Chapter 8. Hormones and Sex
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
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
Carrie Arnold There was one sound that biologist Rusty Gonser always heard at Cranberry Lake — and there was one sound that he would never hear again. Every summer for more than 25 years, Gonser and his wife, Elaina Tuttle, had made the trip to this field station in the Adirondack Mountains — a 45-minute boat ride from the nearest road. Now, as he moored his boat to the shaky wooden dock, he heard a familiar and short song that sounded like 'oh-sweet-Canada'. The whistle was from a white-throated sparrow calling hopefully for a mate. What he didn't hear was the voice or laughter of his wife. For the first time, Gonser was at Cranberry Lake alone. Just a few weeks earlier, Tuttle had died of breast cancer. Her entire career, and most of Gonser's, had been devoted to understanding every aspect of the biology of the white-throated sparrow (Zonotrichia albicollis). Less than six months before she died this year at the age of 52, the couple and their team published a paper1 that was the culmination of that work. It explained how a chance genetic mutation had put the species on an extraordinary evolutionary path. The mutation had flipped a large section of chromosome 2, leaving it unable to pair up with a partner and exchange genetic information. The more than 1,100 genes in the inversion were inherited together as part of a massive 'supergene' and eventually drove the evolution of two different 'morphs' — subtypes of the bird that are coloured differently, behave differently and mate only with the opposite morph. Tuttle and Gonser's leap was to show that this process is nearly identical to the early evolution of certain sex chromosomes, including the human X and Y. The researchers realized that they were effectively watching the bird evolve two sex chromosomes, on top of the two it already had. © 2016 Macmillan Publishers Limited,
By Usha Lee McFarling, There’s something wrong with the brain banks created to study the dangers of repeated trauma to the head: Almost all the brains donated so far belonged to men. It’s just one example of how the study of brain trauma in women lags behind—even though women get concussions at higher rates than men in many sports and may suffer more severe and persistent symptoms. “If concussion is the invisible injury, then females are the invisible population within that injury,” said Katherine Snedaker, a licensed clinical social worker from Norwalk, Conn., who founded the nonprofit PINK Concussions in 2013 to focus attention on the issue. Evidence is building that the response to traumatic injury is different enough in females that they might benefit from gender-specific treatment, as they do with cardiac disease. But the data to create such guidelines simply aren’t there. “It’s an incredible gap in our knowledge,” said Angela Colantonio, director of the Rehabilitation Science Institute at the University of Toronto. “It’s just not acceptable.” When Colantonio examined 200 studies on prognosis after mild traumatic brain injury, she found only 7 percent separated out women. And if female athletes are overlooked, other groups vulnerable to concussion—aging women, women in prison, and domestic abuse survivors—have been nearly entirely ignored. © 2016 Scientific American
By JAN HOFFMAN BOWLING GREEN, Ky. — Crosby J. Gardner has never had a girlfriend. Now 20 and living for the first time in a dorm here at Western Kentucky University, he has designed a fast-track experiment to find her. He ticks off the math. Two meals a day at the student dining hall, three courses per meal. Girls make up 57 percent of the 20,068 students. And so, he sums up, gray-blue eyes triumphant, if he sits at a table with at least four new girls for every course, he should be able to meet all 11,439 by graduation. “I’m Crosby Gardner!” he announces each time he descends upon a fresh group, trying out the social-skills script he had practiced in the university’s autism support program. “What is your name and what is your major?” The first generation of college students with an autism diagnosis is fanning out to campuses across the country. These growing numbers reflect the sharp rise in diagnosis rates since the 1990s, as well as the success of early-learning interventions and efforts to include these students in mainstream activities. But while these young adults have opportunities that could not have been imagined had they been born even a decade earlier, their success in college is still a long shot. Increasingly, schools are realizing that most of these students will not graduate without comprehensive support like the Kelly Autism Program at Western Kentucky. Similar programs have been taking root at nearly 40 colleges around the country, including large public institutions like Eastern Michigan University, California State University, Long Beach, the University of Connecticut and Rutgers. For decades, universities have provided academic safety nets to students with physical disabilities and learning challenges like dyslexia. But students on the autism spectrum need a web of support that is far more nuanced and complex. © 2016 The New York Times Company
Link ID: 22894 - Posted: 11.21.2016
Ramin Skibba Bats sing just as birds and humans do. But how they learn their melodies is a mystery — one that scientists will try to solve by sequencing the genomes of more than 1,000 bat species. The project, called Bat 1K, was announced on 14 November at the annual meeting of the Society for Neuroscience in San Diego, California. Its organizers also hope to learn more about the flying mammals’ ability to navigate in the dark through echolocation, their strong immune systems that can shrug off Ebola and their relatively long lifespans. “The genomes of all these other species, like birds and mice, are well-understood,” says Sonja Vernes, a neurogeneticist at the Max Planck Institute for Psycholinguistics in Nijmegen, Netherlands, and co-director of the project. “But we don’t know anything about bat genes yet.” Some bats show babbling behaviour, including barks, chatter, screeches, whistles and trills, says Mirjam Knörnschild, a behavioural ecologist at Free University Berlin, Germany. Young bats learn the songs and sounds from older male tutors. They use these sounds during courtship and mating, when they retrieve food and as they defend their territory against rivals. Scientists have studied the songs of only about 50 bat species so far, Knörnschild says, and they know much less about bat communication than about birds’. Four species of bats have so far been found to learn songs from each other, their fathers and other adult males, just as a child gradually learns how to speak from its parents1. © 2016 Macmillan Publishers Limited,
Laurence O'Dwyer Until as late as 2013 a joint (or comorbid) diagnosis of autism and attention deficit hyperactivity disorder (ADHD) was not permitted by the most influential psychiatric handbook, the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM is an essential tool in psychiatry as it allows clinicians and researchers to use a standard framework for classifying mental disorders. Health insurance companies and drug regulation agencies also use the DSM, so its definition of what does or doesn’t constitute a particular disorder can have far-reaching consequences. One of the reasons for the prohibition of a comorbid diagnosis of autism and ADHD was that the severity of autism placed it above ADHD in the diagnostic hierarchy, so the inattention that is normally present in autism did not seem to merit an additional diagnosis. Nevertheless, that was an odd state of affairs, as any clinician working in the field would be able to quote studies that point to anything from 30% to 80% of patients with autism also having ADHD. More problematic still is the fact that patients with both sets of symptoms may respond poorly to standard ADHD treatments or have increased side effects. The fifth edition of the DSM opened the way for a more detailed look at this overlap, and just a year after the new guidelines were adopted, a consortium (which I am a part of) at the Radboud University in Nijmegen (Netherlands) called NeuroIMAGE published a paper which showed that autistic traits in ADHD participants could be predicted by complex interactions between grey and white matter volumes in the brain. © 2016 Guardian News and Media Limited
By CHRIS BUCKLEY BEIJING — When Flappy McFlapperson and Skybomb Bolt sprang into the sky for their annual migration from wetlands near Beijing, nobody was sure where the two cuckoos were going. They and three other cuckoos had been tagged with sensors to follow them from northern China. But to where? “These birds are not known to be great fliers,” said Terry Townshend, a British amateur bird watcher living in the Chinese capital who helped organize the Beijing Cuckoo Project to track the birds. “Migration is incredibly perilous for birds, and many perish on these journeys.” The answer to the mystery — unfolding in passages recorded by satellite for more than five months — has been a humbling revelation even to many experts. The birds’ journeys have so far covered thousands of miles, across a total of a dozen countries and an ocean. The “common cuckoo,” as the species is called, turns out to be capable of exhilarating odysseys. “It’s impossible not to feel an emotional response,” said Chris Hewson, an ecologist with the British Trust for Ornithology in Thetford, England, who has helped run the tracking project. “There’s something special about feeling connected to one small bird flying across the ocean or desert.” But to follow a cuckoo, you must first seduce it. The common cuckoo is by reputation a cynical freeloader. Mothers outsource parenting by laying their eggs in the nests of smaller birds, and the birds live on grubs, caterpillars and similar soft morsels. British and Chinese bird groups decided to study two cuckoo subspecies found near Beijing, because their winter getaways were a puzzle. In an online poll for the project, nearly half the respondents guessed they went somewhere in Southeast Asia. © 2016 The New York Times Company
Very stressful events affect the brains of girls and boys in different ways, a Stanford University study suggests. A part of the brain linked to emotions and empathy, called the insula, was found to be particularly small in girls who had suffered trauma. But in traumatised boys, the insula was larger than usual. This could explain why girls are more likely than boys to develop post-traumatic stress disorder (PTSD), the researchers said. Their findings suggest that boys and girls could display contrasting symptoms after a particularly distressing or frightening event, and should be treated differently as a result. The research team, from Stanford University School of Medicine, said girls who develop PTSD may actually be suffering from a faster than normal ageing of one part of the insula - an area of the brain which processes feelings and pain. Image copyright Science Photo Library Image caption The insula, also known as the insular cortex, is linked to the body's experience of pain or emotional experiences of fear The insula, or insular cortex, is a diverse and complex area, located deep within the brain which has many connections. As well as processing emotions, it plays an important role in detecting cues from other parts of the body. The researchers scanned the brains of 59 children aged nine to 17 for their study, published in Depression and Anxiety. © 2016 BBC.
By Solomon Israel, A May-December romance brings benefits for young female gray jays mated to older males, according to new Canadian research. The paper, published this month in the journal Animal Behaviour, used almost four decades of data on a marked population of gray jays in Ontario's Algonquin Park to study how the birds adjust their reproductive habits in response to changes in temperature and other conditions. Gray jays, also known as Canada jays or whisky jacks, don't migrate south in the winter, instead living year-round in boreal forests across Canada and the northern U.S. They manage this feat of survival by caching food all over their large, permanent habitats, then retrieving it during the winter months. The small, fluffy birds take advantage of those winter supplies to nest much earlier than most other birds, laying eggs between late February and March. Gray jays don't migrate during the winter, instead relying on hidden caches of food to feed themselves and their offspring. (Dan Strickland) The researchers found that female gray jays that laid their eggs earlier in the season had the most reproductive success, with a higher survival rate for offspring. ©2016 CBC/Radio-Canada
By Michael-Paul Schallmo, Scott Murray, Most people do not associate autism with visual problems. It’s not obvious how atypical vision might be related to core features of autism such as social and language difficulties and repetitive behaviors. Yet examining how autism affects vision holds tremendous promise for understanding this condition at a neural level. Over the past 50 years, we have learned more about the visual parts of the brain than any other areas, and we have a solid understanding of how neural activity leads to visual perception in a typical brain. Differences in neuronal processing in autism are likely to be widespread, and may be similar across brain regions. So pinpointing these differences in visual areas might reveal important details about processing in brain regions related to social functioning and language, which are not as well understood. Studying vision in autism may also help connect studies of people to those of animal models. Working with animals allows neuroscientists to study neural processing at many different levels—from specific genes and single neurons to small neural networks and brain regions that control functions such as movement or hearing. But animals do not display the complexity and diversity in language and social functioning that people do. By contrast, visual brain processes are similar between people and animals. We can use our rich knowledge of how neurons in animals process visual information to bridge the gap between animals and people. We can also use it to test hypotheses about how autism alters neural functioning in the brain. © 2016 Scientific American
Heidi Ledford Teaching parents of children with autism how to interact more effectively with their offspring brings the children benefits that linger for years, according to the largest and longest-running study of autism interventions. The training targeted parents with 2–4-year-old children with autism. Six years after the adults completed the year-long course, their children showed better social communication and reduced repetitive behaviours, and fewer were considered to have “severe” autism as compared to a control group, according to results published on 25 October in The Lancet1. “This is not a cure,” says child psychiatrist Jonathan Green of the University of Manchester, and an investigator on the study. “But it does have a sustained and substantial reduction in severity and that’s important in families.” John Constantino, a child psychiatrist at Washington University in St. Louis, Missouri, says that the results are “monumentally important”, because there has been little evidence showing that interventions for autism at an early stage are effective — even though researchers already broadly endorse the idea. "It is a rare long-term randomized controlled trial in a field in which there exists almost no data of this kind," he says. But he adds that the magnitude of the improvement was a disappointment, and that there were signs that the effects of treatment were diminishing over time. And although the therapy benefited communication skills and decreased repetitive behaviours, it did not lessen childrens' anxiety — another key symptom of autism. “Perhaps most of all, this underscores how desperately important it is that we develop higher-impact interventions,” he says. © 2016 Macmillan Publishers Limited,
Susan Milius For widemouthed, musical midshipman fish, melatonin is not a sleep hormone — it’s a serenade starter. In breeding season, male plainfin midshipman fish (Porichthys notatus) spend their nights singing — if that’s the word for hours of sustained foghorn hums. Males dig trysting nests under rocks along much of North America’s Pacific coast, then await females drawn in by the crooning. New lab tests show that melatonin, familiar to humans as a possible sleep aid, is a serenade “go” signal, says behavioral neurobiologist Ni Feng of Yale University. From fish to folks, nighttime release of melatonin helps coordinate bodily timekeeping and orchestrate after-dark biology. The fish courtship chorus, however, is the first example of the hormone prompting a launch into song, according to Andrew Bass of Cornell University. And what remarkable vocalizing it is. The plainfin midshipman male creates a steady “mmm” by quick-twitching specialized muscles around its air-filled swim bladder up to 100 times per second in chilly water. A fish can extend a single hum for about two hours, Feng and Bass report October 10 in Current Biology. That same kind of super-fast muscle shakes rattle-snake tails and trills vocal structures in songbirds and bats. |© Society for Science & the Public 2000 - 2016
By Christian Jarrett It’s been said that men and women are so unlike each other, it’s as if they’re from different planets – a claim that continues to amuse and irritate. John Gray’s original mega-selling book Men are from Mars, Women are from Venus, first published in the early 1990s, has sold millions, spawning numerous parodies (such as Katherine Black and Finn Contini’s Women May Be from Venus, But Men are Really from Uranus) and even comedy stage shows, such as Men are from Mars, Women are from Venus, Live! currently playing off Broadway.) While our physical differences in size and anatomy are obvious, the question of psychological differences between the genders is a lot more complicated and controversial. There are issues around how to reliably measure the differences. And when psychologists find them, there are usually arguments over whether the causes are innate and biological, or social and cultural. Are men and women born different or does society shape them that way? These questions are particularly thorny when you consider our differences in personality. Most research suggests that men and women really do differ on some important traits. But are these differences the result of biology or cultural pressures? And just how meaningful are they in the real world? One possibility is that most differences are tiny in size but that combined they can have important consequences. One of the most influential studies in the field, published in 2001 by pioneering personality researchers Paul Costa, Robert McCrae and Antonio Terracciano, involved over 23,000 men and women from 26 cultures filling out personality questionnaires. © 2016 BBC.
Keyword: Sexual Behavior
Link ID: 22746 - Posted: 10.12.2016
By Andy Coghlan More men inevitably means more testosterone-fuelled violence, right? Wrong, according to a comprehensive analysis exploring how a surplus of men or women affect crime rates across the US. In areas where men outnumber women, there were lower rates of murders and assaults as well as fewer sex-related crimes, such as rapes, sex offences and prostitution. Conversely, higher rates of these crimes occurred in areas where there were more women than men. Ryan Schacht of the University of Utah in Salt Lake City and his colleagues analysed sex ratio data from all 3082 US counties, provided by the US Census Bureau in 2010. They compared this with crime data for the same year, issued by the US Federal Bureau of Investigation. They only included information about women and men of reproductive age. For all five types of offence analysed, rising proportions of men in a county correlated with fewer crimes– even when accounting for other potential contributing factors such as poverty. The results suggest that current policies aimed at defusing violence and crime by reducing the amount of men in male-dominated areas may backfire. According to Schacht, when women are in short supply, men must be more dutiful to win and retain a partner. With an abundance of women, men are spoilt for choice and adopt more promiscuous behaviour that brings them into conflict with other men, and more likely to commit sex-related offences. © Copyright Reed Business Information Ltd.
By NICHOLAS BAKALAR Hormonal contraceptives are associated with an increased risk for depression, a large study has found. Danish researchers studied more than a million women ages 15 to 34, tracking their contraceptive and antidepressant use from 2000 to 2013. The study excluded women who before 2000 had used antidepressants or had another psychiatric diagnosis. Over all, compared with nonusers, users of hormonal contraception had an 80 percent increased risk of depression. Some types of contraceptives carried even greater risk. Women who used progestin-only pills more than doubled their risk, for example, while those who used those who used the levonorgestrel IUD (brand name Mirena) tripled their risk. The risk persisted after adjusting for age, age of first intercourse, educational level and other factors. The study, in JAMA Psychiatry, also found that the risk was greater in adolescent girls, but this may be because adolescent girls are especially susceptible to depression. “Even though the risk of depression increases substantially with these drugs — an 80 percent increase is not trivial — most women who use them will not get depressed,” said the senior author, Dr. Oejvind Lidegaard, a clinical professor of obstetrics and gynecology at the University of Copenhagen. “Still, it is important that we tell women that there is this possibility. And there are effective nonhormonal methods of birth control.” © 2016 The New York Times Company
Susan Milius ORLANDO, Fla. — When sex chromosomes among common pill bugs go bad from disuse, borrowed bacterial DNA comes to the rescue. Certain pill bugs grow up female because of sex chromosomes cobbled together with genes that jumped from the bacteria. Genetic analysis traces this female-maker DNA to Wolbachia bacteria, Richard Cordaux, based at the University of Poitiers with France’s scientific research center CNRS, announced September 29 at the International Congress of Entomology. Various kinds of Wolbachia infect many arthropods, spreading from mother to offspring and often biasing their hosts’ sex ratios toward females (and thus creating even more female offspring). In the common pill bug (Armadillidium vulgare), Wolbachia can favor female development two ways. Just by bacterial infection without any gene transfer, bacteria passed down to eggs can make genetic males develop into functional females. Generations of Wolbachia infections determining sex let these pill bugs’ now-obsolete female-making genes degenerate. Which makes it very strange that certain populations of pill bugs with no current Wolbachia infection still produce abundant females. That’s where Cordaux and Poitier colleague Clément Gilbert have demonstrated a second way that Wolbachia makes lady pill bugs — by donating DNA directly to the pill bug genes. The researchers, who share an interest in sex determination, have built a case that Wolbachia inserted feminizing genes into pill bug chromosomes. The bacterial genes thus created a new sex chromosome. 5|© Society for Science & the Public 2000 - 2016
Keyword: Sexual Behavior
Link ID: 22717 - Posted: 10.02.2016
Mia Persson Dogs may look to humans for help in solving impossible tasks thanks to some genes previously linked to social disorders in people. Beagles with particular variants in a gene associated with autism were more likely to sidle up to and make physical contact with a human stranger, researchers report September 29 in Scientific Reports. That gene, SEZ6L, is one of five genes in a particular stretch of beagle DNA associated with sociability in the dogs, animal behaviorist Per Jensen and colleagues at Linköping University in Sweden say. Versions of four of those five genes have been linked to human social disorders such as autism, schizophrenia and aggression. “What we figure has been going on here is that there are genetic variants that tend to make dogs more sociable and these variants have been selected during domestication,” Jensen says. But other researchers say the results are preliminary and need to be confirmed by looking at other dog breeds. Previous genetic studies of dog domestication have not implicated these genes. But, says evolutionary geneticist Bridgett vonHoldt of Princeton University, genes that influence sociability are “not an unlikely target for domestication — as humans, we would be most interested in a protodog that was interested in spending time with humans.” |© Society for Science & the Public 2000 - 2016.