Links for Keyword: Sexual Behavior

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Natasha Gilbert The eye-catching plumage of some male songbirds has long been explained as a result of sexual selection: brighter males compete more successfully for mates, so evolution favours their spread. Females, by contrast, remain drab. A new study turns this explanation on its head. Sexual-selection pressures drive females to evolve dull feathers more strongly than they drive males to become colourful, argues James Dale, an evolutionary ecologist at Massey University in Auckland, New Zealand. That surprising conclusion is based on a data set of plumage colour in nearly 6,000 songbirds, which Dale and his colleagues built. They used their data to ask how various potential evolutionary factors drive male and female plumage colour. If a particular songbird species was polygynous (that is, the males had more than one mate), displayed a large difference in size between males and females, and left care of the young mainly up to the females, then the researchers judged that sexual selection was likely to be an important factor in that species' evolution. The study, published in Nature1, found that sexual selection does play an important role in creating colour differences between male and female plumage. But the contrast is largely driven by females evolving to become drab. “Females are the chief architect of the difference,” says Dale. © 2015 Nature Publishing Group

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: 21605 - Posted: 11.05.2015

By JAMES GORMAN No offense to tenors, but outside of opera, a high male voice is seldom, if ever, considered seductive. Scientific research has shown that women find deep male voices attractive, and the same is true in other species, like howler monkeys. Stories from Our Advertisers But evolution is often stingy in its gifts, and researchers investigating male competition to reproduce have discovered an intriguing trade-off in some species of howler monkeys: the deeper the call, the smaller the testicles. Jacob Dunn of Cambridge University, one of the leaders of the research, said that species evolved either to make lower-frequency sounds, or have larger testicles, but none had both a very low sound and very large testicles. “It’s a great study,” said Stuart Semple, an evolutionary anthropologist at the University of Roehampton in London who was not involved in the research. “It shows this really clear trade-off.” Dr. Dunn and other researchers, including W. Tecumseh Fitch, of the University of Vienna, and Leslie A. Knapp, of the University of Utah, studied the size of a bone in the vocal apparatus, which is directly related to how deep the calls are, and the size of testicles, to come up for averages in nine species of howlers. They had been intrigued by great variations in both the size of the howlers’ hyoid bones in museum collections and in the size of the monkeys’ testicles as seen in the field. Dr. Knapp said that some of them are large enough that they are quite obvious “when you look up into the trees.” They used the museum samples of the bone and living monkeys in zoos for testicle measurements, and reported their findings Thursday in the journal Current Biology. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21554 - Posted: 10.23.2015

By Hanae Armitage CHICAGO, ILLINOIS—When prairie voles choose a mate, there’s no turning back—the “love chemical” oxytocin increases in their brains and they devote themselves to only each other. Although scientists have observed the behavioral and chemical side of prairie vole love, the neural networks behind commitment are still a mystery. Now, a group of scientists are working toward clearing up the neuronal backdrop of long-term love, and yesterday, presented their findings here at the annual meeting of the Society for Neuroscience. Studies have long suggested the nucleus accumbens, a part of the brain involved in reward processing, plays a crucial role in this type of devotion. To get a better look at the neuronal activity of this region, the scientists mounted a small-scale microscope that monitors calcium flux on top of a male prairie vole’s head (the more calcium into the neuron, the more neuronal activity). They saw that when male prairie voles interacted with their special lady vole, neuronal activity in the nucleus accumbens jumped 20% compared with when they interacted with a random female. Upon closer inspection, scientists saw that specific neurons that fired when the voles interacted with their mates stayed silent when they interacting with a different female. The result, though preliminary, indicates that mates stimulate the brain’s reward center in ways that nonmates cannot. © 2015 American Association for the Advancement of Science.

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: 21550 - Posted: 10.23.2015

Sara Reardon Naked mole rats are among the ugliest creatures in the animal kingdom, and they engage in acts that seem repulsive — such as eating one another’s, and their own, faeces. Now researchers have found one biological motivation for this behaviour. When a queen mole rat’s subordinates feed on her hormone-filled faeces, the resulting oestrogen boost causes the beta rats to take care of the queen’s pups, according to results presented on 18 October at the Society for Neuroscience meeting in Chicago, Illinois. Like bees, naked mole rats live in eusocial colonies, with only one queen rat and a few males that can reproduce. The rest of the colony consists of dozens of infertile subordinates that help with tasks such as foraging and defending the nest. The subordinate rats also take care of the queen’s pups as though the babies were their own: they build the nests, lick the pups and keep them warm with their body heat. Because they have no mature sex organs, subordinate rats cannot produce the hormones that would usually drive parenting behaviour. To look at what generates the rats’ caring ways, animal biologist Akiyuki Watarai and behavioural scientist Takefumi Kikusui at Azabu University in Japan played recordings of crying mole-rat pups to subordinate rats. Animals whose queens had just given birth paid more attention to the crying than those from other groups, suggesting that the pregnancy itself triggered subordinates’ maternal instincts. © 2015 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: 21541 - Posted: 10.21.2015

Kerri Smith Scientists have discovered two extra neurons in a worm species that — they thought — already had its entire nervous system mapped. “It is a bit of a shock,” says Richard Poole, a developmental biologist at University College London (UCL), and one of the team that found the neurons by accident. The researchers call them mystery cells of the male, or MCMs, because they are found only in male nematode worms. The neurons help the worms learn when to prioritize mating over eating, revealing how a seemingly simple brain can be capable of a complex learned behaviour — and one that differs between the sexes. Caenorhabditis elegans worms are the model animal of choice for many neuroscientists, because their neural circuits are so simple that they can be mapped in full. They have two sexes: hermaphrodite and male. Hermaphrodites, the best studied, have just 302 neurons, but males have more — the MCMs raise their total to 385 neurons1. The two ‘mystery’ cells were discovered when Poole’s colleague at UCL, Arantza Barrios, was looking at the distribution of a peptide often found in neurons, called pdf-1. She saw cells light up where she thought they should not — near the worm’s nose. The neurons develop when male worms reach maturity, the researchers worked out. Their report is published in Nature1. Sex or food? © 2015 Nature Publishing Group,

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: 21514 - Posted: 10.15.2015

By SINDYA N. BHANOO Tiny nematode worms called Caenorhabditis elegans have a peculiar reproductive story: Most females are hermaphrodites that make sperm, self-fertilize and produce more hermaphrodites. Males are few, and are known to mate with each other. Now, a new study reports that a variation in a single gene results in male worms with excretory pores that attract the sexual attentions of other males. “Other males copulate with this excretory pore, located on the neck,” said Matthew Rockman, a biologist at New York University. He and his colleagues reported their findings in the journal Current Biology. Although male worms are rare in the wild, they are easily bred in the laboratory. Researchers report that the gene variant, known as plep-1, may somehow be altering the chemical profile of the excretions in a way that makes them more attractive to other males. Copulation often does not work out well for the male that is approached, Dr. Rockman said. Males that mate with the excretory pore of another male usually leave behind a plug that weakens the worm and reduces life expectancy. Hermaphrodites with the variation of the same gene also have a lower life expectancy and do not reproduce as well. Next, the researchers want to learn what it is about a mutation in the plep-1 gene that makes males attractive to other males. © 2015 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: 21503 - Posted: 10.13.2015

Ed Yong This week, a team from the University of California, Los Angeles claimed to have found several epigenetic marks—chemical modifications of DNA that don’t change the underlying sequence—that are associated with homosexuality in men. Postdoc Tuck Ngun presented the results yesterday at the American Society of Human Genetics 2015 conference. Nature News were among the first to break the story based on a press release issued by the conference organisers. Others quickly followed suit. “Have They Found The Gay Gene?” said the front page of Metro, a London paper, on Friday morning. Meanwhile, the mood at the conference has been decidedly less complimentary, with several geneticists criticizing the methods presented in the talk, the validity of the results, and the coverage in the press. Ngun’s study was based on 37 pairs of identical male twins who were discordant—that is, one twin in each pair was gay, while the other was straight—and 10 pairs who were both gay. He analysed 140,000 regions in the genomes of the twins and looked for methylation marks—chemical Post-It notes that dictate when and where genes are activated. He whittled these down to around 6,000 regions of interest, and then built a computer model that would use data from these regions to classify people based on their sexual orientation. The best model used just five of the methylation marks, and correctly classified the twins 67 percent of the time. “To our knowledge, this is the first example of a biomarker-based predictive model for sexual orientation,” Ngun wrote in his abstract. The problems begin with the size of the study, which is tiny. The field of epigenetics is littered with the corpses of statistically underpowered studies like these, which simply lack the numbers to produce reliable, reproducible results.

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: 21502 - Posted: 10.13.2015

By Kat Long In the delivery room, the (slight) odds are that a newborn is a baby boy, not a girl. Males make up 51.3 percent of live births in the U.S., a rate that has remained about constant for the past seven decades. Experts assumed that this male-skewed sex ratio began at conception, but a new analysis of fetal records shows that the chances overall of finding a boy or a girl start out at 50–50 and change over the course of pregnancy—leaning female, then male, then female again as nine months pass. In the most comprehensive study of its kind to date, biologist Steven Hecht Orzack of the Fresh Pond Research Institute in Massachusetts and his collaborators analyzed roughly 36 million fertility treatment records, prenatal tests, induced abortions and U.S. Census data points. They discovered several nodes at which the sex ratio wavered from 50–50. Those vacillations most likely arise because of genetic and chromosomal abnormalities that cause natural abortions at various stages of gestation, write the study's authors in the Proceedings of the National Academy of Sciences USA. “This is basic knowledge about human pregnancy that we didn't have before,” Orzack says. “Demographers, developmental biologists, and many more can all get something out of this study.” © 2015 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21500 - Posted: 10.12.2015

By Bill Berkrot (Reuters) - U.S. researchers on Thursday said they had found a way to predict male sexual orientation based on molecular markers that control DNA function, but genetics experts warned that the research has important limitations and will not provide definitive answers to a potential biological basis for sexual preference. Findings from the study, which has yet to be published or reviewed in detail by other scientists, were presented at a meeting of the American Society of Human Genetics in Baltimore. It followed 37 pairs of identical male twins in which one was homosexual and one heterosexual, and 10 sets of twins in which both males were homosexual. The study found that the presence of specific epigenetic marks in nine areas of the human genome could predict homosexual preference with up to 70% accuracy. The epigenome is sometimes described as molecular "switches" that can turn on or silence individual genes in DNA. Scientists believe epigenetic differences can be influenced by environmental and lifestyle factors, from exposure to chemicals to parental nurturing. "To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers," Tuck Ngun, lead researcher on the study from the David Geffen School of Medicine of the University of California, Los Angeles, said in a statement. Genetics experts who critiqued the findings said it was premature to draw any conclusions on the predictive powers of epigenetic markers. © 2015 Scientific American

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: 21496 - Posted: 10.10.2015

Gay or straight? A saliva test can predict the answer, and get it right 67 per cent of the time – for male identical twins at least. The test, which uses clues from tiny modifications to a person’s genome, is the first that claims to detect sexual orientation. Many scientists have expressed caution over the results, while concerns over potential misuse of the test have led the study’s lead researcher to quit the project entirely. “The scientific benefit to understanding [why people vary in sexual orientation] is obvious to anyone with an iota of curiosity,” says Michael Bailey at Northwestern University in Evanston, Illinois. “The predictive test needs replication on larger samples in order to know how good it is, but in theory it’s quite interesting.” Over the last two decades, several studies have suggested that sexual orientation is, in part, down to our genes. Perhaps the biggest splash was made in 1993 by Dean Hamer’s team at the National Cancer Institute in Bethesda, Maryland, when they found that gay brothers tended to share a sequence of five genetic markers in a region of the X chromosome. The same region has been implicated in other studies of sexual orientation since, although researchers haven’t been able to single out “gay genes”. Other observations also suggest a genetic basis for sexual orientation, such as the mysterious fraternal birth order effect. For every male pregnancy a woman has, a subsequent son has a 33 per cent higher chance of being homosexual, although no one knows why. The overall chance is still low, however, rising from around 2 per cent to just 6 per cent for a third son. © Copyright Reed Business Information Ltd.

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: 21493 - Posted: 10.09.2015

By Jessica Schmerler Many studies trumpet the positive effects of oxytocin. The hormone facilitates bonding, increases trust and promotes altruism. Such findings earned oxytocin its famous nickname, the “love hormone.” But more recent research has shown oxytocin has a darker side, too: it can increase aggression, risk taking and prejudice. A new analysis of this large body of work reveals that oxytocin's effects on our brain and behavior actually look a lot like another substance that can cut both ways: alcohol. As such, the hormone might point to new treatments for addiction. Researchers led by Ian Mitchell, a psychologist at the University of Birmingham in England, conducted the meta-analysis, which reveals that both oxytocin and alcohol reduce fear, anxiety and stress while increasing trust, generosity and altruism. Yet both also increase aggression, risk taking and “in-group” bias—favoring people similar to ourselves at the expense of others, according to the paper published in August in Neuroscience and Biobehavioral Reviews. The scientists posit that these similarities probably exist because oxytocin and alcohol act at different points in the same chemical pathway in the brain. Oxytocin stimulates release of the neurotransmitter GABA, which tends to reduce neural activity. Alcohol binds to GABA receptors and ramps up GABA activity. Oxytocin and alcohol therefore both have the general effect of tamping down brain activity—perhaps explaining why they both lower inhibitions. © 2015 Scientific American

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: 21485 - Posted: 10.07.2015

Susan Milius Bachelor prairie voles can’t tell females of their species apart. Yet the clueless fellows can change, forming pair-bonds for life with the opposite sex and even distinguishing between two female strangers. Bachelors aren’t blind or stupid; they recognize individual males among their fellow short-tailed Microtus ochrogaster rodents scurrying through old fields in the center of North America. And males are certainly interested in the interchangeable females. In lab tests, bachelors claw and bite at cage dividers between the sexes, says Alexander Ophir of Cornell University. Conquering the divide and mating with a female after just six hours of her company can form a lifelong pair-bond between voles. Only about 5 percent of mammal species live this socially monogamous lifestyle, and the voles have played starring roles in studies of the neurobiology of bonding. (Social monogamists, including both voles and some Homo sapiens, don’t entirely forgo extra-pair encounters.) A pair-bonded couple can crowd three litters of young into their roughly six to nine months of life in the wild, Ophir says. One aid to speeding through family life: Females can get pregnant as soon as they give birth. “You sometimes see pups being delivered as males are trying to copulate with the female,” he says. Pair-bonding requires recognizing at least one female. “It’s all well and good to fall in love, but if you don’t know who you fell in love with, it’s worthless,” Ophir says. And paired-up voles can go further. Tests show they notice the difference between two females they have never mated with, Ophir and former student Tomica Blocker report in the October Animal Behaviour. © Society for Science & the Public 2000 - 2015

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: 21480 - Posted: 10.06.2015

By Margaret M. McCarthy “We have raised our children in a gender-neutral household since the day they were born, and we never allowed any sort of weapons, not even a water pistol,” a young mother told me emphatically from the microphone in the lecture hall where I’d just given a talk on the differences between male and female brains. “But the other day my seven-year-old son bit his peanut butter and jelly sandwich into the shape of a gun and started shooting his little sister with it!” The audience laughed appreciatively; everyone had a similar story. “What did we do wrong?” she pleaded. This story is a common refrain I hear when discussing my research on sex differences in the brain. There is no single correct answer when it comes to human behavior. Some researchers would insist that there is nothing parents can do to suppress the innate tendencies of boys to gravitate to guns and trucks while girls prefer dolls and tea sets. Others would disagree, arguing that there is no inherent biological difference between the brains of boys and girls. Rather, it is the parents’ own implicit biases and those of society at large that influence their children to behave in gender-typical ways. In the end, my response is that sex differences in the brain are more than some would like and less than others believe. Just how large those differences are, however, is the crux of an ongoing debate in science. And how much a brain’s function can be attributed to biology versus cultural expectations is a challenging question to answer. Confounding the issue is the concept of gender, a purely human construct that can itself influence brain development. Gender refers to both personal and societal perceptions of one’s sex, and embodies all the complexities of cultural expectations, inherent biases, and predetermined norms of behavior, each of which differs for boys and girls and can affect the young brain. © 1986-2015 The Scientist

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21472 - Posted: 10.03.2015

By Martin Enserink AMSTERDAM—Is being a woman a disadvantage when you're applying for grant money in the Netherlands? Yes, say the authors of a paper published by the Proceedings of the National Academy of Sciences (PNAS) this week. The study showed that women have a lower chance than men of winning early career grants from the Netherlands Organization for Scientific Research (NWO), the country's main grant agency. NWO, which commissioned the study, accepted the results and announced several changes on Monday to rectify the problem. "NWO will devote more explicit attention to the gender awareness of reviewers in its methods and procedures," a statement said. But several Dutch scientists who have taken a close look at the data say they see no evidence of sexism. The PNAS paper, written by Romy van der Lee and Naomi Ellemers of Leiden University's Institute of Psychology, is an example of a classic statistical trap, says statistician Casper Albers of the University of Groningen, who tore the paper apart in a blog post yesterday. (In Dutch; a shortened translation in English is here.) Albers says he plans to send the piece as a commentary to PNAS as well. Van der Lee and Ellemers analyzed 2823 applications for NWO's Veni grants for young researchers in the years 2010, 2011, and 2012. Overall, women had a success rate of 14.9%, compared with 17.7% for men, they wrote, and that difference was statistically significant. But Albers says the difference evaporates if you look more closely at sex ratios and success rates in NWO's nine scientific disciplines. Those data, which Van der Lee and Ellemers provided in a supplement to their paper, show that women simply apply more often in fields where the chance of success is low. © 2015 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: 21439 - Posted: 09.24.2015

By Virginia Morell Standing 2 meters tall and weighing as much as 1000 kilograms, European bison (Bison bonasus) are impressive animals. These cousins of the American bison—nearly driven to extinction in the last century—are being reintroduced in small herds across Europe, leading some farmers and forest managers to worry that the large herbivores will destroy their habitat. To better understand how the bison decide when and where to move, scientists studied a herd of 43 individuals in the Reserve Biologique des Monts-d’Azur in the Alpes-Maritimes region of France. They recorded the animals’ movements for 4 hours daily, identifying leaders, what type of action led others to follow, and where the herd moved. The herd wasn’t guided by a single leader, the scientists report in the November issue of Animal Behaviour. Instead, any individual regardless of sex or age could prompt the group to move, although most decisions were made by adult females—as is the case with most ungulates. A bison shows that it plans to change its location by taking at least 20 steps without stopping or lowering its head to graze. A potential leader was most likely to be followed if it walked in the direction that most of the others were facing—suggesting that bison vote with their feet. The researchers suspect that most leaders are adult females because they require higher quality food when lactating or pregnant. Wildlife managers can use this research to reduce human-bison conflicts, the scientists say. They need only identify a herd’s leaders, fit them with GPS collars, and install a virtual fence of alarms and electrical shocks. It should then be possible to control the leaders’ movements—and, thus, those of the entire herd.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21432 - Posted: 09.23.2015

By Emily DeMarco When it comes to finding a mate in the animal kingdom, females tend to gravitate toward males who appear strong and healthy. But a new study in zebra finches reveals that the small, gray-striped birds prefer mates with similar interests, such as a penchant for exploring the world. The drive for this compatibility is so strong that when scientists forced the females to mate up with males not of their choosing, the birds were more likely to cheat and shirk their parental duties, leading to more deaths among their chicks. The research “suggests that having a mate you’re behaviorally compatible with is very important from an evolutionary perspective for zebra finches,” says behavioral ecologist Sasha Dall of the University of Exeter, Cornwall, in the United Kingdom, who wasn’t involved in the study. Scientists have long been puzzled by female zebra finches. As opposed to females of other bird species, which tend to prefer males with brighter plumage or longer tails (traits that suggest that the males have good, healthy genes), female zebra finches seem to choose mates for some mysterious reason known only to each lady bird. Sometimes one will go for the guy with the bright red beak, sometimes the male with the thrilling song, sometimes neither. So what’s really driving this mate choice? In the past, scientists have speculated that a desire for compatibility might be the answer. But they have disagreed over whether the birds are on the lookout for males with the right genes (genetic compatibility between the partners might help lower the high rates of embryonic mortality seen in the species) or the right behaviors. © 2015 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: 21412 - Posted: 09.15.2015

By Susan Milius The larger Pacific striped octopus hunts shrimp using a strategy worthy of a schoolyard prank. And that’s not the only oddity about the species. It’s only the second octopus known with females that prolong motherhood, instead of dying after weeks of all-out coddling a single brood. But what everyone wants to talk about, researchers who study the species have found, is beak-to-beak mating. Before writhing, wrestling videos of the larger Pacific striped octopus (nicknamed LPSO), biologists knew of two forms of eight-armed sex. Some species mate at a distance, says Roy Caldwell of the University of California, Berkeley. The male extends one arm, always the same one, toward the female and up under her mantle. A travel-ready package of sperm emerges onto his skin and settles into a specialized groove on his mating arm. Waves of arm flexing resembling mammal intestinal motions nudge the packet toward one of two openings to her reproductive tracts. “It’s a messy way of reproducing,” Caldwell says. A lot of sperm packets “are wasted and go floating off.” Distance mating has other challenges. In an Indonesian octopus species, Caldwell’s former student Christine Huffard of the Monterey Bay Aquarium Research Institute discovered males hunkered in their dens sending an arm across the seafloor into the den of the female next door. On occasion, such females leave their dens on some octopus errand, dragging the male along by his mating arm. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21389 - Posted: 09.09.2015

Shankar Vedantam Girls often outperform boys in science and math at an early age but are less likely to choose tough courses in high school. An Israeli experiment demonstrates how biases of teachers affect students. RENEE MONTAGNE, HOST: At early ages, girls often outperform boys in math and science classes. Later, something changes. By the time they get into high school, girls are less likely than boys to take difficult math courses and less likely, again, to go into careers in science, technology, engineering or medicine. To learn more about this, David Greene spoke with NPR social science correspondent Shankar Vedantam. SHANKAR VEDANTAM, BYLINE: Well, the new study suggests, David, that some of these outcomes might be driven by the unconscious biases of elementary school teachers. What's remarkable about the new work is it doesn't just theorize about the gender gap, it actually has very hard evidence. Edith Sand at Tel Aviv University and her colleague, Victor Lavy, analyzed the math test scores of about 3,000 students in Tel Aviv. When the students were in sixth grade, the researchers got two sets of math test scores. One set of scores were given by the classroom teachers, who obviously knew the children whom they were grading. The second set of scores were from external teachers who did not know if the children they were grading were either boys or girls. So the external teachers were blind to the gender of the children. © 2015 NPR

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: 21374 - Posted: 09.02.2015

They are rather diminutive to be kings of the jungle, but two species of mirid bug make sounds similar to the roars of big cats. These calls have never before been heard in insects, and we’re not sure why, or how, the insects produce the eerie calls. The roars are too weak to be heard by humans without a bit of help. But Valerio Mazzoni of the Edmund Mach Foundation in Italy and his team made them audible by amplifying them using a device called a laser vibrometer. The device detects the minute vibrations that the bugs produce on the leaves on which they live. “When you listen to these sounds through headphones you’d think you were next to a tiger or lion,” Mazzoni. The team found that when two males were introduced on the same leaf, they seemed to compete in roaring duets. When one insect heard a roar, it always sounded its own, apparently in response. This suggests that, as in big cats, the roars might serve to establish dominance or attract females. Female mirids don’t seem to roar. But unlike the roars of big cats, the sounds produced by bugs are transmitted through the solid material beneath their feet, usually a leaf, rather than by the vibration of air molecules. Thousands of insect species communicate through such vibration, but these roars are unlike any other known insect noise. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21357 - Posted: 08.29.2015

Nell Greenfieldboyce Picking a mate can be one of life's most important decisions. But sometimes people make a choice that seems to make no sense at all. And humans aren't the only ones — scientists have now seen apparently irrational romantic decisions in frogs. Little tungara frogs live in Central America, and they're found everywhere from forests to ditches to parking lot puddles. These frogs are only about 2 centimeters long, but they are loud. The males make calls to woo the females. Amanda Lea, a biologist in the laboratory of Mike Ryan at the University of Texas, Austin, says past studies have given scientists a pretty good idea of what the females find appealing. "They tend to like longer calls. They also like lower-frequency calls," says Lea. "Then, the other thing that's a really big one for these gals is the 'call rate.' They love faster call rates. The faster a male can call, the better." But in real life, love is complicated. Female frogs face countless suitors. So Lea and Ryan wondered: Would a female really always pick the male that scored highest on the froggy love-call meter? To find out, they put female frogs in a room with some loudspeakers. From one speaker the scientists played a recording of frog call that had a really fast rate. But other features in this voice were less attractive. Then the researchers played a second, different call for the female frogs. This voice was more attractive, but it was slower. The ladies had to make a choice. "They have two traits to evaluate," Lea explains. "They have the call rate and they have the attractiveness of the call." © 2015 NPR

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21351 - Posted: 08.28.2015