Women whose left index and ring fingers are different lengths are more likely to be lesbians, a study suggests. Scientists measured the fingers of 18 pairs of female identical twins, where one was straight and the other gay. On average, the lesbians, but not the straight twins, had different sized index and ring fingers, typically a male trait, but only on the left hand. This may be the result of exposure to more testosterone in the womb, the University of Essex researchers said. The scientists also measured the fingers of 14 pairs of male identical twins, where one was straight and the other gay, but found no link. Both men and women were exposed to the "male" hormone, testosterone, in the womb - but some may be exposed more than others, the scientists said. Study author Dr Tuesday Watts, from the psychology department at Essex University, said: "Because identical twins, who share 100% of their genes, can differ in their sexual orientations, factors other than genetics must account for the differences. "Research suggests that our sexuality is determined in the womb and is dependent on the amount of male hormone we are exposed to or the way our individual bodies react to that hormone, with those exposed to higher levels of testosterone being more likely to be bisexual or homosexual. © 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: 25591 - Posted: 10.18.2018

Gina Mantica Have you ever seen a picture of a mother dog caring for an unusual baby, like a kitten? This sort of animal adoption story is an example of a phenomenon known as alloparenting: care provided to offspring that are not genetically related. We humans may toss around the phrase “It takes a village to raise a child,” but there are cases in the animal world where this is more literally true. Naked mole-rats, wrinkly mammals of the East African desert, offer an example of the whole “village” cooperating to raise offspring. Each individual naked mole-rat has a specific job. Like in a honeybee hive, a naked mole-rat colony has one queen, whose job it is to reproduce. There are just a few sexually reproductive males, who mate with the queen. All the others, both male and female, are either soldiers that protect the colony or workers that forage for food, dig tunnels and care for the queen’s offspring, known as pups. Until now, no one had a physiological explanation for why naked mole-rat workers care for pups that aren’t their own. Normally when a mom gives birth, estrogen levels are high and progesterone levels drop, resulting in maternal behaviors such as feeding or grooming. In many unusual adoption stories, like that of the mother dog caring for a kitten, the adoptive mom will have recently given birth to her own offspring – meaning her hormone levels have left her primed and ready to care for offspring, even those that aren’t her own. © 2010–2018, The Conversation US, Inc.

Related chapters from BN8e: 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: 25577 - Posted: 10.16.2018

By Ann Gibbons When it comes to gorillas, the males who help females out with their infants get benefits. The benefits? More babies. A new study of male gorillas in the wild in Rwanda has found that those who spend the most time grooming infants and resting with them—others’ offspring as well as their own—have about five times more offspring than males who don’t help out with the little ones. This is surprising, scientists say, because male caretaking isn’t usually considered a smart reproductive strategy in primate species where access to females is intensely competitive. Instead, researchers thought the most successful strategy for males would be to put more time and energy into outcompeting other males for a mate, as chimps do. That strategy still works for many male gorillas, who dominate small harems of females. But in 40% of the groups of mountain gorillas studied at the Dian Fossey Gorilla Fund’s Karisoke Research Center in Volcanoes National Park in Rwanda there is more than one male in a group, sometimes as many as nine. And those males need to be resourceful to get a female’s attention. © 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: 25571 - Posted: 10.15.2018

Marc Bekoff Ph.D. "Despite many efforts to narrow the gender gap in leadership roles, women remain universally underrepresented in the top leadership positions in virtually every discipline, including in the sciences, politics and business. We were therefore interested in pursuing a non-traditional approach to understanding this phenomenon by looking for clues in societies of non-human animals." "We have much to learn from the fascinating ways that natural selection has favored behavioral traits of non-human animals. By studying non-human mammals where female rule the roost, we may gain insights into secrets for smashing the glass ceiling." I recently learned about a new research paper published in The Leadership Quarterly by Mills College biologist Dr. Jennifer Smith and her colleagues entitled "Obstacles and opportunities for female leadership in mammalian societies: A comparative perspective." I'd already read a short summary of this landmark study in a New Scientist piece titled "The 7 non-human mammals where females rule the roost," and was thrilled when Dr. Smith agreed to be interviewed about this detailed data-driven study that "elucidates barriers to female leadership, but also reveals that traditional operationalizations of leadership are themselves male-biased." Our interview went as follows. Why did you and your colleagues conduct the research you did concerning female leadership in non-human mammalian societies? Can you please explain the importance of the comparative perspective for readers who don't know what this entails? © 2018 Sussex Publishers, LLC

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: 25567 - Posted: 10.12.2018

Hannah Devlin Science correspondent Healthy mice with two mothers have been born for the first time in a study that pushes the boundaries of reproductive science. Mice with two fathers were also born, but only survived a couple of days, the Chinese team behind the work reported. There is no imminent prospect of the techniques being used clinically in people, but the findings demonstrate that the biological barriers to same-sex reproduction can, technically, be overcome. “This shows us what’s possible,” said Wei Li, of the Chinese Academy of Sciences and a senior author of the paper. Scientists have previously managed to produce baby mice with same-sex parents, but the offspring had serious abnormalities and the methods used often required convoluted sequences of genetic manipulations, sometimes involving several generations of mice. The work explores a long-standing question in biology: that of why in mammals, equal genetic contributions from both a mother and a father are necessary. Elsewhere in the animal kingdom – in hammerhead sharks and komodo dragons, for instance – no genetic contribution from a father is required. A major barrier in mammals is a phenomenon known as “imprinting”, where for 100 or so genes only the copy that came from the mother or only the copy that came from the father are ever switched on. In the genome, maternal and paternal contributions are all jumbled together but these genes carry a chemical tag, labelling which parent the gene originated from in the first place. © 2018 Guardian News and Media Limited

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25566 - Posted: 10.12.2018

By Steph Yin Termites are often dismissed as nothing but home-destroying pests, less charismatic than bees, ants or even spiders. In fact, termites have been doing incredible things since the time of dinosaurs, maintaining complex societies with divisions of labor, farming fungus and building cathedrals that circulate air the way human lungs do. Now, add “overthrowing the patriarchy” to that list. In a study published this week in BMC Biology, scientists reported the first discovery of all-female termite societies. Among more than 4,200 termites collected from coastal sites in southern Japan, the researchers did not find a single male. Toshihisa Yashiro, a postdoctoral fellow at the University of Sydney and lead author of the paper, said in an email that he was utterly surprised by the discovery: “I got a headache, because we believed that having both males and females is the rule in termite societies.” The complete loss of males is rare across the animal kingdom, especially in animals with advanced societies. All-female lineages have previously been documented in a few ant and honey bee species, but their colonies are already dominated by queens and female workers. Termites, in contrast, are known for having colonies in which males and females both participate in social activities. Dr. Yashiro’s research is the first, in other words, to demonstrate that males can be discarded from advanced societies in which they once played an active role. His team collected 74 mature colonies of Glyptotermes nakajimai, a termite that nests in drywood, from 15 sites in Japan. Thirty-seven of the colonies were asexual and exclusively female, while the rest were mixed-sex. Egg-laying queens in asexual colonies stored no sperm in their reproductive organs and laid unfertilized eggs. © 2018 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: 25505 - Posted: 09.29.2018

by Angie Seech When I first started doing research into the changes that occur in a woman’s brain during pregnancy and the postpartum, I continued to come across the name of Jodi Pawluski, Ph.D., a researcher in the field of perinatal mental health. After reading this amazing review paper, I reached out to Jodi and her colleagues to thank her for her important work. Since that one email, I’ve had the opportunity to thank her in person and spend some time talking with her about perinatal mental health. Besides being a wonderful person, she is truly passionate about what she does and about helping women. Just read some of her answers to my questions about her research and views on the present and future status of maternal mental health and I’m sure you’ll agree! What is your ultimate goal as a researcher in this field? This is such a great, but broad, question! My ultimate goal is to have policies change to incorporate the importance of maternal mental and physical health for the mother. I also want these policies to value, promote, and support research on the neurobiology of motherhood and maternal mental illness. There is so much more that we need to know, but without support and interest we, as scientists, clinicians, parents, can’t find answers to our many questions. What is your most important question? Or the question that you really want to find the answer to in your career? At the moment I am doing some really interesting work on how maternal antidepressant medication use, such as SSRIs, can affect the neurobiology of the mother and developing offspring, using rodent models. One of my goals is to find out why some women respond well to SSRIs, such as Prozac, during the perinatal period and why others don’t. This is an important question and ultimately will allow for more precise and effective treatments. During my career I hope that my research significantly contributes to understanding how maternal mental illness affects the maternal brain and contributes to find ways in which we can safely and effectively treat these diseases. 2018 © MOMMY BRAIN EDU |

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 25483 - Posted: 09.24.2018

By Douglas Quenqua For solitary animals, giant pandas have an awful lot to say to one another. Their vocal repertoire comprises more than a dozen distinct grunts, barks and squeaks, most of which amount to some version of “leave me alone.” But when mating season rolls around, both male and female giant pandas turn to their preferred come-hither call: a husky, rapid vibrato that’s commonly known as the bleat. The bleat not only alerts other pandas to the presence of an available mate, it contains important information about the vocalist’s size and identity. Given the dense bamboo thicket that limits visual contact in most panda habitats and the brevity of panda mating season — females ovulate just once a year and can conceive for only a few days — the pandas’ ability to perceive the bleat is critical to reproduction among this once-endangered species. Now, researchers have determined that the bleat works best as a local call. A panda can discern aspects of a caller’s identity. like its size, from a bleat within about 65 feet, but the caller’s gender is only perceptible within about 33 feet, according to a study published Thursday in Scientific Reports. Megan Owen, a conservation ecologist at the San Diego Zoo Institute for Conservation Research and an author of the study, offered a human analogy for how this ability works. “If you’re walking into a crowded room and someone calls out your name, there’s a certain point where you can identify who that is, or maybe you can identify that it’s a male or female that is calling your name,” she said. “There’s information that’s encoded in that call, but that information degrades over distance.” To conduct the study, Dr. Owen and her colleagues — including Ben Charlton, another San Diego institute researcher who has studied panda bleats — obtained recordings of giant pandas from Chengdu, China, during breeding season. They then played those recordings through a speaker in a section of the San Diego Zoo Safari Park that contains bamboo similar in type and density to a typical panda habitat. By placing recording devices throughout the bamboo, the researchers were able to capture and analyze the bleats from various distances. © 2018 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: 25475 - Posted: 09.21.2018

By Jason Arment She was a cat lover with cotton-candy-colored hair and obnoxious tastes in music but similar politics to mine. While texting on Tinder, she suggested I might get to play with her kitty. We agreed that we would take her cat out to the park some time but that we would start with dinner and a drink. There were no other hints to me that anything thrilling might happen beyond my riding my motorcycle from Denver to Boulder for the meeting. Sitting together at an Italian restaurant, we got past the cat conversation and progressed to politics and music, jokes and laughter. We were communicating freely and enjoying each other’s company — pretty much everything I wanted out of a first date. As the waitress picked up the check, my date invited me back to her place. I went. I still didn’t think anything was going to happen until we were going to settle in to watch a movie and she changed her clothes right in front of me. So many veterans’ stories begin with them coming back home to find it’s a place with which they no longer identify. I don’t want to overstate my problems, but as a man who went to Iraq as a proud Marine only to realize what was happening there was nothing short of catastrophic, I started to rethink where exactly my heart aligned with my nation and where it fractured and split. © 2018 The New York Times Company

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: 25467 - Posted: 09.20.2018

By Meredith Wadman Controversy is exploding around a paper published earlier this month in PLOS ONE by a public health expert at Brown University describing reports by parents that their children suddenly experienced unease with the gender they were assigned at birth; the paper calls the condition “rapid onset gender dysphoria” (ROGD). The paper, by physician-scientist Lisa Littman, is drawing fierce criticism from transgender advocates, who call it antitransgender because it suggests that some cases of gender dysphoria may be “socially contagious.” They say the paper has serious methodological flaws, noting that Littman interviewed only parents, not the young people themselves, and recruited from websites frequented by parents who were concerned about their children’s apparently sudden gender transitions. Meanwhile, the reactions of Brown and the journal are being assailed by critics who accuse them of caving to political pressure. On Monday, PLOS ONE announced it is conducting a postpublication investigation of the study’s methodology and analysis. “This is not about suppressing academic freedom or scientific research. This is about the scientific content itself—whether there is anything that needs to be looked into or corrected,” PLOS ONE Editor-in-Chief Joerg Heber in San Francisco, California, told ScienceInsider in an interview yesterday. Also on Monday, Brown officials removed the university’s press release highlighting the paper from its website. On Tuesday, Bess Marcus, dean of Brown’s School of Public Health, wrote in an open statement that the university acted “in light of questions raised about research design and data collection related to the study.” She added that people in the Brown community have raised concerns that the study’s conclusions “could be used to discredit efforts to support transgender youth and invalidate the perspectives of members of the transgender community.” © 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: 25405 - Posted: 08.31.2018

Laurel Hamers Dealing with poop is an unavoidable hazard of raising children, regardless of species. But for naked mole rats, that wisdom is especially salient. During pregnancy, the scat of a naked mole rat queen — the only female in the colony that reproduces, giving birth to a few dozen pups each year — contains high levels of the sex hormone estradiol. When subordinate female naked mole rats eat that poop, the estradiol they pick up cues them to snap into parenting mode and care for the queen’s offspring, researchers report the week of August 27 in the Proceedings of the National Academy of Sciences. In colonies of naked mole rats (Heterocephalus glaber), lower-ranking females don’t have developed ovaries and don’t reproduce. They also don’t experience the pregnancy-induced hormonal shifts that usually cue parenting behaviors, yet they still care for the queen’s babies. Researchers gave poop pellets from nonpregnant queens to subordinates for nine days. One group got pellets with added estradiol, to mimic pregnancy poop. Levels of estradiol increased in the dung of subordinate females that ate the hormone-packed pellets, suggesting that scat snacks could induce measurable hormonal changes. And those mole rats were more responsive to the cries of pups than those that didn’t get the hormone boost, the team found. |© Society for Science & the Public 2000 - 2018.

Related chapters from BN8e: 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: 25383 - Posted: 08.28.2018

By Steph Yin Pipefish, along with their cousins sea horses and sea dragons, defy convention in love and fertility. In a striking role reversal, fathers give birth instead of mothers. During courtship, females pursue males with flashy ornaments or elaborate dances, and males tend to be choosy about which females’ eggs they’ll accept. Once pregnant, these gender-bending fathers invest heavily in their young, supplying embryos with nutrients and oxygen through a setup similar to the mammalian placenta. But this investment may also be cruelly conditional, according to a new study in Proceedings of the Royal Society B. Studying pipefish, scientists found evidence that pregnant fathers spontaneously abort or divert fewer resources to their embryos when faced with the prospects of a superior mate — in this case, an exceptionally large female. The researchers named their finding the “woman in red” effect, after the eponymous 1984 Gene Wilder film about a married man’s obsession with a woman in a red dress that becomes damaging to his family life. The reported effect is an interesting instance of sexual conflict, which is ubiquitous among animals, said Sarah Flanagan, a pipefish expert at the University of Canterbury in New Zealand. If you’re a romantic, you might think of mating as harmonious. But in nature, reproduction is more often a vicious power struggle between mothers and fathers with competing interests. A maternal analogue to the “woman in red” effect occurs among mice. Males are willing to kill a female’s offspring, if they are unrelated to him, before mating with her. In anticipation, a pregnant mother may terminate her pregnancy when exposed to a new male, rather than spending resources on doomed offspring. © 2018 The New York Times Company

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: 25378 - Posted: 08.25.2018

Leah Rosenbaum A firefly’s blinking behind is more than just a pretty summer sight. It’s known that fireflies flash to attract mates (SN Online: 8/12/15) — but the twinkles may serve another purpose as well. Jesse Barber, a biologist at Boise State University, had a hunch that the lights also warn off potential nighttime predators. He wasn’t the first person with this hypothesis. As far back as 1882, entomologist G.H. Bowles wrote of fireflies: “May not the light then serve … as a warning of their offensiveness to creatures that would devour them?” But the theory hadn’t been tested, until now. “We always assumed that bats don’t use vision for much,” Barber says. Many species of fireflies are “chemically protected,” meaning they taste awful to predators, Barber says. Yet if an insect doesn’t offer a warning of its bad taste, it may get sampled anyway. Barber noticed that, unlike moths, which signal their toxicity to bats with noises, fireflies don’t make a peep (SN Online: 7/3/13). He wondered if lightning bugs were warning bats of their disgusting taste with their blinking lights. Barber and colleagues wanted to see if it took bats longer to learn to avoid fireflies when the flashings were masked. The team began by introducing fireflies to three bats that had never encountered the bugs before. The bats learned to avoid the bright creatures “after just a few interactions,” Barber says. Those early exchanges went something like: catch, taste, drop. Soon, the bats avoided the fireflies completely. |© Society for Science & the Public 2000 - 2018. All rights reserved.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25371 - Posted: 08.24.2018

By Nicole M. Baran When Kathleen Morrison stepped onto the stage to present her research on the effects of stress on the brains of mothers and infants, she was nearly seven and a half months pregnant. The convergence was not lost on Morrison, a postdoctoral researcher at the University of Maryland School of Medicine, nor on her audience. If there ever was a group of scientists that would be both interested in her findings and unfazed by her late-stage pregnancy, it was this one. Nearly 90 percent were women. It is uncommon for any field of science to be dominated by women. In 2015, women received only 34.4 percent of all STEM degrees.1 Even though women now earn more than half of PhDs in biology-related disciplines, only 36 percent of assistant professors and 18 percent of full professors in biology-related fields are women.2 Yet, 70 percent of the speakers at this year’s meeting of the Organization for the Study of Sex Differences (OSSD), where Morrison spoke, were women. Women make up 67 percent of the regular members and 81 percent of trainee members of OSSD, which was founded by the Society for Women’s Health Research. Similarly, 68 percent of the speakers at the annual meeting of the Society for Behavioral Neuroendocrinology (SBN) in 2017 were women. In the field of behavioral neuroendocrinology, 58 percent of professors and 62 percent of student trainees are women. The leadership of both societies also skews female, and the current and recent past presidents of both societies are women. It wasn’t always this way. As Elizabeth Adkins-Regan, a professor emerita at Cornell University and the recent past president of the SBN puts it: “The whole field was founded by guys!” “It was not a women’s field in the beginning,” agrees C. Sue Carter, director of the Kinsey Institute and professor of biology at Indiana University. © 2018 NautilusThink Inc

Related chapters from BN8e: 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: 25341 - Posted: 08.17.2018

Yao-Hua Law What can males wear to look sexier? For zebra finches, the trick seemed simple: add a dash of red to their legs. Research conducted in the 1980s found that slipping red bands onto the legs of male birds turned them into sex magnets. Those studies became iconic in sexual selection research because they provided something rare in the discipline: strong, consistent effects. But data accumulated in recent years question these influential findings. Zebra finches (Taeniopygia guttata) are native Australian birds with a bright red-orange beak. They form monogamous breeding pairs in which the male and female cooperate to raise young. Easy to rear in captivity, zebra finches are model organisms for research in cognition and sexual selection. In the 1980s, ornithologist Nancy Burley, then at the University of Illinois, found that placing plastic leg bands of different colors—used by scientists to identify individual birds—on the legs of zebra finches affected the birds’ chances of mating. Burley reported, first in Science and then in other leading journals, that females preferred red-banded males and disliked green-banded males. Females also spent more time caring for nestlings sired by red-banded males. Burley’s results inspired subsequent research in female choice and maternal effects. But results contradictory to Burley’s began to emerge in the late 1990s. And this March, Wolfgang Forstmeier of the Max Planck Institute for Ornithology and colleagues published the strongest disagreement yet. Forstmeier’s lab ran eight experiments and analyzed unpublished data from four other labs and found no effects of leg-band colors on the reproductive success of male or female zebra finches. The new study also included a meta-analysis of 39 published studies, including 22 that supported leg-band color effects. The meta-analysis found that effect sizes shrank as sample sizes increased—a sign of selective reporting. © 1986 - 2018 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: 25333 - Posted: 08.15.2018

By Bilal Choudhry Killifish are a family of freshwater fish that have evolved to survive in the most difficult of situations. Here in the United States, for instance, the Atlantic killifish is known for having adapted to live in heavily polluted places like the Lower Passaic River. But in small murky puddles that come after heavy rains in parts of East Africa, another killifish, called Nothobranchius furzeri, or the African annual fish, has developed its own unique adaptations to its environment. Its embryos are able to enter a state of diapause, similar to hibernation in bears, when conditions aren’t right. It turns out that entering dormancy isn’t the only thing that’s unusual about this African killifish. In a paper published on Monday in Current Biology, a team of Czech researchers report that N. furzeri has the quickest known rate of sexual maturity of any vertebrate — approximately two weeks. By studying the fish’s unusual life cycle, they hope to gain insights into the process of aging in other vertebrates, including us. Dr. Martin Reichard, a biologist who is studying the evolution of aging at the Czech Academy of Sciences’ Institute of Vertebrate Biology, led a team of colleagues to Mozambique to study the fish’s developmental stages in the wild. There, they were able to observe embryos buried in the sand that had entered a dormant state. They also documented their maturation after rainfall. When N. furzeri receive cues from their environment, they can be flexible in sexual development. Under these circumstances, their embryos enter a stage of dormancy called embryonic diapause, a reproductive strategy that extends their gestational period and helps them survive unfavorable conditions, like a dry season. But when it rains, they undergo rapid growth, going from juvenile fish to mature adults that are able to reproduce in about two weeks. © 2018 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: 25304 - Posted: 08.07.2018

Abby Olena To convince female Drosophila melanogaster flies to mate, males sing—that is, they vibrate their wings to serenade females. In more than 50 years of studying these songs, scientists thought there were only two song modes, known as pulse and sine. But in a study published today (July 26) in Current Biology, researchers found that there are actually two different types of pulse songs, lengthening the set list to three and paving the way for a greater understanding of how the brain generates behavior. “The beauty of the paper is that it demonstrates the hidden complexity in these fruit fly songs,” says David Stern, a biologist at the Howard Hughes Medical Institute’s Janelia Research Campus who did not participate in the work. “Even what we thought was one song type hides really interesting variation, and this is a beautiful quantitative description of that underlying complexity that most of us missed in the past.” In a 2014 Nature study, Princeton biologist Mala Murthy and colleagues used computational models to predict which song male flies would produce based on sensory cues they received during courtship. The researchers’ models accounted for much of the variability in the males’ choice of song modes, but not all of it. Murthy says that one reason the models didn’t account for all the variability could be that they were missing information about the song itself. © 1986 - 2018 The Scientist.

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: 25266 - Posted: 07.28.2018

According to a new National Institutes of Health-funded study, it is not destiny that brings two fruit flies together, but an evolutionary matchmaker of sorts that made tiny adjustments to their brains’ mating circuits, so they would be attracted to one another while rejecting advances from other, even closely-related, species. The results, published in Nature, may help explain how a specific female scent triggers completely different responses in different male flies. “This study reveals how a very small tweak in brain wiring can result in large changes in very complex social behaviors, which can ultimately determine the fate of a species,” said Jim Gnadt, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), which supported the study. “Understanding how variation in brain circuits leads to changes in behavior is one of the primary goals of the NIH’s BRAIN Initiative and this study provides a piece of the puzzle.” Vanessa Ruta, Ph.D., professor at Rockefeller University in New York City, and her colleagues used cutting-edge genetic tools to compare the brain circuits behind courtship behavior in two closely related species of fruit fly, D. melanogaster and D. simulans. Previous studies showed that although males from both species could detect a specific pheromone, or scent, called 7,11-heptacosadiene (7,11-HD), their reactions to it were very different. Male D. melanogaster flies found it attractive while D. simulans males avoided females that carried it. In this study, Dr. Ruta and her team discovered that slight differences in the way the fly’s brains are wired may control these opposite reactions.

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: 25217 - Posted: 07.17.2018

By Jeré Longman Researchers have found flaws in some of the data that track and field officials used to formulate regulations for the complicated cases of Caster Semenya of South Africa, the two-time Olympic champion at 800 meters, and other female athletes with naturally elevated testosterone levels. Three independent researchers said they believed the mistakes called into question the validity of a 2017 study commissioned by track and field’s world governing body, the International Federation of Athletics Associations, or I.A.A.F., according to interviews and a paper written by the researchers and provided to The New York Times. The 2017 study was used to help devise regulations that could require some runners to undergo medical treatment to lower their hormone levels to remain eligible for the sport’s most prominent international competitions, like the Summer Games. The researchers have called for a retraction of the study, published last year in the British Journal of Sports Medicine. The study served as an underpinning for rules, scheduled to be enacted in November, which would establish permitted testosterone levels for athletes participating in women’s events from 400 meters to the mile. “They cannot use this study as an excuse or a reason for setting a testosterone level because the data they have presented is not solid,” one of the independent researchers, Erik Boye of Norway, said Thursday. The I.A.A.F. has updated its research, which was published last week, again in the British Journal of Sports Medicine. “The I.A.A.F. will not be seeking a retraction of the 2017 study,” the governing body said in a statement on Thursday. “The conclusions remain the same.” But the statement did little to dampen criticism by the independent researchers. The I.A.A.F. seems “bound to lose” an intended challenge by Semenya to the Court of Arbitration for Sport, a kind of Supreme Court for international athletics, said Boye, a cancer researcher and an antidoping expert. © 2018 The New York Times Company

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: 25200 - Posted: 07.13.2018

Yao-Hua Law It’s easy to tell a male from a female shark. Flip it over. If it has a pair of claspers — finger-like extensions jutting from the end of the pelvic fins — it is male; no claspers means female. Like a penis, claspers deliver sperm inside the female. That was marine biologist Alissa Barnes’ understanding until she dissected seven bigeye houndsharks (Iago omanesis) with claspers and found a complete female reproductive system in each. None of the seven sharks had any internal male sex organs. Six were pregnant. Barnes, of the Dakshin Foundation, shared her findings June 25 at the 5th International Marine Conservation Congress in Kuching, Sarawak, Malaysia. Barnes stumbled upon these hermaphrodite sharks at a port in Odhisa in eastern India in 2017. She was surveying local fishers to see if changes in their practices might explain a decline in hauls of sharks and rays. When she checked what the fishing vessels brought in, Barnes noticed two oddities. Male bigeye houndsharks greatly outnumbered females. And though males of this deepwater species are smaller than females, she saw immature males as large as female adults. Sensing something amiss, she took some sharks back to her lab for dissection. “I was amazed,” says Barnes, who admits she squealed during the dissections. Even before opening the fish, she had pressed on the bellies of the "male" sharks and felt the pups inside. |© Society for Science & the Public 2000 - 2018.

Related chapters from BN8e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 25195 - Posted: 07.12.2018