Chapter 12. Sex: Evolutionary, Hormonal, and Neural Bases
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By Clare Wilson Could a brain stimulation device change our sex drive? The first study of this approach suggests that people’s libido can be turned up or down, depending on the device’s setting. The study didn’t measure how much sex people had in real life, instead it measured participant’s sexual responsiveness. Unusually, this was done by fixing customised vibrators to people’s genitals and gauging how their brainwaves changed when they expected a stimulating buzz. “You want to see if they want what you’re offering,” says Nicole Prause at the University of California, Los Angeles. “This is a good model for sexual desire.” The technique involves transcranial magnetic stimulation (TMS), where a paddle held above the head uses a strong magnetic field to alter brain activity. It can be used to treat depression and migraines, and is being investigated for other uses, including preventing bed-wetting, and helping those with dyslexia. The part of the head targeted in this study – called the left dorsolateral prefrontal cortex, roughly above the left temple – is involved in the brain’s reward circuitry. © Copyright Reed Business Information Ltd.
Keyword: Sexual Behavior
Link ID: 22936 - Posted: 12.01.2016
Carrie Arnold There was one sound that biologist Rusty Gonser always heard at Cranberry Lake — and there was one sound that he would never hear again. Every summer for more than 25 years, Gonser and his wife, Elaina Tuttle, had made the trip to this field station in the Adirondack Mountains — a 45-minute boat ride from the nearest road. Now, as he moored his boat to the shaky wooden dock, he heard a familiar and short song that sounded like 'oh-sweet-Canada'. The whistle was from a white-throated sparrow calling hopefully for a mate. What he didn't hear was the voice or laughter of his wife. For the first time, Gonser was at Cranberry Lake alone. Just a few weeks earlier, Tuttle had died of breast cancer. Her entire career, and most of Gonser's, had been devoted to understanding every aspect of the biology of the white-throated sparrow (Zonotrichia albicollis). Less than six months before she died this year at the age of 52, the couple and their team published a paper1 that was the culmination of that work. It explained how a chance genetic mutation had put the species on an extraordinary evolutionary path. The mutation had flipped a large section of chromosome 2, leaving it unable to pair up with a partner and exchange genetic information. The more than 1,100 genes in the inversion were inherited together as part of a massive 'supergene' and eventually drove the evolution of two different 'morphs' — subtypes of the bird that are coloured differently, behave differently and mate only with the opposite morph. Tuttle and Gonser's leap was to show that this process is nearly identical to the early evolution of certain sex chromosomes, including the human X and Y. The researchers realized that they were effectively watching the bird evolve two sex chromosomes, on top of the two it already had. © 2016 Macmillan Publishers Limited,
By Usha Lee McFarling, There’s something wrong with the brain banks created to study the dangers of repeated trauma to the head: Almost all the brains donated so far belonged to men. It’s just one example of how the study of brain trauma in women lags behind—even though women get concussions at higher rates than men in many sports and may suffer more severe and persistent symptoms. “If concussion is the invisible injury, then females are the invisible population within that injury,” said Katherine Snedaker, a licensed clinical social worker from Norwalk, Conn., who founded the nonprofit PINK Concussions in 2013 to focus attention on the issue. Evidence is building that the response to traumatic injury is different enough in females that they might benefit from gender-specific treatment, as they do with cardiac disease. But the data to create such guidelines simply aren’t there. “It’s an incredible gap in our knowledge,” said Angela Colantonio, director of the Rehabilitation Science Institute at the University of Toronto. “It’s just not acceptable.” When Colantonio examined 200 studies on prognosis after mild traumatic brain injury, she found only 7 percent separated out women. And if female athletes are overlooked, other groups vulnerable to concussion—aging women, women in prison, and domestic abuse survivors—have been nearly entirely ignored. © 2016 Scientific American
Ramin Skibba Bats sing just as birds and humans do. But how they learn their melodies is a mystery — one that scientists will try to solve by sequencing the genomes of more than 1,000 bat species. The project, called Bat 1K, was announced on 14 November at the annual meeting of the Society for Neuroscience in San Diego, California. Its organizers also hope to learn more about the flying mammals’ ability to navigate in the dark through echolocation, their strong immune systems that can shrug off Ebola and their relatively long lifespans. “The genomes of all these other species, like birds and mice, are well-understood,” says Sonja Vernes, a neurogeneticist at the Max Planck Institute for Psycholinguistics in Nijmegen, Netherlands, and co-director of the project. “But we don’t know anything about bat genes yet.” Some bats show babbling behaviour, including barks, chatter, screeches, whistles and trills, says Mirjam Knörnschild, a behavioural ecologist at Free University Berlin, Germany. Young bats learn the songs and sounds from older male tutors. They use these sounds during courtship and mating, when they retrieve food and as they defend their territory against rivals. Scientists have studied the songs of only about 50 bat species so far, Knörnschild says, and they know much less about bat communication than about birds’. Four species of bats have so far been found to learn songs from each other, their fathers and other adult males, just as a child gradually learns how to speak from its parents1. © 2016 Macmillan Publishers Limited,
By CHRIS BUCKLEY BEIJING — When Flappy McFlapperson and Skybomb Bolt sprang into the sky for their annual migration from wetlands near Beijing, nobody was sure where the two cuckoos were going. They and three other cuckoos had been tagged with sensors to follow them from northern China. But to where? “These birds are not known to be great fliers,” said Terry Townshend, a British amateur bird watcher living in the Chinese capital who helped organize the Beijing Cuckoo Project to track the birds. “Migration is incredibly perilous for birds, and many perish on these journeys.” The answer to the mystery — unfolding in passages recorded by satellite for more than five months — has been a humbling revelation even to many experts. The birds’ journeys have so far covered thousands of miles, across a total of a dozen countries and an ocean. The “common cuckoo,” as the species is called, turns out to be capable of exhilarating odysseys. “It’s impossible not to feel an emotional response,” said Chris Hewson, an ecologist with the British Trust for Ornithology in Thetford, England, who has helped run the tracking project. “There’s something special about feeling connected to one small bird flying across the ocean or desert.” But to follow a cuckoo, you must first seduce it. The common cuckoo is by reputation a cynical freeloader. Mothers outsource parenting by laying their eggs in the nests of smaller birds, and the birds live on grubs, caterpillars and similar soft morsels. British and Chinese bird groups decided to study two cuckoo subspecies found near Beijing, because their winter getaways were a puzzle. In an online poll for the project, nearly half the respondents guessed they went somewhere in Southeast Asia. © 2016 The New York Times Company
Very stressful events affect the brains of girls and boys in different ways, a Stanford University study suggests. A part of the brain linked to emotions and empathy, called the insula, was found to be particularly small in girls who had suffered trauma. But in traumatised boys, the insula was larger than usual. This could explain why girls are more likely than boys to develop post-traumatic stress disorder (PTSD), the researchers said. Their findings suggest that boys and girls could display contrasting symptoms after a particularly distressing or frightening event, and should be treated differently as a result. The research team, from Stanford University School of Medicine, said girls who develop PTSD may actually be suffering from a faster than normal ageing of one part of the insula - an area of the brain which processes feelings and pain. Image copyright Science Photo Library Image caption The insula, also known as the insular cortex, is linked to the body's experience of pain or emotional experiences of fear The insula, or insular cortex, is a diverse and complex area, located deep within the brain which has many connections. As well as processing emotions, it plays an important role in detecting cues from other parts of the body. The researchers scanned the brains of 59 children aged nine to 17 for their study, published in Depression and Anxiety. © 2016 BBC.
By Solomon Israel, A May-December romance brings benefits for young female gray jays mated to older males, according to new Canadian research. The paper, published this month in the journal Animal Behaviour, used almost four decades of data on a marked population of gray jays in Ontario's Algonquin Park to study how the birds adjust their reproductive habits in response to changes in temperature and other conditions. Gray jays, also known as Canada jays or whisky jacks, don't migrate south in the winter, instead living year-round in boreal forests across Canada and the northern U.S. They manage this feat of survival by caching food all over their large, permanent habitats, then retrieving it during the winter months. The small, fluffy birds take advantage of those winter supplies to nest much earlier than most other birds, laying eggs between late February and March. Gray jays don't migrate during the winter, instead relying on hidden caches of food to feed themselves and their offspring. (Dan Strickland) The researchers found that female gray jays that laid their eggs earlier in the season had the most reproductive success, with a higher survival rate for offspring. ©2016 CBC/Radio-Canada
Susan Milius For widemouthed, musical midshipman fish, melatonin is not a sleep hormone — it’s a serenade starter. In breeding season, male plainfin midshipman fish (Porichthys notatus) spend their nights singing — if that’s the word for hours of sustained foghorn hums. Males dig trysting nests under rocks along much of North America’s Pacific coast, then await females drawn in by the crooning. New lab tests show that melatonin, familiar to humans as a possible sleep aid, is a serenade “go” signal, says behavioral neurobiologist Ni Feng of Yale University. From fish to folks, nighttime release of melatonin helps coordinate bodily timekeeping and orchestrate after-dark biology. The fish courtship chorus, however, is the first example of the hormone prompting a launch into song, according to Andrew Bass of Cornell University. And what remarkable vocalizing it is. The plainfin midshipman male creates a steady “mmm” by quick-twitching specialized muscles around its air-filled swim bladder up to 100 times per second in chilly water. A fish can extend a single hum for about two hours, Feng and Bass report October 10 in Current Biology. That same kind of super-fast muscle shakes rattle-snake tails and trills vocal structures in songbirds and bats. |© Society for Science & the Public 2000 - 2016
By Christian Jarrett It’s been said that men and women are so unlike each other, it’s as if they’re from different planets – a claim that continues to amuse and irritate. John Gray’s original mega-selling book Men are from Mars, Women are from Venus, first published in the early 1990s, has sold millions, spawning numerous parodies (such as Katherine Black and Finn Contini’s Women May Be from Venus, But Men are Really from Uranus) and even comedy stage shows, such as Men are from Mars, Women are from Venus, Live! currently playing off Broadway.) While our physical differences in size and anatomy are obvious, the question of psychological differences between the genders is a lot more complicated and controversial. There are issues around how to reliably measure the differences. And when psychologists find them, there are usually arguments over whether the causes are innate and biological, or social and cultural. Are men and women born different or does society shape them that way? These questions are particularly thorny when you consider our differences in personality. Most research suggests that men and women really do differ on some important traits. But are these differences the result of biology or cultural pressures? And just how meaningful are they in the real world? One possibility is that most differences are tiny in size but that combined they can have important consequences. One of the most influential studies in the field, published in 2001 by pioneering personality researchers Paul Costa, Robert McCrae and Antonio Terracciano, involved over 23,000 men and women from 26 cultures filling out personality questionnaires. © 2016 BBC.
Keyword: Sexual Behavior
Link ID: 22746 - Posted: 10.12.2016
By Andy Coghlan More men inevitably means more testosterone-fuelled violence, right? Wrong, according to a comprehensive analysis exploring how a surplus of men or women affect crime rates across the US. In areas where men outnumber women, there were lower rates of murders and assaults as well as fewer sex-related crimes, such as rapes, sex offences and prostitution. Conversely, higher rates of these crimes occurred in areas where there were more women than men. Ryan Schacht of the University of Utah in Salt Lake City and his colleagues analysed sex ratio data from all 3082 US counties, provided by the US Census Bureau in 2010. They compared this with crime data for the same year, issued by the US Federal Bureau of Investigation. They only included information about women and men of reproductive age. For all five types of offence analysed, rising proportions of men in a county correlated with fewer crimes– even when accounting for other potential contributing factors such as poverty. The results suggest that current policies aimed at defusing violence and crime by reducing the amount of men in male-dominated areas may backfire. According to Schacht, when women are in short supply, men must be more dutiful to win and retain a partner. With an abundance of women, men are spoilt for choice and adopt more promiscuous behaviour that brings them into conflict with other men, and more likely to commit sex-related offences. © Copyright Reed Business Information Ltd.
By NICHOLAS BAKALAR Hormonal contraceptives are associated with an increased risk for depression, a large study has found. Danish researchers studied more than a million women ages 15 to 34, tracking their contraceptive and antidepressant use from 2000 to 2013. The study excluded women who before 2000 had used antidepressants or had another psychiatric diagnosis. Over all, compared with nonusers, users of hormonal contraception had an 80 percent increased risk of depression. Some types of contraceptives carried even greater risk. Women who used progestin-only pills more than doubled their risk, for example, while those who used those who used the levonorgestrel IUD (brand name Mirena) tripled their risk. The risk persisted after adjusting for age, age of first intercourse, educational level and other factors. The study, in JAMA Psychiatry, also found that the risk was greater in adolescent girls, but this may be because adolescent girls are especially susceptible to depression. “Even though the risk of depression increases substantially with these drugs — an 80 percent increase is not trivial — most women who use them will not get depressed,” said the senior author, Dr. Oejvind Lidegaard, a clinical professor of obstetrics and gynecology at the University of Copenhagen. “Still, it is important that we tell women that there is this possibility. And there are effective nonhormonal methods of birth control.” © 2016 The New York Times Company
Susan Milius ORLANDO, Fla. — When sex chromosomes among common pill bugs go bad from disuse, borrowed bacterial DNA comes to the rescue. Certain pill bugs grow up female because of sex chromosomes cobbled together with genes that jumped from the bacteria. Genetic analysis traces this female-maker DNA to Wolbachia bacteria, Richard Cordaux, based at the University of Poitiers with France’s scientific research center CNRS, announced September 29 at the International Congress of Entomology. Various kinds of Wolbachia infect many arthropods, spreading from mother to offspring and often biasing their hosts’ sex ratios toward females (and thus creating even more female offspring). In the common pill bug (Armadillidium vulgare), Wolbachia can favor female development two ways. Just by bacterial infection without any gene transfer, bacteria passed down to eggs can make genetic males develop into functional females. Generations of Wolbachia infections determining sex let these pill bugs’ now-obsolete female-making genes degenerate. Which makes it very strange that certain populations of pill bugs with no current Wolbachia infection still produce abundant females. That’s where Cordaux and Poitier colleague Clément Gilbert have demonstrated a second way that Wolbachia makes lady pill bugs — by donating DNA directly to the pill bug genes. The researchers, who share an interest in sex determination, have built a case that Wolbachia inserted feminizing genes into pill bug chromosomes. The bacterial genes thus created a new sex chromosome. 5|© Society for Science & the Public 2000 - 2016
Keyword: Sexual Behavior
Link ID: 22717 - Posted: 10.02.2016
By Jessica Boddy Activity trackers like Fitbits and Jawbones help fitness enthusiasts log the calories they burn, their heart rates, and even how many flights of stairs they climb in a day. Biologist Cory Williams of Northern Arizona University in Flagstaff is using similar technology to track the energy consumption of arctic ground squirrels in Alaska—insight that may reveal how the animals efficiently forage for food while avoiding being picked off by golden eagles. This week, Williams published a study in Royal Society Open Science that compared the activity levels of male and female squirrels. He found that although males spend a lot more time outside of their burrows, they’re pretty lazy, and sometimes just bask in the sun during warmer months. Females, on the other hand, have limited time to spare when caring for their young, and use it to run around and forage for themselves and their babies. In addition to previous work on arctic ground squirrel hibernation and seasonal differences in behavior, the finding is helping his team figure out why males tend to be more susceptible to being eaten. Williams sat down with Science to talk about creating a squirrel Fitbit, catching the animals in the wild, and how technology is improving ecological research. This interview has been edited for brevity and clarity. Q: What got you interested in studying arctic ground squirrels? A: It’s one of the only arctic animals that keeps a rigid schedule even when there’s no light/dark cycle for 6 week—meaning, they emerge from and return to their burrows the same time every day and they eat the same time each day, even though the sun stays in the sky for weeks and weeks. So I started to deploy the energy tracking technologies to better understand how the squirrels use energy through the seasons. © 2016 American Association for the Advancement of Science
Keyword: Sexual Behavior
Link ID: 22714 - Posted: 09.30.2016
By Clare Wilson IT HAS been blamed for brain shrinkage, impotence, divorce and paedophilia – and in April this year, Utah declared it a public health hazard. Warnings about pornography come not just from religious or conservative groups – former Playboy model and actor Pamela Anderson also recently cautioned against its “corrosive effects”. Yet survey after survey shows porn use is common among men and not exactly rare in women, so can it really be so dangerous? Or could it even have benefits? While there is research into the effects of porn, a great deal of it is contradictory. Even the same studies are interpreted differently by those on opposite sides of the debate. Some feel it is a menace to society, while others think that attitude belongs with 1980s hysteria over video nasties. Anti-porn campaigners chiefly argue that it is addictive and hijacks the brain’s normal reward pathways. Like heroin addicts who crave more of their drug to get the same high, users find they are no longer aroused by real sex and resort to increasingly harder-core material, or so the theory goes. Of course, there are other concerns over pornography, such as its depictions of violence, exploitation and sexual consent. But male addiction is an increasing focus of anti-porn campaigns. Campaigners say that an excess of porn prompts users to spurn their partners and seek out images of bestiality, rape scenes, and child abuse. Some schools in Scotland now warn that viewing adult images leads to impotence, coercion and abuse. “This kind of escalation is described over and over again,” says Gary Wilson, a retired biology lecturer and author of website and book Your Brain on Porn. © Copyright Reed Business Information Ltd.
Keyword: Sexual Behavior
Link ID: 22706 - Posted: 09.29.2016
By Karl Gruber Five lionesses in Botswana have grown a mane and are showing male-like behaviours. One is even roaring and mounting other females. Male lions are distinguished by their mane, which they use to attract females, and they roar to protect their territory or call upon members of their pride. Females lack a mane and are not as vocal. . New Scientist Live: Book tickets to our festival of ideas and discovery – 22 to 25 September in London But sometimes lionesses grow a mane and even behave a bit like males. However, until now, reports of such maned lionesses have been extremely rare and largely anecdotal. We knew they existed, but little about how they behave. Now, Geoffrey D. Gilfillan at the University of Sussex in Falmer, UK, and colleagues have reported five lionesses sporting a mane at the Moremi Game Reserve in Botswana’s Okavango delta. Gilfillan started studying these lionesses back in March 2014, and for the next two years he focused on recording the behaviour of one of them, called SaF05. She had an underdeveloped mane and was larger than most females. “While SaF05 is mostly female in her behaviour – staying with the pride, mating males – she also has some male behaviours, such as increased scent-marking and roaring, as well as mounting other females,” says Gilfillan. © Copyright Reed Business Information Ltd.
By Colin Barras It is not just about speed. The only songbird known to perform a rapid tap dance during courtship makes more noise with its feet during its routines than at other times. The blue-capped cordon-bleu (Uraeginthus cyanocephalus) from East Africa is blessed with the attributes of a Broadway star: striking good looks, a strong singing voice – and fine tap-dancing skills. The dances are so fast that they went unnoticed until 2015, when Masayo Soma at Hokkaido University in Japan and her colleagues captured the performances on high-speed film. The bird’s speciality is a left-right-left shuffle – only with the feet striking the perch up to 50 times a second. The vision of some birds operates at a faster rate than that of humans, so the cordon-bleu’s dance may simply be about creating an impressive visual performance. But it could also be about winning over a potential mate with rhythm. To explore the idea, Soma and her colleagues recorded audio of the courtship dances, which both males and females perform. They found that the tap dances are unusually loud: the feet strike the branch with enough force to generate sound averaging 30 decibels. This typically drops to just 20 decibels when a bird’s feet strike the branch as it hops around when it is not performing, which means the step sounds are not just a by-product of movement. © Copyright Reed Business Information Ltd.
Keyword: Sexual Behavior
Link ID: 22665 - Posted: 09.19.2016
Carrie Arnold Could a protein that originated in a virus explain why men are more muscular than women? Viruses are notorious for their ability to cause disease, but they also shape human biology in less obvious ways. Retroviruses, which insert their genetic material into our genomes to copy themselves, have left behind genes that help to steer our immune systems and mold the development of embryos and the placenta. Now researchers report in PLOS Genetics that syncytin, a viral protein that enables placenta formation, also helps to increase muscle mass in male mice1. These results could partially explain a lingering mystery in biology: why the males of many mammalian species tend to be more muscular than females. “As soon as I read it, my mind started racing with the potential implications,” says evolutionary virologist Aris Katzourakis of the University of Oxford, UK. About 8% of the 3 billion pairs of As, Ts, Gs and Cs that make up our DNA are viral detritus. Many of those viral hand-me-downs have degraded into useless junk — but not all, as a series of discoveries over the past 15 years has revealed. In 2000, scientists discovered that syncytin, a protein that enables the formation of the placenta, actually originated as a viral protein that humans subsequently ‘borrowed’2. That original viral protein enables the retrovirus to fuse with host cells, depositing its entire genome into the safe harbour of the cytoplasm. Syncytin has changed little from this ancestral protein form; it directs certain placental cells to fuse with cells in the mother’s uterus, forming the outer layer of the placenta. © 2016 Macmillan Publishers Limited
By NATALIE ANGIER The female bonobo apes of the Wamba forest in the Democratic Republic of Congo had just finished breakfast and were preparing for a brief nap in the treetops, bending and crisscrossing leafy branches into comfortable day beds. But one of the females was in estrus, her rump exceptionally pink and swollen, and four males in the group were too excited to sleep. They took turns wildly swinging and jumping around the fertile female and her bunkmates, shaking the branches, appearing to display their erections and perforating the air with high-pitched screams and hoots. Suddenly, three older, high-ranking female bonobos bolted up from below, a furious blur of black fur and swinging limbs and, together with the female in estrus, flew straight for the offending males. The males scattered. The females pursued them. Tree boughs bounced and cracked. Screams on all sides grew deafening. Three of the males escaped, but the females cornered and grabbed the fourth one — the resident alpha male. He was healthy, muscular and about 18 pounds heavier than any of his captors. But no matter. The females bit into him as he howled and struggled to pull free. Finally, “he dropped from the tree and ran away, and he didn’t appear again for about three weeks,” said Nahoko Tokuyama, of the Primate Research Institute at Kyoto University in Japan, who witnessed the encounter. When the male returned, he kept to himself. Dr. Tokuyama noticed that the tip of one of his toes was gone. “Being hated by females,” she said in an email interview, “is a big matter for male bonobos.” The toe-trimming incident was extreme but not unique. Describing results from their long-term field work in the September issue of Animal Behaviour, Dr. Tokuyama and her colleague Takeshi Furuichi reported that the female bonobos of Wamba often banded together to fend off male aggression, and in patterns that defied the standard primate rule book. © 2016 The New York Times Company
By Jesse Singal Back in 2014, a bigoted African leader put J. Michael Bailey, a psychologist at Northwestern, in a strange position. Yoweri Museveni, the president of Uganda, had been issuing a series of anti-gay tirades, and — partially fueled by anti-gay religious figures from the U.S. — was considering toughening Uganda’s anti-gay laws. The rhetoric was getting out of control: “The commercialisation of homosexuality is unacceptable,” said Simon Lokodo, Uganda’s ethics minister. “If they were doing it in their own rooms we wouldn’t mind, but when they go for children, that’s not fair. They are beasts of the forest.” Eventually, Museveni said he would table the idea of new legislation until he better understood the science of homosexuality, and agreed to lay off Uganda’s LGBT population if someone could prove to him homosexuality was innate. That’s where Bailey comes in: He’s a leading sex researcher who has published at length on the question of where sexual orientation comes from. LGBT advocates began reaching out to him to explain the science of homosexuality and, presumably, denounce Museveni for his hateful rhetoric. But “I had issues with rushing out a scientific statement that homosexuality is innate,” he said in an email, because he’s not sure that’s quite accurate. While he did write articles, such as an editorial in New Scientist, explaining why he thought Museveni’s position didn’t make sense, he stopped short of calling homosexuality innate. He also realized that in light of some recent advances in the science of sexual orientation, it was time to publish an article summing up the current state of the field — gathering together all that was broadly agreed-upon about the nature and potential origins of sexual orientation. (In the meantime, Museveni did end up signing the anti-gay legislation, justifying his decision by reasoning that homosexuality “was learned and could be unlearned.”) © 2016, New York Media LLC.
By Simon Oxenham It can seem like barely a week goes by without a new study linking the stage in a woman’s monthly cycle to her preferences in a sexual partner. Reportedly, when women are ovulating they are attracted to men who are healthier, more dominant, more masculine, have higher testosterone levels– the list goes on. But do women really exhibit such behavioural changes – and why are we so fascinated by the idea that they do? A popular theory in evolutionary psychology is that women seek out men with better genes while they are ovulating to have short term affairs with, so as to produce healthier babies. These men may not necessarily stick around for the long haul, but appear particularly attractive when a woman is in the fertile stage of her cycle. During the non-fertile phase, the theory goes that women seek out men who are more likely to make reliable long-term partners and good fathers. But something smells a bit fishy here. Are women really evolutionarily hard-wired to cuckold their partners? Or might the attraction of a salacious hypothesis – with slightly sexist overtones – be shaping some of this research? Masculine all month A review of these kinds of studies is now challenging this often-told story. Wendy Wood at the University of Southern California and her team have analysed 58 studies – some of which were never published – and found that this theory is largely unsupported by evidence. © Copyright Reed Business Information Ltd.