Chapter 8. Hormones and Sex

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Elle Hunt About 150 years ago, and “almost a lifetime” either side, Charles Darwin was beleaguered by the problem of the peacock’s tail. Just the sight of a feather, he wrote in April 1860, “makes me sick!” The plumage of the male bird represented a hole in his theory of evolution. According to Victorian thinking, beauty was divine creation: God had designed the peacock for his own and humankind’s delight. In, On The Origin of Species, published the previous year, Darwin had challenged the dominant theory of creationism, arguing that man had been made not in God’s image but as a result of evolution, with new species formed over generations in response to their environment. But beauty, and a supposed aesthetic sense in animals (“We must suppose [that peahens] admire [the] peacock’s tail, as much as we do,” he wrote), took Darwin the best part of his life to justify – not least because the theory he eventually landed upon went against the grain of his entire worldview. Sexual selection was of strategic importance to Darwin, says Evelleen Richards, an honorary professor in history and philosophy of science at the University of Sydney: it was a naturalistic account for aesthetic differences between male and female animals of the same species, shoring up his defence of natural selection.

Keyword: Evolution; Sexual Behavior
Link ID: 23642 - Posted: 05.22.2017

Susan Milius The supermoms of the mammal world are big, shy redheads. Studying growth layers in orangutan teeth shows that mothers can nurse their youngsters for eight-plus years, a record for wild mammals. Teeth from a museum specimen of a young Bornean orangutan (Pongo pygmaeus) don’t show signs of weaning until 8.1 years of age. And a Sumatran orangutan (P. abelii) was still nursing during the few months before it was killed at 8.8 years, researchers report May 17 in Science Advances. Tests also show that youngsters periodically start to taper off their dependence on their mother’s milk and then, perhaps if solid food grows scarce, go back to what looks like an all-mom diet. Such on-again, off-again nursing cycles aren’t known in other wild mammals, says study coauthor Tanya Smith, an evolutionary anthropologist at Griffith University in Nathan, Australia. Marks of milk drinking Two images of a cross section of a first molar from a 4.5-year-old Bornean orangutan are shown. At left, numbers indicate days from birth (dotted line, starting with 0) when particular spots formed. At right, colors indicate concentrations of barium, which increase (shading toward red) when the youngster depended more on mother’s milk. A greenish swath at the top indicates nursing as an infant that gave way to blue as solid food became part of the diet. Yellow and red streaks indicate repeated times when the youngster again depended mostly on milk for nutrition. oragutan molar |© Society for Science & the Public 2000 - 2017.

Keyword: Sexual Behavior; Development of the Brain
Link ID: 23632 - Posted: 05.18.2017

Nicola Davis Humans can determine a dog’s mood by the sound of its growl, scientists have found, with women showing greater ability than men. While previous studies have found that humans can unpick the context of barks, the latest study investigated whether the same was true of canine grumbles, with some previous research suggesting humans struggle to differentiate between playful and aggressive vocalisations. “It is an important thing that humans are capable [of recognising] the emotional state of another species just based on the vocal characteristics,” said Tamás Faragó, first author of the study from Eötvös Loránd University in Hungary. To tackle the conundrum, Faragó and colleagues used previously captured recordings of 18 dogs growling in three contexts: guarding food from other dogs, playing tug-of-war with humans, and being threatened by the approach of a stranger. The researchers monitored several features, including the length of each growl and its frequency. Two sets of the recordings, which included two growls from each context, were played to 40 adults. Each participant was asked to record their impression of the first set of growls on a sliding scale, rating their perception of the dog for five emotions: fear, aggression, despair, happiness and playfulness. © 2017 Guardian News and Media Limited

Keyword: Animal Communication; Sexual Behavior
Link ID: 23621 - Posted: 05.17.2017

By Hannah Furfaro, Children whose fathers are highly intelligent are at a 31 percent higher risk of autism than those whose fathers are of average intelligence, according to unpublished results presented today at the 2017 International Meeting for Autism Research in San Francisco, California. The work supports observations that date back to the 1940s, when Leo Kanner and Hans Asperger noted in separate reports that the fathers of children with autism tended to be highly intelligent and in several cases worked in technical fields. A 2012 study also showed that children from regions in the Netherlands where high-tech jobs are prevalent are more likely to have autism than those who live in other regions. In the new study, lead investigator Renee Gardner, assistant professor at Karolinska Institutet in Stockholm, set out to investigate whether the historical lore has validity. She and her colleagues matched medical records for 309,803 children whose fathers were conscripted into the Swedish military with their father’s scores on the technical portion of the Swedish intelligence quotient (IQ) test. They found a one-third higher risk of autism in children whose fathers’ IQ scores are 111 or higher than in those whose fathers’ scores cluster around 100. The researchers controlled for possible confounding factors such as families’ socioeconomic status and parental age, education level and history of inpatient psychiatric treatment. IQ indicators: They found the opposite relationship between a father’s IQ and his child’s chances of having intellectual disability or attention deficit hyperactivity disorder (ADHD). In particular, children of men with an IQ of 75 or below had a four-and-a-half times higher risk of intellectual disability. The chance of ADHD was 65 percent higher than average for children whose fathers had an IQ in that low range. © 2017 Scientific American

Keyword: Autism; Intelligence
Link ID: 23614 - Posted: 05.15.2017

By STEPH YIN In most mammals, us included, biological sex is determined by a lottery between two letters: X and Y, the sex chromosomes. Inherit one X each from mom and dad, and develop ovaries, a womb and a vagina. Inherit an X from mom and a Y from dad, and develop testes and a penis. But there are rare, mysterious exceptions. A small number of rodents have no Y chromosomes, yet are born as either females or males, not hermaphrodites. Now, scientists may be one step closer to figuring out how sex determination works in one of these rodents. In a study published in Science Advances on Friday, Japanese scientists suggested that cells of the endangered Amami spiny rat, from Japan, are sexually flexible and capable of adapting to either ovaries or testes. When the researchers injected stem cells derived from a female rat into male embryos of laboratory mice, the cells developed into and survived as sperm precursors in adult males. The result was surprising since scientists have never been able to generate mature sperm from female stem cells, largely because sperm production normally requires the Y chromosome. Found only in the subtropical forests of an island in Japan called Amami Oshima, Amami spiny rats are threatened by habitat destruction, competition with black rats not native to the island and predation by mongooses and feral cats and dogs. Their range has been reduced to less than 300 square miles, an area smaller than New York City. Both female and male Amami spiny rats have only one X chromosome, an arrangement only known to occur in a handful of rodents among mammals. Arata Honda, associate professor at the University of Miyazaki and the lead author of the paper, said in an email that he was partly motivated to study Amami spiny rats in the hope that learning about them might reduce their risk of extinction. © 2017 The New York Times Company

Keyword: Sexual Behavior
Link ID: 23611 - Posted: 05.13.2017

Amy Maxmen Cells that prune connections between neurons in babies’ brains as they grow are thought to have a role in autism spectrum disorder. Now, a study suggests that the number and behaviour of these cells — called microglia — vary in boys and girls, a finding that could help to explain why many more boys are diagnosed with autism and related disorders. Donna Werling, a neurogeneticist at the University of California, San Francisco, and her colleagues found that genes associated with microglia are more active in male brains than in female brains in the months before birth. “This suggests there is something fundamentally different about male and female brain development,” she says. The research, to be presented on 13 May at the International Meeting for Autism Research in San Francisco, California, is still preliminary. Very little is known about how microglial trimming behaviour affects brain development. But the study by Werling’s team “is the kind of work that makes you say ‘Wow, this is really interesting, and we should take it seriously’”, says Kevin Pelphrey, a neuroscientist at Yale School of Medicine in New Haven, Connecticut. There are two to five times many males with autism as females. Although the disorder — whose cause remains elusive — is widely acknowledged to be underdiagnosed in girls, psychiatrists agree that there is a significant disparity between the numbers of male and female cases. It suggests that biological differences between the sexes are involved. © 2017 Macmillan Publishers Limited,

Keyword: Autism; Glia
Link ID: 23605 - Posted: 05.12.2017

By Ann Griswold, Much of what Stephen Shore knows about romance he learned in the self-help aisle of a bookstore near the Amherst campus of the University of Massachusetts. In college, Shore, who has autism, began to wonder if women spoke a language he didn’t understand. Maybe that would explain the perplexing behavior of a former massage student with whom he traded shiatsu sessions, who eventually told him she had been hoping for more than a back rub. Or the woman he met in class one summer, who had assumed she was his girlfriend because they spent most nights cooking, and often shared a bed. Looking back, other people’s signs of romantic interest seemed to almost always get lost in translation. Shore turned to the self-help shelves to learn the unspoken language of love: He pored over chapters on body language, facial expression and nonverbal communication. By the time he met Yi Liu, a woman in his graduate-level music theory class at Boston University, he was better prepared. On a summer day in 1989, as they sat side by side on the beach, Liu leaned over and kissed Shore on the lips. She embraced him, then held his hand as they looked out at the sea. “Based on my research,” he says, “I knew that if a woman hugs you, kisses you and holds your hand all at the same time, she wants to be your girlfriend; you better have an answer right away.” The couple married a year later, on a sunny afternoon in June 1990. Shore was diagnosed with autism around age 3, about a year after he lost his few words and began throwing tantrums. Doctors advised his parents to place him in an institution. Instead, they immersed him in music and movement activities, and imitated his sounds and behavior to help him become aware of himself and others. He began speaking again at 4 and eventually recovered some of the social skills he had lost. © 2017 Scientific American

Keyword: Autism; Sexual Behavior
Link ID: 23586 - Posted: 05.06.2017

By Alice Klein It is pest control without poison. A new type of bait that stops rats from having babies is helping to tackle infestations in several US cities. The bait – known as ContraPest – was approved by the US Environmental Protection Agency last August. It makes rats infertile by triggering early menopause in females and impairing sperm production in males. There are no side effects and the rats eventually die of natural causes. The technique is considered more benign than other control strategies being investigated, such as gene drive, which can be used to spread infertility genes through pest populations. A recent report by the US National Academies of Sciences warned that gene drive could have unforeseen consequences. The first field trial of ContraPest, conducted in the New York City Subway in 2013, halved the resident rat population in three months. Two more trials have now been completed in the US – one at a large-scale farm and one in an urban area – both in East Coast cities. Rat numbers at the farm fell by one-third over three months. In the urban area, population growth was suppressed during the peak breeding season so that the population expanded at only one-third the expected rate. “You’ll never wipe out rats completely – they’re too smart,” says Brandy Pyzyna from SenesTech, the biotechnology company in Arizona that developed the bait. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 23583 - Posted: 05.06.2017

By Jef Akst Drawing on data on organ-, tissue-, and individual-specific gene expression from the Genotype-Tissue Expression (GTex) Portal, Shmuel Pietrokovski and Moran Gershoni of the Weizmann Institute of Science in Israel developed a comprehensive map of genes that are differentially expressed in men and women. The study was inspired by work the duo conducted several years ago, in which they found that mutations accumulated in genes for sperm formation likely because they were expressed only in men, not in women. As a result, even harmful mutations would only cause problems to half the population; unaffected women would continue to pass on the defective gene without any hit to their fitness. To explore whether other genes expressed differentially between the sexes might be similarly subject to mutation accumulation, Pietrokovski and Gershoni examined some 20,000 protein-coding genes, of which around 6,500 were expressed more in one sex than the other somewhere in the body. And sure enough, selection was effectively weaker in these genes, leading to the pile up of deleterious mutations. “The more a gene was specific to one sex, the less selection we saw on the gene,” Gershoni told the institute’s news publication, Weizmann Wonder Wander, this week (May 3). “The basic genome is nearly the same in all of us, but it is utilized differently across the body and among individuals,” he continued. “Thus, when it comes to the differences between the sexes, we see that evolution often works on the level of gene expression.” © 1986-2017 The Scientist

Keyword: Sexual Behavior
Link ID: 23581 - Posted: 05.06.2017

By RICHARD O. PRUM In a mossy forest in the western Andes of Ecuador, a small, cocoa-brown bird with a red crown sings from a slim perch. Bip-Bip-WANNGG! It sounds like feedback from an elfin electric guitar. Three rival birds call back in rapid response. These male club-winged manakins are showing off to attract female mates. Their strange songs are associated with an even stranger movement. Instead of opening their beaks, they flick their wings open at their sides to make the Bips, and then snap their wings up over their backs to produce the extraordinary WANNGG. They are singing with their wings, and their potential mates seem to find the sound very alluring. This is an evolutionary innovation — a whole new way to sing. But the evolutionary mechanism behind this novelty is not adaptation by natural selection, in which only those who survive pass on their genes, allowing the species to become better adapted to its environment over time. Rather, it is sexual selection by mate choice, in which individuals pass on their genes only if they’re chosen as mates. From the peacock’s tail to the haunting melodies of the wood thrush, mate choice is responsible for much of the beauty in the natural world. Most biologists believe that these mechanisms always work in concert — that sex appeal is the sign of an objectively better mate, one with better genes or in better condition. But the wing songs of the club-winged manakin provide new insights that contradict this conventional wisdom. Instead of ensuring that organisms are on an inexorable path to self-improvement, mate choice can drive a species into what I call maladaptive decadence — a decline in survival and fecundity of the entire species. It may even lead to extinction. © 2017 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 23580 - Posted: 05.06.2017

Mark Zdechlik Health officials in Minnesota have been scrambling to contain a measles outbreak that has sickened primarily Somali-American children in the state. So far health officials have identified 34 cases, still mostly in Hennepin County, and they're worried there will be more. In Minnesota, the vast majority of kids under two get vaccinated against measles. But state health officials say most Somali-American 2-year-olds have not had the vaccine — about six out of ten. As the outbreak spreads, that statistic worries health officials, including Michael Osterholm, who directs the University of Minnesota's Center for Infectious Disease Research and Policy. Understanding The History Behind Communities' Vaccine Fears Shots - Health News Understanding The History Behind Communities' Vaccine Fears "It is a highly concentrated number of unvaccinated people," he says. "It is a potential kind of gas-and-match situation." Measles is a highly contagious respiratory disease that causes a rash and fever. It can be deadly, but the Centers for Disease Control and Prevention says two doses of vaccination are about 97 percent effective in heading off the disease. The Minnesota Department of Health says the outbreak began in Hennepin County, home to Minneapolis and the heart of the nation's Somali-American community. © 2017 npr

Keyword: Autism
Link ID: 23574 - Posted: 05.05.2017

By Simon Makin The past few decades have seen intensive efforts to find the genetic roots of neurological disorders, from schizophrenia to autism. But the genes singled out so far have provided only sketchy clues. Even the most important genetic risk factors identified for autism, for example, may only account for a few percent of all cases. Much frustration stems from the realization that the key mutations elevating disease risk tend to be rare, because they are less likely to be passed on to offspring. More common mutations confer only small risks (although those risks become more significant when calculated across an entire population). There are several other places to look for the missing burden of risk, and one surprising possible source has recently emerged—an idea that overturns a fundamental tenet of biology and has many researchers excited about a completely new avenue of inquiry. Accepted dogma holds that—although every cell in the body contains its own DNA—the genetic instructions in each cell nucleus are identical. But new research has now proved this assumption wrong. There are actually several sources of spontaneous mutation in somatic (nonsex) cells, resulting in every individual containing a multitude of genomes—a situation researchers term somatic mosaicism. “The idea is something that 10 years ago would have been science fiction,” says biochemist James Eberwine of the University of Pennsylvania. “We were taught that every cell has the same DNA, but that's not true.” There are reasons to think somatic mosaicism may be particularly important in the brain, not least because neural genes are very active. © 2017 Scientific American

Keyword: Development of the Brain; Genes & Behavior
Link ID: 23565 - Posted: 05.04.2017

By Elizabeth Pennisi When, 6 years ago, divers captured on video a cuckolding attempt among squidlike animals called cuttlefish, experts were stunned. “The violence was beyond anything we had ever seen in the laboratory,” says Roger Hanlon, an ecologist at the Marine Biological Laboratory in Woods Hole, Massachusetts, who had been studying captive cuttlefish for years. Now, by carefully analyzing the behavior of the two males involved, he and his colleagues suggest the stepwise escalation of their fight likely required more brainpower than many researchers thought invertebrates had, they report this week in American Naturalist. The video (above) first shows a common European male cuttlefish (Sepia officinalis) mating with a female. While he escorts her to where she will lay her eggs, a second male suddenly appears and chases him away. But the first male doesn’t give up, and as his rival starts to get fresh with the female, the scuffle gets ever more intense. The rivals squirt ink at each other and jet about. Then, their dark markings turn even darker, and they engage in a quick battle of biting, grappling, and cork-screwing that soon sends the intruder scurrying off. Now that the scientists know how such explosive situations come about, they hope to recreate those circumstances in the lab to study male rivalries more systematically. © 2017 American Association for the Advancement of Science. A

Keyword: Aggression; Sexual Behavior
Link ID: 23564 - Posted: 05.04.2017

Jon Brooks Max, age 13, is agender — neither male nor female. When referring to Max, you don't use "he" or "she;" you use "they." Once strictly a pronoun of the plural variety, "they" is now doing double duty as singular, too — referring to individuals, like Max, who do not see gender as an either/or option. (NPR agreed not to use Max's last name, because the family feared the sort of online threats that have been made to other transgender families.) If the whole he/she pronoun thing feels awkward to you, Max is sympathetic — and patient. 'We are seeing more and more kids saying, 'You know what? What's with this either-or business? What's with this boy-girl and you have to fit in one box or the other?' " Diane Ehrensaft, psychologist, Child and Adolescent Gender Center, UCSF Benioff Children's Hospital "I can't expect anyone to use the right pronouns for me because it's not a thing that people know," Max tells me. "It's been great being myself, but it's also been really hard for people to get it, and for even family to get pronouns and stuff." We're talking in Max's room at home, where posters on the wall showcase the teen's love of theater: Peter Pan, Tarzan, The Pirates of Penzance. Max is old enough now to enjoy using make-up — blush, foundation, lipstick — but still young enough to enjoy going with their mom to see "Willy Wonka & The Chocolate Factory." (The review from Max: Gene Wilder's great!) From these surroundings, you wouldn't think the room's occupant is someone who has already poked and prodded at the most fundamental sense of who they are. Really, this is just a kid's room. © 2017 npr

Keyword: Sexual Behavior
Link ID: 23562 - Posted: 05.02.2017

By Abigail Beall You can’t eat, you can’t sleep and all you can think about is your next fix. You may be addicted to love. Intense romance can often come with symptoms resembling addiction – euphoria, craving, dependence, withdrawal and relapse – and brain scans have shown that it can be linked to drug-addiction-like activity in the brain’s reward centres. But the idea that people can be addicted to love is contentious. “It gets complicated because people disagree on the correct theory of addiction, and people especially disagree about what we mean when we use the term ‘love’ ”, says Brian Earp, at the Oxford University Centre for Neuroethics. “I think it is when you realise you do not want to be in love yet cannot avoid it, and it causes bad things, like abuse, that we cross the line into something addiction-like,” says Anders Sandberg, also at the Oxford University Centre for Neuroethics. Now Earp and his team have found evidence that there are in fact two different types of love addiction, after reviewing 64 studies of love and addiction published between 1956 and 2016. They found that people who feel desperately alone when not in a relationship, and try to replace an ex-partner straight away, could have what the team has called a “narrow” form of love addiction.

Keyword: Drug Abuse; Sexual Behavior
Link ID: 23552 - Posted: 04.29.2017

By Debra W. Soh The reasons behind why people are gay, straight, or bisexual have long been a source of public fascination. Indeed, research on the topic of sexual orientation offers a powerful window into understanding human sexuality. The Archives of Sexual Behavior recently published a special edition devoted to research in this area, titled “The Puzzle of Sexual Orientation.” One study, conducted by scientists at the University of Lethbridge in Alberta, Canada, offers compelling, cross-cultural evidence that common genetic factors underlie same-sex, sexual preference in men. In southern Mexico, individuals who are biologically male and sexually attracted to men are known as muxes. They are recognized as a third gender: Muxe nguiiu tend to be masculine in their appearance and behavior, while muxe gunaa are feminine. In Western cultures, they would be considered gay men and transgender women, respectively. Several correlates of male androphilia — biological males who are sexually attracted to men — have been shown across different cultures, which is suggestive of a common biological foundation among them. For example, the fraternal birth order effect—the phenomenon whereby male androphilia is predicted by having a higher number of biological older brothers—is evident in both Western and Samoan cultures. Interestingly, in Western society, homosexual men, compared with heterosexual men, tend to recall higher levels of separation anxiety — the distress resulting from being separated from major attachment figures, like one’s primary caregiver or close family members. Research in Samoa has similarly demonstrated that third-gender fa’afafine—individuals who are feminine in appearance, biologically male, and attracted to men—also recall greater childhood separation anxiety when compared with heterosexual Samoan men. Thus, if a similar pattern regarding separation anxiety were to be found in a third, disparate culture—in the case, the Istmo region of Oaxaca, Mexico—it would add to the evidence that male androphilia has biological underpinnings. © 2017 Scientific American

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 23540 - Posted: 04.26.2017

By CATHERINE SAINT LOUIS In her 30s, Sophie Marat, now 42, used to record herself reading poetry aloud, then play it back to hear if she sounded like a woman. Ms. Marat, who is transgender, had spent years trying to remake her voice in private by speaking in a higher pitch but ultimately felt that her efforts were hopeless. “I was feeling like changing my voice to match my gender identity was almost impossible,” she said. “It was terrible.” Ms. Marat’s transition from male to female has been a gradual evolution. She had come out to friends and family back home in Mexico, then began to wear skirts to work as a software engineer in Manhattan. Still, her confidence would falter with everyday tasks like ordering takeout. “It was really painful to speak on the phone,” she said, “because they would reply, ‘O.K., sir.’” That was before she started her weekly sessions with a voice therapist at New York University’s speech-language-hearing clinic, one of a growing number of programs that cater to transgender clients seeking to retrain their voices. Just as some transgender women and men choose to take hormones or have surgery, or choose neither, some seek to feminize or masculinize their voices. Many say they want a voice that matches their appearance or that the change allows them to escape unwanted attention. There’s also a growing recognition among health professionals who have transgender patients that altering one’s voice can improve quality of life and reduce distress. After eight months, she had raised her pitch, worked on moving her resonance forward and finishing phrases with an open ending, rather than bluntly. “This isn’t just a sidebar,” said Sandy Hirsch, a Seattle-based speech language pathologist who was a co-author of the pioneering textbook on transgender voice and communication therapy. “It’s an integral part of care for transgender people as they transition.” © 2017 The New York Times Company

Keyword: Sexual Behavior; Language
Link ID: 23539 - Posted: 04.26.2017

By Lauren Gravitz, Connor was diagnosed with autism early — when he was just 18 months old. His condition was already obvious by then. “He was lining things up, switching lights on and off, on and off,” says his mother, Melissa. He was bright, but he didn’t speak much until age 3, and he was easily frustrated. Once he started school, he couldn’t sit still in class, called out answers without raising his hand and got visibly upset when he couldn’t master a math concept or a handwriting task quickly enough. “One time, he rolled himself up into the carpet like a burrito and wouldn’t come out until I got there,” Melissa recalls. (All families in this story are identified by first name only, to protect their privacy.) Connor was prescribed his first psychiatric drug, methylphenidate (Ritalin), at age 6. That didn’t last long, but when he was 7, his parents tried again. A psychiatrist suggested a low dose of amphetamine and dextroamphetamine (Adderall), a stimulant commonly used to treat attention deficit hyperactivity disorder (ADHD). The drug seemed to improve his time at school: He was able to sit still for longer periods of time and focus on what his teachers were saying. His chicken-scratch handwriting became legible. Then, it became neat. Then perfect. And then it became something Connor began to obsess over. “We were told that these are the gives and takes; if it’s helping him enough to get through school, you have to decide if it’s worth it,” Melissa says. It was worth it — for a while. © 2017 Scientific American

Keyword: Autism
Link ID: 23531 - Posted: 04.25.2017

Paula Span “During the past four weeks, have you been tired? Been exhausted? Had difficulty getting motivated to do anything at all?” These questions — which a substantial chunk of the population probably could answer in the affirmative — appeared on a questionnaire used in a major European study published recently in The New England Journal of Medicine. The authors were researching the effectiveness of a drug that is widely, if controversially, used to treat older adults with subclinical hypothyroidism, better known as a slightly underactive thyroid. So many Americans take that medication — levothyroxine (brand name Synthroid) — that it topped the list of prescription drugs dispensed in the United States in 2015, according to the research firm QuintilesIMS Institute. With 121 million prescriptions annually, levothyroxine outpaced statins, blood pressure meds — and everything else. A Johns Hopkins survey published last year found that more than 15 percent of older Americans were taking it. So you’d think these study results would come as shocking news: The European team reported that in older people with mild hypothyroidism, the drug had no significant effect on symptoms. At all. Instead, the results bolstered what a number of geriatricians and endocrinologists have suspected for years. “It’s a strong signal that this is an overused medication,” said Dr. Juan Brito, an endocrinologist at the Mayo Clinic. “Some people really need this medicine, but not the vast majority of people who are taking it.” © 2017 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 23522 - Posted: 04.22.2017

Carl Zimmer The oldfield mouse doesn’t seem extraordinary. With soulful black eyes and tiny teacup ears, the rodent lives a humdrum life scurrying about meadows and beaches in the Southeast. But field biologists have long known that when it comes to sex and family life, this mouse is remarkable: Peromyscus polionotus is monogamous — an exception among mammals — and a solicitous parent. Fathers and mothers will dig burrows together and build elaborate nests when pups are on the way; after they’re born, the father will help tend to the pups, retrieving them when they fall out of the nest, licking them, and huddling to keep them warm. In a pioneering study published on Wednesday in the journal Nature, researchers at Harvard University identified a genetic basis for this distinctive behavior. It is the first time that scientists have linked DNA to variations in parenting habits among mammals. Dieter Lukas, an evolutionary biologist at the University of Cambridge who was not involved in the research, hailed the study as a sophisticated tour de force, saying that uncovering these links “is like designing a tool to follow individual threads through a large colorful tapestry.” The findings may one day help scientists make sense of how human couples bond and care for their children. Mammals share many of the genes governing the production of hormones and neurotransmitters in the brain. Variations in how they function may explain why most species are promiscuous, why a few are monogamous — and why some, like humans, are somewhere in between. “We can go from the bottom up and build our knowledge base, and then ask questions about human biology,” said Gene E. Robinson, a biologist at the University of Illinois who was not involved in the new work. © 2017 The New York Times Company

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 23516 - Posted: 04.20.2017