Chapter 8. Hormones and Sex
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By Julia Calderone As we sat in my car outside a silent movie theater in Los Angeles, my friend anxiously opened a plastic bag containing a white T-shirt she’d slept in for the past three nights. “Does it smell like me?” she asked nervously, gesturing the open end toward my face. I stuck my nose into the bag and inhaled. We were about to attend a pheromone-based speed dating party with the following rules: 1. Find a clean white T-shirt. 2. Sleep in only that shirt for three consecutive nights. 3. Bring the shirt to the party sealed in a bag. As we walked into the theater, coordinators assigned each of our bags a unique color-coded sticker (pink for female, blue for male), and tossed them into a pile. A pack of hipsters nursing PBRs sat in the wooden theater seats, slightly amused by the bizarre 70s Egyptian-themed silent porn projected onto the screen. In the courtyard, 20-somethings mingled by the outdoor bar. Did they think alcohol would make us okay with sniffing strangers’ dirty laundry? Mounds of bags sat on two long tables – beckoning our nostrils. We were instructed to sniff as many T-shirts of the sex we were attracted to, and select shirts that innately smelled the sexiest. I came across bag number 166, which shockingly smelled exactly like my grandmother’s house – a delightful mix of Christmas and chicken parmesan. The point was to trust our instincts, right? I went with it. © 2013 Scientific American
By Neuroskeptic This morning, the world woke up to the news that Scientists discover the difference between male and female brains Britain’s Independent today actually made that their front page. They went on to discuss “the hardwired difference that could explain why men are ‘better at map reading’”. The rest of the world’s media were no less excited. Well. I don’t have time to get into criticizing the media or decrying gender stereotypes, so let’s just stick to the science. The study in question, published in PNAS, is called Sex differences in the structural connectome of the human brain. The authors used diffusion tensor imaging (DTI) to estimate the integrity of the white matter tracts going in various directions at each point in the brain. In a large sample of 428 males and 521 females aged from 8 to 22, they report sex differences in the pattern of white matter connectivity. In general, the female brains were ‘more connected’ than the male, except in the cerebellum: here’s the plot for a summary measure, the Participation Coefficient. I have two issues with this: Head Motion. A perennial Neuroskeptic favorite, this one. A paper just last week showed convincingly that even modest amounts of head movement during the MRI scan causes changes in DTI. Various commentators on Twitter and elsewhere swiftly pointed out that it’s not implausible that men and women might move different amounts on average, so that might account for at least some of these results.
Ian Sample, science correspondent Scientists have drawn on nearly 1,000 brain scans to confirm what many had surely concluded long ago: that stark differences exist in the wiring of male and female brains. Maps of neural circuitry showed that on average women's brains were highly connected across the left and right hemispheres, in contrast to men's brains, where the connections were typically stronger between the front and back regions. Ragini Verma, a researcher at the University of Pennsylvania, said the greatest surprise was how much the findings supported old stereotypes, with men's brains apparently wired more for perception and co-ordinated actions, and women's for social skills and memory, making them better equipped for multitasking. "If you look at functional studies, the left of the brain is more for logical thinking, the right of the brain is for more intuitive thinking. So if there's a task that involves doing both of those things, it would seem that women are hardwired to do those better," Verma said. "Women are better at intuitive thinking. Women are better at remembering things. When you talk, women are more emotionally involved – they will listen more." She added: "I was surprised that it matched a lot of the stereotypes that we think we have in our heads. If I wanted to go to a chef or a hairstylist, they are mainly men." The findings come from one of the largest studies to look at how brains are wired in healthy males and females. The maps give scientists a more complete picture of what counts as normal for each sex at various ages. Armed with the maps, they hope to learn more about whether abnormalities in brain connectivity affect brain disorders such as schizophrenia and depression. © 2013 Guardian News and Media Limited
By PAM BELLUCK Scientists have been eager to see if oxytocin, which plays a role in emotional bonding, trust and many biological processes, can improve social behavior in people with autism. Some parents of children with autism have asked doctors to prescribe it, although it is not an approved treatment for autism, or have purchased lower-dose versions of the drug over the counter. Scientifically, the jury is out, and experts say parents should wait until more is known. Some studies suggest that oxytocin, sometimes called the “love hormone,” improves the ability to empathize and connect socially, and may decrease repetitive behaviors. Others find little or no impact, and some research suggests that it can promote clannish and competitive feelings, or exacerbate symptoms in people already oversensitive to social cues. Importantly, nobody knows if oxytocin is safe or desirable to use regularly or long term. Now, the first study of how oxytocin affects the brains of children with autism finds hints of promise — and also suggestions of what its limitations might be. On the promising side, the small study, published Monday in The Proceedings of the National Academy of Sciences, found that the hormone, given as an inhalant, generated increased activity in parts of the brain involved in social connection. This suggests not only that oxytocin can stimulate social brain areas, but also that in children with autism these brain regions are not irrevocably damaged but are plastic enough to be influenced. The limitations could include a finding that oxytocin prompted greater brain activity in children with the least severe autism. Some experts said that this could imply that oxytocin may work primarily in less-impaired people, but others said it might simply suggest that different doses are needed. © 2013 The New York Times Company
By PAUL BLOOM In 1780, Immanuel Kant wrote that “sexual love makes of the loved person an Object of appetite.” And after that appetite is sated? The loved one, Kant explained, “is cast aside as one casts away a lemon which has been sucked dry.” Many contemporary feminists agree that sexual desire, particularly when elicited by pornographic images, can lead to “objectification.” The objectifier (typically a man) thinks of the target of his desire (typically a woman) as a mere thing, lacking autonomy, individuality and subjective experience. This idea has some laboratory support. Studies have found that viewing people’s bodies, as opposed to their faces, makes us judge those people as less intelligent, less ambitious, less competent and less likable. One neuroimaging experiment found that, for men, viewing pictures of sexualized women induced lowered activity in brain regions associated with thinking about other people’s minds. The objectification thesis also sits well with another idea that many psychologists, including myself, have defended, which is that we are all common-sense dualists. Even if you are a staunch science-minded atheist, in everyday life you still think of people as immaterial conscious beings — we inhabit fleshy bodies, but we are not ourselves physical. To see someone as a body is in opposition to thinking of her as a mind, then, and hence a heightened focus on someone’s body tends to strip away her personhood. But this analysis is too simple. It’s not literally true that women in pornography are thought of as inanimate and unfeeling objects; if they were, then they would just as effectively be depicted as unconscious or unresponsive, as opposed to (as is more often the case) aroused and compliant. Also, as the philosophers Martha Nussbaum and Leslie Green have pointed out, being treated as an object isn’t necessarily a bad thing. Imagine that you are sitting outside on a sunny day, and you move behind someone so that she blocks the sun from your eyes. You have used her as an object, but it’s hard to see that you’ve done something wrong. © 2013 The New York Times Company
In the 1970s pop hit “Paradise by the Dashboard Light,” famed rocker Meat Loaf wails to his tired old lover: “[I]f I gotta spend another minute with you I don't think that I can really survive.” Turns out that interactions with the opposite sex really do control life span, at least if you’re an insect or a worm. Sexually frustrated fruit flies perish prematurely, a study has just found. And another experiment reveals that in nematodes—nearly microscopic roundworms—males kill members of the opposite sex by spurring what resembles premature aging. An animal’s environment shapes its longevity, sometimes in surprising ways. For example, placing lab animals on a meager diet that replicates food scarcity in the wild extends survival in many species. And, oddly enough, dulling nematodes’ and flies’ sense of smell or taste stretches their life span. An animal’s environment also includes the other members of its species that it interacts with, such as potential mates and rivals. Researchers have identified some impacts of these interactions on life span. For example, because a male fruit fly’s seminal fluid contains toxins, mating can be fatal for females. Now, Scott Pletcher, a geneticist at the University of Michigan, Ann Arbor, and colleagues have shown that sexually unsatisfied fruit flies give up the ghost faster that usual. The researchers played a dirty trick on some male fruit flies, housing them with other males that had been genetically altered to exude female pheromones, or scent molecules. Normal males woo these she-males but can’t mate with them. Pletcher and colleagues report online today in Science that the sexually thwarted males pined away. Their stored fat dwindled, their ability to endure stress declined, and their life span shrank by more than 10%. The researchers also measured a reduction in female flies’ longevity if they hobnobbed with macho females that released male pheromones. © 2013 American Association for the Advancement of Science.
Regina Nuzzo The gut may know better than the head whether a marriage will be smooth sailing or will hit the rocks after the honeymoon fades, according to research published today in Science1. Researchers have long known that new love can be blind, and that those in the midst of it can harbour positive illusions about their sweetheart and their future. Studies show that new couples rate their partner particularly generously, forgetting his or her bad qualities, and generally view their relationship as more likely to succeed than average2. But newlyweds are also under a lot of conscious pressure to be happy — or, at least, to think they are. Now a four-year study of 135 young couples has found that split-second, 'visceral' reactions about their partner are important, too. The results show that these automatic attitudes, which aren’t nearly as rosy as the more deliberate ones, can predict eventual changes in people’s marital happiness, perhaps even more so than the details that people consciously admit. The researchers, led by psychologist James McNulty of Florida State University in Tallahassee, tapped into these implicit attitudes by seeing how fast newlyweds could correctly classify positively and negatively themed words after being primed by a photo of their spouse for a fraction of a second. If seeing a blink-of-the-eye flash of a partner’s face conjures up immediate, positive gut-level associations, for example, the participant will be quicker to report that 'awesome' is a positive word and slower to report that 'awful' is a negative one. Researchers used the difference between these two reaction times as a measurement of a participant’s automatic reaction. © 2013 Nature Publishing Group
By RONI CARYN RABIN Women are more likely than men to die after a heart attack, and some researchers have suggested a reason: Doctors may be misdiagnosing women more often because their symptoms differ from those experienced by men. But a study published Monday indicates that too much has been made of gender differences in chest pain, the hallmark symptom of heart disease. Although the researchers found some distinctions, no pattern was clearly more characteristic of women or could be used to improve heart attack diagnosis in women, the authors concluded. “We should stop treating women differently at the emergency room when they present with chest pain and discomfort,” said Dr. Maria Rubini Gimenez, a cardiologist at University Hospital Basel and lead author of the new study, published in JAMA Internal Medicine. Instead, she said, all patients with acute chest pain must be evaluated for heart attack with appropriate diagnostics, including an electrocardiogram and blood tests. Roughly 80 percent of people who have chest pain and discomfort are suffering from indigestion, acid reflux or another relatively benign condition, said Dr. John G. Canto, director of the chest pain center at Lakeland Regional Medical Center in Lakeland, Fla., who has researched heart attack diagnosis. “The trick is, how do you figure out the 15 to 20 percent actually having a heart attack?” he said. The new research confirms “that there is a lot of overlap in symptoms between patients who are having a heart attack and those who aren’t, and there is a lot of overlap in symptoms between men and women.” The new study examined 2,475 patients, including 796 women, who reported to emergency rooms at nine hospitals in Switzerland, Spain and Italy complaining of acute chest pain between April 21, 2006, and Aug. 12, 2012. Copyright 2013 The New York Times Company
A whiff of oxytocin may help love not fade away. Researchers asked 20 unmarried men in multiyear relationships to rank the attractiveness of pictures of their partner, acquaintances, and strangers. When the men received a nasal spray of oxytocin—which is released by the body during sexual arousal—they rated their partners more highly but not the other women. MRI scans show that after an oxytocin dose, areas of the brain associated with rewards, which also drive drug addiction, were more active when the men saw pictures of their partner, the researchers report online today in the Proceedings of the National Academy of Sciences. The finding could help explain the biological roots of monogamy in humans: Being in a long-term relationship raises a person's oxytocin levels, which in turn increase the psychological reward of spending more time with that person. The cycle, the team concluded, could literally lead to an addiction to one’s lover. © 2013 American Association for the Advancement of Science
By MARY LOU JEPSEN IN my early 30s, for a few months, I altered my body chemistry and hormones so that I was closer to a man in his early 20s. I was blown away by how dramatically my thoughts changed. I was angry almost all the time, thought about sex constantly, and assumed I was the smartest person in the entire world. Over the years I had met guys rather like this. I was not experimenting with hormone levels out of idle curiosity or in some kind of quirky science experiment. I was on hormone treatments because I’d had a tumor removed along with part of my pituitary gland, which makes key hormones the body needs to function. This long journey may have started as early as 1978, when I was 13. I spent a summer in intensive care with an unknown disease. After that summer, I never thought I would live a long life. So I wanted to live, to do interesting, fascinating work in the limited time I thought I had left. I took on the math-intensive art form of holography, and in my early 20s traveled the world, living on university fellowships to pursue this esoteric craft. I didn’t date much, really — perhaps because I didn’t have many hormones, though I didn’t know that at the time. I worked as an artist, played in a band, met Andy Warhol, Christo, Lou Reed and David Byrne. I had fun. But the gravity of my illness grew in the 1990s. The growth that shut down my pituitary gland’s ability to produce hormones did so insidiously over many years. By my early 20s it was, I suspect in retrospect, causing misdiagnosis of symptoms that were most likely caused by lack of hormones like cortisol. No diagnosis was found, despite the efforts of many doctors. I was a doctoral student in electrical engineering at an Ivy League school, but was growing progressively worse. I routinely slept about 20 hours a day, lived with a constant blistering headache and frequent vomiting, and was periodically wheelchair-bound. Large sections of my skin cycled through a rainbow of colors and sores, half of my face wouldn’t move as if Novocain had been applied. I drooled. Worse: I felt stupid. I couldn’t subtract anymore. I couldn’t make a to-do list, let alone accomplish items on one. I recognized that I wasn’t capable of continuing in graduate school. Utterly defeated, I filled out the paperwork to drop out. © 2013 The New York Times Company
By NATASHA SINGER One afternoon a few months ago, a 45-year-old sales representative named Mike called “The Dr. Harry Fisch Show,” a weekly men’s health program on the Howard Stern channel on Sirius XM Radio, where no male medical or sexual issue goes unexplored. “I feel like a 70-year-old man in a 45-year-old body,” Mike, from Vancouver, British Columbia, told Dr. Fisch on the live broadcast. “I want to feel good. I don’t want to feel tired all day.” A regular listener, Mike had heard Dr. Fisch, a Park Avenue urologist and fertility specialist, talk about a phenomenon called “low testosterone” or “low T.” Dr. Fisch likes to say that a man’s testosterone level is “the dipstick” of his health; he regularly appears on programs like “CBS This Morning” to talk about the malaise that may coincide with low testosterone. He is also the medical expert featured on IsItLowT.com, an informational website sponsored by AbbVie, the drug maker behind AndroGel, the best-selling prescription testosterone gel. Like many men who have seen that site or commercials or online quizzes about “low T,” Mike suspected that diminished testosterone was the cause of his lethargy. And he hoped, as the marketing campaigns seem to suggest, that taking a prescription testosterone drug would make him feel more energetic. “I took your advice and I went and got my testosterone checked,” Mike told Dr. Fisch. Mike’s own physician, he related, told him that his testosterone “was a little low” and prescribed a testosterone medication. Mike also said he had diabetes and high blood pressure and was 40 pounds overweight. Dr. Fisch explained that conditions like obesity might be accompanied by decreased testosterone and energy, and he urged Mike to exercise more and to lose weight. But if Mike had trouble overhauling his diet and exercise habits, Dr. Fisch said, taking testosterone might give him the boost he needed to do so. “If it gives you more energy to exercise,” Dr. Fisch said of the testosterone drug, “I’m all for it.” © 2013 The New York Times Company
Erika Check Hayden Researchers have shown that just two genes from the Y chromosome — that genetic emblem of masculinity in most mammals — are all that is needed for a male mouse to conceive healthy offspring using assisted reproduction. The same team had previously reported1 that male mice missing only seven genes from their Y chromosomes could father healthy babies. The study brings researchers one step closer to creating mice that can be fathers without any contribution from the Y chromosome at all. The findings also have implications for human infertility, because the work suggests that the assisted-reproduction technique used in the mice might be safer for human use than is currently thought. “To me it is a further demonstration that there isn't much left on the poor old Y chromosome that is essential. Who needs a Y?” says Jennifer Marshall Graves, a geneticist at the La Trobe Institute of Molecular Science in Melbourne, Australia, who was not involved in the research. An embryo without a Y chromosome normally develops into a female, but biologists have long questioned whether the entire chromosome is necessary to produce a healthy male. A single gene from the Y chromosome, called Sry, is known to be sufficient to create an anatomically male mouse — albeit one that will be infertile because it will lack some of the genes involved in producing sperm — as researchers have shown by removing the Y chromosome and inserting Sry into other chromosomes. Why it takes two © 2013 Nature Publishing Group
Keyword: Sexual Behavior
Link ID: 18956 - Posted: 11.23.2013
By Rahul K. Parikh, The message showed up on my desk one day while I was seeing a patient. Its choppy shorthand read: “Admits to injecting testosterone. Now decreased libido. Call back to discuss.” The caller was a 15-year-old lacrosse player who hadn’t been part of my practice long. Like many boys in his age group, he rarely came to the office. When I responded to his message later that afternoon, the young man carried his end of the conversation with the typical terseness of a teenager. “Where did you get the steroids?” I asked. “On the Internet.” “How long did you use them?” “A few months.” “And what are you experiencing now?” He told me his nipples were sore and swollen. “I’ve been more tired and moody as well.” My patient was experiencing classic side effects of steroid use. About 6 percent of teenagers admit to using performance-enhancing drugs, according to a recent survey, though it’s easy to assume that that number is low. How many teens would admit to using such drugs, even anonymously to a researcher? And yet here was one teen, forced by the drug’s side effect, having to make an embarrassing confession to me and his family. (Details of this case have been altered to protect patient privacy.) Despite my patient’s fear, I was confident that a young, healthy teenager who briefly used steroids would bounce back, though it might take some time — and patience — for his symptoms to dissipate. When I explained this to my patient, he told me that he wanted his testosterone level tested, to make sure there wasn’t something more seriously wrong. I got the sense that he thought there was some way I could magically undo the harm he had caused himself. I paused and considered his request, which came across more like an order. © 1996-2013 The Washington Post
Female mice that compete in promiscuous environments have sexier smelling sons, research has found. Scientists in Utah, US, studied the pheromones produced in the urine of male mice. They found that those whose mothers competed for mates were more sexually attractive to females. But this success was short-lived: their life spans were shorter than mice with monogamous parents. Adam Nelson from the University of Utah completed the study alongside senior author Prof Wayne Potts. It is published in the journal Proceedings of the National Academy of Sciences. "Only recently have we started to understand that environmental conditions experienced by parents can influence the characteristics of their offspring. This study is one of the first to show this kind of 'epigenetic' process working in a way that increases the mating success of sons," said Prof Potts. Epigenetics is the study of how differences in a parent's environment can influence how its offspring's genes are expressed. The researchers studied domestic mice which are usually paired in a cage and therefore breed with only one partner. To reintroduce the social competition wild mice experience, lab mice were kept in "mouse barns" which were large enclosures divided by mesh to create territories. The mice were able to climb over the mesh to access nest boxes, feeding stations and drinking water. BBC © 2013
By JOHN TIERNEY How aggressive is the human female? When the anthropologist Sarah B. Hrdy surveyed the research literature three decades ago, she concluded that “the competitive component in the nature of women remains anecdotal, intuitively sensed, but not confirmed by science.” Science has come a long way since then, as Dr. Hrdy notes in her introduction to a recent issue of Philosophical Transactions of the Royal Society devoted entirely to the topic of female aggression. She credits the “stunning” amount of new evidence partly to better research techniques and partly to the entry of so many women into scientific fields once dominated by men. The existence of female competition may seem obvious to anyone who has been in a high-school cafeteria or a singles bar, but analyzing it has been difficult because it tends be more subtle and indirect (and a lot less violent) than the male variety. Now that researchers have been looking more closely, they say that this “intrasexual competition” is the most important factor explaining the pressures that young women feel to meet standards of sexual conduct and physical appearance. The old doubts about female competitiveness derived partly from an evolutionary analysis of the reproductive odds in ancient polygynous societies in which some men were left single because dominant males had multiple wives. So men had to compete to have a chance of reproducing, whereas virtually all women were assured of it. But even in those societies, women were not passive trophies for victorious males. They had their own incentives to compete with one another for more desirable partners and more resources for their children. And now that most people live in monogamous societies, most women face the same odds as men. In fact, they face tougher odds in some places, like the many college campuses with more women than men. © 2013 The New York Times Company
SAN DIEGO, CALIFORNIA—Compulsive gamblers aren’t necessarily greedier than the rest of us—their brains may just be wired to favor money over sex. That’s the conclusion of a study presented here today at the Society for Neuroscience conference. This tendency to prioritize money over more basic desires resembles other addictions like alcoholism, researchers say, and could point toward new therapies. Of the millions of people who gamble for fun or profit, about 1% to 2% qualify as pathological gamblers. They can't quit despite encountering serious negative consequences—going into debt, damaging relationships, and even smashing up slot machines and getting arrested when the habit gets out of control. This inability to stop even after sustained loss is one reason gambling recently became the first behavioral addiction to be recognized by psychiatry's most frequently used diagnostic manual, the DSM-5, says Guillaume Sescousse, a neuroscientist at the Radboud University Nijmegen in the Netherlands who led the new study. After all, he says, professional poker players can play for 10 hours a day and not be considered addicts—so long as they can stop when their luck runs out. Researchers have long hypothesized that the basis for gambling addiction might be hypersensitivity to the highs of winning money, caused by dysfunctional wiring in neural circuits that process reward. Studies have produced conflicting results, however, so Sescousse decided to investigate an alternative hypothesis. He wondered if instead of being overly sensitive to monetary reward, compulsive gamblers were less sensitive to other rewarding things, like alcohol and sex. © 2013 American Association for the Advancement of Science
Brian Owens The hordes of microbes that inhabit every nook and cranny of every animal are not just passive hitchhikers: they actively shape their hosts’ well-being and even behaviour. Now, researchers have found evidence that bacteria living in the scent glands of hyenas help to produce the smells that the animals use to identify group members and tell when females are ready to mate. Kevin Theis, a microbial ecologist at Michigan State University in East Lansing, had been studying hyena scent communication for several years when, after he gave a talk on the subject, someone asked him what part the bacteria might play. “I just said, ‘I don’t know’,” he says. He started investigating. He found that for 40 years, scientists had wondered whether smelly bacteria were involved in animals' chemical communication. But experiments to determine which bacteria were present had been inconclusive, because the microbes had to be grown in culture, which is not possible with all bacteria. However, next-generation genetic sequencing would enable Theis to identify the microbes in a sample without having to grow them in a dish. Using this technique, Theis and his colleagues last year published a study1 that identified more types of bacterium living in the hyenas’ scent glands than the 15 previous studies of mammal scent glands combined. In both spotted hyenas (Crocuta crocuta) and striped hyenas (Hyaena hyaena), most of the bacteria were of a kind that ferments nutrients exuded by the skin and produces odours. “The diversity of the bacteria is enough to potentially explain the origin of these signals,” says Theis. Now, they have found that the structure of the bacterial communities varied depending on the scent profiles of the sour, musky-smelling 'pastes' that the animals left on grass stalks to communicate with members of their clan. In addition, in the spotted hyenas, both the bacterial and scent profiles varied between males and females, and with the reproductive state of females — all attributes that hyenas are known to be able to infer from scent pastes. The work is published this week in Proceedings of the National Academy of Sciences. © 2013 Nature Publishing Group
Anjan Chatterjee Before I realized what was happening, the patient reached down between my legs and grabbed my genitals. It was 1985, in the middle of the night during my medicine internship. I was working about 110 hours a week. Every third night I was on call and felt lucky if I got a couple of hours of sleep. That night, I was taking care of this patient for another intern. On my endless “to do” list was the task of placing an intravenous line. When I got to her room it was dark. I didn’t know what her medical condition was. I was focused on starting her IV and then moving on to my next task. I turned on the soft light over her hospital bed and gently woke her. She seemed calm. I loosened her restrained arm to look for a good vein. That was when she grabbed me. Even in my sleep-, food-, and sex-deprived state, I recognized that my charms were not the reason for her attention. She acted indiscriminately. She grabbed nurse’s breasts and students’ buttocks with the same enthusiasm. I had not yet started my neurology residency and did not know that she was suffering from a human version of Klüver-Bucy syndrome. The syndrome is named after Heinrich Klüver, a psychologist, and Paul Bucy, a neurosurgeon, who observed that rhesus monkeys changed profoundly when their anterior-medial temporal lobes were removed. They became placid. They were no longer fearful of objects they would normally avoid. They became “hyper-oral,” meaning they would put anything and everything in their mouth. They also became hypersexual. A similar syndrome occurs in humans. The patient I encountered that night had an infection affecting parts of her brain analogous to those parts in monkeys that Paul Bucy removed. All the cultural and neural machinery that puts a check on such behavior was dissolved by her infection. She displayed sexual desire, the deep-rooted instinct that ensures the survival of our species, in its most uninhibited form. © 2013 Salon Media Group, Inc.
Keyword: Sexual Behavior
Link ID: 18904 - Posted: 11.10.2013
Where, exactly, does the sand flea have sex? On the dusty ground, where it spends the first half of its life? Or already nestled snugly in its host—such as in a human foot—where it can suck the blood it needs to nourish its eggs? The answer to this question, which has long puzzled entomologists and tropical health experts, seems to be the latter. A new study, in which a researcher let a sand flea grow inside her skin, concludes that the parasites most likely copulate when the females are already inside their hosts. Tunga penetrans, also known as the chigger flea, sand flea, chigoe, jigger, nigua, pique, or bicho de pé, is widespread in the Caribbean, South America, and sub-Saharan Africa. The immature female burrows permanently into the skin of a warm-blooded host—it also attacks dogs, rats, cattle, and other mammals—where over 2 weeks it swells up to many times its original size, reaching a diameter of up to 10 mm. Through a small opening at the end of its abdominal cone, the insect breathes, defecates, and expels eggs. The female usually dies after 4 to 6 weeks, still embedded in the skin. Native to the Caribbean, sand fleas infected crewmen sailing with Columbus on the Santa Maria after they were shipwrecked on Haiti. They and others brought the parasite back to the Old World, where it eventually became endemic across sub-Saharan Africa. Even today it is an occasional stowaway, showing up in European and North American travel clinics in the feet of tourists who have gone barefoot on tropical beaches. For people living in infested regions, however, the flea is a serious public health issue. What starts as a pale circle in the skin turns red and then black, becoming painful, itchy—and often infected, a condition called tungiasis. One flea seems to attract others, and people can be infested with dozens at once. © 2013 American Association for the Advancement of Science
By Brian Switek I’m going to ruin sea otters for you. Or at least I’m going to tarnish their reputation as some of the most charming little beasties in the seas. For as cute as they are while intertwining paws at an aquarium, frolicking among the wafting fronds of California kelp forests, or smashing sea urchins open with stones, some sea otters have developed the disturbing habit of humping and drowning baby seals. When I first heard about the behavior from a marine biologist friend of mine, I didn’t quite believe sea otters could be so diabolical. Maybe the bad behavior was just a rumor. But no, the strange sea otter attacks on baby seals are a reality and have even made their way into the technical literature. In 2010, California Department of Fish and Game biologist Heather Harris and colleagues reported 19 individual cases of male sea otters trying to mate with, and often fatally injuring, harbor seal pups in the Monterey Bay, Calif. area between 2000 and 2002 alone. Delivered in the scientific deadpan required of such papers, the Aquatic Mammals report attributes the incidents to three male sea otters “observed harassing, dragging, guarding, and copulating with harbor seals,” persisting for up to seven days after the otters killed the objects of their misguided advances. The ordeal must have been horrific for the seals. The victims that were necropsied by veterinarians had lesions around the nose, eyes, flippers, and genitals, including perforations in the vaginal and rectal tracts. A painful and confusing end for the poor pups. © 2013 The Slate Group, LLC.