A 2012 study from Australia suggested a new theory. Researchers studied fruit flys and found that mutations in the DNA of mitochondria accounts for at least some of the difference between life expectancies for males and females throughout the entire animal kingdom. As an example, the life expectancy of a male chimpanzee is 45 years, compared to 59 for the female. The average male mosquito lives a week; the female a month.
The study supports what scientists have long known – that at least some of the difference in longevity between men and women is in their genes. Natural selection favors reproduction over longevity, in essence using the body simply as a vehicle for passing on genes. Males have shorter lifespans because once they pass on their genes, they are disposable. Females are built to stick around to raise the young to maturity -- especially in species like humans who take many years to mature.
A related theory suggests that males compete with one another for the attention of females. The male who proves his mettle by engaging in risky behaviors like hunting and fighting is more likely to attract the female and therefore pass on his genes. But unfortunately for males, the more risky the behavior, the shorter the lifespan.
All this may be true. But scientists estimate that only about 30 percent of the variation in longevity can be attributed to genetics. The rest depends on environmental factors – your exposures and your behaviors. So what can men do to increase their life expectancy?
Take fewer risks. Men in their late teens and 20s go through a testosterone surge that tends to produce aggressive and risky behaviors. Young men drive too fast, don't wear their seatbelts; they fight and experiment with deadly weapons. Even today, this leads to a higher death rate among young men, as more men than women die in car accidents as well as other types of accidents and homicides. (One current example: The New York Times reported that 64 people were shot in Chicago last weekend -- 56 males and 8 females.) And we all know that risky behavior doesn't always end when a man turns 30.
Get a safer job. Traditionally, men took on dangerous jobs, from the military to mining, while women filled safer jobs such as teaching, nursing or child care. In our modern times, dangerous jobs have become safer, and the gender gap is closing. Nevertheless, men still work most of the dangerous jobs in America, from fisherman to farmer, roofer to truck driver.
Don't smoke or drink too much. Man tend to party more than women, and it takes its toll on their health. Fortunately, this gender gap is shrinking, as over the last two decades men have smoked less and less.
Eat a healthier diet. Men eat more meat, more high-fat snacks, more high-fructose corn syrup -- all leading to higher levels of cholesterol. A diet with more fruits and vegetables (which reduce colon cancer) and less red meat (which reduces risk of both cancer and heart disease) will help men improve their health and extend their life expectancy.
Deal with your stress. Researchers once thought that men suffered more stress because of their demanding jobs. That may no longer be so true, as women are working more, earning more and shouldering more financial responsibility for themselves and their families. But one thing is certain. Men internalize their stress, or deal with it in harmful ways, such as drinking or fighting. Men also have higher suicide rates than women. And stress plays an important role in heart disease. So it's crucial for men to find healthful outlets for stress, through sports, counseling, meditating or support groups.
Go to the doctor. It's an old joke, but some men out of a false sense of bravado won't go to the doctor, no matter how much it hurts. While it may not be necessary for young males to undergo an annual physical, older men should see their doctor regularly. And make sure to keep up to date with preventative care, from monitoring cholesterol to screening for prostate and colon cancer.
One last note: Women shouldn't take a longer life expectancy for granted. The gender gap has been closing. According to a report from the University of Washington, between 1989 and 2009, life expectancy increased by 4.6 years for men, but only 2.7 years for women. Let's hope any further narrowing of the gap is not due to women acting like males, but men behaving more like women.