only after being injected with testosterone. To find out if they sang in the wild, he and his colleagues goaded them by placing a live, caged female in their territories. The researchers also played recordings of a soft trill that females make when they are receptive to mating. In all, 17 females, along with 25 males, interacted with the caged females. Half the females dived and lunged at them, and a minority also performed aggressive tail-spreads not normally seen in females. Three of the females sang songs similar to those of males. “The context in which the songs were observed – responding to a female intruder – suggests these songs have an aggressive, territorial function,” says Reichard. “But we can’t say whether female song is specific to female intruders without also measuring their response to male intruders.” The females also reacted badly to attempts by males to woo the intruder female, both with song and other courtship behaviours such as puffing up their feathers and spreading their tails. Dark-eyed juncos are monogamous, and the females sought to keep their mates faithful by aggressively chasing them away from the rival female. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Animal Communication
Link ID: 24255 - Posted: 10.28.2017

Angus Chen Tobacco companies put a lot of effort into giving cigarettes sex appeal, but the more sensual smoke might actually belong to marijuana. Some users have said pot is a natural aphrodisiac, despite scientific literature turning up mixed results on the subject. At the very least, a study published Friday in the Journal of Sexual Medicine suggests that people who smoke more weed are having more sex than those who smoke less or abstain. But whether it's cause or effect, isn't clear. The researchers pulled together data from roughly 50,000 people who participated in an annual Centers for Disease Control and Prevention survey during various years between 2002 and 2015. "We reported how often they smoke – monthly, weekly or daily – and how many times they've had sex in the last month," says Dr. Michael Eisenberg, a urologist at Stanford University Medical Center and the senior author on the study. "What we found was compared to never-users, those who reported daily use had about 20 percent more sex. So over the course of a year, they're having sex maybe 20 more times." People who consumed marijuana daily had sex 7.1 times a month, on average, for women and 6.9 times for men. Women who didn't use marijuana at all had sex 6 times a month, on average, while men who didn't use marijuana had sex an average of 5.6 times a month. © 2017 npr

Keyword: Drug Abuse; Sexual Behavior
Link ID: 24246 - Posted: 10.27.2017

By Renee Joy Dufault, Steven G. Gilbert According to the CDC, autism prevalence continues to climb with 8 year old boys afflicted 4.5 times more often than girls. What makes matters worse is the fact that many boys with autism are also diagnosed with ADHD. These disorders severely impact the learning process in the classroom environment and lead to a lifelong economic burden both for the afflicted individual and society. Researchers estimated the annual economic burden in the U.S. for autism alone in 2015 was $162-$367 billion. If the autism prevalence continues to rise, researchers predict the costs will likely exceed those of ADHD and diabetes by 2025. It is imperative that families receive the support they need to prevent and manage these disorders which often occur in tandem. Proper management requires an understanding of the causes or “risk factors.” One cause associated with both disorders is exposure to heavy metals found in a poor diet. Heavy metal exposures may occur from the consumption of highly processed foods that contain ingredients with allowable concentrations of lead and inorganic mercury. Furthermore, these heavy metals may accumulate in blood especially when diet does not include adequate minerals to support the gene activity needed to metabolize and excrete them. Researchers led by Alabdali recently found higher blood lead and mercury levels are correlated with the severity of social and cognitive impairment in children with autism. What this means is parents will have more difficulty managing their child with autism and ADHD as the mercury and/or lead concentration levels rise in his blood. © 2017 Scientific American

Keyword: Autism; Sexual Behavior
Link ID: 24234 - Posted: 10.24.2017

By Aylin Woodward Not in my backyard. Territorial songbirds in New Zealand reacted more aggressively towards males encroaching on their territory if those rivals sang more complicated songs. The tui birds perceived these snappy singers as greater territorial threats than their simpler singing counterparts. Birdsong has two main functions: defending a territory and attracting a mate, says Samuel Hill at Massey University in Auckland, New Zealand. For tui (Prosthemadera novaeseelandiae), territory defence is a key concern. “There are flowering and fruiting trees year round in New Zealand, so the tui always have resources to defend,” says Hill. This explains why “they natter all year round”. Warbling away takes lots of energy, so males may be showing off their physical endurance to females. Long and complicated songs may also be a sign of skill, as to sing them birds must use superfast vocal muscles to control rapid acoustic changes. In other songbirds, like zebra finches, females prefer males that sing harder songs. This hasn’t been tested in tui, but Hill says the complexity of a male’s song is probably a proxy for more relevant measures of his quality, like body condition and cognitive ability. If that is so, Hill reasoned, breeding male tui would take umbrage at potential rivals singing at the edge of their territory, particularly if their songs were complex and they were therefore strong competitors. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Animal Communication
Link ID: 24227 - Posted: 10.21.2017

By Helen Thomson THE most detailed study ever of brain activity during orgasm has discovered why climaxing makes women feel less pain, and shown that “switching off” isn’t necessary. Nan Wise at Rutgers University, New Jersey, and her colleagues recruited 10 women to lie in a functional MRI scanner and stimulate themselves to orgasm. They then repeated the experiment but had the volunteers’ partners stimulate them. The team was able to follow brain activity in 20-second intervals to see what happens just before, during and after orgasm. Back in 1985, Wise’s colleagues Beverly Whipple and Barry Komisaruk, both at Rutgers, discovered that during self-stimulation and orgasm, women’s ability to withstand painful finger squeezing increased by 75 per cent, and the level of squeezing at which women noticed the pain more than doubled. Now Wise’s team has explained why. At the point of orgasm, the brain’s dorsal raphe nucleus area becomes more active. This region plays a role in controlling the release of serotonin, which can act as an analgesic, dampening the sensation of pain. Her team also saw a burst of activity in the nucleus cuneiformis, which is a part of systems thought to help us control pain through thought alone. “Together, this activity – at least in part – seems to account for the pain attenuating effect of the female orgasm,” says Wise. It’s not yet clear why pain sensation decreases during orgasm, or if men experience the same phenomenon. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Attention
Link ID: 24221 - Posted: 10.20.2017

By NICHOLAS BAKALAR Lack of sleep may raise the risk for gestational diabetes. Gestational diabetes — abnormally high blood sugar that develops during pregnancy — can lead to excessive birth weight, preterm birth or respiratory distress in the baby, among other problems. It can also increase the mother’s risk for Type 2 diabetes later in life. Researchers pooled data from eight studies involving 17,595 women. Seven of the studies depended on self-reports of sleep, and one measured sleep duration. After adjusting for variables such as age, body mass index and ethnicity, they found that women who slept less than 6.25 hours a night were almost three times as likely to have gestational diabetes as those who slept more. The study is in Sleep Medicine Reviews. The reasons for the link are not known, but the authors suggest that hormonal changes in pregnancy as well as systematic inflammation tied to lack of sleep can lead to insulin resistance and high blood glucose levels. But the study is observational and does not prove a causal relationship between poor sleep and gestational diabetes. “Minimizing sleep disruption is important — limiting caffeine, avoiding electronics at bedtime and so on,” said the lead author, Dr. Sirimon Reutrakul, an associate professor of medicine at the University of Illinois at Chicago. “It’s another factor that may influence overall health. But it’s easier said than done.” © 2017 The New York Times Company

Keyword: Sleep; Sexual Behavior
Link ID: 24215 - Posted: 10.19.2017

By Karen Weintraub Each time health care workers grab a pint of blood for an emergency transfusion, they make sure the donor and recipient have compatible blood types. But they do not pay attention to the donor’s sex. A new study raises questions as to whether that should change. In the first large study to look at how blood transfusions from previously pregnant women affect recipients’ health, researchers discovered men under 50 were 1.5 times more likely to die in the three years following a transfusion if they received a red blood cell transfusion from a woman donor who had ever been pregnant. This amounts to a 2 percent increase in overall mortality each year. Female recipients, however, did not appear to face an elevated risk. The study of more than 42,000 transfusion patients in the Netherlands was published Tuesday in JAMA The Journal of the American Medical Association. The American Red Cross and the researchers themselves were quick to say the study is not definitive enough to change the current practice of matching red blood cell donors to recipients. But if this explosive finding is confirmed with future studies, it could transform the way blood is matched—and it would suggest millions of transfusion patients worldwide have died prematurely. “If this turns out to be the truth, it’s both biologically interesting and extremely clinically relevant,” says Gustaf Edgren, an expert who was not involved in the study but co-wrote an editorial about it. “We certainly need to find out what’s going on.” Edgren, an associate professor of epidemiology at the Karolinska Institute and a hematologist at Karolinska University Hospital in Stockholm, says his own research suggests the donor’s sex makes no difference to the transfused patient. “Our data is really not compatible with this finding,” he says. © 2017 Scientific American

Keyword: Sexual Behavior; Neuroimmunology
Link ID: 24214 - Posted: 10.19.2017

By DOUGLAS QUENQUA In the days after his son was born, Rob Sandler found the thrill of becoming a new father replaced with dark feelings of dread and hopelessness. Those feelings, coupled with sleep deprivation and stress, culminated in a panic attack during his son’s bris. As a group of old friends was saying goodbye after the ceremony, “I had this feeling that they were leaving and I was stuck in this situation that would never get any better,” said Mr. Sandler, a marketing executive in Dallas. “I just felt trapped.” What followed was months of sadness, anxiety and — perhaps most worrisome of all — a feeling of acute disappointment in his own ability to be a good parent. In recent years, a growing body of research, and the increasing visibility of dads like Mr. Sandler, has given rise to the idea that you don’t have to give birth to develop postpartum depression, the so-called “baby blues.” Studies suggest that the phenomenon may occur in from 7 percent to 10 percent of new fathers, compared to about 12 percent of new mothers, and that depressed dads were more likely to spank their children and less likely to read to them. Now, a University of Southern California study has found a link between depression and sagging testosterone levels in new dads, adding physiological weight to the argument that postpartum depression isn’t just for women anymore. The study also found that while high testosterone levels in new dads helped protect against depression in fathers, it correlated with an increased risk of depression in new moms. “We know men get postpartum depression, and we know testosterone drops in new dads, but we don’t know why,” said Darby Saxbe, a professor of psychology at U.S.C. and an author of the new report. “It’s often been suggested hormones underlie some of the postpartum depression in moms, but there’s been so much less attention paid to fathers. We were trying to put together the pieces to solve this puzzle.” © 2017 The New York Times Company

Keyword: Depression; Sexual Behavior
Link ID: 24203 - Posted: 10.17.2017

By John Horgan To help my students appreciate how science reflects cultural prejudices, I often cite examples from psychiatry. The Diagnostic and Statistical Manual of Mental Disorders, or DSM, which the American Psychiatric Association compiles as a guide to diagnosis and treatment of illness, listed homosexuality as a "sociopathic personality disturbance” in the DSM-I, published in 1952, and as a “sexual deviation” in the DSM-II, published in 1968 (see Further Reading). Homosexuality has been treated with lobotomies, chemical castration, electrical shocks and nausea-inducing drugs as well as psychotherapy. I then tell my students about a bizarre gay-conversion experiment carried out in 1970 by a leading brain-implant researcher, Dr. Robert G. Heath of Tulane University in New Orleans. I mentioned Heath in my recent profile of Jose Delgado, a pioneer in the use of brain implants to manipulate patients’ minds and behavior. Heath was arguably even more ambitious than Delgado in his experiments, and he was not a fringe figure. He had degrees in psychiatry and neurology from Columbia and the University of Pennsylvania. n 1949 he founded Tulane’s department of psychiatry and neurology. He oversaw the department until 1980 but continued working into the 1990s. In his 1996 book Exploring the Mind-Brain Relationship, he reviews his career and speculates that someday “biological methods” might make it possible “for man to live in harmony with his fellow man.” © 2017 Scientific American,

Keyword: Sexual Behavior
Link ID: 24198 - Posted: 10.16.2017

Jo Marchant Male scientists are more likely to share their published work than are women — but only with other men, a study of hundreds of researchers has found. Humans are generally considered to be a highly cooperative species, says Jorg Massen, a cognitive biologist at the University of Vienna. But most of the evidence for that assumption comes from artificial situations such as computerized cooperation tasks. “I wanted to test human prosociality in an everyday situation,” he says. So he chose one of the most competitive situations he could think of: his own field of research psychology. To investigate cooperation among psychologists, Massen turned his fellow researchers into guinea pigs. He and his colleagues e-mailed nearly 300 researchers and asked them to share either a PDF of one of their latest papers, or some raw data (pretending that they wanted to include it in a meta-analysis). The results were published in Scientific Reports on 10 October1. In general, the scientists contacted were highly cooperative, with almost 80% willing to share a PDF and almost 60% willing to send raw data. “I was surprised,” says Massen. “Humans are prosocial even in this competitive field.” Even more unexpected, however, was a strong gender difference in how the scientists responded to the request for help. Massen and his colleagues had wondered whether men might respond more favourably to women, or vice versa. In fact, men were more likely to share, but only with other men. A male–male request was 15% more likely to be granted than any other gender combination. © 2017 Macmillan Publishers Limited,

Keyword: Sexual Behavior; Aggression
Link ID: 24188 - Posted: 10.13.2017

By Helen Thomson The most detailed study yet of orgasm brain activity has discovered why climaxing makes women feel less pain and shown that ‘switching off’ isn’t necessary. It’s not easy to study the brain during orgasm. “A brain scanner like fMRI is the least sexy place in the world,” says Nan Wise at Rutgers University in Newark, New Jersey. “It’s noisy, claustrophobic and cold.” There is also the problem of keeping your head still – movement of little more than the width of a pound coin can render data useless. Despite these hurdles, Wise and her colleagues recruited 10 heterosexual women to lay in a fMRI scanner and stimulate themselves to orgasm. They then repeated the experiment but had their partners stimulate them. Wise’s custom-fitted head stabiliser allowed the team to follow brain activity in 20 second intervals to see what happens just before, during, and after an orgasm. Pain relief Back in 1985, Wise’s colleagues Beverly Whipple and Barry Komisaruk, both at Rutgers, discovered that, during self-stimulation and orgasm, women are less likely to notice painful squeezing of a finger, and can tolerate more of this pain. They found that women’s ability to withstand pain increased by 75 per cent during stimulation, while the level of squeezing at which women noticed the pain more than doubled. Now Wise’s team has explained why. At the point of orgasm, the dorsal raphe nucleus area of the brain becomes more active. This region plays a role in controlling the release of the brain chemical serotonin, which can act as an analgesic, dampening the sensation of pain. © Copyright New Scientist Ltd.

Keyword: Sexual Behavior; Attention
Link ID: 24187 - Posted: 10.13.2017

Dean Burnett Another day, another powerful man embroiled in a sinister sexual scandal decades in the making. This time it’s powerful Hollywood figure Harvey Weinstein. The moral, ethical and political aspects of this whole mess have been covered extensively elsewhere, and will no doubt continue to be so over the coming days and weeks. However, recent reports suggest that Weinstein has checked himself into a European rehab clinic for sex addiction. This has been met with some not-inconsiderable cynicism, but, even if it is true, wondering whether Weinstein is a sex addict overlooks a more fundamental question: is anyone a sex addict? Because that diagnosis, as commonplace as it may seem, is far from established psychiatric fact. Many people do believe sex addiction is real and serious problem, while others dismiss it outright. Despite it being a widely-used term, it doesn’t feature in either the DSM-V or ICD-10, the two main sources for officially-recognised psychiatric disorders the world over (although that’s not a guarantee of consensus either). How can something that seems, to many, to be so straightforward be the subject of so wide a debate? We all know what sex is, we all know what addiction is, what’s the issue? First, sex is a fundamental drive inherent in practically every human. A large percentage of our brain’s systems are responsible for or at least involved in it. An underlying need to seek out sex and an ability to engage in it as and when we like is a remarkably human trait (well, maybe bonobos too). This has many significant consequences for how our societies and cultures work, but one relevant problem is, at what point do you want sex too much? Because that’s not an easy thing to pin down. Those who don’t support the idea of sex addiction often argue that it’s another attempt to pin a clinical diagnosis on “normal” human behaviour (like the dispute around grief in the DSM-V). Some even compare it to gay conversion therapy, in how it medicalises and tries to undo what is an expression of human sexuality. © 2017 Guardian News and Media Limited

Keyword: Sexual Behavior; Drug Abuse
Link ID: 24185 - Posted: 10.12.2017

By Sara Van Note On a recent Saturday morning, two-year-old Ryleigh and five-year-old Colton Arnett play with brightly colored play dough in the family room of their Albuquerque home. Colton narrates his creations with a gap-toothed smile. “I’m going to use a mold. I’m going to make a boat.” Ryleigh echoes him enthusiastically, “Mold! Boat!” An estimated 30,000 New Mexicans carry the mutation, and the numbers are increasing. Their mother, Lori Dunworth, remarks that Colton and his sister don’t usually play so well together. “Usually she’s a bit of a bully when it comes to toys.” Both Ryleigh and Colton receive speech therapy because of something that happened to Colton several years ago, when Dunworth and her husband, Toby Arnett, first noticed that Colton, who was two at the time, was making repeating clicking sounds while his face twitched on one side. After one episode lasted over 20 minutes, they called their doctor, who told them to take him to the hospital immediately. Colton had suffered a seizure, and scans would later reveal masses in his brain — lesions, it turned out, caused by abnormal blood vessels. “The original impact was devastating,” Arnett says. Colton was ultimately diagnosed with Cerebral Cavernous Malformations (CCM), a rare disease that can cause seizure, stroke, and death. He also tested positive for a genetic mutation that causes the disease, known as the Common Hispanic Mutation. Colton’s sister and his mom also have the mutation. Dunworth had no idea she was the carrier. “I’ve never had any symptoms, no seizures, no paralysis, no nothing,” she says. Copyright 2017 Undark

Keyword: Epilepsy; Genes & Behavior
Link ID: 24184 - Posted: 10.12.2017

Hannah Devlin Forget negotiations over who takes out the bin, new research suggests that the ideal home temperature is the vexed question most likely to split households down gender lines. A study found that one third of couples dispute this issue and that four in 10 women covertly turn up the heating behind their partner’s back. The research, which was sponsored by Corgi Homeplan, a company that installs and maintains boilers and thermostats, probably falls short of the rigours of peer-reviewed science. However, there is strong evidence to back up the idea that women are more sensitive to the cold. A 2015 study by Dutch scientists, for instance, found that women are comfortable at a temperature 2.5C warmer than men, typically between 24-25C. Men and women have roughly the same core body temperature, at over 37C; in fact, some studies have found the female core body temperature is slightly higher. However, our perception of temperature depends more on skin temperature, which, for women, tends to be lower. One study reported that the average temperature of women’s hands exposed to cold was nearly 3C degrees lower than that observed in men. The female hormone oestrogen contributes to this because it slightly thickens the blood, reducing the flow to capillaries that supply the body’s extremities. This means that, in women, blood flow to the tips of fingers and toes tends to shut off more readily when it is cold. Research has shown that women tend to feel colder around ovulation, when estrogen levels are high. © 2017 Guardian News and Media Limited

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 24181 - Posted: 10.12.2017

By Jessica Hamzelou For the first time, researchers have shown that being born by C-section can contribute to obesity in mice. This probably happens because the procedure disrupts a newborn’s microbiome. Until fairly recently, babies were thought to be born with sterile guts free from bacteria. But we now know that babies are born with a gutful of microbes, and that at least some of these come from a mother’s vaginal canal during birth. Babies born by C-section are thought to miss out on these bacteria, which could explain why their microbiomes look different. The ecosystem of microbes that live inside us has been implicated in a range of health issues, so this may explain why babies born by C-section are more likely to grow up overweight, and to develop allergies and asthma in later life. To test if C-sections really do lead to heavier babies, Maria Dominguez-Bello at New York University and her colleagues performed C-sections on 34 pregnant mice, and compared the resulting pups to 35 that were born vaginally. By the time the mice had grown into adults 15 weeks later, there were stark difference in body weight between the two groups. The mice born by C-section were, on average, 33 per cent heavier than those born vaginally. Females seemed particularly affected, says Dominguez-Bello. While the C-section males were around 20 per cent heavier than their vaginally-born counterparts, the females were 70 per cent heavier, she says. “We were very surprised to see this,” she says. “We have no idea why it’s happening.” © Copyright New Scientist Ltd.

Keyword: Obesity
Link ID: 24180 - Posted: 10.12.2017