Chapter 8. Hormones and Sex
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By Andy Coghlan Can tiny brains grown in a dish reveal the secrets of sociability? Balls of brain tissue generated from stem cells are enabling us to understand the underlying differences between people who struggle to be sociable and those who have difficulty reining themselves in. Alysson Muotri at the University of California, San Diego, and his team created the mini-brains by exposing stem cells taken from the pulp of children’s milk teeth to cocktails of growth factors that help them mature. Eventually, they can develop as many as six layers of cerebral cortex – the outer surface of the brain. This region is much more sophisticated in humans than in other animals, and houses important circuitry governing our most complex thoughts and behaviours, including socialising with others. Each mini-brain is approximately 5 millimetres across. “Though they’re not as well defined as they are in a real brain, they resemble what you find in an embryonic fetus,” says Muotri. To understand how brain development affects sociability, the team used donated cells from children with autism and Rett syndrome, both of which are associated with impaired communication skills. They also used cells from children with Williams syndrome, a condition characterised by a hyper-sociable nature. People with Williams syndrome can be unable to restrain themselves from talking to complete strangers. © Copyright Reed Business Information Ltd.
By Alice Klein Mothers hold their children more on the left and wild mammals seem to keep their young more on that so too, at least when fleeing predators. Now it seems many mammal babies prefer to approach their mother from one side too – and the explanation may lie in the contrasting talents of each half of the brain. In mammals, the brain’s right hemisphere is responsible for processing social cues and building relationships. It is also the half of the brain that receives signals from the left eye. Some researchers think this explains why human and ape mothers tend to cradle their babies on the left: it is so they can better monitor their facial expressions with their left eye. Now, Janeane Ingram at the University of Tasmania, Australia, and her colleagues have looked at whether animal infants also prefer to observe their mum from one side. The team studied 11 wild mammals from around the world: horses, reindeer, antelopes, oxen, sheep, walruses, three species of whale and two species of kangaroo. Whenever an infant approached its mother from behind, the researchers noted whether it positioned itself on its mum’s left or right side. They recorded almost 11,000 position choices for 175 infant-mother pairs. Infants of all species were more likely to position themselves so that their mother was on their left. This happened about three-quarters of the time. © Copyright Reed Business Information Ltd.
By Virginia Morell Japanese macaques and sika deer live comfortably together on Japan’s Yakushima Island: The deer eat fruit the monkeys drop from the trees, and the monkeys groom and sometimes hitch a ride on the deer. But a couple years ago, one of the macaques took this relationship to a new level. Unable to get a mate of his own kind, this low-ranking snow monkey used the deer’s back for his pleasure (as pictured, and also shown in this not-suitable-for-work video). He did not penetrate her, but did ejaculate, and the deer then licked her back clean, researchers report in the current issue of Primates. The monkey was later seen attempting to mount another deer, but she objected and threatened him. He also guarded his unlikely love interests, chasing away any other male monkeys who came near. Scientists have only reported one other case of sexual relations in the wild between unrelated species. That one involved male Antarctic fur seals coercing king penguins; once, after sating his lust, the seal ate the bird. In both cases, scientists suspect that the males were unable to acquire a mate of their own kind, and seasonal hormonal surges led them to seek love elsewhere. © 2017 American Association for the Advancement of Science.
Keyword: Sexual Behavior
Link ID: 23074 - Posted: 01.10.2017
By Ellen Hendriksen Pop quiz: what’s the first thing that comes to mind when I say “ADHD”? a. Getting distracted b. Ants-in-pants c. Elementary school boys d. Women and girls Most likely, you didn’t pick D. If that’s the case, you’re not alone. For most people, ADHD conjures a mental image of school-aged boys squirming at desks or bouncing off walls, not a picture of adults, girls, or especially adult women. Both scientists and society have long pinned ADHD on males, even though girls and women may be just as likely to suffer from this neurodevelopmental disorder. Back in 1987, the American Psychiatric Association stated that the male to female ratio for ADHD was 9 to 1. Twenty years later, however, an epidemiological study of almost 4,000 kids found the ratio was more like 1 to 1—half girls, half boys. © 2017 Scientific American
By Andy Coghlan Is the fabled “cuddle hormone” really a “warmone”? Oxytocin levels surge in troops of chimpanzees preparing for conflict with rival groups to defend or expand their territory. The finding is at odds with the prevailing image of oxytocin as something that helps strengthen bonds between parent and infant, or foster friendships. But given its capacity to strengthen loyalty, oxytocin could also be a warmonger hormone that helps chimps galvanise and cooperate against a common enemy. Catherine Crockford of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and her colleagues monitored two rival groups of chimpanzees in the Taï National Park in Ivory Coast, each containing five males and five females, for prolonged periods between October 2013 and May 2015. Thanks to trust built up between the team and the chimps, the team could safely track and video the groups – even during conflict, observing at close quarters what was happening. Crucially, the team was also able to pipette up fresh samples from soil when chimps urinated. The samples revealed that oxytocin levels surge in the mammals whenever the chimps on either side prepared for confrontation, or when either group took the risk of venturing near or into rival-held territories. These surges dwarfed the oxytocin levels seen during activities such as grooming, collaborative hunting for monkey prey or food sharing. © Copyright Reed Business Information Ltd.
By Kevin McCarthy There’s a dearth of safety data for melatonin, but there are a number of potential concerns, especially for children. “I think we just don’t know what the potential long-term effects are, particularly when you’re talking about young children,” said Dr. Judith Owens, director of the Center for Pediatric Sleep Disorders at Boston Children’s Hospital. “Parents really need to understand that there are potential risks.” The pineal gland in the brain ramps up production of the hormone melatonin in the evening, as light fades, to encourage sleep, and it turns down production in the early morning hours. Synthetic forms of the hormone are also sold as a dietary supplement; because melatonin is found in some foods, like barley, olives and walnuts, it is regulated as a nutritional supplement rather than a drug, as most other hormones are. In adults, studies have found melatonin to be effective for jet lag and some sleep disorders. It is also hugely popular as a sleep aid for children and can be useful for sleep disorders among those with attention-deficit disorders or autism, Dr. Owens said. “I rarely see a family come in with a child with insomnia who hasn’t tried melatonin,” she said. “I would say at least 75 percent of the time when they come in to see us” at the sleep clinic, “they’re either on melatonin or they’ve tried it in the past.” While short-term use of the hormone is generally considered safe, it can have side effects, including headaches, dizziness and daytime grogginess, which could pose a risk for drivers. Melatonin can also interfere with blood pressure, diabetes and blood thinning medications. © 2017 The New York Times Company
National Institutes of Health (NIH) researchers have discovered molecular mechanisms that may underlie a woman’s susceptibility to disabling irritability, sadness, and anxiety in the days leading up to her menstrual period. Such premenstrual dysphoric disorder (PMDD) affects 2 to 5 percent of women of reproductive age, whereas less severe premenstrual syndrome (PMS) is much more common. “We found dysregulated expression in a suspect gene complex which adds to evidence that PMDD is a disorder of cellular response to estrogen and progesterone,” explained Peter Schmidt, M.D. of the NIH’s National Institute of Mental Health, Behavioral Endocrinology Branch. “Learning more about the role of this gene complex holds hope for improved treatment of such prevalent reproductive endocrine-related mood disorders.” Schmidt, David Goldman, M.D., of the NIH’s National Institute on Alcohol Abuse and Alcoholism, and colleagues, report on their findings January 3, 2017 in the journal Molecular Psychiatry. “This is a big moment for women’s health, because it establishes that women with PMDD have an intrinsic difference in their molecular apparatus for response to sex hormones – not just emotional behaviors they should be able to voluntarily control,” said Goldman. By the late 1990s, the NIMH team had demonstrated (link is external) that women who regularly experience mood disorder symptoms just prior to their periods were abnormally sensitive to normal changes in sex hormones — even though their hormone levels were normal. But the cause remained a mystery.
By Alice Callahan Can psychiatric medications alter the mother-baby bond? I am having a baby in a month and am on an antidepressant, antipsychotic and mood stabilizer. I don't feel a natural instinct to mother or connect to my baby yet. Could it be because of my medications? It’s normal for expectant parents to worry if they don’t feel a strong connection to the baby right away. “Those kinds of mixed fears and anxieties are really common in most pregnancies, certainly first pregnancies,” said Dorothy Greenfeld, a licensed clinical social worker and professor of obstetrics and gynecology at Yale School of Medicine. Bonding is a process that takes time, and while it can begin in pregnancy, the relationship between parent and child mostly develops after birth. Psychiatric conditions, and the medicines used to treat them, can complicate the picture. Antidepressants, the most widely used class of psychiatric drugs, do not seem to interfere with a woman’s attachment to the fetus during pregnancy, as measured by the amount of time the mother spends thinking about and planning for the baby, a 2011 study in the Archives of Women’s Mental Health found. On the other hand, the study found that women with major depression in pregnancy had lower feelings of maternal-fetal attachment, and this sense of disconnection intensified with more severe symptoms of depression. “Depression can definitely affect a person’s ability to bond with their baby, to feel those feelings of attachment, which is why we encourage treatment so strongly,” said Dr. Amy Salisbury, the study leader and a professor of pediatrics and psychiatry at the Alpert Medical School at Brown University. “That’s more likely to interfere than the medication itself.” There is less research on the effects of other types of mental health medications on mother-baby bonding, but psychiatric medications can have side effects that might interfere with parenting. For example, a small percentage of people taking mood-stabilizing medications have feelings of apathy, and that could hinder the bonding process, said Dr. Salisbury. And some mental health medications, depending on dosage and combination, might make a person feel too sedated. But again, letting mental illness go untreated is likely far riskier for both the mother and the baby. © 2016 The New York Times Company
By Laura Beil, Justin Shamoun began to hate his body a few weeks into seventh grade. He was a year younger than his suburban Detroit classmates, having skipped a grade. Many of his peers were entering puberty, their bodies solidifying into sleek young men. Justin still had the doughy build of a boy. After gym class one day, someone told Justin he could probably run faster if he weren’t so fat. The remark crushed him. Ashamed, he started hiding his body under ever-baggier clothes and making excuses to skip P.E., the pool, anywhere required to expose bare skin. Finally, he decided to fix himself. He dove headlong into sports and cut back on food. Before long, he was tossing his lunch into the garbage and picking at his dinner. He ate just enough to blunt his hunger, until the time came when he ate barely at all. The thought that he had an eating disorder never occurred to him. Long considered an affliction of women, eating disorders — the most deadly of all mental illnesses — are increasingly affecting men. The National Eating Disorders Association predicts that 10 million American men alive today will be affected, but that number is only an estimate based on the limited research available. The official criteria for diagnosing eating disorders were updated to be more inclusive of men only in 2013. And last year, Australian researchers writing in the Journal of Eating Disorders noted that “the prevalence of extreme weight control behaviors, such as extreme dietary restriction and purging” may be increasing at a faster rate in men than women. © 2016 Scientific American
By Heather M. Snyder For more than 25 years, Mary Read was a successful nurse in Lititz, Pennsylvania. But in 2010, at the age of 50, she started having trouble with her memory and thinking, making it difficult for her to complete routine tasks and follow instructions at work. The problems worsened, bringing her career to an abrupt end. In 2011, her doctor conducted a comprehensive evaluation, including a cognitive assessment, and found that she was in the early stages of younger-onset Alzheimer’s, which affects hundreds of thousands of people under 65. A year earlier, Elizabeth Wolf faced another sort of upheaval. The 36-year-old community health program director was forced to abandon her own career, home and community in Vermont when both of her parents were diagnosed with Alzheimer’s three months apart. Wolf took the difficult decision to move back into her childhood home in Mount Laurel, New Jersey in order to become their primary caregiver. These stories are not unusual. Alzheimer’s dementia disproportionately affects women in a variety of ways. Compared with men, 2.5 times as many women as men provide 24-hour care for an affected relative. Nearly 19 percent of these wives, sisters and daughters have had to quit work to do so. In addition, women make up nearly two-thirds of the more than 5 million Americans living with Alzheimer’s today. According to the Alzheimer’s Association 2016 Alzheimer’s Disease Facts and Figures, an estimated 3.3 million women aged 65 and older in the United States have the disease. To put that number in perspective, a woman in her sixties is now about twice as likely to develop Alzheimer’s as breast cancer within her lifetime. © 2016 Scientific American
Morwenna Ferrier Is my face attractive? Don’t answer that. Not because I’m ducking out of this, but because you can’t. Attractiveness is subjective, perhaps the most subjective question of all; that we outsource the answer to Google (and we do, in our droves) is ironic since it depends on a bias that is impossible to unpack. Yet in searching the internet for an answer, it also reveals the question to be one of the great existential tensions of our time. Because, as we all know, being attractive is absolutely 100% the A-road to happiness. If you are Googling to rate your attractiveness, then you are probably working on the assumption that you aren’t. You’re also, possibly, more vulnerable and susceptible to being told that you aren’t. In short, you’re a sitting duck, someone who had a sore throat and who asked good old Dr Google for advice only to be told it was cancer. Still, it’s only in investigating precisely why Google is the last person you should ask – being a search engine therefore insentient – that you can start cobbling together an idea of what attractiveness really is. It’s worth starting with semantics. Beauty is not attractiveness and vice versa, though we commonly confuse the two. Beauty (arguably) has a template against which we intuit and against which we measure ourselves. It is hinged around genetics and a particular look associated with this politically correct (and largely western-governed) model. Darwin wouldn’t agree: “It is certainly not true that there is in the mind of man any universal standards of beauty with respect to the human body,” he said. But a lot has changed since his time. © 2016 Guardian News and Media Limited
Keyword: Sexual Behavior
Link ID: 23030 - Posted: 12.28.2016
By Laurence O’Dwyer Daniel Tammet correctly recited the first 22,514 digits of Pi over the course of five hours and nine minutes. Less well-known, but similarly impressive, is the ability of a Clark’s nutcracker (Nucifraga columbiana)—a bird commonly found along the western flanks of North America—to remember where it stores thousands of separate caches of food. Tammet, who has autism spectrum disorder, is a savant. Some researchers have proposed that Clark’s nutcrackers might also represent a type of autistic savant. However, the unique abilities of a person with an autism spectrum disorder and savant syndrome usually comes at the price of social deficits. Experts in animal cognition who have examined similar abilities in birds and other creatures maintain that nonhuman animals that exhibit savant-like behavior do not display any equivalent dysfunction. The prodigious memory of the Clark’s nutcracker seems to be accompanied by an enlarged hippocampus compared with related species of birds that have not developed caching abilities, but in all other respects the bird seems to function normally. The hippocampus is a brain structure that is crucial for memory formation. In other words, its hyper-performance in one domain does not appear to come at a cost in another. (Admittedly, it is difficult to determine whether Clark’s nutcrackers are socially competent birds.) The “gift at a price” idea stems in part from the left hemisphere dysfunction and right hemisphere compensation that is often associated with savant syndrome. © 1986-2016 The Scientist
Laura Sanders Pregnancy changes nearly everything about an expectant mother’s life. That includes her brain. Pregnancy selectively shrinks gray matter to make a mom’s brain more responsive to her baby, and those changes last for years, scientists report online December 19 in Nature Neuroscience. “This study, coupled with others, suggests that a women’s reproductive history can have long-lasting, possibly permanent changes to her brain health,” says neuroscientist Liisa Galea of the University of British Columbia in Vancouver, who was not involved in the study. Researchers performed detailed anatomy scans of the brains of 25 women who wanted to get pregnant with their first child. More scans were performed about two months after the women gave birth. Pregnancy left signatures so strong that researchers could predict whether women had been pregnant based on the changes in their brains. The women who had carried a child and given birth had less gray matter in certain regions of their brains compared with 20 women who had not been pregnant, 19 first-time fathers and 17 childless men. These changes were still evident two years after pregnancy. A shrinking brain sounds bad, but “reductions in gray matter are not necessarily a bad thing,” says study coauthor Elseline Hoekzema, a neuroscientist at Leiden University in the Netherlands. A similar reduction happens during adolescence, a refinement that is “essential for a normal cognitive and emotional development,” says Hoekzema, who, along with colleagues, did most of the work at Universitat Autònoma de Barcelona. Following those important teenage years, pregnancy could be thought of almost as a second stage of brain maturing, she says. |© Society for Science & the Public 2000 - 2016.
By Sarah DeWeerdt, Toddlers with autism are oblivious to the social information in the eyes, but don’t actively avoid meeting another person’s gaze, according to a new study. The findings support one side of a long-standing debate: Do children with autism tend not to look others in the eye because they are uninterested or because they find eye contact unpleasant? “This question about why do we see reduced eye contact in autism has been around for a long time,” says study leader Warren Jones, director of research at the Marcus Autism Center in Atlanta, Georgia. “It’s important for how we understand autism, and it’s important for how we treat autism.” If children with autism dislike making eye contact, treatments could incorporate ways to alleviate the discomfort. But if eye contact is merely unimportant to the children, parents and therapists could help them understand why it is important in typical social interactions. The work also has implications for whether scientists who study eye contact should focus on social brain regions rather than those involved in fear and anxiety. Lack of eye contact is among the earliest signs of autism, and its assessment is part of autism screening and diagnostic tools. Yet researchers have long debated the underlying mechanism. The lack-of-interest hypothesis is consistent with the social motivation theory, which holds that a broad disinterest in social information underlies autism features. On the other hand, anecdotal reports from people with autism suggest that they find eye contact unpleasant. Studies that track eye movements as people view faces have provided support for both hypotheses. © 2016 Scientific American
Link ID: 22994 - Posted: 12.17.2016
The important role vitamin D plays in early life is back in the spotlight after Australian researchers noticed a link between a deficiency during pregnancy and autism. The study found pregnant women with low vitamin D levels at 20 weeks’ gestation were more likely to have a child with autistic traits by the age of six. The finding has led to calls for the widespread use of vitamin D supplements during pregnancy, just as taking folate has reduced the incidence of spina bifida in the community. “This study provides further evidence that low vitamin D is associated with neurodevelopmental disorders,” said Professor John McGrath from the University of Queensland’s Brain Institute, who led the research alongside Dr Henning Tiemeier from the Erasmus Medical Centre in the Netherlands. McGrath said supplements might reduce the incidence of autism, a lifelong developmental condition that affects, among other things, how an individual relates to their environment and other people. “We would not recommend more sun exposure, because of the increased risk of skin cancer in countries like Australia,” he said. “Instead, it’s feasible that a safe, inexpensive, and publicly accessible vitamin D supplement in at-risk groups may reduce the prevalence of this risk factor.” Vitamin D usually comes from exposure to the sun, but it can also be found in some foods and supplements. While it’s widely known vitamin D is vital for maintaining healthy bones, there’s also a solid body of evidence linking it to brain growth. © 2016 Guardian News and Media Limited
Link ID: 22988 - Posted: 12.14.2016
By Claire Asher We pride ourselves on our big brains, but when it comes to figuring out whether people or other animals with particularly big brains do better than others, the evidence has been lacking. Now, for the first time, a study in red deer is showing that bigger brained mammals tend to be more successful in the wild, and that brain size is a heritable trait that they can pass on to their offspring. Corina Logan from the University of Cambridge and her team have looked at the skulls of 1314 red deer (Cervus elaphus) from the Isle of Rum. The complete life histories of the deer are well known thanks to the Isle of Rum Red Deer Project, which has been collecting data on the island for more than 40 years, spanning seven deer generations. “This kind of study has not been conducted before because it requires long-term data from a large number of individuals,” says Logan. Heritable heads The team found that the ratio of skull volume to body size was highly heritable, explaining 63 per cent of variation between individuals. Female deer with larger skulls lived significantly longer and raised more offspring to adulthood, though it’s not clear yet why bigger brains are advantageous to females. © Copyright Reed Business Information Ltd.
By Sam Wong Size matters. Bigger genitals mean more mating success for male mosquito fish, a relative of the guppy. But the development of longer male organs prompts females to evolve bigger brains to help them escape overeager mates. Mating among mosquito fish is far from romantic. The male makes no effort to court partners, instead sneaking up and attempting to copulate by force up to a thousand times a day. It uses a modified anal fin, the gonopodium, to deliver sperm into the female. In this sort of mating system, the relationship between males and females can resemble that between predators and prey, which commonly involve an evolutionary arms race where adaptations on one side are closely matched by changes on the other. For example, big-brained predators tend to prey on big-brained prey, as the two try to outsmart each other. Séverine Buechel and colleagues at Stockholm University in Sweden wondered if a similar arms race was going on between male and female mosquito fish. Do females evolve bigger brains to defend against sneaky males, and do males evolve bigger brains in response? To test this, the team looked at what happened to brain size when males were bred to have longer gonopodia. Male mosquito fish have long gonopodia compared with related species in which coercion is not the dominant mating strategy, and males with longer gonopodia tend to be more successful at mating. The researchers found that breeding more well-endowed males led to bigger-brained females. But there was no arms race: male brains didn’t get bigger at the same time. © Copyright Reed Business Information Ltd.
Barbara J. King Birdsong is music to human ears. It has inspired famous composers. For the rest of us, it may uplift the spirit and improve attention or simply be a source of delight, fun and learning. But have you ever wondered what birds themselves hear when they sing? After all, we know that other animals' perceptions don't always match ours. Anyone who lives with a dog has probably experienced their incredible acute hearing and smell. Psychologists Robert J. Dooling and Nora H. Prior think they've found an answer to that question — for, at least, some birds. In an article published online last month in the journal Animal Behaviour, they conclude that "there is an acoustic richness in bird vocalizations that is available to birds but likely out of reach for human listeners." Dooling and Prior explain that most scientific investigations of birdsong focus on things like pitch, tempo, complexity, structural organization and the presence of stereotypy. They instead focused on what's called temporal fine structure and its perception by zebra finches. Temporal fine structure, they write, "is generally defined as rapid variations in amplitude within the more slowly varying envelope of sound." Struggling to fully grasp that definition, I contacted Robert Dooling by email. In his response, he suggested that I think of temporal fine structure as "roughly the difference between voices when they are the same pitch and loudness." Temporal fine structure is akin, then, to timbre, sometimes defined as "tone color" or, in Dooling's words, the feature that's "left between two complex sounds when the pitch and level are equalized." © 2016 npr
By Clare Wilson Could a brain stimulation device change our sex drive? The first study of this approach suggests that people’s libido can be turned up or down, depending on the device’s setting. The study didn’t measure how much sex people had in real life, instead it measured participant’s sexual responsiveness. Unusually, this was done by fixing customised vibrators to people’s genitals and gauging how their brainwaves changed when they expected a stimulating buzz. “You want to see if they want what you’re offering,” says Nicole Prause at the University of California, Los Angeles. “This is a good model for sexual desire.” The technique involves transcranial magnetic stimulation (TMS), where a paddle held above the head uses a strong magnetic field to alter brain activity. It can be used to treat depression and migraines, and is being investigated for other uses, including preventing bed-wetting, and helping those with dyslexia. The part of the head targeted in this study – called the left dorsolateral prefrontal cortex, roughly above the left temple – is involved in the brain’s reward circuitry. © Copyright Reed Business Information Ltd.
Keyword: Sexual Behavior
Link ID: 22936 - Posted: 12.01.2016
Nancy Shute Getting the flu while pregnant doesn't appear to increase the child's risk of being diagnosed with autism later on, a study finds, and neither does getting a flu shot while pregnant. The study, published Tuesday in JAMA Pediatrics, tries to tease apart subtle questions of risk and risk avoidance. Some smaller, earlier studies have found an association between serious viral infections in pregnancy or maternal fever in pregnancy and increased autism risk. This much larger study finds no such ties, though the authors note that it shouldn't be the last word on the topic. This study examined the health records of 196,929 children who were born at Kaiser Permanente facilities in Northern California between 2000 and 2010. They found that 3,101 children, or 1.6 percent, had been diagnosed with autism through June 2015. The researchers then looked at the mothers' health records to see if they had been diagnosed with flu while pregnant and whether they'd gotten a flu shot. Less than 1 percent of women had the flu; about 23 percent got a flu shot while pregnant, a number that rose from 6 percent in 2000 to 58 percent in 2010. They found no correlation overall between having the flu while pregnant and increased autism risk in children. © 2016 npr