August 09, 2010
Mate Competition Shortens Male Lifespans?

Guys, surround yourself with lots of women in order to live longer.

BOSTON, Mass. (Aug 9, 2010) "Love stinks!" the J. Geils band told the world in 1980, and while you can certainly argue whether or not this tender and ineffable spirit of affection has a downside, working hard to find it does. It may even shorten your life.

A new study shows that ratios between males and females affect human longevity. Men who reach sexual maturity in a context in which they far outnumber women live, on average, three months less than men whose competition for a mate isn't as stiff. The steeper the gender ratio (also known as the operational sex ratio), the sharper the decline in lifespan.

"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," says Nicholas Christakis, senior author on the study and professor of medicine and medical sociology at Harvard Medical School as well as professor of sociology at Harvard University's Faculty of Arts and Sciences. "A 65-year-old man is typically expected to live another 15.4 years. Removing three months from this block of time is significant."

So guys are going to suffer shorter lives in nations like China and India where female fetuses are preferentially aborted.

Send your boys to high schools that are predominately female.

First, they examined information from the Wisconsin Longitudinal Study, a long-term project involving individuals who graduated from Wisconsin high schools in 1957. The researchers calculated the gender ratios of each high-school graduating class, then ascertained how long the graduates went on to live. After adjusting for a multitude of factors, they discovered that, 50 years later, men from classes with an excess of boys did not live as long as men whose classes were gender-balanced. By one measurement, mortality for a 65-year-old who had experienced a steeper sex ratio decades earlier as a teenager was 1.6 percent higher than one who hadn't faced such stiff competition for female attention.

Next, the research team compared Medicare claims data with census data for a complete national sample of more than 7 million men throughout the United States and arrived at similar results (for technical reasons, the study was unable to evaluate results for women who outnumbered men at sexual maturity).

I wonder what the mechanism is by which life expectancy is shortened. Hormonal mechanisms that increase stress?

Share |      Randall Parker, 2010 August 09 11:44 PM  Aging Studies


Comments
Carl said at August 10, 2010 12:14 AM:

The Trivers-Willard effect might might confound this in some cases:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004195

Brett Bellmore said at August 10, 2010 3:56 AM:

Well, there's evidence that regular sex is good for your health, and one presumes that regular sex is easier for men to come by where there are substantially more women than men. It might not be the competition at all, but the inevitable failure in the competition, that shortens those lives.

PacRim Jim said at August 10, 2010 1:50 PM:

Wonder how this applies to homosexuals?

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