Links for Keyword: Sexual Behavior

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by Bethany Brookshire Spring will be here soon. And with daffodils, crocuses and other signs of spring comes a burst of birdsong as males duke it out to get female attention. While the males trill loud songs, the females sit quietly, choosing who will be the lucky male. Vocal male and quiet female songbirds are common in temperate zones, and have given rise to a common assumption. The best male songs get picked for reproduction, and this sexual selection results in complex song; females just listen and choose, so female song should be rare. After all, females don’t need to sing to attract mates. But it turns out this commonly held assumption is not true. A new study shows that the majority of females of songbird species do sing, and it’s likely that the ancestor of modern songbirds was also a vocal diva. The results challenge the old wisdom about female songbirds, and suggest that when it comes to female song, it’s not all about sex. Karan Odom, a behavioral ecologist at the University of Maryland, Baltimore County, has always been interested in birdsong. “As I began to study it in depth,” she says, “I realized there was a lot that’s unknown, and one area was the extent to which females were singing and the role that song plays in males and females.” Odom and her colleagues did a survey of 44 songbird families, going through bird handbooks and other sources to find records of whether males, females or both were singers. In results published March 4 in Nature Communications, they showed that female melodies are not rare at all. In fact, 71 percent of the species surveyed have singing ladies. So much for that quiet, retiring female bird. © 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: 19361 - Posted: 03.13.2014

By Ella Davies Reporter, BBC Nature Peacocks make fake sex sounds to attract females' attention, scientists say. The birds are known for shaking their tail feathers but Canadian researchers have revealed a further sexual tactic. Peacocks have a wide vocabulary of calls, and during mating they make a distinctive hoot. Biologists also recorded males making this sound when out of sight of females and suggest such deception could prove rewarding for the birds. Peacocks are one of the most obvious examples of advertising sexual fitness in the animal kingdom with their eye-catching plumage and strutting courtship displays. The mating behaviour takes place in open areas of land referred to as a "lek". When a male has successfully attracted a female, or peahen, it rushes at her making a distinctive hooting call before attempting to mate. These calls are loud enough to be heard from a distance, prompting scientists to investigate what benefit this has. "It's much louder than it needs to be to communicate with just the female that the male is trying to mate with," explained Dr Roslyn Dakin from the University of British Columbia, Canada, who co-authored the study. BBC © 2014

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19352 - Posted: 03.12.2014

by Colin Barras Treat them mean, keep them keen? Female preying mantis and black widow spiders are notorious for their tendency to kill and eat males before, during or after sex. The behaviour is clearly risky, though – not least because the scent of a dead rival hardly encourages other males to try their luck. Or so we thought. For male Pennsylvania grass spiders, the whiff of dead male seems to be exactly what they look for in a mate. They are far more likely to approach a female if she has recently killed and eaten a male. Grass spiders are found across North America. With a body length – not including legs – of 17 millimetres, the Pennsylvania grass spider is among the largest. It's harmless to humans, though, spending most of its time hiding away in a tunnel at the corner of its flat, sheet-like web. Unlike many arachnids, grass spiders don't produce sticky webs. But they can move surprisingly quickly, dashing out of their tunnel to grab any insect that ventures too near. It's not just insects that have reason to fear female Pennsylvania grass spiders. Males of the species can find themselves on the wrong end of a female's voracious appetite when the two meet to breed. As mating strategies go, it seems a pretty foolhardy one: studies suggest females in urban settings are typically approached by no more than three – and as few as zero – males during their 3-week-long breeding season. Cannibalism seems to leave the females at risk of self-inflicted celibacy. © Copyright Reed Business Information Ltd

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19351 - Posted: 03.12.2014

Think women can’t do math? You’re wrong—but new research shows you might not change your mind, even if you get evidence to the contrary. A study of how both men and women perceive each other's mathematical ability finds that an unconscious bias against women could be skewing hiring decisions, widening the gender gap in mathematical professions like engineering. The inspiration for the experiment was a 2008 study published in Science that analyzed the results of a standardized test of math and verbal abilities taken by 15-year-olds around the world. The results challenged the pernicious stereotype that females are biologically inferior at mathematics. Although the female test-takers lagged behind males on the math portion of the test, the size of the gap closely tracked the degree of gender inequality in their countries, shrinking to nearly zero in emancipated countries like Sweden and Norway. That suggests that cultural biases rather than biology may be the better explanation for the math gender gap. To tease out the mechanism of discrimination, two of the authors of the 2008 study, Paola Sapienza and Luigi Zingales, economic researchers at Northwestern University’s Kellogg School of Management in Evanston, Illinois, and the University of Chicago Booth School of Business in Illinois, respectively, teamed up with Ernesto Reuben, an experimental psychologist at Columbia Business School in New York City, to design an experiment to test people's gender bias when it comes to judging mathematical ability. Study participants of both genders were divided into two groups: employers and job candidates. The job was simple: As accurately and quickly as possible, add up sets of two-digit numbers in a 4-minute math sprint. (The researchers did not tell the subjects, but it is already known that men and women perform equally well on this task.) © 2014 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 14: Attention and Consciousness
Link ID: 19348 - Posted: 03.11.2014

Londa Schiebinger. In Madrid a couple of years ago, I was interviewed for Spanish newspapers. When I later ran the text through Google Translate, I got a shock: I was referred to repeatedly as “he”. Like much science and technology, Google Translate has a male default. When I drive a car, the seatbelt is not designed to accommodate breast tissue. Any medicines I take are more likely to have been tested on male than on female animals. There are moral issues here: women pay taxes and buy products and should not be short-changed. But scientific objectivity is at stake, too. Because medical research is done mainly in males, there is a male bias in, for example, the choice of drug targets. Science is halving the potential field of innovation. This is not about active discrimination; the bias is largely unconscious. Google Translate defaults to the masculine pronoun because 'he' is more commonly found on the Web than 'she'. Yet that is changing: an analysis of American-English texts in Google Books shows that the ratio of masculine to feminine pronouns has fallen to around 2:1, from a peak of 4:1 in the 1960s. In the summer of 2012, I invited Google and several language-processing experts to a Gendered Innovations workshop at Harvard University in Cambridge, Massachusetts. They listened to the problem for about 20 minutes, then said: “We can fix that!” Although it is complicated, the search for solutions is on. Fixing the problem is great, but constantly retrofitting for women is not the best road forwards. A better way is to include gender at all relevant phases of research — when setting priorities, gathering and analysing data, evaluating results, developing patents and, finally, transferring ideas to markets. Science and technology should take into account the biological and social needs of both women and men. Unconscious sex and gender bias can be socially harmful and expensive. © 2014 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: 19329 - Posted: 03.06.2014

By Deborah Kotz Glaring gaps persist in medical researchers’ efforts to understand gender differences in common diseases, two decades after the passage of pivotal legislation mandating that more women be included in government-funded clinical trials, concludes a report being released Monday at a women’s health summit in Boston. The authors said research still lags on understanding how treatments for heart disease—the number one killer of women—affect the sexes differently, because women make up only one-third of the participants in clinical trials to test new drugs and medical devices, and most of these studies don’t report results for men and women separately. Women who don’t smoke are, for unknown reasons, three times more likely than non-smoking men to get lung cancer, but they’re still less likely than men to enroll in lung cancer studies, notes the report from Brigham and Women’s Hospital. And twice as many women suffer from depression as men, but fewer than 45 percent of animal studies to better understand anxiety and depression use female lab animals. “Women are now routinely included in clinical trials, but we are far from achieving equity in biomedical research,” said report leader Dr. Paula Johnson, executive director of the Brigham’s Connors Center for Women’s Health and Gender Biology. To address research disparities, the authors recommended that government agencies, drug manufacturers, hospital review boards that approve studies, and medical journal editors institute substantial changes to make women’s health a research priority. © 2014 Boston Globe Media Partners, LLC

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19318 - Posted: 03.04.2014

Sara Reardon A flipped mental switch is all it takes to make a fly fall in love — even if its object of desire is a ball of wax. A technique called thermogenetics allows researchers to control fly behaviour by activating specific neurons with heat. Combining the system with techniques that use light to trigger neurons could help to elucidate how different neural circuits work together to control complex behaviours such as courtship. Optogenetics — triggering neurons with light — has been successful in mice but has not been pursued much in flies, says Barry Dickson, a neuroscientist at the Howard Hughes Medical Institute's Janelia Farm Research Campus in Ashburn, Virginia. A fibre-optic cable embedded in a mouse’s brain can deliver light to cells genetically engineered to make light-activated proteins, but flies are too small for these fibre optics. Neither will these cells be activated when the flies are put into an illuminated box, because most wavelengths of visible light cannot penetrate a fly’s exoskeleton. Heat can penetrate the exoskeleton, however. Researchers have already studied fly behaviour by adding a heat-activated protein called TRPA1 to neural circuits that control behaviours such as mating and decision-making. When these flies are placed in a hot box, the TRPA1 neurons begin to fire within minutes and drive the fly’s actions1. But it would be better to trigger the behaviours more quickly. So Dickson’s lab has developed a system called the Fly Mind-Altering Device (FlyMAD), which uses a video camera to track the fly as it moves around in a box. The device then shines an infrared laser at the fly to deliver heat directly to the head. Dickson’s group presented the system last October at the Neurobiology of Drosophila conference at Cold Spring Harbor Laboratory in New York, and he is now submitting the work to a peer-reviewed journal. © 2014 Nature Publishing Group

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 19310 - Posted: 03.01.2014

Carl Zimmer Forcing male flies into monogamy has a startling effect: After a few dozen generations, the flies become worse at learning. This discovery, published on Wednesday in the Proceedings of the Royal Society, isn’t a biological excuse for men who have strayed from their significant other. Instead, it’s a tantalizing clue about why intelligence evolved. The new study was carried out by Brian Hollis and Tadeusz J. Kawecki, biologists at the University of Lausanne in Switzerland. They investigated a fly species called Drosophila melanogaster that normally has a very un-monogamous way of life. To find a mate, the male flies seek out females on rotting pieces of fruit. They often engage in battles to chase their rivals away, and then pick a female to court. “The males will do this wing song, where they use one wing or the other to generate a song,” said Dr. Hollis. This wing song may last from 10 minutes to an hour. Virgin females usually accept the overtures. But if a female has just mated, she will reject a new male’s advances. “If a male comes at her from behind and she’s not interested, she’ll kick at him with her rear legs,” said Dr. Hollis. If a couple of days have passed since her last mating, however, the female may choose to mate again. Seven years ago, while he was a graduate student at Florida State University, Dr. Hollis set out to study how the competition among males shapes their evolution. He began breeding two groups of flies — one polygamous, the other monogamous. In 2011, he took his flies to the University of Lausanne, where he met Dr. Kawecki, an expert on learning. The two scientists wondered if the different mating habits of Dr. Hollis’s flies had altered their brains. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 19309 - Posted: 03.01.2014

On 24 February, Uganda’s president, Yoweri Museveni, signed a draconian Anti-Homosexuality Bill into law, after 2 months of declining to do so. Science, he says, changed his mind—in particular, the findings of a special scientific committee his Health Ministry had appointed earlier in the month. “Their unanimous conclusion was that homosexuality, contrary to my earlier thinking, was behavioural and not genetic,” Museveni wrote to President Barack Obama on 18 February, in response to Obama’s pleas that he not sign the bill. “It was learnt and could be unlearnt.” But some scientists on the committee are crying foul, saying that Museveni and his ruling party—Uganda’s National Resistance Movement (NRM)—misrepresented their findings. “They misquoted our report,” says Paul Bangirana, a clinical psychologist at Makerere University in Kampala. “The report does not state anywhere that homosexuality is not genetic, and we did not say that it could be unlearnt.” Two other committee members have now resigned to protest the use of their report to justify the harsh legislation, which mandates life imprisonment for “aggravated homosexuality,” such as sexual acts with a minor, and prison terms of 7 to 14 years for attempted and actual homosexual acts, respectively. The law was first introduced into Uganda’s Parliament in 2009, but withdrawn after widespread objections to provisions that could have included the death penalty. As he signed the new version, passed by Parliament last 20 December, Museveni claimed that “mercenaries” were recruiting young people into gay activities. © 2014 American Association for the Advancement of Science

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: 19296 - Posted: 02.26.2014

By Sandhya Somashekhar, The Food and Drug Administration has approved 24 drugs for the treatment of male sexual dysfunction. For women, that number is zero. The disparity reflects drugmakers’ difficulties in unlocking the secret to revving up women’s sex drive. It also has become a rallying point for women’s advocates and even some members of Congress, who suggest that federal regulators seem more eager to approve sex-enhancing drugs for men than for women. It isn’t every day that political leaders and groups such as the National Organization for Women get involved in the drug- approval process, particularly for “lifestyle” drugs. But the unsuccessful quest for a “female Viagra” is sparking complicated questions about a woman’s right to a pill that may improve her sex life — and about how much of a libido lift is enough to be judged effective by the FDA. A drug called flibanserin, touted by some as the “little pink pill,” the counterpoint to Viagra’s little blue pill, was developed 12 years ago. Last month, women’s groups were disappointed when the FDA asked for further safety tests on the medication. Some critics say the agency — consciously or not — may be succumbing to society’s squeam­ishness about women’s sexual desires compared with those of men. “It looks to me like there are more hurdles being put in front of this drug than there have been on drugs addressing male dysfunction,” said Terry O’Neill, president of NOW. “Obviously, everyone only wants drugs to get on the market if they are proven safe and effective. But we don’t want attitudes to get in the way of a good drug.” © 1996-2014 The Washington Post

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19274 - Posted: 02.20.2014

by Laura Sanders A new analysis of cows shows that mamas make more milk for daughters. Other studies have hinted that human moms produce different milk for sons than for daughters, so perhaps lactating women also boost production for daughters. I love eavesdropping on people’s overly detailed coffee orders. You, sir, with the temerity to order a skinny split quad shot latte no whip no foam, with a side of lemon? Your extreme customizing just made my day. Such personalization was running through my mind as I read a recent study on cows. It turns out that another beverage is also subject to the specific, exacting standards of its drinker: milk. And the customer’s bossy demands seem to start before he or she is born. Heifers produce more milk for daughters than sons, Katie Hinde and colleagues report February 3 in PLOS ONE. When a cow gives birth to her first female, she makes about 1.6 percent more milk than she would have for a son, Hinde and colleagues found by analyzing the dairy records from a million and a half cows. And because calves born at dairy farms are taken away from their mothers soon after birth, the female calves’ requests to “make me more milk” must have come during pregnancy. Another interesting finding: The first pregnancy had an outsized effect on the cow’s future milk production. Cows that had sons first saw a slight bump in production when they got pregnant with a daughter, but didn’t catch up to the cows that had a daughter followed by a son. The first born daughter set the mom’s milk-making machinery on high, and that’s where it stayed for subsequent pregnancies. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19237 - Posted: 02.11.2014

You probably saw dozens of people’s faces today, many more if you live in a city. You may not have been conscious of it, but you were subtly judging every one by its beauty. Your eyes are drawn to more attractive faces, and the almost inescapable result is that more attractive people have advantages in almost every aspect of life, from job interviews to prison sentencing. But what drives us to crave beauty? According to one theory, gazing upon beauty stimulates the brain’s μ-opioid receptors (MOR), thought to be a key part of our biochemical reward system. At least in rodents, stimulating or inhibiting MOR neurotransmission not only tweaks the animals’ appetite for sex or food, but also the strength of their preferences for particular foods or mates. Is our preference for pretty faces driven by the same biochemical reward circuit? To find out, researchers invited 30 heterosexual men to browse a series of female faces on a computer (one pictured). Each man received either a dose of the MOR-stimulating drug morphine, the opioid receptor–inhibiting drug naltrexone, or a placebo. The results, published today in Molecular Psychiatry, suggest that we seek out beautiful faces at least in part because our brains reward us. Not only did stimulating MOR neurotransmission cause men to linger longer on faces that they rated as more beautiful, but the beauty rating also became more extreme, with beautiful faces rated as even more attractive relative to the rest of the faces. Inhibiting MOR had the opposite effects. The findings are yet more evidence that our social interactions are strongly influenced by the invisible hand of evolution, pushing us to find attractive mates. But the question remains, how do we decide which face is attractive in the first place? © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 19232 - Posted: 02.11.2014

By Matt McGrath Environment correspondent, BBC News Successful professional cyclists are seen as more handsome than their struggling colleagues, according to new research. Women rated facial attractiveness among riders in the 2012 Tour de France, won by Britain's Sir Bradley Wiggins. The top 10% of performers were rated on average as 25% better looking than the laggards. The scientists conclude that humans have evolved to recognise athletic performance in faces. The research has been published in the Royal Society journal, Biology Letters. Some biologists argue that evolution has shaped women to select mates on the basis that they would either make good fathers or would pass on good genes. Healthy, physically fit men would on average be seen as more attractive by women. A number of other studies in recent years have suggested that women have a sophisticated radar for athletic performance, rating those with greater sporting skill as more attractive. This new work, though, set out to test if the same applied to more inherent physical qualities such as stamina and endurance. Cycle of life Dr Erik Postma, from the Institute of Evolutionary Biology at the University of Zurich, asked people to rate the attractiveness of 80 professional cyclists from the 2012 Tour de France. The cyclists were all of a similar physical stature, were tanned and around the same age. BBC © 2014

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19214 - Posted: 02.06.2014

Controversy delights Dick Swaab; brains delight him; complexity delights him, though I don't know if you'd get that from reading his book, We Are Our Brains, in which causal links are made quite casually, like a man doing a crossword with a pencil. The Dutch neurologist is, after a 50-year career, a giant in the field. He is a professor of neurobiology at the University of Amsterdam. His directorship of the Dutch Institute for Brain Research yielded material that has been sent to 500 other research groups in 25 countries. He has propounded groundbreaking theories in his specialist area: the impact on brain development in the womb. Nonetheless, his book, despite directing itself squarely to the layperson, has been miles more successful than he thought, selling 100,000 copies ("the publishers say they knew it would be a hit. But at the start, they only printed 3,000 copies. So I know that is not true."). There are a number of lines you might file under, "Well, there's a curiosity" (for instance: "In professional violinists, the part of the cerebral cortex that directs the fingers of the left hand is five times as large as it is in people who don't play a stringed instrument"). And yet the real fireworks of the book are both more predictable and more profound: Swaab says hormones and chemical substances in utero affect the development of our sexual orientation or, put more simply, you have a gay brain by the time you are born. Male and female brains have "hundreds of differences", which explain all the ways in which men and women are different; "phobia, impulsiveness, ADHD and depression later in life" can be traced back to a mother's fearfulness during pregnancy, which activates her baby's "fear axis". © 2014 Guardian News

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19189 - Posted: 01.30.2014

Parasites don’t just cause nasty infections; they can also take over the minds of their hosts. The Ophiocordyceps fungus, for example, forces ants to climb up the stems of plants, where they die and release the fungus’s spores into the air to infect more ants. Likewise, it would make sense for sexually transmitted parasites to force their hosts to have sex more. But biologists have found very few examples of this in nature. A new study may explain why. To figure out why there isn’t more “sexual mind control” in nature, theoretical ecologist Ludek Berec, of the Biology Centre of the Academy of Sciences of the Czech Republic, and biological mathematician Daniel Maxin, of Valparaiso University in Indiana, turned to mathematical modeling. They created two strains of a hypothetical parasite species: an “ancestor” that did not make its hosts have sex more, and a mutant that did. Then they turned the two strains loose in a hypothetical host population and watched the parasites compete until the mutant strain either died out or replaced its ancestor. If the mutant strain replaced its ancestor, the researchers introduced a new mutant that had even more power over its host’s sex life. They then watched the two strains compete again, introduced yet another, stronger mutant when the old one outcompeted its predecessor, and so on. In this way, the species as a whole could “evolve” to exert more or less sexual mind control over its host. © 2014 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19180 - Posted: 01.29.2014

By SINDYA N. BHANOO In pursuit of a mate, male fruit flies often engage in combat, battling one another with their front legs. But when the flies are brothers, they are more likely to cooperate, researchers are reporting. In a new study in the journal Nature, Tommaso Pizzari, a zoologist at the University of Oxford, and colleagues write that brother flies live longer as a result. And there are clear benefits for females who live among brothers: They have a longer reproductive life span, a faster rate of egg production and a greater chance of laying eggs that mature to adulthood. The researchers exposed female flies in a laboratory to several different sets of males — three brothers; two brothers and an unrelated male; and three unrelated males. The most peaceful groups were the ones with three brothers, perhaps because supporting one’s kin is an alternative way to pass on common genes. “You can improve your reproductive success yourself or help individuals who also share your genes,” Dr. Pizzari said. Although fruit flies have been extensively studied in labs, the structure of their natural societies remain a bit of a mystery. © 2014 The New York Times Compan

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: 19168 - Posted: 01.25.2014

by Erika Engelhaupt Twerking is so 50 million years ago. In fact, it’s probably much older than that. Today, the provocative, butt-shaking dance move is enough of a social phenomenon to merit a word in the dictionary (with twerking defined about as tastefully as possible here by actor Morgan Freeman), but animals have been shaking their hindquarters for ages, for a variety of purposes (more on that below). Black widow spiders are the latest documented twerkers. In their case, it’s the males that shake their rears. Black widow females are aggressive predators and will immediately kill any prey detected in their webs. This presents a problem for males approaching a female to mate; in this case a literal misstep means becoming the female’s dinner. To figure out how the males avoid being eaten (at least before mating), researchers at Simon Fraser University in Canada measured vibrations created by males and by prey in webs of western black widows (Latrodectus hesperus). They compared the vibrations, and the females’ responses, to those of the hobo spider (Tegenaria agrestis), a species in which females rarely attack courting males. To capture the details of small vibrations, they used a fun tool called a laser Doppler vibrometer, which measures small changes in a laser beam aimed at a surface. Sure enough, black widow males appeared to have a death-avoidance strategy. They produced vibrations different from thrashing prey by means of “lengthy andrepeated bouts of abdominal tremulations” averaging 43 wiggles per second, the researchers report January 17 in Frontiers in Zoology. You can see a male's moves in this video: © Society for Science & the Public 2000 - 2014

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: 19167 - Posted: 01.25.2014

|By Stephanie Pappas and LiveScience Even water tastes sweeter when you're in love, new research finds. But not every emotion heightens the senses. Jealousy fails to bring out bitter or sour tastes, despite metaphors that suggest it might, researchers report in the December 2013 issue of the journal Emotion. That love alters one's sensory perceptions and jealousy does not is important to psychologists who study what are called "embodied" metaphors, or linguistic flourishes people quite literally feel in their bones. For example, studies have shown that people induced to feel lonely rate the temperature of the room as colder than do their unprimed counterparts. And the idea that important things have heft plays out physically, too: When someone believes a book is important, it feels heavier. But "just because there is a metaphor does not necessarily imply that we will get these kind of sensations and perception effects," said study researcher Kai Qin Chan, a doctoral candidate at Radboud University Nijmegen in the Netherlands. After seeing previous research on emotional metaphors, like the studies linking loneliness to coldness and heaviness to importance, Chan and his colleagues wanted to expand the question. "We always say, 'love is sweet,' 'honey baby,' this kind of thing," Chan told LiveScience. "We thought, let's see whether this applies to love." © 2014 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 19163 - Posted: 01.25.2014

By CARL ZIMMER The term “X chromosome” has an air of mystery to it, and rightly so. It got its name in 1891 from a baffled biologist named Hermann Henking. To investigate the nature of chromosomes, Henking examined cells under a simple microscope. All the chromosomes in the cells came in pairs. All except one. Henking labeled this outlier chromosome the “X element.” No one knows for sure what he meant by the letter. Maybe he saw it as an extra chromosome. Or perhaps he thought it was an ex-chromosome. Maybe he used X the way mathematicians do, to refer to something unknown. Today, scientists know the X chromosome much better. It’s part of the system that determines whether we become male or female. If an egg inherits an X chromosome from both parents, it becomes female. If it gets an X from its mother and a Y from its father, it becomes male. But the X chromosome remains mysterious. For one thing, females shut down an X chromosome in every cell, leaving only one active. That’s a drastic step to take, given that the X chromosome has more than 1,000 genes. In some cells, the father’s goes dormant, and in others, the mother’s does. While scientists have known about this so-called X-chromosome inactivation for more than five decades, they still know little about the rules it follows, or even how it evolved. In the journal Neuron, a team of scientists has unveiled an unprecedented view of X-chromosome inactivation in the body. They found a remarkable complexity to the pattern in which the chromosomes were switched on and off. © 2014 The New York Times Company

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: 19157 - Posted: 01.21.2014

by Susan Milius For springtails, sex can be an Easter egg hunt. Many males of the tiny soil organisms sustain their species by leaving drops of sperm glistening here and there in the landscape in case a female chooses to pick one up. “The male never meets the female,” says Zaira Valentina Zizzari of VU University Amsterdam, who studies a species of these extreme loners called Orchesella cincta. Just about every degree of mating intimacy, from unseen sperm donors to elaborate courtship and internal insemination, shows up in springtails. That makes the ancient group — which may not belong to the insects but to another set of six-legged arthropods on its own evolutionary trajectory — a treasure trove for biologists studying sex. In O. cincta, little brown-and-white males roam the leaf litter making no apparent effort to find a female. Instead, males pause here and there for a few seconds to leave behind white stalks topped by a shiny-coated globes, each holding more than 1,000 sperm. Sperm on a stalk is still viable after sitting two days in the lab. Outdoors it may not last so long. “You have a lot of rivals searching for sperm just to destroy it,” Zizzari says. Males eat rivals’ sperm. Given the rivalry, it wouldn’t be surprising if males engaged in an arms race to produce more sperm stalks than their competitors. But Zizzari was surprised to discover that male O. cincta make fewer sperm packages when a competitor is sperm-dotting the neighborhood. Maybe he’s enhancing the few he makes with extra sex appeal, Zizzari mused. To test the idea, she offered lab females a choice of globes from males with rivals or those made by an uncrowded guy. © Society for Science & the Public 2000 - 2014

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 19152 - Posted: 01.20.2014