Links for Keyword: Sexual Behavior

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// by Jennifer Viegas Single parenting takes on new extremes for certain starfish that are hermaphrodites -- male and female at the same time and, in some cases, self-fertilizing. The species faces high risk of extinction, according to new research. The dire situation faced by the non-mating starfish, Parvulastra parvivipara and Parvulastra vivipara, helps to explain why so many organisms, including humans, have sex. Genetic diversity and the dispersal of youngsters support population growth. The plight of the starfish, documented in the latest issue of the journal Biology Letters, reveals how a life without sex but with self-fertilization could result in eventual oblivion. “There are quite a few reasons why these species are vulnerable,” senior author Michael Hart of Simon Fraser University’s Department of Biological Sciences told Discovery News. “The whole species could be wiped out.” Hart and his team studied the starfish, which are restricted to high intertidal pools of South Australia and Tasmania. These starfish also go by the nickname "sea cushions," since they look a bit more like a cushion than a star when viewed from the side. Most adult starfish of other species do reproduce via a separate male and female. Females usually produce eggs that males fertilize in the seawater. At that point, the fertilized eggs develop and grow before becoming little starfish that will attach themselves to the substrate and start the whole process over again. © 2013 Discovery Communications, LLC.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18470 - Posted: 08.07.2013

By Luciana Gravotta Small gains now or big rewards later? The conundrum plagues every decision we make, whether we are investing or dieting. Now researchers find that men and women use different strategies to make such choices. Researchers use gambling games to understand what we do when immediate rewards are pitted against long-term gains. Most of these games find no major differences in how men and women play. An experimental setup called the Iowa Gambling Task (IGT), however, finds consistent—and large—differences between the behavior of men and women: men are better at figuring out the strategy that reaps the bigger payoff. Players are given four decks of cards, and they choose one card at a time from any deck they want. Each card has a win or loss amount on it, and each deck has its own unique payout pattern. Two of the decks contain cards that dole out large or frequent rewards, but consistently choosing cards from these decks leads to losses in the long run. The other two decks provide a modest amount of cash per win but less loss over time, so they offer long-term gains for players who pick from them most frequently. These patterns are carefully obscured so that the winning strategy is not obvious. A review published in February in Behavioural Brain Research finds that men focus on the big picture, watching their total earnings and quickly homing in on which of the decks will lead to gains in the long run. Women focus on details such as the frequencies of wins and losses for each deck, missing the overall impact each deck has on their total balance. Sensitive to losses, women tend to switch to a different deck as soon as they are pinged with a setback, making it more difficult for them to identify the prize deck. © 2013 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18458 - Posted: 08.05.2013

By CARL ZIMMER “Monogamy is a problem,” said Dieter Lukas of the University of Cambridge in a telephone news conference this week. As Dr. Lukas explained to reporters, he and other biologists consider monogamy an evolutionary puzzle. In 9 percent of all mammal species, males and females will share a common territory for more than one breeding season, and in some cases bond for life. This is a problem — a scientific one — because male mammals could theoretically have more offspring by giving up on monogamy and mating with lots of females. In a new study, Dr. Lukas and his colleague Tim Clutton-Brock suggest that monogamy evolves when females spread out, making it hard for a male to travel around and fend off competing males. On the same day, Kit Opie of University College London and his colleagues published a similar study on primates, which are especially monogamous — males and females bond in over a quarter of primate species. The London scientists came to a different conclusion: that the threat of infanticide leads males to stick with only one female, protecting her from other males. Even with the scientific problem far from resolved, research like this inevitably turns us into narcissists. It’s all well and good to understand why the gray-handed night monkey became monogamous. But we want to know: What does this say about men and women? As with all things concerning the human heart, it’s complicated. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18453 - Posted: 08.03.2013

Elizabeth Pollitzer Transplanting muscle-derived stem cells into diseased muscle regenerates it — a phenomenon that holds major potential for human therapies. But for years, researchers were puzzled by the unpredictability of these cells — sometimes they would promote fast regeneration, at other times none at all. Then, in 2007, a group led by Johnny Huard, a stem-cell researcher at the University of Pittsburgh in Pennsylvania, hit on the rather surprising explanation — sex1. Muscle stem cells taken from female mice regenerate new muscle much faster than those from male mice when transplanted into diseased muscle of mice of either sex. Researchers have also found that cells taken from male and female mice respond differently to stress2, and that human cells exhibit wildly different concentrations of many metabolites across the sexes3. Evidence is mounting that cells differ according to sex, irrespective of their history of exposure to sex hormones. These differences could have major implications for the susceptibility to and course of many diseases, their diagnosis and treatment. However, most cell biologists do not note whether the cells they are using come from males or females4. Between 1997 and 2001, ten prescription drugs were withdrawn from the market by the US Food and Drug Administration (FDA), eight of which were more dangerous to women than to men (see go.nature.com/ksindo). The ingredients used in non-prescription drugs can also pose greater health risks to women. In 2000, for instance, the FDA took steps to remove phenylpropanolamine, a component of many over-the-counter medications, from all drug products because of a reported increased risk of bleeding into the brain or into tissue around the brain in women but not in men. Such drug therapies are developed through basic research — but what if sex-related differences in studied cells contribute in a significant way to the observed effects? © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 5: The Sensorimotor System
Link ID: 18440 - Posted: 08.01.2013

By Melissa Hogenboom Science reporter, BBC News Male zebra finches that fail to socialise with females during adolescence are less successful at courtship later in life, a study says. This effect mimics the "loser effect" where, after a defeat, an animal is more likely to lose a subsequent fight. Social friendships at a young age were also found to be more important than physical and social attractiveness. The findings are reported in Proceedings of the Royal Society B: Biological Sciences. The loser effect has been well demonstrated in many species, from spiders and fish to birds. After a fight hormonal levels change which negatively affects performance in further fights. Now scientists have found a similar effect for mating. Adolescent males who failed to pair with a juvenile female were later unsuccessful with females they encountered in adulthood. Scientists also paired young males as a control in the experiment. They found that if males failed to pair with another male, it had no effect on their later success. Mylene Mariette, from the University de Saint-Etienne, France, and lead author of the study said: "We know that social interaction is important for some aspects of development, like the role of males to teach youngsters to sing, but so far no study has looked at the effect of how interaction between juveniles affects their behaviour as adults." BBC © 2013

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18433 - Posted: 07.31.2013

By CARL ZIMMER The golden lion tamarin, a one-pound primate that lives in Brazil, is a stunningly monogamous creature. A male will typically pair with a female and they will stay close for the rest of their lives, mating only with each other and then working together to care for their young. To biologists, this deeply monogamous way of life — found in 9 percent of mammal species — is puzzling. A seemingly better evolutionary strategy for male mammals would be to spend their time looking for other females with which to mate. “Monogamy is a problem,” said Dieter Lukas of the University of Cambridge in a telephone news conference on Monday. “Why should the male keep to one female?” The evolution of monogamy has inspired many different ideas. “These hypotheses have been suggested for the past 40 years, and there’s been no resolution of the debate,” said Kit Opie of the University College London in an interview. On Monday, Dr. Opie and Dr. Lukas each published a large-scale study of monogamy that they hoped would resolve the debate. But they ended up coming to opposing conclusions, which means the debate over monogamy continues. Dr. Lukas, co-author of a paper in the journal Science with Tim Clutton-Brock of Cambridge, looked at 2,545 species of mammals, tracing their mating evolution from their common ancestor some 170 million years ago. The scientists found that mammals shifted from solitary living to monogamy 61 times over their evolution. They then searched for any factors that these mammals had in common. They concluded that monogamy evolves when females become hostile with one another and live in ranges that do not overlap. When females live this way, they set up so much distance between one another that a single male cannot prevent other males from mating with them. Staying close to one female became a better strategy. Once males began doing so, they sometimes evolved to provide care to their offspring as well. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18429 - Posted: 07.30.2013

By Susan Milius When a peacock fans out the iridescent splendor of his train, more than half the time the peahen he’s displaying for isn’t even looking at him. That’s the finding of the first eye-tracking study of birds. In more than 200 short clips recorded by eye-tracking cameras, four peahens spent less than one-third of the time actually looking directly at a displaying peacock, says evolutionary biologist Jessica Yorzinski of Purdue University in West Lafayette, Ind. When peahens did bother to watch the shimmering male, they mostly looked at the lower zone of his train feathers. The feathers’ upper zone of ornaments may intrigue human observers, but big eyespots there garnered less than 5 percent of the female’s time, Yorzinski and her colleagues report July 24 in the Journal of Experimental Biology. These data come from a system that coauthor Jason Babcock of Positive Science, an eye-tracking company in New York City, engineered to fit peahens. Small plastic helmets hold two cameras that send information to a backpack of equipment, which wirelessly transmits information to a computer. One infrared head camera focuses on an eye, tracking pupil movements. A second camera points ahead, giving the broad bird’s-eye view. The rig weighs about 25 grams and takes some getting used to. If a peahen with no experience of helmets gets the full rig, Yorzinski says, “she just droops her head to the ground.” Adding bits of technology gradually, however, let Yorzinski accustom peahens to walking around, and even mating, while cameraed up. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 7: Vision: From Eye to Brain
Link ID: 18406 - Posted: 07.25.2013

Should I stay or should I go? Well, how much food do you have? In some organisms, sexual desire is expressed by leaving, that is, by bidding adieu to a delicious pile of food and wandering off in search of a mate. But not just any mate, a mate with food! Lipton et al., at Albert Einstein College of Medicine, use the “leaving assay” to measure male sexual desire. Their subject is the elegant, rod-like worm, Caenorhabditis elegans.* They start by placing males on their preferred food source; then they measure how often males exit in search of mating partners. You can see the trails they leave in the substrate in this video of C. elegans appropriating Harlem art and culture. How do the researchers know “leaving” is a sex behavior? Context. Leaving a food source occurs only in a sexual context, and the leaving assay is being used to tease apart the threads that control the appetites for food and sex. First, a quick lesson in the fascinating sexuality of C. elegans. Males are not interested in other males, but they search intensely for a mating partner of the other sex. Note that I said “other sex” not “opposite sex.” There are no female C. elegans. Males of this species mate enthusiastically with hermaphrodites. Hermaphrodites can, of course, self-fertilize, but sexual unions between males and hermaphrodites are far more fruitful than selfing. For hermaphrodites, mating with a male will produce more offspring, and for males, hermaphrodites are the only crying game in town.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 18341 - Posted: 07.03.2013

by Traci Watson For the male dark fishing spider, the price of love is death. New research shows that the male Dolomedes tenebrosus (right) expires just after the height of passion, despite no visible assault by his partner. Scientists collected the common U.S. arachnids (see image) in Nebraska parks and did a little matchmaking. In 25 observed matings, after the male stuffed his sperm into the female's body using his antennalike pedipalp, he immediately went limp and his legs curled underneath him, researchers report online today in Biology Letters. By counting the pulse rate in the spiders' abdomens, researchers measured the heartbeat of motionless males and confirmed that they do indeed die. As if death weren't sacrifice enough, the scientists found that lovemaking also disfigures the male. In most spiders, part of the male's pedipalp swells to deliver sperm before shrinking to normal size. In D. tenebrosus, the pedipalp remains enormously enlarged and presumably useless even after the deed is done. Evolutionary theory predicts male monogamy—such as that shown by the dark fishing spider—when females are larger than males. Smaller animals are more likely to survive to mating age than big ones, the thinking goes, making larger females scarcer than smaller males. And that means males must settle for just one inamorata. True to theory, the female dark fishing spider, whose outstretched legs span a human's palm, outweighs her man 14-to-1. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18293 - Posted: 06.20.2013

By Brigid Schulte, Unlike the male pundits, politicians and even financiers who’ve opined freely recently about what they consider “natural” roles for mothers and fathers, with mom at home and dad at work, behavioral neuroscientist Kelly Lambert’s methodical approach has led her to a much more complicated conclusion. From her perch at Randolph-Macon College in rural Ashland, Va., Lambert has spent years designing elaborate experiments to test nurturing in both male and female rodents. She anesthetizes the animals, carefully removes their brains, firms the brains up with formalin, freezes them, then shaves them into slices thinner than a strand of human hair to study under a microscope. What Lambert’s rodent brain slices are revealing is nothing short of revolutionary, challenging the loud pundits and long-held cultural views that only mothers are wired for nurture. Lambert, one of a small but growing number of scientists who study the biology of father behavior, is finding that not just mothers experience surges of hormones associated with bonding and nurturing. The same hormones increase, though not to the same degree, in fathers. Rat mothers are not the only ones whose brains become sharper, making them more efficient foragers and more courageous and level-headed than females without offspring. Lambert has found that the same is true of fathers’ brains. Fatherhood makes the male California deer mouse smarter, too. © 1996-2013 The Washington Post

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 18282 - Posted: 06.17.2013

Helen Shen The case of the missing bird penis is a long-standing mystery in evolutionary biology. But the identification of a molecular mechanism that controls penis loss in birds goes some way to solving this conundrum. Roughly 97% of avian species sport little or nothing in the way of a phallus, despite reproducing by internal fertilization. A study published today in Current Biology1 shows that the development of chicken penises is cut short by signals that promote cell death. “This paper would be in Nature or Science if it were about people,” says Richard Prum, an evolutionary ornithologist at Yale University in New Haven, Connecticut. “The whole result is entirely novel.” Male chickens, which possess only a rudimentary phallic nub, pump their sperm into females using a 'cloacal kiss' — a move that presses together the male and female cloacas, openings used for waste excretion and copulation. By contrast, ducks boast large and elaborately coiled penises that can measure about half the length of their bodies2. To better understand the signals that control penis growth, researchers led by Martin Cohn, a developmental biologist at the University of Florida in Gainesville, looked for differences between developing duck and chicken embryos. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18246 - Posted: 06.08.2013

By Susan Milius Lyrebirds are famous for the mimicked sounds they sing, but they now have another claim to fame: They dance to their own songs. “Just as we waltz to waltz music but we salsa to salsa music, so lyrebirds perform different dance movements to different types of songs,” says Anastasia Dalziell of the Australian National University in Canberra. She and her colleagues scrutinized videos of male superb lyrebirds (Menura novaehollandiae) showing off in the wild for possible mates. The males’ combinations of hums, clicks, trills and other sexy syllables fell into four distinctive song types, the researchers say. At least the first three types are not mimicry but lyrebird originals, Dalziell says. In courtship, males sing the songs in a fairly predictable order and usually match each to its own mix of dance moves and postures. The birds side-step, turn and flare their outsized lyre-shaped tails. Matching a type of music with a style of gesture is not unique to humankind, the researchers report June 6 in Current Biology. Performing for females, a male lyrebird dances to the music he makes. And yes, the bird makes the noises heard in the video. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Language and Our Divided Brain
Link ID: 18244 - Posted: 06.08.2013

By Breanna Draxler Is it a coincidence that the word vole is an anagram of love? Probably so, but since prairie voles mate for life, they have since been designated as the unofficial species used to study monogamy in lab animals. And a new study finds that their rare partnerships are cemented by chemical changes on their genes, called epigenetic changes, that result from their sexual encounters. When a prairie vole (Microtus ochrogaster) finds a mate, the two form a strong bond. Not only do they stay together for life and share child care duties, but the lovers will guard their mates aggressively against voles of the opposite sex. Scientists knew from previous studies that this bonding was regulated by neurotransmitters—chemical communicators in the brain such as oxytocin, which is linked to sex and reproduction, and vasopressin, associated with social recognition. However researchers were unsure what the biological basis was for such a sharp behavioral shift after mating. To find out, scientists at Florida State University paired up virgin male and female voles and gave the couples a cage together for a number of hours. Some couples were allowed to mate while others were prevented from doing so. The non-mating female voles instead received drug injections in the nucleus accumbens, a part of the brain’s pleasure center. The drugs affected the voles’ epigenetics by unwinding their DNA so that genes for vasopressin and oxytocin receptors were more highly transcribed.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 18237 - Posted: 06.06.2013

A patient at the Kwong Wah and Queen Elizabeth Hospitals discovered he was also a woman when he came for treatment for a swelling abdomen. Photo: Nora Tam A 66-year-old apparently male patient made a stunning discovery when he sought treatment for swelling in his abdomen. The swelling was a cyst on his ovary and he was in fact a woman. The condition was caused by a very rare combination of two genetic disorders. One, Turner syndrome, causes women to lack some female features, including the ability to get pregnant. Sufferers usually look like women, but in this case the patient also had congenital adrenal hyperplasia (CAH), which boosted the male hormones and made the patient look like a man. The case was reported by doctors from Kwong Wah Hospital and Queen Elizabeth Hospital, who treated the patient. It was published in the Hong Kong Medical Journal yesterday. "The patient, by definition, is a woman who cannot get pregnant. But she also has CAH, which gave her the appearance of a man," Chinese University paediatrics professor Ellis Hon Kam-lun said. "It's an interesting and very rare case of having the two combinations. It probably won't be seen again in the near future." The 66-year-old Vietnam-born Chinese man is an orphan. He has a beard, small penis and no testes. Just 1.37 metres tall, he has decided to continue perceiving himself as a male and may receive male hormone treatment, the report said. © 2013 South China Morning Post Publishers Ltd

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 18236 - Posted: 06.06.2013

By Susan Milius After death, male guppies can keep on siring offspring because females store sperm for so long. As a result, a living male in a stream in Trinidad can end up competing with long-gone fish from his grandfather’s generation. At its most posthumously successful, stored ghost sperm sired about one in four of the offspring among wild guppies released into a stream, evolutionary biologist Andrés López-Sepulcre of École Normale Supérieure in Paris and his colleagues report June 5 in Proceedings of the Royal Society B. Biologists have long known that female Poecilia reticulata guppies store sperm. The cells clump in little pockets in a female’s ovarian cavity and feed on sugars released by ovarian tissue. Storage in itself isn’t unusual, López-Sepulcre says. Some crabs, turtles, lizards, bats and other creatures preserve sperm for later use. Posthumous reproduction by stored sperm also isn’t unheard of. “The fun part of our study,” López-Sepulcre says, “is that you have males who are alive and males who are dead competing with each other.” Researchers deployed guppies in several streams as part of a study on evolutionary change. Every month researchers catch, check and release as many fish as possible to track deaths and births. They also genetically analyze parenthood of the fish. Female guppies give live birth to broods of two to about 10 youngsters, with not all sired by the same male. Females live about 15 months; males about three. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18230 - Posted: 06.05.2013

Zoe Cormier Love really does change your brain — at least, if you’re a prairie vole. Researchers have shown for the first time that the act of mating induces permanent chemical modifications in the chromosomes, affecting the expression of genes that regulate sexual and monogamous behaviour. The study is published today in Nature Neuroscience1. Prairie voles (Microtus ochrogaster) have long been of interest to neuroscientists and endocrinologists who study the social behaviour of animals, in part because this species forms monogamous pair bonds — essentially mating for life. The voles' pair bonding, sharing of parental roles and egalitarian nest building in couples makes them a good model for understanding the biology of monogamy and mating in humans. Previous studies have shown that the neurotransmitters oxytocin and vasopressin play a major part in inducing and regulating the formation of the pair bond. Monogamous prairie voles are known to have higher levels of receptors for these neurotransmitters than do voles who have yet to mate; and when otherwise promiscuous montane voles (M. montanus) are dosed with oxytocin and vasopressin, they adopt the monogamous behaviour of their prairie cousins. Because behaviour seemed to play an active part in changing the neurobiology of the animals, scientists suspected that epigenetic factors were involved. These are chemical modifications to the chromosomes that affect how genes are transcribed or suppressed, as opposed to changes in the gene sequences themselves. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 18221 - Posted: 06.03.2013

“Which way do you swing?” It’s such a simple, but loaded question. Social-economic issues aside, even the biological basis of sexual preference is hotly debated. Homosexual behavior isn’t limited to humans; it’s evolutionarily conserved in species as diverse as the lowly fruit fly to the mighty lion. Some argue that genes are involved, but so far the hunt for “gay genes” have only led to dead ends (and a lot of controversy!). Sex hormones are the next suspect, but they seem to only change sex drive, not so much preference. Now this study suggests that the answer may be as simple as one SINGLE neurotransmitter: serotonin. First off, why serotonin? We know that serotonin is involved in sexual behaviour. SSRI antidepressants, like Celexa and Zoloft, work by increasing the amount of serotonin in the synapses. This relieves depressive symptoms, but has the unfortunate side effect of lowering libido. Many other studies converge to support the same simple conclusion: more serotonin=less sexual behaviour, less serotonin= more sexual behaviour. But what about PREFERENCE? The same group published a highly controversial study a few years ago, in which they argued that abolishing serotonin in male mice wiped out their preference for females. These mice showed sexual interest in both males and females, and mounted both sexes equally when given the chance. It caused quite a stir back then, with many pointing out that their conclusions were premature. One major problem is that serotonin-lacking mice are much more likely to engage in sexual behavior. Hence, they might have just been so horny that they didn’t care to pick-and-choose, mounting everything within sight regardless of gender.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 18204 - Posted: 05.30.2013

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

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18191 - Posted: 05.25.2013

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

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 18178 - Posted: 05.21.2013

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

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 8: Hormones and Sex
Link ID: 18148 - Posted: 05.14.2013