メディエイゴ

“Love stinks!(1)” the J. Geils band(2) told the world in 1980, and while you can certainly argue whether or not this tender and ineffable(3) spirit of affection has a downside(4), working hard to find it does. It may even shorten(5) your life.

A new study shows that ratios between(6) males and females affect human longevity(7). Men who reach sexual maturity(8) in a context in which they far outnumber(9) women live, on average(10), three months less than men whose competition for a mate(11) isn’t as stiff. The steeper(12) the gender ratio(13) (also known as the operational sex ratio(14)), the sharper the decline in lifespan(15).

“At first blush(16), a quarter of a year may not seem like much, but it is comparable to(17) the effects of, say, taking a daily aspirin(18), or engaging in moderate(19) exercise,” says Nicholas Christakis, senior author(20) on the study and professor of medicine and medical sociology(21) at Harvard Medical School as well as professor of sociology(22) at Harvard University’s Faculty(23) of Arts and Sciences. “A 65-year-old man is typically(24) expected to live another 15.4 years. Removing three months from this block of time is significant.”

These results are published in the August issue of the journal Demography(25).

An association between gender ratios and longevity had been established through studies of animals before, but never in humans. To search for a link in people, Christakis collaborated with(26) researchers(27) from the Chinese University of Hong Kong, the University of Wisconsin and Northwestern University. The researchers looked at two distinct datasets(28).