Two researchers have reviewed the body of research on the effects of birth control pills on both women and men’s perceptions of attractiveness, and have come to some provocative conclusions. Women on the pill are less attracted to hyper-masculine men, they found, and don’t show the typical propensity towards men who are genetically dissimilar from themselves. In addition, women on the pill may lack the attractiveness edge that’s associated with ovulation, the study found.
An alarmist, tabloid-esque summary of the findings might read like this: Pill-taking women aren’t hotties, and they pick girlie men who are likely to give them ugly babies. But of course, there’s a lot more complexity to the findings. The contraceptive pill alters monthly fluctuations in hormones associated with the menstrual cycle, mimicking the more stable hormonal conditions associated with pregnancy [New Scientist]. While mounting evidence suggests that having one’s hormonal levels smoothed out in this way alters some of the laws of attraction between men and women, scientists hasten to add that hormones aren’t everything.
The new study (pdf), published in Trends in Ecology and Evolution, looked first at research that’s been conducted on women’s preferences for men. Women who aren’t on the pill have shown a preference for certain types of men while they’re ovulating: they prefer men with more traditionally masculine facial features, and have also been shown to prefer the smell of men who are genetically dissimilar (which in humanity’s earlier days, when inbreeding was a danger, would have been an advantage). Women on the pill don’t show these same preferences. But many would argue that personality is a far better way to choose a life partner than what they smell like. One recent study involving speed-dating experiments suggested that although women might say they prefer the scent of men with dissimilar immune systems, this doesn’t correspond with the men they actually chose to go out with [New Scientist].
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Organisms evolve to fit the world around them–but if the changes don’t work out, can a creature reverse the process? Say, for example, an insect originally eats a wide variety of tree leaves, but then evolves to live exclusively on the leaves from one type of tree that is abundant in its habitat; if that tree goes extinct, can the bug reverse course? A new study in Nature sheds some light on such questions, which have perplexed evolutionary biologists for many decades.
More than a century ago, the French–born Belgian palaeontologist Louis Dollo proposed that evolution cannot retrace its steps to restore a lost trait — an idea that has remained controversial [Nature News]. So researchers set out to test “Dollo’s Law” on the molecular level, studying a protein called the glucocorticoid receptor, which binds to the hormone cortisol to regulate the stress response. Study coauthor Joseph Thornton says that at least in this protein’s case, new mutations make it practically impossible for evolution to reverse direction. “They burn the bridge that evolution just crossed” [The New York Times], he says.
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Trouble is mounting for the South African athlete who was suspected of having an unfair advantage in women’s track events because of male characteristics. After 18-year-old Caster Semenya thumped the competition at an 800-meter race in Berlin, sports officials announced that Semenya would be subjected to a battery of tests to determine her gender. Now, unconfirmed sources have reported that the tests showed Semenya has both female and male reproductive organs, and her future in women’s sports is in doubt.
Newspapers in Australia reported that while Semenya’s external genitalia is female, she doesn’t have ovaries and instead has internal testes that produce the hormone testosterone. If the reports are accurate, Semenya probably benefited from that hormone boost by gaining muscle mass. But it now seems clear that there is no disciplinary action to be taken, because even if Semenya has high male hormone levels, it is not because of medical cheating. But that leaves a moral and ethical quandary and a medical issue which anyone else in the same position would be able to work out in private – for Semenya, it is all public [ABC Sport].
Experts says that based on the information reported, Semenya may have a condition called androgen insensitivity syndrome, in which the fetus develops functional testes, but then stops developing male characteristics. As a result, the baby develops down the “default” female route. The testes are there but usually do not descend and remain hidden in the body and the condition does not become apparent until adolescence when the girl does not start her period [BBC News]. Medical experts also note that internal testes can grow malignant tumors, and say that some doctors advise removing them as a precautionary measure.
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When 18-year-old Caster Semenya blew past the competition in the women’s 800-meter race at the World Athletics Championships in Berlin this week, she got more than a gold medal. The South African athlete ran straight into a controversy about both the nature of gender and hers in particular. Some other runners contend that Semenya, with her stereotypically masculine build, is really a man, while the more temperate governing body, the International Association of Athletic Federations, says it needs to determine if she has male characteristics that give her an unfair advantage. To settle the question, the IAAF has ordered tests by a gynecologist, an endocrinologist, a gender expert, and a psychologist.
Gender expert Richard Auchus says assigning sex was hardly as easy as sizing someone up visually…. “For 99 percent of the population it’s easy to determine…. But one percent of the population have conditions that make it not so straightforward” [The New York Times]. In the 1960s, athletic federations began testing athletes by scraping cells from their mouths and testing them for a pair of X chromosomes, which typically establishes a person’s sex as female (as opposed to the XY chromosomes typically carried by males). But the tests were halted in the 1990s as critics pointed out that there are medical conditions that lead individuals with two X chromosomes to develop masculine characteristics, and others that mean individuals with one X and one Y chromosome never develop masculine characteristics. Some other individuals also exist outside the usual sexes of XX females and XY males; these may include males who are XXY, further confusing the tests [Nature News].
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Unscrupulous athletes may soon find it much harder to get away with juicing. Anti-doping agencies are trying out “biological passports,” electronic records for individual athletes which provide baseline measurements of substances in their blood and urine. The record is built up over time through repeated sampling, and later tests can look for suspicious changes that may indicate the use of performance enhancing substances. As cycling has been particularly hammered by allegations of doping athletes, the International Cycling Agency has lead the charge on biological passports. Over a year, it took around 8300 blood samples from 804 cyclists. It recently revealed that a small number of these athletes’ profiles are “under further scrutiny” [New Scientist].
Doping has gone far beyond obvious substances like steroids; in recent years athletes have been caught injecting hormones for a competitive edge, and even getting transfusions of their own blood to discreetly boost their red blood cell counts. The biological passport would combat this increasingly sophisticated arsenal of tricks. Rather than ordinary spot-testing approaches, which look for unnatural ratios between biological constituents in a single sample or for direct chemical evidence of known doping agents, the passport allows investigators to see the big picture—any deviations from the rider’s test-established norm that might result from doping, even if the specific drug or tactic remains unknown [Scientific American].
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It may be old news that people who work the night shift tend to have higher rates of certain medical conditions. But researchers say they have established a direct link between an abnormal sleep cycle and altered hormone levels, which can disrupt metabolism and increase the risk of heart disease, diabetes, and obesity. As soon as their circadian rhythms became separated from a day-night cycle, test subjects’ levels of key metabolic hormones went haywire—the most compelling evidence yet that shift work isn’t just an inconvenience, but an occupational hazard [Wired News].
The study, published in the Proceedings of the National Academy of Sciences, maps a clear path from work-sleep cycles to metabolic disregulation to disease [Wired News]. Scientists cannot yet explain the exact connection between metabolism and the circadian rhythm, the roughly 24-hour cycle that biological and behavioral processes are based on. But they believe the trigger to be a decrease in the hormone leptin, which the body uses to regulate appetite, that results when the circadian rhythm is disrupted.
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The global economic crisis has everybody looking for scapegoats–and now we may have a couple, in the form of a pair of genes that influence people’s desire to take financial risks. The two genes regulate dopamine, the brain chemical associated with reward and risk-taking, and serotonin, the chemical linked to mood and anxiety. In a new study, researchers found that people with the “high-risk” version of the dopamine gene tended to invest in risky but potentially lucrative propositions, while those with the “high anxiety” version of serotonin managed their money more carefully [Reuters].
While an experiment showed a clear correlation between the genes and risk-taking behavior, study coauthor Camelia Kuhnen says the results don’t suggest that all bankers should get their DNA tested. “I wouldn’t want to oversell this as a screening device to find good traders…. Even if I have a gene that predisposes me to taking a lot of financial risk, I could go through a stock market crash that will make me less risk-taking” [Scientific American], says Kuhnen.
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Men who want to know if they’d make it as day traders on Wall Street just have to look down at the fingers, according to a new study. The longer their ring fingers are in relation to their pointer fingers, the more likely they are to have what it takes to make millions on the trading floor. Previous research has found that the digit ratio reflects how much testosterone an unborn baby was exposed to in the womb. Those exposed to high levels of the hormone are more sensitive as adults to testosterone that creates feelings of confidence and encourages risk-taking, said study author John Coates [Bloomberg].
Coates has previously shown that traders who register the highest levels of testosterone in the morning make the most money through the course of the day, and this new study adds to the earlier work by suggesting that their advantage may have been innate, not learned. Although it may come as no surprise that testosterone could be a big player in the mano-a-mano world of Wall Street, the research offers the best evidence yet of the hormone’s role in determining which would-be Masters of the Universe will thrive. It also supports the growing recognition that biology plays a role in complex human behaviors, and that financial choices in particular are often less rational than economists appreciated [Washington Post].
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Dosing menopausal women with testosterone may be the key to helping those with low libidos get back in the mood, according to a new study. Proctor & Gamble Pharmaceuticals has published the results of a new trial of their testosterone patch, called Intrinsa, and say the results are encouraging for frustrated older women seeking a “Viagra for women.” However, nagging safety concerns are likely to keep the drug off the market in the United States for some time to come (although the drug is already on sale in Europe): During the new study, four of the test subjects using the patch developed breast cancer.
The 52-week study included 814 women with sexual desire disorder, characterized by troublesome low sexual desire or function…. The women were asked to keep sexual encounter diaries, and researchers used other established measures to assess sexual response during the six-month evaluation phase of the study. They found that compared to placebo users, the women who used the 300 microgram patch reported significant improvements in sexual functioning, including desire, arousal, orgasm, and pleasure [WebMD].
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Male-to-female transsexuals are more likely to have a genetic variant that may cause weaker testosterone signals in the brain during early development, according to a new study. Researchers say the finding is another piece of evidence that there is a genetic component to these men’s strong feelings that they’re really women who were born into the wrong body, a theory many experts have long endorsed based on anecdotal evidence. “People who come to our clinic describe how they knew they were different at a very early age, just three or four years old. This is something that people are born with,” Dr [Trudy] Kennedy said [Sydney Morning Herald].
The findings are important, but lead researcher Vincent Harley admits he hasn’t discovered a clear, single cause of transsexualism. While the genetic link was statistically significant, it was weak – 55% of the transsexuals had the [genetic variant], compared with 50% of normal men. Harley agrees that many more genes related to male-to-female transsexualism probably remain to be discovered [New Scientist].
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Teenage boys with behavior problems may be able to blame their brain chemistry, according to a new study. Psychologists studied boys with a history of antisocial behavior and measured their levels of the hormone cortisol, which usually surges during stressful situations, causing people to focus and behave more cautiously. They found that the troubled boys didn’t have the normal cortisol spike when they were put under stress, suggesting that they weren’t getting a chemical signal to regulate their emotions and actions.
Researchers say the findings suggest that some bad behavior should be considered a form of mental illness. “Most research has looked at social factors like peer groups, family life and socioeconomic factors,” said [lead researcher] Graeme Fairchild…. “These findings basically indicate that antisocial behavior is probably more biologically based than many people recognize and is similar to conditions like depression and anxiety” [Reuters].
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In a finding that has particular relevance right now, as the American public looks for scapegoats for the current financial crisis, a new study has found that men with higher levels of testosterone are inclined to make riskier financial decisions. Just how much riskier? Those with 33 percent more testosterone than average men invested 10 percent more of their dough. The findings are based on saliva samples from 98 male Harvard students taken before they played an investment game with $250 in real money [Scientific American].
Researchers say they didn’t outright prove that it was Wall Street men’s hormones that got us into this mess, but that the evidence is strongly suggestive. “Although our findings do not address causality, we believe that testosterone may influence how individuals make risky financial decisions,” said researcher Coren Apicella…. A recent study also showed that stock market traders made more money on days when their testosterone levels were highest [LiveScience].
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Researchers have found a gene in men that’s linked to happy marriages, according to a new study. The gene determines how the brain responds to a hormone that has previously been shown to cause monogamous behavior in prairie voles; researchers found that men with a certain variant of the gene were less likely to be married to their partners, and if they were married, they were more likely to have had a marital crisis and to have discussed the possibility of divorce.
In the study, researchers studied the genetics of more than 550 men who were in relationships, and then asked both the men and their partners a series of questions. Men with a variant of the gene tended to score badly on a questionnaire designed to assess how well they bond with their partner and were more likely to report having suffered marital difficulties…. The wives of those who were married were also less satisfied with their marriage than women whose husbands did not have that genetic variant [Telegraph].
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A study of an experimental prostate cancer drug showed dramatic results that have thrilled researchers: The drug shrank prostate tumors and doubled survival rates in more than 70 percent of patients with an aggressive form of prostate cancer. The test subjects were men whose cancer had not responded to other treatments, and who had a life expectancy of about a year.
Although the study, which was published in the Journal of Clinical Oncology [subscription required], covered only 21 patients, the drug is now being tested in more than 250 men with what appears to be similar results, experts said. “There is a general sense in the prostate cancer community that this agent is extremely promising and is very likely to have an important role in the management of prostate cancer patients,” said Dr. Howard M. Sandler [Los Angeles Times]. Experts say the drug could reach the doctors’ offices by 2011.
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Despite the International Olympic Committee’s vow to vigilantly test for performance enhancing drugs at the Summer Olympics in Beijing, some scientists and sports doctors say that athletes are likely to cheat at the games, and get away with it.
The focus is on erythropoietin (EPO), a hormone naturally produced by the kidneys which regulates red blood cell production. When extra EPO is injected before a competition, it boosts performance by increasing the amount of red blood cells in an athlete’s body; those blood cells then carry more oxygen to the hard-working muscles.
Anti-doping agencies regularly test athletes for EPO, but some researchers say the agencies can’t develop tests fast enough to keep up with new “copycat” versions of EPO, often produced by pharmaceutical companies in India, Cuba, and China. These cheap versions of EPO, often called biosimilars, can be easily bought over the internet…. Some scientists who track and monitor the development of copycat EPO drugs say there could be up to 80 different versions now being manufactured in different parts of the world [BBC News].
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