Chapter 8. Hormones and Sex

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By Grace Huckins Genes on the X and Y chromosomes—and especially those on the Y—appear to be associated with autism likelihood, according to a study focused on people who have missing or extra sex chromosomes. The findings add to the ongoing debate about whether autism’s sex bias reflects a male vulnerability, a female protective effect or other factors. “The Y chromosome is often left out of genetic discovery studies. We really have not interrogated it in [autism] studies very much,” says Matthew Oetjens, assistant professor of human genetics at Geisinger Medical Center’s Autism and Developmental Medicine Institute, who led the new work. There is a clear sex difference in autism prevalence: Men are about four times as likely as women to have a diagnosis. But uncovering the reasons for that discrepancy has proved challenging and contentious. Multiple biological factors may play a role, in addition to social factors—such as the difficult-to-measure gulfs between how boys and girls are taught to behave. Add on the possibility of diagnostic bias and the question starts to look less like a scientific problem and more like a politically toxic Gordian knot. But there are some threads that researchers can pull to disentangle these effects, as the new study illustrates. People with sex chromosome aneuploidies—or unusual combinations of sex chromosomes, such as XXY in those with Klinefelter syndrome or a single X in Turner syndrome—provide a unique opportunity to examine how adding or taking away chromosomes can affect biology and behavior. Previous studies noted high rates of autism in people with sex chromosome aneuploidies, but those analyses were subject to ascertainment bias; perhaps those people found out about their aneuploidies only after seeking support for their neurodevelopmental conditions. © 2024 Simons Foundation

Keyword: Autism; Sexual Behavior
Link ID: 29596 - Posted: 12.11.2024

By Tim Vernimmen Few people are fond of earwigs, with their menacing abdominal pincers — whether they’re skittering across your floor, getting comfy in the folds of your camping tent or minding their own business. Scientists, too, have given them short shrift, compared with the seemingly endless attention they have lavished on social insects like ants and bees. Yet there are a handful of exceptions. Some researchers have made conscious career decisions to dig into the hidden, underground world where earwigs reside, and have found the creatures to be surprisingly interesting and social, if still not exactly endearing. Work in the 1990s and early 2000s focused on earwig courtship. These often-intricate performances of attraction and repulsion — in which pincers and antennae play prominent roles — can last hours, and the mating itself as long as 20 hours, at least in one Papua New Guinea species, Tagalina papua. The females usually decide when they’ve had enough, though males of some species use their pincers to restrain the object of their desire. Males of the bone-house earwig Marava arachidis (often found in bone meal plants and slaughterhouses) are particularly coercive, says entomologist Yoshitaka Kamimura of Keio University in Japan, who has studied earwig mating for 25 years. “They bite the female’s antennae and use a little hook on their genitalia to lock them inside her reproductive tract.” Size matters

Keyword: Sexual Behavior; Evolution
Link ID: 29559 - Posted: 11.16.2024

Andrew Gregory Health editor Doing more than an hour of moderate intensity exercise each week may reduce the severity of “baby blues” and almost halve the risk of new mothers developing major clinical depression, the largest analysis of evidence suggests. However, researchers behind the study acknowledged that finding the time amid so many new responsibilities and challenges would not be easy, and recovery from childbirth should be prioritised. New mothers could restart exercise with “gentle” walks, which they could do with their babies, and then increase to “moderate” activity when they were ready, they added. This moderate physical activity could include brisk walking, water aerobics, stationary cycling or resistance training, according to the team of academics in Canada. Maternal depression and anxiety are relatively common after giving birth and associated with reduced self-care and compromised infant caregiving and bonding, which could in turn affect the child’s cognitive, emotional and social development, the researchers said. Conventional treatments for depression and anxiety in the first weeks and months after giving birth mostly involve drugs and counselling, which are often associated with, respectively, side-effects and poor adherence, and lack of timely access and expense. Research has previously shown that physical activity is an effective treatment for depression and anxiety in general. But until now it has not been known whether it could reduce the severity of the baby blues in the first few weeks after giving birth or lower the risk of major postpartum depression several months later. © 2024 Guardian News & Media Limited

Keyword: Depression; Hormones & Behavior
Link ID: 29548 - Posted: 11.09.2024

By Phie Jacobs Whether it’s two newlyweds going in for a smooch after saying “I do” or a parent soothing their child’s scraped knee, kissing is one of humanity’s most recognizable symbols of affection. Clay tablets from ancient Mesopotamia dating to 2500 B.C.E. provide the earliest archaeological evidence of romantic kissing. But the behavior may be older than civilization itself, with some studies suggesting Neanderthals swapped spit with modern humans—and shared each other’s oral microbes—more than 100,000 years ago. Some researchers have suggested kissing evolved from behaviors such as sniffing, nursing babies, or even parents passing chewed-up food to their offspring. But in an article published this month in Evolutionary Anthropology, evolutionary psychologist Adriano Lameira of the University of Warwick offers another hypothesis. Drawing on his knowledge of great ape behavior, Lameira suggests kissing got its start as a fur grooming ritual still observed in modern-day chimpanzees and other great apes. Science sat down with Lameira to learn more about his work. This interview has been edited for length and clarity. Q: What made you want to study kissing? A: It’s a behavior that is charged with so much meaning and symbolism, perhaps the most iconic way of how we show affection on an individual and societal level. I was surprised to find that we know so little about its evolution and nature. In our lab, we’re mostly intrigued by the evolution of language, dance, and imagination. But in the largest sense we’re interested in behaviors and rituals that are evolutionary heirlooms from our apelike ancestors—things our ancestors did that set us on course towards who we are today. Q: Do other animals kiss, or is the behavior unique to humans? © 2024 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 29532 - Posted: 10.30.2024

By Claudia López Lloreda Success tends to breed success. For instance, when a mouse dominates its opponents over and over, it becomes increasingly aggressive—helping to ensure victory in future fights. This “winner effect” takes hold thanks to multiple changes in synaptic plasticity, according to new findings published today in Cell. The results begin to reveal the mechanisms behind various forms of aggression seen in animals, says Jacob Nordman, assistant professor of molecular and integrative physiology at Southern Illinois University, who was not involved in the work. “There’s some aggression that is defensive; there’s some aggression that is pathological; there’s some aggression that’s territorial,” he says. “There might be a set of behaviors and, in turn, a set of circuits and possibly plasticity within those circuits, that speak to that.” Innate aggression is controlled by the ventromedial hypothalamus (VMH)—also known as the “attack” center—which shapes an animal’s social behaviors and fear response. But aggression can be learned, too. When paired with a mouse that is naturally docile, a more dominant mouse will eventually attack the other—and if it prevails, it tends to pick even longer fights with rivals over the coming days, thanks to synapse strengthening and increased activity in the VMH, a 2020 study reported. Full-blown and more generalized aggression emerges after even longer winning streaks, and it involves additional mechanisms, the new study suggests: Changes to neuronal excitability and dendritic spine morphology help cement the animal’s hawkishness. “Aggression is malleable—you can shape it,” says Scott Russo, professor of neuroscience at the Icahn School of Medicine at Mount Sinai, who was not involved with the study. “It’s not something that’s defined only by genetics, but that actually these circuits that support aggressive social behavior can change as a consequence of experience.” © 2024 Simons Foundation

Keyword: Aggression; Hormones & Behavior
Link ID: 29524 - Posted: 10.19.2024

By Sofia Quaglia Parenting can be lots of work for a bird: all that flying back and forth transporting grubs and insects to a nest of demanding young. But some birds manage to forgo caring for their chicks — while still ensuring they’re well looked after. These birds lay their eggs in the nests of other birds that unknowingly adopt the hatchlings, nourishing and protecting them as their own. Only about 1 percent of all bird species resort to this sneaky family planning method, called obligate brood parasitism, but it has evolved at least seven separate times in the history of birds and is a way of life for at least 100 species. Since some brood parasites rely on several different bird species as foster parents, more than a sixth of all species in the avian world care for chicks that aren’t their own at some point. Throughout the millennia, these trespassers have evolved ingenious ways to fool the hosts, and the hosts have developed equally clever ways to protect themselves and their own. At each stage of the nesting cycle, it’s a game of subterfuge that plays out in color, sound and behavior. “There’s always something new — it’s like, ‘Oh, man, this group of birds went down a slightly different pathway,’” says behavioral ecologist Bruce Lyon of the University of California, Santa Cruz, who studies the black-headed duck (Heteronetta atricapilla), the sole obligate parasitic duck species. While many mysteries remain, new research is constantly unearthing just how intense this evolutionary tug-of-war can get.

Keyword: Sexual Behavior; Evolution
Link ID: 29505 - Posted: 10.05.2024

By Laura Sanders Pregnancy overhauls a woman’s body. The brain is no exception. A detailed study of a woman’s brain before, during and after pregnancy revealed sweeping neural changes, some of which stuck around months after her baby was born. The dataset, published September 16 in Nature Neuroscience, is the first comprehensive view of the neural changes that accompany gestation — a sort of “what to expect when you’re expecting” for the brain. “The results of this case study are astonishing,” says neuroscientist Clare McCormack of New York University Langone Health. “Here we see, for the first time in humans, the extent of brain changes that are under way throughout pregnancy.” This research joins a small number of other studies aimed at understanding the female brain at various stages of life (SN: 9/29/22). Collectively, the work suggests that the process of becoming a mother, called matrescence, is another stage of development, like the brain overhaul that happens in adolescence (SN: 2/27/23). Earlier experiments mostly compared brains of women before and after their pregnancies and inferred what happens in between (SN: 12/19/16). “There was a missing piece,” McCormack says. “The nine months of pregnancy was a black box, and we could only guess what that trajectory looks like.” With four MRI scans before pregnancy, 15 scans during pregnancy and seven scans in the two years after the baby was born, the new study follows the entire arc for one mother. © Society for Science & the Public 2000–2024.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 29485 - Posted: 09.18.2024

By Ellen Barry A study of adolescent brain development that tested children before and after coronavirus pandemic lockdowns in the United States found that girls’ brains aged far faster than expected, something the researchers attributed to social isolation. The study from the University of Washington, published on Monday in the Proceedings of the National Academy of Sciences, measured cortical thinning, a process that starts in either late childhood or early adolescence, as the brain begins to prune redundant synapses and shrink its outer layer. Thinning of the cortex is not necessarily bad; some scientists frame the process as the brain rewiring itself as it matures, increasing its efficiency. But the process is known to accelerate in stressful conditions, and accelerated thinning is correlated with depression and anxiety. Scans taken in 2021, after shutdowns started to lift, showed that both boys and girls had experienced rapid cortical thinning during that period. But the effect was far more notable in girls, whose thinning had accelerated, on average, by 4.2 years ahead of what was expected; the thinning in boys’ brains had accelerated 1.4 years ahead of what was expected. “That is a stunning difference,” said Patricia K. Kuhl, a director of the Institute for Learning and Brain Sciences at the University of Washington and one of the study’s authors. The results, she added, suggested that “a girl who came in at 11, and then returned to the lab at age 14, now has a brain that looks like an 18-year-old’s.” Dr. Kuhl attributed the change to “social deprivation caused by the pandemic,” which she suggested had hit adolescent girls harder because they are more dependent on social interaction — in particular, talking through problems with friends — as a way to release stress. The difference between the genders “is just as clear as night and day,” Dr. Kuhl said. “In the girls, the effects were all over the brain — all the lobes, both hemispheres.” © 2024 The New York Times Company

Keyword: Stress; Development of the Brain
Link ID: 29477 - Posted: 09.11.2024

By Frieda Klotz For five years, Clare Dolman took lithium to manage her bipolar disorder. The medicine kept her happy and well with few side effects, and she described it as a wonder drug. But when she began to plan for a pregnancy, her psychiatrist advised her to go off the medication to protect the fetus. This was 1988, and it was the standard guidance at the time. While Dolman experienced some stresses during the pregnancy, her mood remained stable. But soon after giving birth, she began to experience mild hallucinations. “I thought, yes, there’s something wrong here,” she recalled. “But I had the insight still to see that I was getting ill, and my husband knew I was getting ill because he had seen me really bad.” She went on to spend five weeks in the hospital. Clare Dolman at the launch of the Bipolar Commission at the U.K. Parliament. Dolman, who has bipolar disorder, stopped taking lithium during her own pregnancies more than 30 years ago. She later became a mental health advocate and has studied the experiences of pregnant women with the illness. Visual: Courtesy of Clare Dolman Bipolar disorder involves extreme fluctuations in mood and is classified into different types according to symptoms and severity. For women with the condition, pregnancy can be a fraught endeavor as they balance the health of their growing fetus with their own mental state. Many, like Dolman, stop taking the medications that keep them well — which can lead to a recurrence of symptoms — and some avoid pregnancy altogether.

Keyword: Schizophrenia; Sexual Behavior
Link ID: 29475 - Posted: 09.11.2024

By Darren Incorvaia Imagine being a male firefly when suddenly the telltale flashing of a female catches your eye. Enthralled, you speed toward love’s embrace — only to fly headfirst into a spider’s web. That flashy female was in fact another male firefly, himself trapped in the web, and the spider may have manipulated his light beacon to lure you in. This high-stakes drama plays out nightly in the Jiangxia District of Wuhan, China. There, researchers have found that male fireflies caught in the webs of the orb-weaver spider Araneus ventricosus flash their light signals more like females do, which leads other males to get snagged in the same web. And weirdly, the spiders might be making them do this, almost like hunters blowing a duck call to attract prey. “The idea that a spider can manipulate the signaling of a prey species is very intriguing,” said Dinesh Rao, a spider biologist at the University of Veracruz in Mexico. “They show clearly that a trapped firefly in the web attracts more fireflies.” Dr. Rao was not involved in the research, but served as a peer reviewer of the paper published Monday in the journal Current Biology. Xinhua Fu, a zoologist at Huazhong Agricultural University in Wuhan, was in the field surveying firefly diversity when he first noticed that male fireflies seemed to end up ensnared in orb-weaver spider webs more often than females. Wondering if the spiders were somehow specifically attracting males, he teamed up with Daiqin Li and Shichang Zhang, animal behavior experts from nearby Hubei University, to get to the bottom of this sticky mystery. Working near paddy fields and ponds, the researchers observed the flashing of trapped male fireflies and saw that it more closely resembled that of females than of free-flying males. Trapped males flashed using only one of their two bioluminescent lantern organs, and they made one flash at a time rather than multiple flashes in quick succession, the same lighting signals females send when trying to attract males. © 2024 The New York Times Company

Keyword: Animal Communication; Sexual Behavior
Link ID: 29443 - Posted: 08.21.2024

By Erin Garcia de Jesús An appetite-stimulating protein can reverse anorexia in mice. Mice with lack of appetite and weight loss — symptoms similar to people with anorexia — that were genetically tweaked to secrete a protein called ACBP ate more food and weighed more than anorexic animals with an ACBP deficit, researchers report August 14 in Science Translational Medicine. The finding points to a potential treatment target for people with the eating disorder. “Anorexia is a whole brain and body illness” that is difficult to treat, says psychiatrist and neuroscientist Rachel Ross, who wasn’t involved with the new work. “One of the major challenges is that the brain of a person with anorexia is directly fighting against their body.” While the body screams for food, the brain prioritizes the need to restrict weight (SN: 7/26/13). Globally, around 1 percent of women and 0.2 percent of men develop the disorder. Roughly just a third of those people fully recover. Yet, no drugs are available; treatment typically involves medical care to stabilize weight and therapy to mend patients’ relationships with food. Some cancer patients can also develop a similar disorder called cancer cachexia, which comes from an impaired metabolism, that is similarly tough to treat (SN: 7/30/24). “Anything that has the potential to provide some sort of mechanism that would be useful for creating a new therapeutic is huge,” says Ross, of Albert Einstein College of Medicine and Montefiore Health System in New York City. And although there’s no guarantee the results will apply to people, the new findings suggest that ACBP, a protein that helps turn on parts of the brain that arouse appetite, may have that potential. © Society for Science & the Public 2000–2024.

Keyword: Obesity; Hormones & Behavior
Link ID: 29435 - Posted: 08.15.2024

By Liam Drew In November 2008, neuroscientist Susana Carmona — then a postdoc studying attention deficit hyperactivity disorder — was driving two colleagues to a party when one of them revealed that she was thinking about having a child. The trio became so engulfed in conversation about how pregnancy might change her brain that they diverted from the party and headed to their laboratory to search the literature. They found numerous studies in rodents, but in humans, “there was basically nothing at all”, says Carmona. Shocked by this gap in research, Carmona and her colleagues convinced their mentor at the Autonomous University of Barcelona, Spain, Oscar Vilarroya, to let them run a study using magnetic resonance imaging (MRI) to measure the neuroanatomy of women before they became pregnant, and then again after they gave birth. Squeezed in alongside their main projects, the investigation took eight years and included dozens of participants. The results, published in 2016, were revelatory1. Two to three months after giving birth, multiple regions of the cerebral cortex were, on average, 2% smaller than before conception. And most of them remained smaller two years later. Although shrinkage might evoke the idea of a deficit, the team showed that the degree of cortical reduction predicted the strength of a mother’s attachment to her infant, and proposed that pregnancy prepares the brain for parenthood. Today, Carmona, now at the Gregorio Marañón Health Research Institute in Madrid, is one of several scientists uncovering how pregnancy and parenthood transform the brain. Elseline Hoekzema, one of Carmona’s passengers that evening in 2008, is another. In 2022, Hoekzema, who is now at the Amsterdam University Medical Centre in the Netherlands, confirmed that the cortical regions that shrink during pregnancy also function differently for at least a year after giving birth2. These studies and others, say researchers, highlight a transformational life event that has long been neglected by neuroscience — one that around 140 million women experience annually.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 29418 - Posted: 08.02.2024

By Miryam Naddaf Researchers have identified neurons in the brains of baby mice that enable them to form a unique, strong bond with their mother in the first few days of life. Stimulating these neurons in mouse pups that had been separated from their mother could mimic the soothing effect of their mother’s presence, and reduced behaviours associated with stress. The findings, published today in Science1, offer fresh clues about the formation of the mother–infant bond in mammals, and could help researchers to better understand how brain development influences behaviour. “We know very little about how the brains of infants make sense of their social world,” says study co-author Marcelo Dietrich, a neurobiologist at Yale University in New Haven, Connecticut. “When I started my lab ten years ago, and I wanted to study this kind of stuff, people said it was delusional. It will fail. It’s too difficult.” Now, “we show that it’s possible: one can do rigorous science and try to understand these mechanisms that are potentially very important for development and health”. “I see these neurons as the ‘I feel good with mommy’ neurons,” says Catharine Dulac, a neuroscientist at the University of Harvard in Cambridge, Massachusetts. “The features that [they] discovered provide some framework to think about humans.” Bonding in the brain Dietrich and his team studied nursing mouse pups that were between 16 and 18 days old. They used live imaging techniques to record activity in the zona incerta (ZI), a thin layer of grey matter located below the thalamus, while the animals interacted with their mother. © 2024 Springer Nature Limited

Keyword: Sexual Behavior
Link ID: 29409 - Posted: 07.27.2024

By Phie Jacobs Is there really such a thing as a “male” or “female” brain? Sex certainly seems to affect a person’s risk of developing various psychiatric and other brain-related conditions—but scientists aren’t entirely sure why. Attention-deficit/hyperactivity disorder for example, is more commonly diagnosed in individuals who were assigned male at birth (AMAB), whereas those assigned female at birth (AFAB) are more likely to exhibit symptoms of anxiety. It’s unclear, however, whether these differences are actually driven by sex, or have more to do with how people are perceived and treated based on their sex or gender. Now, new research suggests sex and gender are associated with distinct brain networks. Published today in Science Advances, the findings draw on brain imaging data from nearly 5000 children to reveal that gender and sex aren’t just distinct from one another in society—they also play unique roles in biology. In science, the term “biological sex” encompasses a variety of genetic, hormonal, and anatomical characteristics. People are typically assigned “male” or “female” as their sex at birth, although the medical establishment in recent years has begun to acknowledge that sex doesn’t always fall neatly into binary categories. Indeed, about 0.05% of children born in the United States are assigned intersex at birth. Gender, by contrast, has more to do with a person’s attitudes, feelings, and behavior—and may not always align with the sex they were assigned at birth. These nuances often go unrecognized in neuroscience, says Sheila Shanmugan, a reproductive psychiatrist at the University of Pennsylvania who wasn’t involved in the new study. Sex and gender-based differences in the brain “have historically been understudied,” she explains, “and terms describing each are often conflated.” © 2024 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Brain imaging
Link ID: 29393 - Posted: 07.13.2024

By Lauren J. Young Kimberly Chauche, a corporate secretary in Lincoln, Neb., says she’s always been overweight. When she was as young as five years old, her doctors started trying to figure out why. Since then her life has involved nutritionists and personal trainers, and eventually she sought therapists to treat her compulsive eating and weight-related anxiety. Yet answers never arrived, and solutions never lasted. At 43, Chauche was prescribed a weight-loss medi­cation called Wegovy—one of a new class of drugs that mimic a hormone responsible for insulin pro­duction. She took her first dose in March 2024, in­jecting it into herself with a needle. Within a couple of months she had lost almost 20 pounds, and that felt great. But the weight loss seemed like a bonus com­pared with a startling change in how she reacted to food. She noticed the shift almost immediately: One day her son was eating popcorn, a snack she could never resist, and she walked right past the bowl. “All of a sudden it was like some part of my brain that was always there just went quiet,” she says. Her eating habits improved, and her anxiety eased. “It felt almost surreal to put an injector against my leg and have happen in 48 hours what decades of intervention could not ac­complish,” she says. “If I had lost almost no weight, just to have my brain working the way it’s working, I would stay on this medication forever.” Chauche is hardly alone in her effusive descriptions of how Wegovy vanquished her intrusive thoughts about food—an experience increasingly referred to as the “quieting of food noise.” Researchers—some of whom ushered in the development of these blockbuster drugs—want to understand why. Among them is biochemist Svetlana Mojsov of the Rockefeller University, who has spent about 50 years investigating gut hormones that could be key to regulating blood glucose levels. In seeking potential treatments for type 2 diabetes, Mojsov ultimately focused on one hormone: glucagonlike peptide 1, or GLP-1. Her sequence of the protein in the 1980s became the initial template for drugs like Wegovy. The medications, called GLP-1 receptor agonists, use a synthetic version of the natural substance to activate the hormone’s receptors. The first ones arrived in 2005. In 2017 the U.S. Food and Drug Administration approved semaglutide—now widely known as Ozempic. © 2024 SCIENTIFIC AMERICAN,

Keyword: Obesity; Hormones & Behavior
Link ID: 29373 - Posted: 06.26.2024

By Claire Yuan Men and women experience pain differently, and until now, scientists didn’t know why. New research says it may be in part due to differences in male and female nerve cells. Pain-sensing nerve cells from male and female animal tissues responded differently to the same sensitizing substances, researchers report June 3 in Brain. The results suggest that at the cellular level, pain is produced differently between the sexes. The results might allow researchers “to come up with drugs that would be specific to treat female patients or male patients,” says Katherine Martucci, a neuroscientist who studies chronic pain at Duke University School of Medicine and was not involved in the study. “There’s no debate about it. They’re seeing these differences in the cells.” Some types of chronic and acute pain appear more often in one sex, but it’s unclear why. For instance, about 50 million adults in the United States suffer from chronic pain conditions, many of which are more common in women (SN: 5/22/23). Similar disparities exist for acute conditions. Such differences prompted pain researcher Frank Porreca of the University of Arizona Health Sciences in Tucson and colleagues to study nerve cells called nociceptors, which can act like alarm sensors for the body. The cells’ pain sensors, found in skin, organs and elsewhere in the body, can detect potentially dangerous stimuli and send signals to the brain, which then interprets the information as pain. In some cases, the nerve cells can become more sensitive to outside stimulation, registering even gentle sensations — like a shirt rubbing sunburned skin — as pain. © Society for Science & the Public 2000–2024.

Keyword: Pain & Touch; Sexual Behavior
Link ID: 29366 - Posted: 06.24.2024

By Sara Reardon Specific nerve cells on the penis and clitoris detect vibrations and then become activated, causing sexual behaviours such as erections, a study in mice has revealed1. The findings could lead to new treatments for conditions such as erectile dysfunction, or for restoring sexual function in people with lower-body paralysis. Krause corpuscles — nerve endings in tightly wrapped balls located just under the skin — were first discovered in human genitals more than 150 years ago. The structures are similar to touch-activated corpuscles found on people’s fingers and hands, which respond to vibrations as the skin moves across a textured surface. But there is little research into how the genital corpuscles work and how they are involved in sex, probably because the topic is sometimes considered taboo. “It’s been hard to get people to work on this because some people have a hard time talking about it,” says David Ginty, a sensory neurobiologist at Harvard Medical School in Boston, Massachusetts, who led the team that conducted the latest research. “But I don’t, because the biology is so interesting.” Ginty and other sensory biologists have long wanted to study these mysterious neuron balls. But activating and tracking specific neurons was nearly impossible until advanced molecular techniques emerged in the past 20 years. In a 19 June paper in Nature1, Ginty and his collaborators activated the Krause corpuscles in both male and female mice using various mechanical and electrical stimuli. The neurons fired in response to low-frequency vibrations in the range of 40–80 hertz. Ginty notes that these frequencies are generally used in many sex toys; humans, it seems, realized that this was the best way to stimulate Krause corpuscles before any official experiments were published. © 2024 Springer Nature Limited

Keyword: Sexual Behavior; Pain & Touch
Link ID: 29365 - Posted: 06.24.2024

By Virginia Morell Leaping over waves or body surfing side by side, dolphins are a fun-loving bunch. But their frolicking—and that of species from hyenas to humans—has long baffled evolutionary biologists. Why expend so much energy on play? A new study offers an intriguing explanation: Juvenile male dolphins use play to acquire the skills required for fathering calves, researchers report today in the Proceedings of the National Academy of Sciences. Most significantly, the scientists found the most playful males go on to have more calves as adults. The study is likely to spur further research into play behavior in additional species, other scientists say. “It’s exciting research, and it solves an evolutionary puzzle,” says Jennifer Smith, a behavioral ecologist at the University of Wisconsin–Eau Claire. “This is the first study to link play behavior in the wild to reproductive success.” Since 1982, scientists have observed some 200 male Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the exceptionally clear waters of Shark Bay in Australia. About 20 years ago, the researchers noticed that young males, 4 to 12 years old, often played together as if they were herding a fertile female, flanking her on either side, while swimming in sync with each other and making popping vocalizations. This kind of “synchronicity is crucial for male reproduction,” says Kathryn Holmes, a behavioral biologist with the Shark Bay Dolphin Research project and lead author of the new study. The young dolphins’ behaviors were strikingly similar to those of the adults. “We wondered if this was ‘play practice’ for the adult behaviors,” Holmes says. So she and her colleagues closely tracked 28 juvenile males for 4 to 5 months over several years, recording their interactions and play behaviors. When socializing, the males “played almost continuously,” Holmes says. “They seemed to never tire of their games.” © 2024 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 29353 - Posted: 06.11.2024

By Amorina Kingdon Like most humans, I assumed that sound didn’t work well in water. After all, Jacques Cousteau himself called the ocean the “silent world.” I thought, beyond whales, aquatic animals must not use sound much. How wonderfully wrong I was. In water a sound wave travels four and a half times faster, and loses less energy, than in air. It moves farther and faster and carries information better. In the ocean, water exists in layers and swirling masses of slightly different densities, depending on depth, temperature, and saltiness. The physics-astute reader will know that the density of the medium in which sound travels influences its speed. So, as sound waves spread through the sea, their speed changes, causing complex reflection or refraction and bending of the sound waves into “ducts” and “channels.” Under the right circumstances, these ducts and channels can carry sound waves hundreds and even thousands of kilometers. What about other sensory phenomena? Touch and taste work about the same in water as in air. But the chemicals that tend to carry scent move slower in water than in air. And water absorbs light very easily, greatly diminishing visibility. Even away from murky coastal waters, in the clearest seas, light vanishes below several hundred meters and visibility below several dozen. So sound is often the best, if not only, way for ocean and freshwater creatures to signal friends, detect enemies, and monitor the world underwater. And there is much to monitor: Earthquakes, mudslides, and volcanic activity rumble through the oceans, beyond a human’s hearing range. Ice cracks, booms, and scrapes the seafloor. Waves hiss and roar. Raindrops plink. If you listen carefully, you can tell wind speed, rainfall, even drop size, by listening to the ocean as a storm passes. Even snowfall makes a sound. © 2024 NautilusNext Inc.,

Keyword: Animal Communication; Sexual Behavior
Link ID: 29341 - Posted: 06.04.2024

By Sumeet Kulkarni As spring turns to summer in the United States, warming conditions have started to summon enormous numbers of red-eyed periodical cicadas out of their holes in the soil across the east of the country. This year sees an exceptionally rare joint emergence of two cicada broods: one that surfaces every 13 years and another with a 17-year cycle. They last emerged together in 1803, when Thomas Jefferson was US president. This year, billions or even trillions of cicadas from these two broods — each including multiple species of the genus Magicicada — are expected to swarm forests, fields and urban neighbourhoods. To answer readers’ cicada questions, Nature sought help from three researchers. Katie Dana is an entomologist affiliated with the Illinois Natural History Survey at the University of Illinois at Urbana-Champaign. John Lill is an insect ecologist at George Washington University in Washington DC. Fatima Husain is a cognitive neuroscientist at the University of Illinois at Urbana-Champaign. Their answers have been edited for length and clarity. Why do periodical cicadas have red eyes? JL: We’re not really sure. We do know that cicadas’ eyes turn red in the winter before the insects come out. The whole coloration pattern in periodical cicadas is very bright: red eyes, black and orange wings. They’re quite different from the annual cicadas, which are green and black, and more camouflaged. It’s a bit of an enigma why the periodical ones are so brightly coloured, given that it just makes them more obvious to predators. There are no associated defences with being brightly coloured — it kind of flies in the face of what we know about bright coloration in a lot of other animals, where usually it’s some kind of signal for toxicity. There also exist mutants with brown, orange, golden or even blue eyes. People hunt for blue-eyed ones; it’s like trying to find a four-leaf clover. © 2024 Springer Nature Limited

Keyword: Animal Communication; Sexual Behavior
Link ID: 29339 - Posted: 06.04.2024