Researchers at Harvard have found that men who "reach sexual maturity in a context in which they far outnumber women" check out on average three months earlier than their counterparts who are part of more gender-balanced populations. The less favorable the male-to-female ratio, the larger the cut in lifespan.
Study author Nicholas Christakis, MD, PhD, said in a release:
"At first blush, a quarter of a year may not seem like much, but it is comparable to the effects of, say, taking a daily aspirin, or engaging in moderate exercise... A 65-year-old man is typically expected to live another 15.4 years. Removing three months from this block of time is significant."
The findings were based on two data sets: one from a long-term project looking at individuals who graduated from Wisconsin high schools in 1957, and the other compiled from the Medicare claims and census responses of more than 7 million men throughout the United States.
The researchers didn't look at the effect of imbalanced gender ratios on women. Nor did they investigate the mechanisms behind their findings on men, but:
Christakis suspects that it arises from a combination of social and biological factors. After all, finding a mate can be stressful, and stress as a contributor to health disorders has been well documented.
Says Christakis, "We literally come to embody the social world around us, and what could be more social than the dynamics of sexual competition?"