Chapter 8. Hormones and Sex
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By DANIEL BERGNER Linneah sat at a desk at the Center for Sexual Medicine at Sheppard Pratt in the suburbs of Baltimore and filled out a questionnaire. She read briskly, making swift checks beside her selected answers, and when she was finished, she handed the pages across the desk to Martina Miller, who gave her a round of pills. The pills were either a placebo or a new drug called Lybrido, created to stoke sexual desire in women. Checking her computer, Miller pointed out gently that Linneah hadn’t been doing her duty as a study participant. Over the past eight weeks, she took the tablets before she planned to have sex, and for every time she put a pill on her tongue, she was supposed to make an entry in her online diary about her level of lust. “I know, I know,” Linneah said. She is a 44-year-old part-time elementary-school teacher, and that day she wore red pants and a canary yellow scarf. (She asked that only a nickname be used to protect her privacy.) “It’s a mess. I keep forgetting.” Miller, a study coordinator, began a short interview, typing Linneah’s replies into a database that the medication’s Dutch inventor, Adriaan Tuiten, will present to the Food and Drug Administration this summer or fall as part of his campaign to win the agency’s approval and begin marketing what might become the first female-desire drug in America. “Thinking about your desire now,” Miller said, “would you say it is absent, very low, low, reasonable or present?” “Low.” This was no different from Linneah’s reply at the trial’s outset two months before. © 2013 The New York Times Company
By Sandra G. Boodman, ‘Oh my God,” Leigh Partridge remembers thinking, her mind reeling as she tried to contemplate the unimaginable. “This cannot be happening again.” Doctors in the emergency room of Children’s Hospital of Philadelphia (CHOP) had just told Partridge that a mass in the abdomen of her 16-year-old daughter might be cancer. Further testing would be required. To Partridge, who had lost her husband two years earlier when brain cancer killed him in a matter of months, the possibility that their middle daughter might have a malignancy was terrifying. “I didn’t even know who to call to come sit with me,” Partridge recalled. “The person who was supposed to be with me wasn’t there” anymore. Allison Partridge, then a high school junior, had found the fist-size tumor in her abdomen the previous evening while lying in bed at home. For months, Allie had suffered from severe and worsening pain in her lower abdomen and tailbone, which she usually tried to minimize or deny to protect herself and her mother. But now the pain and the giant lump were too obvious to downplay. “My mom was definitely freaking out a lot more than I was,” Allie recalled. Her hospitalization in April 2011 was both traumatic and a turning point, revealing the unusual cause of her problem as well as the essential clue — unknown to her mother — that was overlooked by doctors. © 1996-2013 The Washington Po
By Scicurious Aging happens. As you get older, your body slows down, eventually your brain slows down, too. Some things go gradually, and some go suddenly. To many people, this might seem like a pretty random process. We used to think of aging this way, as just…well cells get old, which means we get old, too. DNA replication after a while starts making errors in repair, the errors build up, and on the whole body scale the whole thing just kind of goes downhill. It seems random. But in fact, it’s not. There are specific proteins which can help control this process. And one of these, NF-kB, in one particular brain region, may have a very important role indeed. NF-kB (which stands for nuclear factor kappa-light-chain-enhancer of activated B cells, which is why we use NF-kB) is a protein complex that has a lot of roles to play. It’s an important starting player in the immune system, where it helps to stimulate antibodies. It’s important in memory and stress responses. NF-kB is something called a transcription factor, which helps to control what DNA is transcribed to RNA, and therefore what proteins will eventually be produced. Transcription factors, as you can see, can have a very large number of functions. But in the hypothalamus, NF-kB may have the added function of helping to control aging. The hypothalamus is an area of many small nuclei (further sub areas of neurons) located at the base of the brain. It’s been coming more and more into vogue lately among neuroscientists. In the past, we were interested in the hypothalamus mostly for its role in controlling hormone release from the dangling pituitary gland before it, but now we are learning that the hypothalamus can play roles in fear, mood, food intake, reproduction, and now…aging. © 2013 Scientific American
By Melanie Tannenbaum Imagine that you’re an infant monkey, and you’ve just been thrown into a cage after several hours in isolation. You’ve been deprived of food, so you’re starving. Facing you are two adult-looking (fake) monkeys, designed to look like each one could potentially be your mother. On the left is a “wire mother,” equipped with a bottle and feeding tube so you can cling to her and fill your belly with milk. On the right is a “cloth mother,” with no bottle, but with a fuzzy terrycloth exterior that will allow for hours of soft, warm snuggles. You can only run to one of the monkeys. Which one will you choose? Six or seven decades ago, many psychologists would have claimed that any affection that we experience towards our parental figures is a purely behaviorist response. After many instances of conditioning a sense of “positive affect” after receiving life-sustaining food from mothers, children associate that positive emotion with these caregivers, an association that serves as the sole explanation for why people “love” their mothers. But that’s not what Harry Harlow thought. Harlow, a psychologist working at the University of Wisconsin – Madison during the 1960s, believed that there was something more important underlying our affection for Mom and Dad than our primal need to eat and survive. He believed that there was an additional factor: Comfort. What Harlow did to test this hypothesis was arguably ingenious, though inarguably cruel.1 Harlow deprived monkeys of food, making them desperately hungry, and then stuck them into a cage where they had a choice of two “mother figures” to run towards. On the left was a wire mother – cold and uncomfortable, yet equipped with a bottle that would feed the baby with life-sustaining nutrients. On the right was a cloth mother – warm, soft, and comfortable, yet unable to provide the infant with any food. If the only reason why we “love” our mothers (and fathers) is based on a conditioned response to our need for food, then the infant monkeys should run to the wire mothers who can feed them every time. © 2013 Scientific American
Researchers at the National Institutes of Health have uncovered firm evidence for what many mothers have long suspected: women’s brains appear to be hard-wired to respond to the cries of a hungry infant. Researchers asked men and women to let their minds wander, then played a recording of white noise interspersed with the sounds of an infant crying. Brain scans showed that, in the women, patterns of brain activity abruptly switched to an attentive mode when they heard the infant cries, whereas the men’s brains remained in the resting state. “Previous studies have shown that, on an emotional level, men and women respond differently to the sound of an infant crying,” said study co-author Marc H. Bornstein, Ph.D., head of the Child and Family Research Section of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the institute that conducted the study. “Our findings indicate that men and women show marked differences in terms of attention as well.” The earlier studies showed that women are more likely than men to feel sympathy when they hear an infant cry, and are more likely to want to care for the infant. Their findings appear in NeuroReport. Previous studies have shown differences in patterns of brain activity between when an individual’s attention is focused and when the mind wanders. The pattern of unfocused activity is referred to as default mode, Dr. Bornstein explained. When individuals focus on something in particular, their brains disengage from the default mode and activate other brain networks.
By Scicurious In the great novel The Great Gatsby, Daisy, one of the love interests of the book, has a beautiful voice. She’s described otherwise, but you don’t really remember what she looked like, you remember how she sounded. Fitzgerald describes her voice as musical, running up and down and the scales when she talks. And you know what he’s talking about. You hear that voice in your head: light, breathy, utterly charming. You don’t really know what she looks like, but from imagining her voice, you know she is beautiful. What is it about this, or any voice, that makes it attractive? Is it the pitch? The tone? The firmness or breathiness of voice? And what is it about that voice, or any voice, that makes you know that someone is beautiful, handsome, masculine, feminine? The authors of this study wanted to see what makes a voice a VOICE. What acoustic factors make it most attractive to women and to men? To do this, they first took 10 young men, and had them rate the attractiveness of a female voice saying “good luck on your exams”. The voice actor said the phrase without any emotion using three different sound qualities: normal, breathy, and pressed (more of a hard tone). They then took the recording of this voice and modified it up and down, to create the phrase in several different pitches and formats. Specifically, they modified it upward toward what they hypothesized to mean “small body size and happiness” or downward toward what they hypothesized to mean “large body size and anger”. They showed that while increasing the pitch (higher) did not increase the attractiveness of the voice, lowering it decreased the attractiveness. And increasing the breathiness of the sentence increased attractiveness. The authors believe that this means that lowering the voice, and presumably indicating a larger body size (larger body size in general means the normal voice will be lower), reduced how attractive the men found the voice. © 2013 Scientific American
Symmetry study deemed a fraud Eugenie Samuel Reich Few researchers have tried harder than Robert Trivers to retract one of their own papers. In 2005, Trivers, an evolutionary biologist at Rutgers University in New Brunswick, New Jersey, published an attention-grabbing finding: Jamaican teenagers with a high degree of body symmetry were more likely to be rated ‘good dancers’ by their peers than were those with less symmetrical bodies. The study, which suggested that dancing is a signal for sexual selection in humans, was featured on the cover of this journal (W. M. Brown et al. Nature 438, 1148–1150; 2005). But two years later, Trivers began to suspect that the study data had been faked by one of his co-authors, William Brown, a postdoctoral researcher at the time. In seeking a retraction, Trivers self-published The Anatomy of a Fraud, a small book detailing what he saw as evidence of data fabrication. Later, Trivers had a verbal altercation over the matter with a close colleague and was temporarily banned from campus. An investigation of the case, completed by Rutgers and released publicly last month, now seems to validate Trivers’ allegations. Brown disputes the university’s finding, but it could help to clear the controversy that has clouded Trivers’ reputation as the author of several pioneering papers in the 1970s. For example, Trivers advanced an influential theory of ‘reciprocal altruism’, in which people behave unselfishly and hope that they will later be rewarded for their good deeds. He also analysed human sexuality in terms of the investments that mothers and fathers each make in child-rearing. © 2013 Nature Publishing Group
By Breanna Draxler The ruse is common in spy movies—an attractive female saunters in at a critical moment and seduces the otherwise infallible protagonist, duping him into giving up the goods. It works in Hollywood and it works in real life, too. Men tend to say yes to attractive women without really scrutinizing whether or not they are trustworthy. But scientists have shown, for the first time, that a drug may be able to overcome this “honey trap,” and help men make more rational decisions. Nearly 100 men participated in the study; half were given minocycline, an antibiotic normally used to treat acne, and half were given a placebo. After four days of this drug regimen, participants played a computerized one-on-one trust game with eight different women, based only on pictures of the female players. In each round, the male player was given $13 and shown a picture of one of the female players. The male player would choose how much money he wanted to keep and how much he wanted to give to the female player. The amount given away was then tripled, and the female player would decide whether to split the money with the man or keep it all for herself. Unbeknownst to the men, however, the women kept the money every time. The researchers also asked the men to evaluate the photos of the females to determine how trustworthy and attractive they appeared, on a scale of 0 to 10.
By Sophie Moura The year I was in fifth grade, I saw a television commercial for tampons. Like most 10-year-olds, I'd never heard of a tampon. But when I asked my mom what one was, she started crying. How do you tell your daughter that she's never going to need tampons? That she won't get her period or have babies, and that those things are the least of what sets her apart? From the outside, there was no sign that the little kid watching TV in a suburb of Pittsburgh was so different. I've always been girly — obsessed with dresses, sparkles, and the color pink, donning felt poodle skirts for Halloween and loving makeup. What isn't obvious is that I have a rare condition called androgen insensitivity syndrome, or AIS. I was born with XY chromosomes, the combination found in boys. With AIS, an XY embryo doesn't respond to the crucial hormones that tell the penis and scrotum to form. At the earliest stage of life, my body missed those signals, and I developed as a girl, with a clitoris and vulva. But what's inside me doesn't match. My parents learned this when I was 6. That year, I collapsed in the shower with a painful lump in my groin. Convinced I had a hernia, my parents, both doctors, rushed me to the hospital. But when surgeons operated (a hernia is tough to X-ray and needs to be fixed surgically), there was no twisted loop of intestine behind that bump. It was a testicle that had started descending. Across my abdomen, they found another one. The upper portion of my vagina, and my cervix, uterus, and fallopian tubes were missing. ©2013 Hearst Communication, Inc.
Keyword: Sexual Behavior
Link ID: 18096 - Posted: 04.30.2013
By Christie Wilcox What does your voice say about you? Our voices communicate information far beyond what we say with our words. Like most animals, the sounds we produce have the potential to convey how healthy we are, what mood we’re in, even our general size. Some of these traits are important cues for potential mates, so much so that the sound of your voice can actually affect how good looking you appear to others. Which, really, brings up one darn good question: what makes a voice sound sexy? To find out, a team spearheaded by University College London researcher Xi Yu created synthetic male and female voices and altered their pitch, vocal quality and formant spacing (an acoustics term related to the frequencies of sound), the last of which is related to body size. They also adjusted the voices to be normal (relaxed), breathy, or pressed (tense). Through several listening experiments, they asked participants of the opposite gender to say which voice was the most attractive and which sounded the friendliest or happiest. The happiest-sounding voices were those with higher pitch, whether male or female, while the angriest were those with dense formants, indicating large body size. As for attractiveness, the men preferred a female voice that is high-pitched, breathy and had wide formant spacing, which indicates a small body size. The women, on the other hand, preferred a male voice with low pitch and dense formant spacing, indicative of larger size. But what really surprised the scientists is that women also preferred their male voices breathy. “The breathiness in the male voice attractiveness rating is intriguing,” explain the authors, “as it could be a way of neutralizing the aggressiveness associated with a large body size.”
Sunanda Creagh, The Conversation Testosterone may trigger a brain chemical process linked to schizophrenia but the same sex hormone can also improve cognitive thinking skills in men with the disorder, two new studies show. Scientists have long suspected testosterone plays an important role in schizophrenia, which affects more men than women. Men are also more likely to develop psychosis in adolescence, previous research has shown. A new study on lab rodents by researchers from Neuroscience Research Australia analysed the impact increased testosterone had on levels of dopamine, a brain chemical linked to psychotic symptoms of schizophrenia. The researchers found that testosterone boosted dopamine sensitivity in adolescent male rodents. “From these rodent studies, we hypothesise that adolescent increases in circulating testosterone may be a driver of increased dopamine activity in the brains of individuals susceptible to psychosis and schizophrenia,” said senior Neuroscience Research Australia researcher and author of the study, Dr Tertia Purves-Tyson, who is presenting her work at the International Congress on Schizophrenia Research in Florida. Dr Philip Mitchell, Scientia Professor and Head of the School of Psychiatry at the University of NSW, said the research was very interesting. © 2013 ScienceAlert Pty Ltd.
Jo Marchant People with genes that make it tough for them to engage socially with others seem to be better than average at hypnotizing themselves. A study published today in Psychoneuroendocrinology1 concludes that such individuals are particularly good at becoming absorbed in their own internal world, and might also be more susceptible to other distortions of reality. Psychologist Richard Bryant of the University of New South Wales in Sydney and his colleagues tested the hypnotizability of volunteers with different forms of the receptor for oxytocin, a hormone that increases trust and social bonding. (Oxytocin's association with emotional attachment also earned it the nickname of 'love hormone'.) Those with gene variants linked to social detachment and autism were found to be most susceptible to hypnosis. Hypnosis has intrigued scientists since the nineteenth-century physician James Braid used it to alleviate pain in a variety of medical conditions, but it has never been fully understood. Hypnotized people can undergo a range of unusual experiences, including amnesia, anaesthesia and the loss of the ability to move their limbs. But some individuals are more affected by hypnosis than others — and no one knows why. Hormones and hypnotism How susceptible someone is to persuasion is an important factor in how easily they can be hypnotized by someone else. Bryant and his colleagues have previously shown that spraying a shot of oxytocin up people’s noses makes them more hypnotizable, and more likely to engage in potentially embarrassing activities such as swearing or dancing at a hypnotist’s suggestion. © 2013 Nature Publishing Group,
by Dennis Normile A human mother rocking a baby in her arms and a cat carrying her kitten by the scruff of its neck have the same physiological effect on both young animals and probably stem from the same maternal instinct to protect their young. That's the conclusion of a new study, which for the first time has compared the physiological impact of maternal carrying behaviors across species. The findings may lead to better parenting techniques for people and possibly to new ways to detect developmental disorders early in life. It's "really fascinating" work, says Oliver Bosch, a neurobiologist at the University of Regensburg in Germany, who was not involved in the research. "No one has looked at [this aspect] of maternal behavior in such detail." Japanese neuroscientist Kumi Kuroda began the study in her own home. She noticed that carrying her newborn baby boy while walking had a rapid calming effect on him. Back in her lab at the RIKEN Brain Science Institute, near Tokyo, she found that picking up mouse pups by the scruff of the neck makes them passive and easy to handle. Kuroda wondered if the same physiological processes were driving both behaviors. She and colleagues recorded pulse rates and observed the crying and squirming behavior of 12 infants, 1 to 6 months old, as each was left alone in a crib, held by its mother sitting in a chair, and carried as the mother walked around. In various durations and combinations of the three conditions, they found that the carried babies cried and squirmed the least and had the lowest pulse rates. Those left in the crib were the fussiest; holding the baby while sitting produced in-between results. What was particularly surprising, Kuroda says, was that when a mother started walking, the infant's pulse dropped, and the crying and squirming stopped within 2 to 3 seconds, not over several minutes. © 2010 American Association for the Advancement of Science.
By Bill Andrews In a paper sure to please lazy stand-up comics and beleaguered husbands everywhere, scientists say that men do indeed have a hard time understanding women. Recent results show that men have a significantly harder time recognizing women’s emotions than they do men’s, and that men seem to use different parts of their brain when ascribing intentions and feelings to women versus men. Previous experiments had suggested that men are naturally wired to be more intuitive toward other men’s mental states and emotions. Eager to figure out why and how this could be, the researchers studied the brains of 22 male participants as they received a version of a well-known empathy test called the “Reading the Mind in the Eyes Test.” (You can take a version of the test online here.) As the name suggests, the test consists of snapshots of pairs of eyes. Pairs of eyes were shown in succession to each participant, who had to determine either the gender or the emotional state of the person pictured. This all took place within an MRI machine, allowing the researchers to see which parts of the brain were active while participants made their determinations. Participants were about equally good at guessing the gender of male and female eyes, but the men did significantly worse at recognizing the emotions of the female eyes. They correctly interpreted about 87 percent of men’s eyes but only about 76 percent of women’s eyes. Participants also took longer to judge women’s emotions—about 40 milliseconds longer on average. Thus, in effect, men can “read” other men’s eyes faster and better, the researchers report in PLOS ONE.
Matt Kaplan By making noise that could potentially expose them to predators, young pied babblers get their parents to give them more attentions. Begging loudly has long been viewed as an offspring’s way of saying “I’m hungry”. But in predator-filled environments, these squawks can put young birds in harm's way, and may be a form of blackmail that forces parents to pay attention and feed the youngsters more than they might otherwise. The discovery comes from a three-year analysis of a well-studied community of pied babbler (Turdoides bicolor) in the Kalahari Desert of South Africa1. Alex Thompson of the University of Cape Town and colleagues from Britain and Australia, spent more than 200 hours observing the animals in the wild and recorded more than 3,000 incidents of parents feeding fledglings. Thompson and his team noted that fledglings were fed an average of 0.12 grams of food per minute when on the ground and away from cover, but just 0.03 grams per minute when begging from the safety of the trees. Furthermore, when the birds were played an audio recording of alarm calls indicating that a ground predator was in the vicinity, parents more than doubled the amount they gave to ground-based youngsters, but made no compensation for those in the trees. Fascinated, the team speculated that the young, which were slower than adults to respond to the alarm calls and cannot escape as quickly from danger, were intentionally putting themselves into a dangerous situation when hungry to force their parents to pay attention and feed them. © 2013 Nature Publishing Group,
by Dennis Normile Puberty has always been a time of stress and emotional turmoil for adolescents and for their parents. And scientists have long recognized that kids who start puberty ahead of their peers are particularly likely to have trouble getting along with other children and with adults. New research suggests that those difficulties can be traced back to even earlier ages, indicating that early puberty may not be the root cause. Australian researchers drew on data for 3491 children, roughly half boys and half girls, who were recruited at ages 4 or 5 and then followed until they reached ages 10 or 11. Every 2 years, a researcher visited each subject's home, evaluated the child, and interviewed the primary caregiver, which in most cases was a parent, who later completed and returned a questionnaire about their child's behavior. The primary caregiver was also asked to judge the child's pubertal status, based on indicators for an early phase of puberty such as breast growth in girls, adult-type body odor, and body hair; and growth spurts, deepening voices in boys, and menstruation in girls for a later stage. Girls typically enter puberty at age 10 or 11 and boys at 11 or 12. The researchers found that 16% of the girls and 6% of the boys in the study had entered puberty early, at age 8 or 9. Previously, researchers thought that any negative effects of early puberty showed up only after puberty's onset. But by tracking a cohort of children from age 4 to 5 to age 10 to 11, they found that problems thought restricted to postpuberty children actually appeared well before puberty. Retrospectively, they were able to show that children who later had early onset puberty had difficulty playing with other children and participating in normal school activities, even when they were 4 or 5 years old. Boys, though not girls, in this group had also showed behavior problems, such as being overactive, losing their tempers, and preferring to play alone from a young age. © 2010 American Association for the Advancement of Science.
By Felicity Muth With the historic supreme court hearings this week, there has been much discussion about homosexuality*. One of the ‘arguments’ that you often hear from the anti-gay rights side is that being gay isn’t natural. Evidence from the animal kingdom would refute this however, as same-sex behaviour is common and found in many different animals. There’s the famous example of ‘Roy’ and ‘Silo’, two male chinstrap penguins that formed a pair bond and raised a chick (‘Tango’) together, later turned into a distinctive children’s book (you can also read about their tragic breakup here – this part has yet to be made into a children’s book). Homosexuality is also common in many insects, and some flour beetle males actually mate 50% of the time with other males. But why does same-sex behaviour occur? How is it maintained by evolution? This is a complex question, and the answer is likely to differ from species to species. For example, flour beetle males that mate with other males can actually transfer to females this way. Other male insects like weevils or fruit flies may just not realise that the individual they’re mating with is also a male (it being better to mate with more animals, and get it ‘wrong’ sometimes, than be too discriminating and miss out on potentially fruitful mating attempts). However, in addition to specific cases, there may also be overarching patterns across species in how homosexuality is selected for and maintained by evolution. While many studies have concentrated on male-male sexual behaviour, females also engage in same-sex behaviour. Laysan albatrosses form female-female partnerships, performing the same mating rituals as in male-female pairs of this species, and these couples can last a lifetime. © 2013 Scientific American
Keyword: Sexual Behavior
Link ID: 17974 - Posted: 04.01.2013
Published by scicurious Today's post comes to you courtesy of Mary Roach (aka, the person I want to be when I grow up). I have a copy of her latest book, Gulp: adventures in the alimentary canal that I am reading for review, and a weird science connoisseur such as myself of course spends half her time in the bibliography section, wherein I located this paper. This paper may thus be taken as a pre-review of the book. Spoiler: so far, the book is FABULOUS, but should never be read while eating. Ah, goat milk. When I think of goat milk, I think of places like farmer's markets, Whole Foods, and little Heidi dancing through the alps. I'll admit to never having drunk raw goat milk (though I do LOVE goat cheese). But after having read this paper, I'm afraid that I do not WANT to try raw goat milk. Why? I'm afraid of the taste...the goaty taste...that is potentially hot, sexy goaty hormones. Hot sexy goat hormones sprayed around in hot, sexy goaty URINE. So, goat milk doesn't usually taste...well, goaty. Usually it tastes pretty much like cow milk (whole fat cow milk, that is). But sometimes, you'll get a bad batch. Nothing's WRONG with it, per se, it's still healthy and not bad, but it's...goaty. The flavor and smell are musky and weird, and not at all tasty. So obviously you want to find the source of that problem. For years, people who raise goats have pinpointed the MALE goat as the source of the issue. Male goats smell very goaty indeed, particularly during the goat mating season (the rutting season). Some of the odors they emit are so strong they can be smelled several hundred meters away. The odors are very volatile, so they will spread easily, and the idea has long been that if your male goat is around the ladies, his manly odors will get on them and in them, and thus in their milk, resulting in goaty milk (which, if the male goat is the cause, means that goaty milk is really just...MANLY). So goat farmers usually keep their male goats at a good distance from the females during the rutting season, to keep the males from getting their...manliness in the milk. Manliness is just not very tasty. Copyright © 2013
By Meghan Rosen With parasitic flies gorging on her guts and the end approaching, a variable field cricket may have only one thing to do: Find a mate. Usually, female Gryllus lineaticeps prefer males with fast chirps. But when being eaten alive by fly larvae, female crickets don’t wait around for a snappy tune. Instead, they settle for slow-chirping sexual partners, evolutionary biologists Oliver Beckers of Indiana University in Bloomington and William Wagner Jr. of the University of Nebraska-Lincoln report in the April Animal Behaviour. Parasitic flies seek out crickets as potential homes (and meal tickets) for their young. Before the fly larvae chew through crickets’ bellies, female crickets have about a week to find a mate and lay eggs before dying. To find out whether infestation lowered females’ mating standards, Beckers and Wagner placed fly larvae on female crickets and then played slow and fast chirp recordings from loudspeakers set in separate corners of a square chamber. Healthy females walked toward the fast chirping sound about 80 percent of the time, while infested females split their devotion about equally. “They don’t invest a lot of time and energy finding the super sexy guy,” says Becker. “They’ll go for the average Joe.” © Society for Science & the Public 2000 - 2013
by Beth Skwarecki If you thought the battle of the genders was complicated, try having seven sexes. When Tetrahymena, a single-celled creature covered in cilia, mates, the offspring isn't necessarily the same sex as either parent—it can be any of seven. Now, researchers have figured out the complex dance of DNA that determines the offspring's sex, and it's a random selection, they report today in PLOS Biology. Each Tetrahymena has a gene for its own sex—or mating type—in its regular nucleus, but it also carries a second nucleus used only for reproduction. This "germline nucleus" contains incomplete versions of all seven mating type genes, which are cut and pasted together until one complete gene remains and the other six have been deleted. The newly rearranged DNA becomes part of the offspring's regular nucleus, determining its mating type. Because the mating type gene helps Tetrahymena recognize others of a different sex, the researchers say that the finding could shed light on how other cells, including those in humans, recognize those that are different from themselves. © 2010 American Association for the Advancement of Science.