Chapter 8. Hormones and Sex
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By LAURIE EDWARDS TO the list of differences between men and women, we can add one more: the drug-dose gender gap. Doctors and researchers increasingly understand that there can be striking variations in the way men and women respond to drugs, many of which are tested almost exclusively on males. Early this year, for instance, the Food and Drug Administration announced that it was cutting in half the prescribed dose of Ambien for women, who remained drowsy for longer than men after taking the drug. Women have hormonal cycles, smaller organs, higher body fat composition — all of which are thought to play a role in how drugs affect our bodies. We also have basic differences in gene expression, which can make differences in the way we metabolize drugs. For example, men metabolize caffeine more quickly, while women metabolize certain antibiotics and anxiety medications more quickly. In some cases, drugs work less effectively depending on sex; women are less responsive to anesthesia and ibuprofen for instance. In other cases, women are at more risk for adverse — even lethal — side effects. These differences are particularly important for the millions of women living with chronic pain. An estimated 25 percent of Americans experience chronic pain, and a disproportionate number of them are women. A review published in the Journal of Pain in 2009 found that women faced a substantially greater risk of developing pain conditions. They are twice as likely to have multiple sclerosis, two to three times more likely to develop rheumatoid arthritis and four times more likely to have chronic fatigue syndrome than men. As a whole, autoimmune diseases, which often include debilitating pain, strike women three times more frequently than men. © 2013 The New York Times Company
Jennifer Raymond I have a bias against women in science. Please don't hold this against me. I am a woman scientist, mentor and advocate for women in science, and an associate dean in my school's Office of Diversity, with a budding field biologist as a daughter. Yet my performance on the Implicit Association Test (https://implicit.harvard.edu/implicit/demo), which measures unconscious associations between concepts, revealed that I have a tendency to associate men with science and career, and women with liberal arts and family. I didn't even need to wait for my score; I could feel that my responses were slower and that I made more mistakes when I had to group science words such as 'astronomy' with female words such as 'wife' rather than male words such as 'uncle'. The results from hundreds of thousands of people indicate that I am not an outlier — 70% of men and women across 34 countries view science as more male than female1. Gender bias is not just a problem in science. A host of studies shows that people tend to rate women as less competent than men across many domains, from musical abilities to leadership2, and that many individuals hold biases about competency on the basis of other irrelevant attributes, such as skin colour, body weight, religion, sexual orientation and parental status. Such biases have important consequences in the workplace. One study showed that mothers are 79% less likely to be hired and are offered US$11,000 less salary than women with no children3. By contrast, the same study shows that parenthood confers an advantage to men in the workplace. © 2013 Nature Publishing Group,
by Tim Wall Some feathered crooners may advertise their size to females by hitting the low notes. Ornithologists at the Max Planck Institute found that only bigger-bodied birds belt out the bass. The physical size of some birds may put a limit on the frequency of the birds’ songs, according to a study published in PLOS ONE. Since only a larger males hit lower notes, females may be able to use deeper voices as a reliable measure of a male’s size. Size matters to some songbird species, with females preferring larger males, so vocal limitations could affect some birds’ love lives. The songs of purple-crowned fairy-wrens, Malurus coronatus coronatus, hit a range of notes. However the study found that in some songs, larger body size related to lower-pitched singing ability. Further study will be needed to prove a relationship among body size, singing frequency and sexual success in fairy-wrens. The authors suggested that body size may be just one of many characteristics advertized by fairy-wrens songs. The authors also noted that low-frequency singing ability may have resulted from good health as the male fairy-wrens grew up. Better health may have allowed better development of singing structures in the birds’ anatomies. The same healthy conditions could have also resulted in larger size. So size and singing would be correlated, but not causally related. © 2013 Discovery Communications, LLC.
By Athena Andreadis Genes are subject to multiple layers of regulation. An early regulatory point is transcription. During this process, regulatory proteins bind to DNA regions (promoters and enhancers) that direct gene expression. These DNA/protein complexes attract the transcription apparatus, which docks next to the complex and proceeds linearly downstream, producing the heteronuclear (hn) RNA that is encoded by the gene linked to the promoter. The hnRNA is then spliced and either becomes structural/regulatory RNA or is translated into protein. Transcription factors are members of large clans that arose from ancestral genes that went through successive duplications and then diverged to fit specific niches. One such family of about fifty members is called FOX. Their DNA binding portion is shaped like a butterfly, which has given this particular motif the monikers of forkhead box or winged helix. The activities of the FOX proteins extend widely in time and region. One of the FOX family members is FOXP2, as notorious as Fox News – except for different reasons: FOXP2 has become entrenched in popular consciousness as “the language gene”. As is the case with all such folklore, there is some truth in this; but as is the case with everything in biology, reality is far more complex. FOXP2, the first gene found to “affect language” (more on this anon), was discovered in 2001 by several converging observations and techniques. The clincher was a large family (code name KE), some of whose members had severe articulation and grammatical deficits with no accompanying sensory or cognitive impairment. The inheritance is autosomal dominant: one copy of the mutated gene is sufficient to confer the trait. When the researchers definitively identified the FOXP2 gene, they found that the version of FOXP2 carried by the KE affected members has a single point mutation that alters an invariant residue in its forkhead domain, thereby influencing the protein’s binding to its DNA targets. © 2013 Scientific American
by Michael Balter Despite recent progress toward sexual equality, it's still a man's world in many ways. But numerous studies show that when it comes to language, girls start off with better skills than boys. Now, scientists studying a gene linked to the evolution of vocalizations and language have for the first time found clear sex differences in its activity in both rodents and humans, with the gene making more of its protein in girls. But some researchers caution against drawing too many conclusions about the gene's role in human and animal communication from this study. Back in 2001, the world of language research was rocked by the discovery that a gene called FOXP2 appeared to be essential for the production of speech. Researchers cautioned that FOXP2 is probably only one of many genes involved in human communication, but later discoveries seemed to underscore its importance. For example, the human version of the protein produced by the gene differs by two amino acids from that of chimpanzees, and seems to have undergone natural selection since the human and chimp lineages split between 5 million and 7 million years ago. (Neandertals were found to have the same version as Homo sapiens, fueling speculation that our evolutionary cousins also had language). In the years since, FOXP2 has been implicated in the vocalizations of other animals, including mice, singing birds, and even bats. During this same time period, a number of studies have confirmed past research suggesting that young girls learn language faster and earlier than boys, producing their first words and sentences sooner and accumulating larger vocabularies faster. But the reasons behind such findings are highly controversial because it is difficult to separate the effects of nature versus nurture, and the differences gradually disappear as children get older. © 2010 American Association for the Advancement of Science
By JANE E. BRODY The title of a recent report on smoking and health might well have paraphrased the popular ad campaign for Virginia Slims, introduced in 1968 by Philip Morris and aimed at young professional women: “You’ve come a long way, baby.” Today that slogan should include: “…toward a shorter life.” Ten years shorter, in fact. The new report is one of two rather shocking analyses of the hazards of smoking and the benefits of quitting published last month in The New England Journal of Medicine. The data show that “women who smoke like men die like men who smoke,” Dr. Steven A. Schroeder, a professor of health and health care at the University of California, San Francisco, wrote in an accompanying editorial. That was not always the case. Half a century ago, the risk of death from lung cancer among men who smoked was five times higher than that among women smokers. But by the first decade of this century, that risk had equalized: for both men and women who smoked, the risk of death from lung cancer was 25 times greater than for nonsmokers, Dr. Michael J. Thun of the American Cancer Society and his colleagues reported. Today, women who smoke are even more likely than men who smoke to die of lung cancer. According to a second study in the same journal, women smokers face a 17.8 times greater risk of dying of lung cancer than women who do not smoke; men who smoke are at 14.6 times greater risk to die of lung cancer than men who don’t. Women who smoke now face a risk of death from lung cancer that is 50 percent higher than the estimates reported in the 1980s, according to Dr. Prabhat Jha of the Center for Global Health Research in Toronto and his colleagues. After controlling for age, body weight, education level and alcohol use, the new analysis found something else: men and women who continue to smoke die on average 10 years sooner than those who never smoked. Copyright 2013 The New York Times Company
by Lizzie Wade When a male wasp decides it's time to settle down and start a family, he releases a chemical calling card in the form of pheromones, broadcasting his location, his availability, and, most importantly, his identity. Most other kinds of insects will either ignore his signal or be repelled by it, but female wasps of his own species will buzz over and get down to business. But how and why did different pheromone blends—and the species that prefer them—evolve in the first place? A new study offers a possible solution to this long-standing evolutionary mystery, suggesting that new sex pheromones may evolve through genetic mutation before potential mates develop the ability to detect them. Scientists have long been impressed by the perfect harmony of chemical communication among insects, especially when it comes to choosing mates by detecting and responding to the sex pheromones of only their own species. But scientists were puzzled by how such a delicate system evolved. If female wasps respond to only a specific blend of pheromones, males that produce even a subtly different blend shouldn't have much luck mating and passing on their mutant genes. It seemed that in order for males to evolve new pheromones, the female insects would need some preexisting adaptation that would cause them to prefer the new chemical blend. But how could they evolve a preference for something they had never encountered and should, logic suggests, find off-putting? In essence, the question is which came first, a new species or its sex pheromone? In order to answer this question, a team of researchers in Germany turned to the Nasonia vitripennis wasp, a species famous for its propensity to lay its parasitic eggs on doomed fly pupae. When the scientists analyzed the N. vitripennis male sex pheromone, they found it contained two important chemicals, which they call RS and RR. RS also turns up in the male sex pheromones of another species of wasp, N. giraulti, whereas RR appears to be unique. © 2010 American Association for the Advancement of Science.
By RAPHAEL SATTER, Associated Press LONDON (AP) — When it comes to mating, guppies treasure their ugly friends — because they look so good by comparison. An article published Wednesday by Britain's Royal Society says that male guppies prefer to associate with their drab-colored counterparts when females were around. "Males actively choose the social context that maximizes their relative attractiveness," the article said. Or, as lead author Clelia Gasparini put it, "If you are surrounded by ugly friends, you look better." Gasparini and her colleagues at Italy's University of Padua built their theory on a kind of guppy dating game. An aquarium was set up with one female in partition on either end. Guppy bachelorette No. 1 had two attractive, brightly-colored males placed on either side of her. Guppy bachelorette No. 2 was stuck with uglier, drab-colored fish. When a male guppy was put in the middle of the tank, and given the choice of which female to sidle up to, Bachelorette No. 2 was the more popular pick, with male guppies spending about 62 percent of their time hanging around her side of the aquarium. What's more, the researchers found that the time guppies spent with bachelorette No. 2 correlated with their unattractiveness. The uglier the guppy, the less likely it was that he would hang around the brightly colored fish placed next to bachelorette No. 1. © 2013 Hearst Communications Inc.
Keyword: Sexual Behavior
Link ID: 17798 - Posted: 02.13.2013
Matt Kaplan The astounding warning colours of the nudibranchs, a diverse group of sea slugs, are certainly enough to attract attention — but even they pale in comparison to the gripping news that one species of the soft-bodied molluscs has a habit of discarding its penis. Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time. This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter. This is a relatively standard arrangement among nudibranchs, so the creatures' sexual organs might all be expected to look roughly the same. But the animals show incredible sex-organ diversity, and it was during an exploration of this diversity in the species Chromodoris reticulata that researchers made their jaw-dropping discovery. A Japanese team led by Ayami Sekizawa at Osaka City University and Yasuhiro Nakashima at Nihon University in Tokyo went scuba diving off the coast of Okinawa to collect the sea slugs. They then placed the creatures in aquaria in pairs. In some cases both members of a pair had been isolated from others for 24 hours; in other cases a recently-mated animal was placed with one that had been in isolation. © 2013 Nature Publishing Group,
Keyword: Sexual Behavior
Link ID: 17797 - Posted: 02.13.2013
By Luciana Gravotta If cupid had studied neuroscience, he’d know to aim his arrows at the brain rather than the heart. Recent research suggests that for love to last, it’s best he dip those arrows in oxytocin. Although scientists have long known that this hormone is essential for monogamous rodents to stay true to their mates, and that it makes humans more trusting toward one another, they are now finding that it is also crucial to how we form and maintain romantic relationships. A handful of new studies show that oxytocin makes us more sympathetic, supportive and open with our feelings—all necessary for couples to celebrate not just one Valentine’s Day, but many. These findings have led some researchers to investigate whether oxytocin can be used in couple therapy. The first bit of evidence that points to oxytocin as nature’s love glue comes from researchers who measured the hormone in couples. Psychology professor Ruth Feldman at Bar-Ilan University in Israel, spent years studying oxytocin’s role in the mother–child bond and recently decided to dive into the uncharted waters of romantic bonds by comparing oxytocin levels in new lovers and singles. “The increase in oxytocin during the period of falling in love was the highest that we ever found,” she says of a study she and her colleagues published in Psychoneuroendocrinology. New lovers had double the amount Feldman usually sees in pregnant women. Oxytocin was also correlated with the longevity of a relationship. Couples with the highest levels were the ones still together six months later. They were also more attuned to each other than the low-oxytocin couples when Feldman asked them to talk about a shared positive experience. © 2013 Scientific American,
Nearly 400 years after William Shakespeare asked, "What is love?," brain imaging studies are allowing scientists to give at least a partial answer. As our calendars get closer to Feb. 14, a day when passion is deeply associated with the heart, love will in fact be in the mind. A recent study shows love is a complex emotion triggered by 12 specific areas of the brain — the network of love. Love is in the mind, not in the heart © 1996-2013 The Washington Post
By Laura Sanders Immune cells that help heal injuries in the adult brain may have a second job early in life, a study in mice reveals. The brain crusaders unexpectedly moonlight as sculptors, shaping a region of the brain into a male-specific form. The cells, called microglia, are mobile garbage disposals that travel around the brain and gobble up damaged cells and infectious agents. But the new study, published in the Feb. 13 Journal of Neuroscience, emphasizes that these cells have diverse functions, says neuroscientist Jean Harry of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., who was not involved in the work. Earlier results hinted that parts of the immune system have a role in building sex differences into the brain, so Kathryn Lenz and her colleagues at the University of Maryland, Baltimore decided to test whether microglia are pulling double duty. The team focused on the preoptic area of the mouse brain—“a place where you see a ton of sex differences,” Lenz says. Early in life, this brain area gets shaped by sex hormones including molecules called estradiol and prostaglandin E2, which work on the male mouse brain. In males, the preoptic area is larger, and the cells there have more elaborate shapes than in females. Scientists think those brain differences drive mating behaviors. Lenz and her colleagues found another difference in the preoptic area between males and females: Young males had about twice as many active microglia as females did. What’s more, a dose of estradiol or prostaglandin E2 in the first few days of life caused female animals to produce the male number of active microglia. © Society for Science & the Public 2000 - 2013
By Morgen Peck Co-sleeping, the practice of sharing a bed with your baby, has a controversial place in modern society. Proponents argue that it increases the parent-child bond, whereas detractors worry about safety. Now an anthropological study adds a new finding to the debate: fathers who sleep next to their babies tend to have significantly lower levels of testosterone than those who sleep in a different room. Lee Gettler, an anthropologist at the University of Notre Dame, compared Filipino men's testosterone levels before having a child and again four years later. Men who reported sleeping on the same surface as their child experienced a steep decline in nighttime testosterone levels not seen in men who slept in another room, according to the paper published in September 2012 in PLOS One. Studies on women have shown that mothers who sleep with their children pass in and out of sleep. The same disruptions in men could possibly decrease testosterone production, Gettler and his co-authors write. Previous work in the same population showed that fathers who fully throw themselves into caring for their children are more likely to have low testosterone, suggesting that hormonal fluctuations may support men in being good fathers. “Lower testosterone might orient men more toward the needs of the partner and children and away from risky behavior and competition with other males—which could conflict with investments in parenting,” Gettler says. © 2013 Scientific American
The offspring of promiscuous baboon males are more successful when they have contact with their father, scientists have found. A study by a team of European researchers has documented increased feeding success when foraging with adult male baboons. Paternity analyses allowed the scientists to determine whether the males were, in fact, the fathers. The findings are published in the journal Behavioural Ecology. Paternal care is uncommon in promiscuous mammals where it is not obvious which male actually is the father. Lead researcher, Dr Elise Huchard of the University of Cambridge's Department of Zoology, told BBC Nature: "Caring for offspring can be costly in terms of time and energy for the parents." She explained that parental care increases the chances of offspring survival, as well as improving an individual's survival and reproductive performance later on in life. "Paternal care is usually observed in species where paternity certainty is high, [such as] in monogamous species," according to Dr Huchard. So when research suggested that juveniles benefitted from paternal input in promiscuous baboon troops, Dr Huchard and colleagues decided to perform field research on two troops of chacma baboons (Papio ursinus) in Tsaobis Leopard Park, central Namibia. BBC © 2013
Keyword: Sexual Behavior
Link ID: 17731 - Posted: 01.29.2013
By RONI CARYN RABIN Most sleeping pills are designed to knock you out for eight hours. When the Food and Drug Administration was evaluating a new short-acting pill for people to take when they wake up in the middle of the night, agency scientists wanted to know how much of the drug would still be in users’ systems come morning. Blood tests uncovered a gender gap: Men metabolized the drug, Intermezzo, faster than women. Ultimately the F.D.A. approved a 3.5 milligram pill for men, and a 1.75 milligram pill for women. The active ingredient in Intermezzo, zolpidem, is used in many other sleeping aids, including Ambien. But it wasn’t until earlier this month that the F.D.A. reduced doses of Ambien for women by half. Sleeping pills are hardly the only medications that may have unexpected, even dangerous, effects in women. Studies have shown that women respond differently than men to many drugs, from aspirin to anesthesia. Researchers are only beginning to understand the scope of the issue, but many believe that as a result, women experience a disproportionate share of adverse, often more severe, side effects. “This is not just about Ambien — that’s just the tip of the iceberg,” said Dr. Janine Clayton, director for the Office of Research on Women’s Health at the National Institutes of Health. “There are a lot of sex differences for a lot of drugs, some of which are well known and some that are not well recognized.” Copyright 2013 The New York Times Company
Keyword: Sexual Behavior
Link ID: 17725 - Posted: 01.29.2013
By BENEDICT CAREY Susan Nolen-Hoeksema, a psychologist and writer whose work helped explain why women are twice as prone to depression as men and why such low moods can be so hard to shake, died on Jan. 2 in New Haven. She was 53. Her death followed heart surgery to correct a congenitally weak valve, said her husband, Richard Nolen-Hoeksema. Dr. Nolen-Hoeksema, a professor at Yale University, began studying depression in the 1980s, a time of great excitement in psychiatry and psychology. New drugs like Prozac were entering the market; novel talking therapies were proving effective, too, particularly cognitive behavior therapy, in which people learn to defuse upsetting thoughts by questioning their basis. Her studies, first in children and later in adults, exposed one of the most deceptively upsetting of these patterns: rumination, the natural instinct to dwell on the sources of problems rather than their possible solutions. Women were more prone to ruminate than men, the studies found, and in a landmark 1987 paper she argued that this difference accounted for the two-to-one ratio of depressed women to depressed men. She later linked rumination to a variety of mood and behavior problems, including anxiety, eating disorders and substance abuse. “The way I think she’d put it is that, when bad things happen, women brood — they’re cerebral, which can feed into the depression,” said Martin Seligman, a professor of psychology at the University of Pennsylvania, who oversaw her doctoral work. “Men are more inclined to act, to do something, plan, beat someone up, play basketball.” © 2013 The New York Times Company
By SABRINA TAVERNISE WASHINGTON — For two decades, millions of Americans have taken Ambien to help them sleep at night. But for years, the Food and Drug Administration has gotten complaints that people felt drowsy the morning after taking the medicine or its successors, and sometimes got into car accidents. On Thursday the agency said that women should be taking half as much, after laboratory studies and driving tests confirming the risks of drowsiness. The new recommendation applies to drugs containing the active ingredient zolpidem, by far the most widely used sleep aid. Using lower doses means less of the drug will remain in the blood in the morning hours, and will reduce the risk that people who use it will be impaired while driving. Sleeping pills have boomed in popularity with the increasingly frantic pace of modern American life. According to IMS, a health care information and technology company, about 60 million prescriptions were dispensed in 2011, up about 20 percent since 2006. About 40 million were for products containing zolpidem. The agency’s announcement was focused on women because they take longer to metabolize the drug than men. An estimated 10 percent to 15 percent of women will have a level of zolpidem in their blood that could impair driving eight hours after taking the pill, while only about 3 percent of men do, said Dr. Robert Temple, an official in the agency’s Center for Drug Evaluation and Research. © 2013 The New York Times Company
By Susan Milius Male European blackbirds monitored in a lab under simulated city lighting started secreting increased levels of testosterone and growing their sexual organs up to a month earlier in the spring than birds kept in country-style darkness, Davide Dominoni of the Max Planck Institute for Ornithology in Radolfzell, Germany, reported January 6 at the annual meeting of the Society for Integrative and Comparative Biology. Dominoni’s colleagues have found that, outside the lab, male blackbirds flying around Munich undergo this growth surge about three weeks earlier than counterparts in a forest just 40 kilometers out of town. Beginning in December 2010, the researchers exposed captive blackbirds to night light levels typical of urban settings. They estimated those levels by outfitting free-flying blackbirds with light-sensitive devices and averaging the urban light exposure. A winter of lab night light sped up the males’ molting and boosted testosterone levels as well as organ development in spring. Continuing the night light treatment through the next winter left the males reproductively shut down in the spring of 2012. The lab night lights probably kept the birds’ seasonal reproductive clocks from resetting at the end of the first breeding season, Dominoni says. That second-year suppression may not be common in the real world, where birds fly around and experience more variety in night lighting, he says. But he sees the lab breeding shutdown as a sign of how big of an impact artificial light might have. © Society for Science & the Public 2000 - 2013
by Carrie Arnold ‘Tis the season for twinkling lights, wrapping paper, and virgin birth. For billions of Christians around the world, the holidays are a time to celebrate Jesus’s birth to the Virgin Mary. But for many animals, virgin birth is far from a miraculous event. Researchers have discovered a growing number of species that reproduce without assistance from the opposite sex. Known formally as parthenogenesis, virgin birth occurs when an embryo develops from an unfertilized egg cell. The development of an embryo usually requires genetic material from sperm and egg, as well as a series of chemical changes sparked by fertilization. In some parthenogenetic species, egg cells don’t undergo meiosis, the typical halving of the cell’s chromosomes, before dividing into new cells. These offspring are generally all female and clones of their mother. Other forms of parthenogenesis occur when two egg cells fuse after meiosis. Biologists think that sexual reproduction evolved as a way to mix the gene pool and reduce the impact of harmful mutations. Still, parthenogenesis can be beneficial if the mother is particularly well adapted to her environment, since all of her offspring will be just as well adapted. © 2010 American Association for the Advancement of Science.
By Kate Clancy I tend to go to bed freezing, especially so in the winter, so I pile our flannel sheet, blanket, and down comforter over me when I settle in to sleep. A few times each menstrual cycle, clustered together in the luteal phase between ovulation and menses, I wake up from sleep completely soaked in my own sweat – not a delightful sight or experience. Usually I get up, change pajamas, and try to find a dry spot on the bed to go back to sleep (I promise the sheets eventually get washed, but I’m not about to wake my husband – and sometimes daughter – to change the bed at 3am). These night sweats started when I was still intensively breastfeeding my daughter and was marathon training, when she was under a year old. At first, I thought it was because we were co-sleeping and we slept next to each other. But I never experienced them next to my husband before that point, and he is a six foot four heat generating machine. When the marathon was over and I returned to less strenuous activity, breastfeeding frequency was also starting to decline. I didn’t get any night sweats again for quite some time. Then there was roller derby. At first, roller derby was a pastime, a recreational activity where I got to learn something totally new and hang out with women I respected. But of course, being the competitive person I am, it became an obsession, and in addition to roller derby practices I was working out quite a lot on my own time. Over the last year I’ve made additional nutritional adjustments to further improve my performance, and I’ve increased the intensity of my off-skates workouts. I work out a minimum of five hours a week, but in the middle of the season it is usually a minimum of nine hours per week. © 2012 Scientific American
Keyword: Hormones & Behavior
Link ID: 17609 - Posted: 12.17.2012