The life expectancy of women is longer than that of men. In fact, in more primitive times women tended to die sooner than men due to the dangers of childbirth and discrimination in the allocation of resources (that is, families often gave more food and medical attention to boys than to girls). One sign that a society is becoming more modern is when women begin to outlve men.
In any case, the life expectancy of women in all developed economies is significantly longer than that of men. In the U.S. one half of women can expect to live to age 80.1 whereas half of men will make it to 74.8—a difference in 5.3 years. One hypothesis to explain this difference is that men age faster than women.
Now researchers from Northern Michigan University writing in the American Journal of Human Biology argue that that hypothesis is wrong. So if men don't age faster, what does bump guys off more quickly than gals? A bit of the explanation is captured in that old joke about what are a redneck's last words? "Hey, y'all watch this!" (Before anyone accuses me of dissing rednecks, I just want to point out that I grew up on a dairy farm in Appalachia.) According to the press release describing the research:
"While men may die earlier on average, much of the difference in mortality rates is due to factors other than physiological decline caused by the aging process," [Brent] Graves [one of the NMU researchers] said. "Males engage in more risk-taking behaviors, which are reflected in much higher death rates—three times those of females in the 15-25-year age group—due to accidents and violence. There is also the physiological cost of testosterone, which suppresses the immune system and results in higher death rates among males due to infectious diseases and cancer.
The deleterious effects of testosterone came up last week during the American Association for the Advancement of Science conference on human enhancement in which I was participating last week. At the conference Michael Rose, an anti-aging researcher at the Univesity of California at Irvine who has bred fruit flies to live 3 times longer than usual, noted that castration may increase a guy's lifespan. Somehow I don't think that that particular longevity treatment is likely to catch on.