Memo to Larry Summers: It’s not just math and science; women are also hugely underrepresented in elite chess. No woman has ever won an official world championship; no major country can boast a female champion; and as of 2004, only 1 percent of grand masters were women. A recent paper on sex discrepancies in competitive chess found scant evidence that either cognitive differences or “old boys’ networks” are to blame for the dearth of women at the top. The authors note that males and females who play chess with the same frequency and have the same rating also improve—and drop out of the game—at the same pace, and that when groups of children start playing, if at least half are girls, the boys’ and girls’ ratings aren’t markedly different. The most consistent explanation for the game’s gender gap is that girls take up chess and enter competitions in much smaller numbers than boys. Why? The authors suggest that girls (or their parents) may be discouraged by the absence of female role models and by the prospect of playing with so many boys.
—“Sex Differences in Intellectual Performance: Analysis of a Large Cohort of Competitive Chess Players,” Christopher F. Chabris (Harvard University) and Mark E. Glickman (Boston University)
The occasional Egyptian royal dynasty aside, we all know we’re not supposed to have sex with our siblings. Now, three evolutionary psychologists studying the cues humans use to determine relatedness have concluded that cultural and religious taboos against incest are superfluous: We’ve evolved to recognize siblings and avoid having sex with them. Their paper, published in a recent issue of Nature, asked more than 600 people about their family histories and interactions with siblings. The results suggest that two main cues help children identify blood relatives: the amount of time another young person spends with a child’s mother as an infant, and the amount of time another young person spends living under the same roof as that child. The “kinship index” created by these cues, the authors argue, regulates two evolutionarily useful attitudes—altruism toward siblings and aversion to incest. Both cues predict the level of disgust a person feels for incest far better than any conscious beliefs about the nature of the relationship in question: You’re more likely to be revolted by the idea of sleeping with a stepsibling you’ve grown up with than with someone you believe to be a blood relation who hasn’t been nursed by the same mother or lived under the same roof. The authors also point out that aversion to sibling incest is strongest among siblings of the opposite sex; and it’s more intense among women, which might be explained by the innate interest women have in giving birth to healthy children.
—“The Architecture of Human Kin Detection,” Debra Lieberman, John Tooby, and Leda Cosmides, Center for Evolutionary Psychology, UCSB; Department of Psychology, University of Hawaii, Honolulu
There’s not much difference between zapping zombies and blasting blood clots, according to a study on doctors at Beth Israel Medical Center in New York City. Following up on previous research suggesting that young doctors are quicker than older ones to pick up “laparoscopic” skills (which allow them to control tiny instruments inside a patient’s body while watching the action on a big TV screen), the study set out to test whether this edge was explained by all the time that younger doctors had spent playing Nintendo as kids. The authors polled 33 surgeons on their video-gaming histories before putting them through a set of laparoscopic challenges—timed and scored surgical drills with nicknames like the “Cobra Rope,” the “Cup Drop,” and the “Terrible Triangle”; they also asked the surgeons to play a video game, such as Super Monkey Ball 2 or Star Wars Racer Revenge. They then sorted the data to see if joystick twiddling makes you a better surgeon. Indeed it does, by a wide margin. Doctors who’d once played for more than three hours a week did the lap-skills course in an average of 64 minutes with 197 errors; doctors who’d never played took 87 minutes and made 314 errors. Overall, the study found that a surgeon’s video-game skills, or lack thereof, explained 31 percent of the variance in laparoscopy performance. Less than 2 percent of the variance was attributed to the number of laparoscopies surgeons had performed. Video games can lower grades and promote obesity, the authors allow, but they can also make for damn fine doctors.
—“The Impact of Video Games on Training Surgeons in the 21st Century,” James C. Rosser et al., Archives of Surgery
Since 2004, the U.S. Food and Drug Administration has warned that taking antidepressants may increase the risk of suicidal thoughts and behavior in children and adolescents. So should Prozac and Zoloft be pulled from the shelves? Not necessarily, suggests a new study published by the National Bureau of Economic Research. The authors examined the effects of selective serotonin reuptake inhibitors (SSRIs), the most commonly taken class of antidepressant, on “completed suicide” rates (as opposed to suicidal tendencies and attempted suicides) over 25 years in 26 countries. They found that an increase in antidepressant sales of one pill per capita (about a 12 percent increase over the sales levels for 2000 in the countries surveyed) correlated with a suicide-mortality decline of about 5 percent. The authors argue that randomized clinical trials—the basis for the FDA’s findings—are a poor way to examine the relationship between SSRIs and suicide-completion rates, because the samples are too small to yield meaningful results and because such trials “exclude those at highest risk for suicide.” (Most clinical trials, for instance, avoid enrolling patients with a history of suicide attempts.) SSRIs, the study contends, are a cost-effective measure against suicide: An additional $20,000 spent on them will avert one suicide death, a cost per life saved far lower than the cost of most other forms of public-health intervention.
—“Anti-Depressants and Suicide,” Jens Ludwig, Dave E. Marcotte, and Karen Norberg, NBER