Nicole Creanza and Kate Snyder How do individuals choose their mates? Why are some more successful at attracting mates than others? These age-old questions are broadly relevant to all animals, including human beings. Darwin’s theory of natural selection offers one way to answer them. Sometimes phrased as “survival of the fittest,” the theory can also apply to mate choice, predicting that it’s beneficial to choose the mate who’s best adapted to surviving in its environment — the fastest runner, the best hunter, the farmer with the highest yields. That’s a bit simplistic as a summary of human sexuality, of course, since people pair up in the context of complex social norms and gender roles that are uniquely human. Researchers like us do think, though, that mate choice in other animals is influenced by these kinds of perceived adaptations. It fits with scientists’ understanding of evolution: If females choose to mate with well-adapted males, their offspring might have a better chance of surviving as well. Advantageous traits wind up passed down and preserved in future generations. But in many species, males try to attract mates by displaying characteristics that seem to be decidedly non-adaptive. These signals – such as a dazzling tail on a peacock or a beautiful tune from a songbird – were originally a big wrench thrown into Darwin’s theory of natural selection. Traits like these seem to do the opposite of making an animal more likely to survive in its environment. A flashy tail display or a showy melody is cumbersome, and it announces you to predators as well as love interests. Darwin got so upset by this inconsistency that he said “The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick.” © 2010–2019, The Conversation US, Inc.

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: 25979 - Posted: 02.22.2019

By Meredith Wadman BethAnn McLaughlin has no time for James Watson, especially not when the 90-year-old geneticist is peering out from a photo on the wall of her guest room at Cold Spring Harbor Laboratory’s Banbury Center. “I don’t need him staring at me when I’m trying to go to sleep,” McLaughlin told a December 2018 gathering at the storied New York meeting center as she projected a photo of her redecorating job: She had hung a washcloth over the image of Watson, who co-discovered DNA’s structure, directed the lab for decades—and is well-known for racist and sexist statements. The washcloth image was part of McLaughlin’s unconventional presentation—by turns sobering, hilarious, passionate, and profane—to two dozen experts who had gathered to wrestle with how to end gender discrimination in the biosciences. McLaughlin, a 51-year-old neuroscientist at Vanderbilt University Medical Center (VUMC) in Nashville, displayed the names of current members of the National Academy of Sciences (NAS) who have been sanctioned for sexual harassment. She urged other NAS members—several of whom sat in the room—to resign in protest, “as one does.” She chided institutions for passing along “harassholes” to other universities. “The only other places that do this are the Catholic Church and the military,” she said. In the past 9 months, McLaughlin has exploded into view as the public face of the #MeToo movement in science, wielding her irreverent, sometimes wickedly funny Twitter presence, @McLNeuro, as part cudgel, part cheerleader’s megaphone. In June 2018, she created a website, MeTooSTEM.com, where scores of women in science, technology, engineering, and math (STEM) have posted mostly anonymous, often harrowing tales of their own harassment. In just 2 days that month, she convinced the widely used website RateMyProfessors.com to remove its “red hot chili pepper” rating for “hotness.” And after launching an online petition, she succeeded last fall in spurring AAAS, which publishes Science, to adopt a policy allowing proven sexual harassers to be stripped of AAAS honors. © 2018 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: 25961 - Posted: 02.13.2019

By Natalie Angier Most female flies take a low-rent approach to parenthood, depositing scores of seed-sized eggs in the trash or on pet scat to hatch, leaving the larvae to fend for themselves. Not so the female tsetse fly. She gestates her young internally, one at a time, and gives birth to them live. When each extravagantly pampered offspring pulls free of her uterus after nine days, fly mother and child are pretty much the same size. “It’s the equivalent of giving birth to an 18-year-old,” said Geoffrey Attardo, an entomologist who studies tsetse flies at the University of California, Davis. The newborn tsetse fly looks like a hand grenade and moves like a Slinky, and if you squeeze it too hard the source of its plumpness becomes clear — or rather a telltale white. The larva, it seems, is just a big bag of milk. “Rupture the gut,” Dr. Attardo said, “and the milk comes spilling out.” And milk it truly is — a nutritional, biochemical and immunological designer fluid that the mother fly’s body has spun from her blood meals and pumped into her uterus, where her developing young greedily gulped it down. Thus fattened on maternal largess, a tsetse fly larva can safely burrow underground and pupate for 30 days before emerging as a full-blown adult with a nasty bite and a notorious capacity to transmit a deadly disease called sleeping sickness. In a recent chemical and genetic analysis of tsetse fly milk, Dr. Attardo and his colleagues were startled to discover how similar it was to the product of the beloved gland that stamps us as mammals. “I was expecting something completely off the wall and different,” he said. “But there are frightening, fascinating overlaps with mammalian milk in the kinds of proteins we see.” © 2019 The New York Times Company

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: 25955 - Posted: 02.12.2019

By Lisa Rapaport New mothers who have friends ready to step in and help them, tend to have toddlers who score better on cognitive tests than the babies of women with smaller social support networks, a U.S. study suggests. Strong social ties to friends and family have long been linked to better behavioral and physical health outcomes for adults. And plenty of previous research also indicates that infants’ and toddlers’ bonds with caregivers can have a lasting impact on children’s emotional, intellectual and social development. But less is known about how the caregivers’ own social connections might influence early childhood cognitive development. For the current study, researchers examined data on 1,082 mother-child pairs. They questioned women about their family structure, friendships and relationships in their communities and also looked at test results from cognitive assessments done when children were 2 years old. Overall, mothers had an average of 3.5 friends in their social support networks. The kids of mothers with more than that tended to have higher cognitive test scores than the kids of those who had fewer, suggesting “network conditions were significantly associated with early cognitive development in children,” the study authors wrote. © 1996-2019 The Washington Post

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: 25954 - Posted: 02.12.2019

Jon Hamilton Women tend to have more youthful brains than their male counterparts — at least when it comes to metabolism. While age reduces the metabolism of all brains, women retain a higher rate throughout the lifespan, researchers reported Monday in the journal Proceedings of the National Academy of Sciences. "Females had a younger brain age relative to males," says Dr. Manu Goyal, an assistant professor of radiology and neurology at Washington University School of Medicine in St. Louis. And that may mean women are better equipped to learn and be creative in later life, he says. The finding is "great news for many women," says Roberta Diaz Brinton, who wasn't connected with the study and directs the Center for Innovation in Brain Science at the University of Arizona Health Sciences. But she cautions that even though women's brain metabolism is higher overall, some women's brains experience a dramatic metabolic decline around menopause, leaving them vulnerable to Alzheimer's. The study came after Goyal and a team of researchers studied the brain scans of 205 people whose ages ranged from 20 to 82. Positron emission tomography scans of these people assessed metabolism by measuring how much oxygen and glucose was being used at many different locations in the brain. The team initially hoped to use the metabolic information to predict a person's age. So they had a computer study how metabolism changed in both men and women. © 2019 npr

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: 25933 - Posted: 02.05.2019

By Jordana Cepelewicz Genitals are among the fastest-evolving features in the animal kingdom. They’re also among the most diverse, arrayed in all shapes and sizes, adorned with spines, hooks and even teeth. Ducks have corkscrew-shaped genitalia. The male sea horse has a brood pouch that receives his mate’s eggs for fertilization and in which he nurtures the resulting offspring until birth. Female cabbage white butterflies have a hinged jaw inside their genital tract. Nature is full of strange reproductive organs with unusual uses. For the most part, though, certain genital morphologies are associated with males, others with females. But in 2014, a tiny insect called the barklouse broke even that rule when researchers reported that the females of all four species of a genus found in the caves of Brazil had a penis. It didn’t just look like a penis but acted like one, too: a penetrative organ the female insects used to anchor themselves to their mates during copulation. Moreover, complementary changes in the genitalia of the males had left them with a small pumping mechanism inside a membranous “vagina-like” cavity. Content from The Coca-Cola Company Sustainability and closed-loop recycling systems must now become a global priority, from emerging nations to the world's largest economies. Read More The finding not only piqued widespread interest (and amusement — the team was awarded a comedic Ig Nobel Prize in 2017), but also led to a debate about whether the scientists involved were correct to refer to the structure, called a gynosome, as a “female penis.” (Some experts, for instance, disagree with that characterization because the gynosome collects sperm rather than delivering it.) © 1996-2019 The Washington Post

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: 25928 - Posted: 02.04.2019

By Kelly Servick In the animal world, monogamy has some clear perks. Living in pairs can give animals some stability and certainty in the constant struggle to reproduce and protect their young—which may be why it has evolved independently in various species. Now, an analysis of gene activity within the brains of frogs, rodents, fish, and birds suggests there may be a pattern common to monogamous creatures. Despite very different brain structures and evolutionary histories, these animals all seem to have developed monogamy by turning on and off some of the same sets of genes. “It is quite surprising,” says Harvard University evolutionary biologist Hopi Hoekstra, who was not involved in the new work. “It suggests that there’s a sort of genomic strategy to becoming monogamous that evolution has repeatedly tapped into.” Evolutionary biologists have proposed various benefits to so-called social monogamy, where mates pair up for at least a breeding season to care for their young and defend their territory. When potential mates are scarce or widely dispersed, for example, forming a single-pair bond can ensure they get to keep reproducing. Neuroscientist Hans Hofmann and evolutionary biologist Rebecca Young at the University of Texas in Austin wanted to explore how the regulation of genes in the brain might have changed when a nonmonogamous species evolved to become monogamous. For example, the complex set of genes that underlie the ability to tolerate the presence of another member of one’s species presumably exists in nonmonogamous animals, but might be activated in different patterns to allow prolonged partnerships in monogamous ones. © 2018 American Association for the Advancement of Science

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: 25847 - Posted: 01.08.2019

By Philippa Roxby Health reporter, BBC News Every year, there are always more baby boys than girls born in England and Wales. Fact. Why? Since records began in 1838, the cries of babies born every year have been predominately male. In not one year, stretching back to the start of Queen Victoria's reign, have girls outnumbered boys at birth. In 2017, in England and Wales, for example, there were 348,071 live male births and 331,035 live female births - a difference of roughly 17,000. And that higher tally of males compared to females born each year is a pattern that has repeated itself for nearly 180 years. In fact, a ratio of roughly 105 male births for every 100 female ones is generally seen as natural and normal. It is fairly consistent around the world, although in some countries like China and India the gap is wider because male offspring are more desirable. More surprisingly, it is a ratio that has been known about since the 17th Century. But why this ratio exists is not yet completely understood - although there are several theories. The first theory is an evolutionary one which says that in order to have an equal number of males and female in adulthood, there have to be slightly more males born. That is because being a male is a dangerous thing. Males are more likely than females to die in childhood and at all stages of life - from accidents, taking risks, suicide and from health problems. © 2018 BBC

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25821 - Posted: 12.26.2018

By Katharine Q. Seelye Eleanor Emmons Maccoby, a distinguished psychologist and a pioneer in the field of gender studies who was the first woman to head the Stanford University psychology department, died on Dec. 11 in Palo Alto, Calif. She was 101. Her death, at a retirement community, was confirmed by her son, Mark, who said the cause was pneumonia. Dr. Maccoby, whom the American Psychological Association listed among the 100 most eminent psychologists of the 20th century, conducted pathbreaking research in child development and gender studies. She explored a wide range of topics, including interactions between parent and child and the effect of divorce on children. But the overarching themes of her long career were the differences between the sexes and how they develop. These were the subjects of two of her most significant books: “The Psychology of Sex Differences” (1974) and “The Two Sexes: Growing Up Apart, Coming Together” (1998). “She advanced our understanding of how girls and boys develop the characteristics that we think of as boy things and girl things,” Dr. John H. Flavell, a psychology professor emeritus at Stanford, said in a telephone interview. The answer involved a complex combination of biological, cognitive and social factors, including the dynamic in which children learn from other children. Dr. Maccoby did not initially consider herself a feminist. But she was gradually awakened by slights along the way, like being not allowed to enter the Faculty Club at Harvard through its front entrance, which was reserved for men, even though she was a member. Asked in a video interview in 2013 how she became interested in gender issues, she replied, “We lived it.” © 2018 The New York Times Company

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: 25817 - Posted: 12.23.2018

By Leslie Nemo If you came across California mice in the wild, you wouldn’t hear a thing. Their jabber is ultrasonic—humans hear it only when it's slowed to five percent its original speed. But that’s when the imperceptible squeaks morph into a vocal range that’d put Mariah Carey to shame. Mice, you see, regularly vocalize to communicate in many different situations—which researchers did not know until recently. “It’s an under-appreciated part of biology of one of most diverse groups of mammals,” says Matina Kalcounis-Rueppell, a professor of biology at University of North Carolina, Greensboro who discovered about a decade ago that these mice vocalize. These sounds range from coos to startling barks. New research published in Frontiers in Ecology and Evolution shows that when these monogamous mice are separated from their mate and then reunited, the animals sometimes don’t handle it well—revealing a new side to their social lives and behavior. Here are some of the mouse calls recorded by Josh Pultorak, who recently earned his PhD with principal investigator Catherine Marler at the University of Wisconsin-Madison in the course of this research. The first sounds, short tweets, are considered friendly, and the most common. The second, slightly longer calls appear when the mice are getting “lovey-dovey”, says Pultorak. The third whale-like yelps are also friendly and connote a strengthening relationship.

Related chapters from BN8e: Chapter 19: Language and Lateralization; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 15: Brain Asymmetry, Spatial Cognition, and Language; Chapter 8: Hormones and Sex
Link ID: 25791 - Posted: 12.17.2018

By Tom Garlinghouse Male and female bees may look similar, but they have dramatically different dining habits, according to a new study. Despite both needing nectar to survive, they get this nutrient from different flowers—so different, in fact, that males and females might as well belong to separate species. To make the find, researchers spent 11 weeks observing the foraging habits of 152 species of bees in several flower-rich New Jersey fields. Then they brought the insects—nearly 19,000 in all—back to the lab and meticulously identified their species and sex. Males and females rarely drank nectar from the same type of flower, the team will report in Animal Behaviour. Using a statistical test the researchers found that male and female bee diets overlap significantly less than would be expected at random. © 2018 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: 25776 - Posted: 12.12.2018

By Daphna Joel and Cordelia Fine In 17th and 18th century Europe, the rise of egalitarian ideals created the need for a scientific account of women’s inferior status. Thus was born gender biological complementarity — the notion that, as historian of science Londa Schiebinger explains in The Mind Has No Sex, “Women were not to be viewed merely as inferior to men but as fundamentally different from, and thus incomparable to, men.” It has been with us in one way or another, roping in science to explain the gender status quo, ever since. At its core is the persistent belief that men’s and women’s natures can be usefully and meaningfully carved into two categories or “natural kinds,” that are distinct, timeless, and deeply biologically grounded. Today’s version of this idea continues a centuries long quest to find the source of this hypothesized divergence in abilities, preferences, and behavior in the brain: You can find this notion at work, for instance, in popular books like John Gray’s “Men Are from Mars, Women Are from Venus” in the 1990s, Louann Brizendine’s “The Female Brain” and “The Male Brain” the following decade, and last year’s “Results at the Top: Using Gender Intelligence to Create Breakthrough Growth” by Barbara Annis and Richard Nesbitt. But a version of the same assumption is also sometimes subtly present in scientific research. Consider, for example, Cambridge University psychologist Simon Baron-Cohen’s influential Empathizing-Systemizing theory of brains and the accompanying “extreme male brain” theory of autism. This presupposes there is a particular “systemizing” brain type that we could meaningfully describe as “the male brain,” that drives ways of thinking, feeling, and behaving that distinguish the typical boy and man from the typical “empathizing” girl and woman. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25747 - Posted: 12.04.2018

Susan Milius Mom nurses her young for weeks on milk that has four times the protein of a cow’s. Yet this mother’s not a mammal. She’s a jumping spider with eight legs and a taste for fruit flies. We mammals have named ourselves after our mammary glands. Yet other animals, from tsetse flies to pigeons, secrete their own versions of milk for their babies. The newly discovered nursing in Toxeus magnus could be the most mammal-like of all, a research team from China proposes in the Nov. 30 Science. Biologists have recognized T. magnus as a species since 1933, but a small spider’s mothering habit was easy to miss. The spiders hunt beasts such as fruit flies and will retreat to a little nest, perhaps attached to a leaf, to raise a family. Study coauthor Zhanqi Chen of the Chinese Academy of Sciences in Menglunzhen, who studies spider behavior, noticed several T. magnus sharing a nest in 2012 and wondered if the species had some sort of extended parental care. It was another five years before he spotted the nursing behavior, when a spiderling clamped itself against mom’s underside one exciting July night in 2017. With a T. magnus female under a microscope, a gentle finger push on the underside of the abdomen will squeeze a tiny bead of white liquid out of a crease called an epigastric furrow, the researchers say. For the first week or so after eggs hatch, a spider mom leaves milk droplets around the nest for the crawling dots of her young to drink. Then nursing turns more mammalian, with little ones pressing themselves against their mother’s body. |© Society for Science & the Public 2000 - 2018

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: 25737 - Posted: 11.30.2018

By Frankie Schembri Fruit flies might not sing songs, make art, or don traditional garments, but that doesn’t mean they don’t have culture. New evidence suggests female fruit flies (Drosophila melanogaster) can create unique dating customs based on the partners they see other female fruit flies select. Cultural traditions—the traits and behaviors that are handed down across generations and spread through social learning—have been found in the grooming patterns of certain apes and the songs of some whales and birds. But scientists had little proof that smaller creatures such as insects could have culture. So researchers set up a series of experiments in which one “observer” female fruit fly watched a “demonstrator” fly pick between two males that differed only in their color—pink or green. When it was their turn to mate, observers chose the same color of mate more than 80% of the time, compared with random chance, researchers report today in Science. The team also tested how reliably preferences were passed to the next generation by placing 12 observers in the center of a hexagonal container surrounded by six demonstrators who went exclusively for either pink or green males. In the next round of mating, the first observers to mate became the demonstrators. Over the course of 36 trials, the pink or green preference “trickled down” to the eighth generation of flies before they started to choose randomly again. © 2018 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: 25733 - Posted: 11.30.2018

By Michael Allen When a peacock catches the attention of a female, he doesn’t just turn her head—he makes it vibrate. That’s the surprising conclusion of a new study, which finds that a male peafowl’s tail feathers create low-frequency sounds that cause feathers on the females’ heads to quiver. The finding is “fascinating,” says Richard Prum, an evolutionary ornithologist at Yale University who was not involved with the work. As far as he knows, it’s the first demonstration that feathers respond to acoustic communication signals from other birds. Scientists have long known that a bird’s feathers can sense vibrations. Much like a rodent’s whiskers, they are coupled to vibration-sensitive nerve cells, allowing them to sense their surroundings. Feathers can, for example, detect changes in airflow during flight, and some seabirds even use feathers on their heads to feel their way through dark, underground crevices. When peacocks are ready to mate, they fan out their iridescent tail feathers (known as trains), before rushing at females, shaking those feathers to catch their attention. But when researchers discovered low-frequency sounds—which are inaudible to humans—coming from this “train rattle” several years back, no one knew how they worked. All they knew was that peahens perked up and paid attention to recordings of these “infrasounds,” even though they couldn’t see the males. © 2018 American Association for the Advancement of Science

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: 25730 - Posted: 11.29.2018

/ By Elizabeth Svoboda In 1997, a Stanford University neuroscientist wrote a letter to his colleagues. He signed the letter with his birth name, Barbara Barres, but made it clear that from now on he wished to be known as Ben. “Whenever I think about changing my gender role, I am flooded with feelings of relief,” he wrote. “Whenever I think about changing my gender role, I am flooded with feelings of relief.” “I hope that despite my trans sexuality you will allow me to continue with the work that, as you all know, I love,” he concluded his letter. To Barres’ great joy, his fellow scientists responded with unwavering support. What they didn’t know was that he’d been unable to sleep for a week as he mulled whether to transition to male or commit suicide. His new autobiography — published, sadly, after his death last year from pancreatic cancer — testifies to his personal courage on two fronts: first, as a dogged investigator of glia, the brain’s most numerous cells, which many had written off as purposeless; and second, as an advocate for female and gender-nonconforming scientists. An intense and sagacious child, Ben Barres — born Barbara — decided he wanted to be a scientist before reaching his fifth birthday. He favored microscopes and chemistry sets over dresses and jewelry. By college, it was clear his genius was equal to his dedication. He earned prestigious scholarships that helped fund a biology degree at MIT, then went on to tackle a medical degree at Dartmouth. The early challenges Barres faced often stemmed from appearing female in a male-dominated field. When he was the only person in an MIT class to solve an artificial intelligence problem, the professor scoffed and insisted his boyfriend must have done the work. Copyright 2018 Undark

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25675 - Posted: 11.13.2018

Chand and several other athletes throughout sports history have failed to qualify to compete in a women's event as a result of their biology. Starting in the 1960s, sex verification tests were done to ensure that only athletes determined to be biologically female could compete as women. That's because in most sports, the top male athletes outcompete the top female athletes by about 10%. More recently the motivation behind testing has shifted to determining whether an athlete has an "unfair" advantage. Since men typically have more testosterone than women and testosterone is linked to athletic performance, current tests measure female athletes' testosterone levels to ensure they are within a certain range. Can a test determine an individual's biological sex? And can testosterone produced by an athlete's own body provide an unfair advantage? pictogram of sprinters Click on "Human Development" to learn about the development of sex organs and characteristics, including hormone levels. Click on "Case Studies" to explore the sex verification tests that have been used throughout sports history by applying them to two fictitious athletes.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25674 - Posted: 11.13.2018

Researchers funded by the National Institutes of Health have reached a milestone in their quest to catalog the brain’s “parts list.” The NIH BRAIN Initiative Cell Census Network (BICCN) has issued its first data release. Posted on a public web portal (link is external) for researchers, it profiles molecular identities of more than 1.3 million mouse brain cells and anatomical data from 300 mouse brains – among the largest such characterizations to date. BICCN research teams (link is external) focused initially on a key area of the mouse motor cortex, an area of the brain that controls movement, as a first major step in the 5-year effort. Initiated in 2017, the BICCN projects aim to build comprehensive, three-dimensional common reference brain atlases that will ultimately integrate molecular, anatomical and functional data on cell types in mouse, human and non-human primate brains. To expedite scientific impact, they are making their data immediately available to the research community via the web portal. “No single research group could do this by themselves—they needed to leverage the power of a team,” explained Joshua Gordon, M.D., Ph.D., director of the National Institute of Mental Health (NIMH), which is helping to coordinate the BRAIN Initiative effort. “The BICCN is a product of nine different teams each bringing to bear their finely-honed tools to the same brain region at the same time. By doing so, they could compare results and create a unified resource for the community.” The new molecular fingerprints cover comprehensive information on gene transcription and epigenomic signature maps of the brain cells. Each type of cell is classified according to its molecular characteristics and identifiable by telltale marker genes.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 8: Hormones and Sex
Link ID: 25638 - Posted: 11.02.2018

By Daniel Engber Two decades ago, in late summer 1998, the journal Nature came out with an outrageous claim: Both women and men, a research paper argued, prefer faces with more “girlish” features. The authors of the study, based in Scotland and Japan, had expected the opposite result—that square-jawed, hunky faces, more Harrison Ford than Leonardo DiCaprio, would be deemed more attractive. “Our team has been working on this study for four years,” one of the scientists, Ian Penton-Voak, told the New York Times in advance of publication. “When it was found early on that there was a preference for feminized male faces, nobody believed it, so we did it again, and again. The preference for a feminized face keeps coming up.” Could it really be the case that everyone prefers a man with a gentle nose and a low-T brow? If so, then why are (or were) Harrison Ford and Leonardo DiCaprio both considered highly sexy? And what about the other sexy ’90s dyads of George Clooney and Jude Law, and Johnny Depp and Nick Nolte? The Nature data were no less perplexing for evolutionary psychologists like Penton-Voak. From that field’s perspective, manly features are indicative of a male’s reproductive fitness. Given this assumption, one might guess that women have evolved to find those traits the most appealing, since they help identify the sort of men with whom you could make the strongest, most immunocompetent children. What would women get from delicate men? A year later, in the summer of ’99, Penton-Voak and colleagues offered the beginnings of an explanation. For a second study, also out in Nature, and also drawn from research done in Scotland and Japan, they once again asked young women to evaluate male faces that had been digitally feminized to varying degrees—only now they had the women do so twice, at different points during their menstrual cycles. They found that a woman’s predilection for men with girlish features waxed and waned throughout the lunar month: When she looked at faces in the days leading up to ovulation, her tastes would tend a bit more masculine; later on she’d flip back the other way. © 2018 The Slate Group LLC

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: 25619 - Posted: 10.26.2018

By Kristina R. Olson On arrival at a friend's house for dinner one night in the fall of 2008, I joined the evening's youngest guest, five-year-old Noah, who was playing on the couch. Little did I know he would single-handedly change the course of my career. As a professor of developmental psychology, hanging out at the kids' table is not unusual for me. I study how children think about themselves and the people around them, and some of my keenest insights have come from conversations like this one. After some small talk, I saw Noah glance around the room, appear to notice that no one was looking and retrieve something from inside his pocket. The reveal was slow but the result unmistakable: a beloved set of Polly Pocket dolls. Over the next few years I got to know Noah well and learned more about his past (all names of children here are pseudonyms to protect their privacy). Noah's parents had first noticed that he was different from his brother in the preschool years. He preferred female playmates and toys more commonly associated with girls, but his parents were unfazed. As he got older, Noah grew out his previously short hair and replaced his fairly gender-neutral wardrobe with one that prominently featured Twinkle Toes—shoes that lit up in pink as he stepped. Unlike many similar kids, Noah's family, friends and school fully accepted him. They even encouraged him to meet other kids like himself, boys who flouted gender norms. Along with the other adults in Noah's life, I couldn't help but wonder: What did Noah's behavior mean? Was he gay? Could he just be a kid who paid less attention to gender norms than most? At the time I had no idea that these questions would soon guide my scientific research. © 2018 Scientific American

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25606 - Posted: 10.23.2018