Links for Keyword: Sexual Behavior

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Grant Tomkinson and Makailah Dyer Examine your fingers. Which is longer? Is it the index finger (the finger you use to point with — technically the second digit, or 2D, counting the thumb), or the ring finger (the fourth digit, or 4D)? The relative length of the index and ring fingers is known as the digit ratio or the 2D:4D. For example, if your index finger is 2.9 inches (or 7.4 cm) long, and your ring finger is 3.1 inches (or 7.9 cm) long, your digit ratio is 0.935 (i.e., 2.9/3.1 or 7.4/7.9). Males typically have lower digit ratios (the ring finger in males is typically longer than the index finger) than females (the fingers are about the same length in females). The ratio does not change much with age. There is some indirect evidence that the digit ratio is determined during early fetal development — as early as the second trimester of pregnancy — by the balance between the steroid hormones testosterone and estrogen. The developing ring finger has a high number of receptors for testosterone: the more testosterone the fetus produces, the longer the ring finger, and so the lower the digit ratio. Our research team wanted to take this finger research a step further: could the differences predict athletic ability, and, if so, how?

Related chapters from BN8e: 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: 24062 - Posted: 09.14.2017

Reza Ziai In recent years, many individuals on the political left have been earnestly conveying the message that what a person is attracted to (i.e. mate preference) is entirely constructed by the environment. Their reasons for doing so seem sincere. Take for example, the oft-cited connection between the media’s portrayal of female standards of beauty and eating disorders like anorexia and bulimia. To postmodernists, since standards of attraction are seen as being environmentally produced, the media’s “stereotypical” portrayal of female beauty is also seen as being environmentally produced, sexist, and therefore, unjustifiable. Postmodernism (see also Critical Theory and The Frankfurt School) combats this perceived bigotry by attempting to justify the need to enforce changes in the status quo. Most notably in recent news, many liberal arts students have attempted to deplatform speakers like Charles Murray, Christina Hoff Sommers, and Ayaan Hirsi Ali from speaking on their campuses. Limiting free speech has been just one way that postmodernism and people on the far-left have tried to control the environment. Reforms (sometimes mandatory ones) have been seen in pronoun usage, soft drink sizes, the media, children’s toys, social attitudes, etc. Their idea is that since the environment (and not biology) affects our attitude, if you change the environment, you change the person, and thus, society is improved. By minimizing or ignoring the role that biology has on human nature, postmodernists can effectively blame all of the ills of the modern world on poorly designed laws, U.S. foreign policy, or Western cultural attitudes. Those who dissent from their view can be denounced as bigots and cast aside.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24061 - Posted: 09.14.2017

Devin Coldewey We count on machine learning systems for everything from creating playlists to driving cars, but like any tool, they can be bent towards dangerous and unethical purposes as well. Today's illustration of this fact is a new paper from Stanford researchers, who have created a machine learning system that they claim can tell from a few pictures whether a person is gay or straight. The research is as surprising as it is disconcerting. In addition to exposing an already vulnerable population to a new form of systematized abuse, it strikes directly at the egalitarian notion that we can't (and shouldn't) judge a person by their appearance, nor guess at something as private as sexual orientation from something as simple as a snapshot or two. But the accuracy of the system reported in the paper seems to leave no room for mistake: this is not only possible, it has been achieved. It relies on cues apparently more subtle than most can perceive — cues many would suggest do not exist. And it demonstrates, as it is intended to, a class of threat to privacy that is entirely unique to the imminent era of ubiquitous computer vision. Before discussing the system itself, it should be made clear that this research was by all indications done with good intentions. In an extensive set of authors' notes that anyone commenting on the topic ought to read, Michal Kosinski and Yilun Wang address a variety of objections and questions. Most relevant are perhaps their remarks as to why the paper was released at all: We were really disturbed by these results and spent much time considering whether they should be made public at all. We did not want to enable the very risks that we are warning against. The ability to control when and to whom to reveal one’s sexual orientation is crucial not only for one’s well-being, but also for one’s safety.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 24046 - Posted: 09.08.2017

By NATALIE ANGIER A normal human baby, according to psychologists, will cry about two hours over the course of a day. A notorious human crybaby, according to her older siblings, parents and the building superintendent, will cry for two hours every two hours, refusing to acknowledge any distinction between crying and other basic infant activities, like “being awake” or “breathing.” Current and former whine enthusiasts, take heart. It turns out that infant crying is not only as natural and justifiable as breathing: The two acts are physically, neurologically, primally intertwined. Scientists have discovered that the small cluster of brain cells in charge of fast, active respiration also grant a baby animal the power to cry. Reporting in the Proceedings of the National Academy of Sciences, Carmen Birchmeier and Luis Hernandez-Miranda, of the Max Delbruck Center for Molecular Medicine in Berlin, and their colleagues showed that infant mice stripped of this key node — a mere 17,000 neurons, located in the evolutionarily ancient hindbrain — can breathe slowly and passively, but not vigorously or animatedly. When they open their mouths to cry, nothing comes out. As a result, their mothers ignore them, and the poorly breathing pups quickly die. “This was an astonishing finding,” Dr. Birchmeier said. “The mother could see the pups and smell the pups, but if they didn’t vocalize, it was as though they didn’t exist.” The new study is just one in a series of recent reports that reveal the centrality of crying to infant survival, and how a baby’s bawl punches through a cluttered acoustic landscape to demand immediate adult attention. The sound of an infant’s cry arouses a far quicker and stronger response in action-oriented parts of the adult brain than do similarly loud or emotionally laden noises, like a dog barking or a neighbor weeping. © 2017 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 24037 - Posted: 09.05.2017

By Sam Wong It seems you can judge an athlete by their face – if they are a man, that is. Male athletes with a higher world ranking tend to be judged as more attractive by women, but there is no such trend among women. Several studies have previously reported a link between facial attractiveness and sporting performance in men, leading to suggestions that women respond to facial cues that reflect athletic ability in potential partners. Some have suggested this is because, in our evolutionary past, women might have benefited from choosing a partner with speed, skill and endurance. As a better hunter, the idea goes, he would have brought home more food, and he might pass on his fitness to their children. But these studies have been criticised, notably for only looking at men. They also tended to focus on team sports, therefore failing to isolate individual performance. To find more evidence, Tim Fawcett and colleagues at the University of Exeter, UK, collected photos of 156 men and women who competed at the 2014 Winter Olympics in the biathlon – an event combining cross-country skiing and shooting. Each athlete was rated for their facial attractiveness by members of the opposite sex, who didn’t know the purpose of the study. © Copyright New Scientist Ltd.

Related chapters from BN8e: 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: 23992 - Posted: 08.25.2017

Tina Hesman Saey Add a new ingredient to the sugar, spice and everything nice needed to make girls. A protein called COUP-TFII is necessary to eliminate male reproductive tissue from female mouse embryos, researchers report in the Aug. 18 Science. For decades, females have been considered the “default” sex in mammals. The new research overturns that idea, showing that making female reproductive organs is an active process that involves dismantling a primitive male tissue called the Wolffian duct. In males, the Wolffian duct develops into the parts needed to ejaculate sperm, including the epididymis, vas deferens and seminal vesicles. In females, a similar embryonic tissue called the Müllerian duct develops into the fallopian tubes, uterus and vagina. Both duct tissues are present in early embryos. A study by French endocrinologist Alfred Jost 70 years ago indicated that the testes make testosterone and an anti-Müllerian hormone to maintain the Wolffian duct and suppress female tissue development. If those hormones are missing, the Wolffian duct degrades and an embryo by default develops as female, Jost proposed. That’s the story written in textbooks, says Amanda Swain, a developmental biologist at the Institute of Cancer Research in London. But the new study “demonstrates that females also have a pathway to make sure you don’t get the wrong ducts,” says Swain, who wrote a commentary in the same issue of Science. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23976 - Posted: 08.19.2017

By Jenna Gallegos Pathogens are real jerks. As if infecting and killing plants and animals isn’t bad enough, they can also turn their hosts into zombies that spread the pathogens to their next victim. Now scientists report that bacteria make some victims summon other victims as their dying act. The bacteria hijack the chemical signaling pathway of insects, making them release a burst of hormones that serve as a beacon to attract friends and potential mates right before the bacteria kill off the host. Like malware marauding as an enticing link, the bacteria attract and then infect. Fruit flies are generally pretty good at avoiding hazards. They can detect when food is infected with a dangerous mold or when a parasitic wasp is nearby, said Markus Knaden, a researcher at the Max Planck Institute for Chemical Ecology in Jena, Germany, who was involved in the study. In both cases, the flies won’t lay their eggs near the infectious agent. That’s why Knaden and colleagues at Cornell University were so surprised when they found that flies were actually attracted to other insects with a certain bacterial infection. “If you’re sitting in a theater and someone next to you is coughing, you move to another chair,” said Bill Hansson, one of the Max Planck authors of the study, published Wednesday in the journal Nature Communications. They expected flies to behave the same way, but instead, healthy flies found their sick friends to be extremely attractive. © 1996-2017 The Washington Post

Related chapters from BN8e: 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: 23964 - Posted: 08.16.2017

Alice H. Eagly It’s no secret that Silicon Valley employs many more men than women in tech jobs. What’s much harder to agree on is why. The recent anti-diversity memo by a now former Google engineer has pushed this topic into the spotlight. The writer argued there are ways to explain the gender gap in tech that don’t rely on bias and discrimination – specifically, biological sex differences. Setting aside how this assertion would affect questions about how to move toward greater equity in tech fields, how well does his wrap-up represent what researchers know about the science of sex and gender? As a social scientist who’s been conducting psychological research about sex and gender for almost 50 years, I agree that biological differences between the sexes likely are part of the reason we see fewer women than men in the ranks of Silicon Valley’s tech workers. But the road between biology and employment is long and bumpy, and any causal connection does not rule out the relevance of nonbiological causes. Here’s what the research actually says. There is no direct causal evidence that biology causes the lack of women in tech jobs. But many, if not most, psychologists do give credence to the general idea that prenatal and early postnatal exposure to hormones such as testosterone and other androgens affect human psychology. In humans, testosterone is ordinarily elevated in males from about weeks eight to 24 of gestation and also during early postnatal development. © 2010–2017, The Conversation US, Inc.

Related chapters from BN8e: 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: 23963 - Posted: 08.16.2017

Conor Friedersdorf This week, headlines across a diverse array of media outlets proclaimed that at least one Google employee was so antagonistic to women that he circulated a 10-page “anti-diversity screed.” That is how Gizmodo characterized the now infamous internal memo when publishing it Saturday. Similar language was used in headlines at Fox News, CNN, ABC News, the BBC, NBC News, Time, Slate, Engadget, The Huffington Post, PBS, Fast Company, and beyond (including a fleeting appearance in a headline here at The Atlantic). But love or hate the memo, which makes a number of substantive claims, some of which I regard as wrongheaded (and which would’ve benefitted greatly from an editor with more emotional intelligence than the author to help him avoid alienating his audience, even if he was determined to raise all of the same arguments), the many characterizations of the memo as “anti-diversity” are inaccurate. Using that shorthand is highly misleading. As many who read past the headlines would later observe, its author, who was later fired, began, “I value diversity and inclusion, am not denying that sexism exists, and don’t endorse using stereotypes. When addressing the gap in representation in the population, we need to look at population level differences in distributions. If we can’t have an honest discussion about this, then we can never truly solve the problem.” The balance of his memo argues that he is not against pursuing greater gender diversity at Google; he says it is against the current means Google is using to pursue that end and the way the company conceives of tradeoffs between the good of diversity and other goods. (c) 2017 by The Atlantic Monthly Group.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23941 - Posted: 08.10.2017

By Jamie Strashin, The look on Melissa Bishop's face said it all. The Canadian 800-metre star had just run the race of her life, at the best possible moment, on the world's biggest stage. "I have never run faster in my life. It's the smartest race I have ever put down on a track," Bishop said of her performance in the final at the Rio Olympics last summer. But it still wasn't enough. Despite setting a new Canadian record (which she has since broken by running a 1:57.01), Bishop finished fourth in the Rio final, missing a bronze medal by 13 hundredths of a second. Perhaps more distressingly, she crossed the line close to two seconds slower than gold medallist Caster Semenya. "I remember seeing my agent and just falling into his arms, thinking, I can't believe this just happened. What just happened?" Bishop recalled. "And then I saw my dad, and my dad is a very emotional man and he was livid. Not because of how I raced, but because of the scenario we were in. And he just kept telling me, 'You have nothing to be ashamed of.'" The "scenario" of finishing well behind Semenya is a familiar one for competitors since the South African burst onto the scene at the 2009 world track and field championships. As an 18-year-old in Berlin, Semenya blasted away her competition, winning by almost two and a half seconds and clocking the fastest time of the year. Caster Semenya dominates 800m at 2009 world championships ©2017 CBC/Radio-Canada.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23933 - Posted: 08.09.2017

/ By Florence Williams The 17th century ushered in an astonishing age of scientific discovery, from Galileo’s positioning of the sun in the heavens to Newton’s Laws of Motion to Francis Bacon’s empiricism. Armed with new swagger and understanding, the scientific rationalists of the day figured the pivot from astronomy and physics to biology would be a piece of cake. The workings of the universe had been proved to adhere to laws and formulas. All would be properly unveiled in due time. “The bold men of science,” Edward Dolnick writes, “raced off to take on the mystery of life and promptly face-planted.” How mistaken they were. As Edward Dolnick writes in his amusing and informative “The Seeds of Life,” “The bold men of science raced off to take on the mystery of life and promptly face-planted.” In fact, they were fairly undone, partly by their own pigheaded biases and partly by the truly mystifying matters of genes and heredity, for which they were woefully ill prepared. It was not until 1875 that a German scientist finally put the sperm and the egg together conceptually. The journey to that insight was sometimes comical, sometimes misguided, and usually revealing of cultural mores, gender politics, and societal blind spots. Consider, for example, the common scientific belief that a woman’s contribution to baby-making must surely be minimal. Copyright 2017 Undark

Related chapters from BN8e: 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: 23921 - Posted: 08.07.2017

Daniel Trotta NEW YORK (Reuters) - While President Donald Trump has thrust transgender people back into the conflict between conservative and liberal values in the United States, geneticists are quietly working on a major research effort to unlock the secrets of gender identity. A consortium of five research institutions in Europe and the United States, including Vanderbilt University Medical Center, George Washington University and Boston Children's Hospital, is looking to the genome, a person's complete set of DNA, for clues about whether transgender people are born that way. Two decades of brain research have provided hints of a biological origin to being transgender, but no irrefutable conclusions. Now scientists in the consortium have embarked on what they call the largest-ever study of its kind, searching for a genetic component to explain why people assigned one gender at birth so persistently identify as the other, often from very early childhood. (reut.rs/2w3Ozg9) Researchers have extracted DNA from the blood samples of 10,000 people, 3,000 of them transgender and the rest non-transgender, or cisgender. The project is awaiting grant funding to begin the next phase: testing about 3 million markers, or variations, across the genome for all of the samples.

Related chapters from BN8e: 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: 23919 - Posted: 08.05.2017

By Abby Olena For more than 50 years, scientists have taken for granted that all snakes share a ZW sex determination system, in which males have two Z chromosomes and females have one Z and one W. But a study, published today (July 6) in Current Biology, reveals that the Central American boa (Boa imperator) and the Burmese python (Python bivittatus) use an XY sex determination system, which evolved independently in the two species. “This work is a culmination of a lot of questions that we’ve had about pythons and boas for a long time,” says Jenny Marshall Graves, a geneticist at La Trobe Univeristy in Melbourne, Australia, who did not participate in the study. Some of these questions came up for Warren Booth, a geneticist and ecologist at the University of Tulsa, as he studied parthenogenesis—the growth and development of offspring in the absence of fertilization. He noticed a pattern for organisms undergoing parthenogenesis: animal species that use a ZW system have only male (ZZ) offspring, and the organisms that use an XY system have only female (XX) offspring. Except this pattern doesn’t hold true for boas and pythons, who consistently produce female offspring by parthenogenesis. Booth contacted Tony Gamble, a geneticist at Marquette University in Milwaukee, Wisconsin, who studies sex chromosomes, to begin a collaboration to investigate whether boas and pythons might actually have X and Y chromosomes. Spurred by Booth’s questions, “I went back and reread some of the early papers” on snake sex chromosomes, says Gamble. “What became clear is that they didn’t show that boas and pythons had a ZW sex chromosome system. They just said it without any evidence.” © 1986-2017 The Scientist

Related chapters from BN8e: 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: 23815 - Posted: 07.09.2017

By Michael Price Male baboons that harass and assault females are more likely to mate with them, according to a new study, adding evidence that sexual intimidation may be a common mating strategy among promiscuous mammals. The study’s authors even argue that the findings could shed light on the evolutionary origins of our own species’ behavior, although others aren’t convinced the results imply anything about people. “I think the data and analyses in this study are first-rate,” says Susan Alberts, a biologist who studies primate behavior at Duke University in Durham, North Carolina. “[But] I also think it’s a big stretch to infer something about the origins of human male aggression towards women.” To conduct the research, Elise Huchard, a zoologist at the National Center for Scientific Research in Montpellier, France, and colleagues examined a group of chacma baboons (Papio ursinus) living in Tsaobis Nature Park in Namibia over a 9-year period. These brownish, dog-sized primates live in troops of dozens of males and females. Females will mate with multiple males throughout the year. The male chacma are about twice the size of females and aggressively fight one another and engage in howling competitions to establish dominance. The more dominant a male is, the more likely he is both to succeed in finding a mate and to sire offspring. Males rarely force females to mate, but after years spent observing the animals in the wild, Huchard noticed that a subtler form of sexual coercion appeared to be going on. “Males often chase and attack some females of their own group when meeting another group, and they generally target sexually receptive females on such occasions,” she says. “I spent a great deal of time studying female mate choice, and my main impression … was that females don't have much room to express any preference.” © 2017 American Association for the Advancement of Science

Related chapters from BN8e: 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: 23813 - Posted: 07.07.2017

By Debra W. Soh If there was a way of telling who in our society is sexually attracted to children, are we entitled to know? A recent study from Georg-August-University Göttingen in Germany suggests that we may need to grapple with this question. Phallometric testing, also known as penile plethysmography, is considered the gold standard in measuring male sexual arousal, and particularly, deviant sexual interests such as pedophilia, which is the sexual interest in prepubescent children, roughly aged 3 to 10. The test involves measuring the volume of blood in the test-taker’s penis using an airtight glass tube (or conversely, measuring penile circumference with a mercury strain gauge) while he is presented with a series of images of children and adults, and audio stories describing a corresponding sexual encounter. Phallometry is commonly used in forensic settings to assess the sexual interests of sex offenders, in order to determine their risk of re-offending. As one can imagine, sex offenders tend not to be forthright about their sexual preferences, which makes phallometry all the more important. It has, however, been criticized because the test can become easier for individuals to fool with each successive assessment. Brain scanning using fMRI holds much promise as a diagnostic tool in evaluating sexual interests, as research has documented a reliable network of brain regions involved in sexual arousal. The current study took this another step by testing whether brain functional activation could be used to infer what someone finds sexually interesting without them knowing. © 2017 Scientific American,

Related chapters from BN8e: 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: 23783 - Posted: 06.28.2017

By Alice Klein Women are missing out on optimum medical treatment because most pre-clinical drug research is done in male animals, a new study suggests. New drugs must be evaluated in animals before being considered for human trials. Over three-quarters of these studies use only male animals because of concerns that female hormone cycles will affect experiments. It is also widely assumed that what works for males will work for females. However, research by Natasha Karp at the Wellcome Trust Sanger Institute in Cambridge and her colleagues casts doubt on this assumption. They compared 234 physical traits in 14,000 male and female lab mice. Sex differences were identified for 57 per cent of quantifiable traits – like cholesterol level and bone mass – and for 10 per cent of qualitative traits, like head shape. In another 40,000 mice, they found that when they switched off specific genes, the effects varied according to sex. This suggests that genetic diseases may manifest themselves differently in males and females and require different treatments, says Karp. These sex nuances mean that drugs optimised for male animals may be less effective in females, or even cause harm, says Karp. Between 1997 and 2001, 8 of the 10 drugs that were pulled from the market in the US posed greater health risks for women – possibly as a result of male-biased animal research, she says. © Copyright New Scientist Ltd.

Related chapters from BN8e: 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: 23780 - Posted: 06.27.2017

By Karl Gruber Birds, fish, and even humans have shattered barriers when it comes to mating rituals, from which partner initiates the courting to which one picks up the check at a fancy restaurant. But things are a bit simpler for frogs, as males and females stick to clearly defined roles: Males serenade the females, and females pick their favorite males to mate. Now, a new study suggests that the smooth guardian frog of Borneo (Limnonectes palavanensis) is an exception to that rule. During the mating season, the female frogs sing to the males in an attempt to win them over—a reversal of the normal process. In fact, if you see a single frog surrounded by a bunch of serenading croakers, called a “lek,” it’s most likely a lucky male being courted by a chorus of females. Males occasionally belt out “advertisement calls” to let females know that they are available. After mating, it’s the males who stay behind to care for the eggs, even taking tadpoles to small ponds after they hatch. This is the first known example of role reversal in singing frogs, scientists write in a recent issue of Behavioral Ecology and Sociobiology. It may even represent the first case of full-blown sex role reversal, which would also require that males do the mate choosing. Researchers are working on that now, but they say that—judging by the high rate of female serenading—males may be the picky ones. © 2017 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23755 - Posted: 06.21.2017

Laurel Hamers When things get hot, embryonic bearded dragon lizards turn female — and now scientists might know why. New analyses, reported online June 14 in Science Advances, reveal that temperature-induced changes in RNA’s protein-making instructions might set off this sex switch. The findings might also apply to other reptile species whose sex is influenced by temperature. Unlike most mammals, many species of reptiles and fish don’t have sex chromosomes. Instead, they develop into males at certain temperatures and females at others. Bearded dragon lizards are an unusual case because chromosome combinations and temperature are known to influence sex determination, says ecologist Clare Holleley of the Commonwealth Scientific and Industrial Research Organisation in Canberra, Australia (SN: 7/25/15, p.7). When eggs are incubated below 32° Celsius, embryonic bearded dragons with two Z chromosomes develop as male, while dragons with a Z and a W chromosome develop as female. But as temperatures creep above 32°, chromosomally male ZZ dragons will reverse course and develop as females instead. “They have two sex chromosomes, but they also have this temperature override,” Holleley says. By comparing bearded dragons that are female because of their chromosomes and those that are female because of environmental influences, Holleley and her colleagues hoped to sort out genetic differences that might point to how the lizards make the switch. The team collected RNA from the brain, reproductive organs and other tissues of normal female, normal male and sex-reversed female Australian central bearded dragons (Pogona vitticeps). Then, the researchers compared that RNA, looking for differences in the ways the lizards were turning on genes. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23745 - Posted: 06.15.2017

Hannah Devlin Science correspondent “Love looks not with the eyes, but with the mind. And therefore is winged Cupid painted blind,” Shakespeare wrote. Now scientists have pinpointed the specific patterns of brain activity that accompany romance, offering a new explanation for why love sends our judgement haywire. As a relationship takes root, the study found, the brain’s reward circuit goes into overdrive, rapidly increasing the value placed on spending time with one’s love interest. This, at least, was the case in the prairie vole, scientists’ animal model of choice for studying the neuroscience of love. Elizabeth Amadei, who co-led the work at Emory University in Atlanta, said: “As humans, we know the feelings we get when we view images of our romantic partners, but, until now, we haven’t known how the brain’s reward system works to lead to those feelings.” In order to get more direct access to what is happening in the brain, Amadei and colleagues turned to the North American voles, which as a species have almost perfected monogamy. They mate for life, share nest-building duties and have an equal role in raising their young – although, like humans, voles have the occasional “extramarital” fling. Using electrical probes, the scientists recorded directly from the brains of female voles as they encountered a potential partner, mated for the first time and began to show signs of having formed a lifelong bond, indicated by “huddling” behaviour.

Related chapters from BN8e: 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: 23692 - Posted: 06.01.2017

By STEPH YIN A female and male get together. One thing leads to another, and they have sex. His sperm fuses with her egg, half of his DNA combining with half of her DNA to form an embryo. As humans, this is how we tend to think of reproduction. But there are many other bizarre ways reproduction can take place. For instance, scientists have discovered a fish carrying genes only from its father in the nucleus of its cells. Found in a type of fish called Squalius alburnoides, which normally inhabits rivers in Portugal or Spain, this is the first documented instance in vertebrates of a father producing a near clone of itself through sexual reproduction — a rare phenomenon called androgenesis — the researchers reported in the journal Royal Society Open Science on Wednesday. The possibility of androgenesis is just one of many mysteries about Squalius alburnoides. It’s not a species in the usual sense, but rather something called a hybrid complex, a group of organisms with multiple parental combinations that can mate with one another. The group is thought to have arisen from hybridization between females of one species, Squalius pyrenaicus, and males of another species, now extinct, that belonged to a group of fish called Anaecypris. To sustain its population, Squalius alburnoides mates with several other closely related species belonging to the Squalius lineage. That it can reproduce at all is unusual enough. Most hybrids, like mules, are sterile because the chromosomes from their parents of different species have trouble combining, swapping DNA and dividing — steps required for egg or sperm production. Squalius alburnoides males circumvent this problem by producing sperm cells that do not divide, and therefore contain more than one chromosome set. This is important because most animals, Squalius alburnoides included, need at least two chromosome sets to survive. © 2017 The New York Times Company

Related chapters from BN8e: 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: 23669 - Posted: 05.27.2017