A recent Harvard study seems to indicate that, among other gender-related factors, menopause may be a major reason for the disparity in average live span between women and men.
The study examined people who had reached the age of 100 and determined that two major evolutionary drives have helped women traditionally live longer. The first is the drive to pass on their genes, and the second is to allow the body to remain healthy enough to raise as many offspring as possible. Menopause allows women to reduce the risk of having children late in life, but allows them to live long enough to help take care of their grandchildren. The study suggested that since a man’s only true purpose is to pass genes on to a daughter who can then perpetuate the species, there has never been an evolutionary reason for living as long as a woman.
Human menopause may have evolved as a response to the amount of time children are dependent upon adults–and especially females–for survival. It’s possible that in early humans, females were frail enough to risk death by the age of thirty-five if they attempted to give birth. Females who’d undergone menopause by that time gained an evolutionary advantage because they didn’t face that potential risk.
Early Adulthood Deaths
That’s one part of the equation, but it doesn’t fully explain why women generally live so much longer than men. It doesn’t seem to matter whether they live in developed or undeveloped countries–women outlive men by at least seven to ten years. The figures are partly skewed by early adulthood, in which men are nearly five times more likely to die between the ages of 15 and 24 than women. Most deaths in that age group are caused by motor vehicles, but homicide, suicide, and other factors also contribute to those figures.
After age twenty-four, however, the difference narrows until people reach 55 to 64, when again more men than women begin to die, often due to heart disease and illnesses related to smoking or alcohol. Heart disease alone kills five out of every 1,000 men in that age group. The female hormone estrogen actually lowers harmful cholesterol and raises the good kind, reducing the risk of both heart disease and stroke.
Lifestyle of the Lucky
Of course, drinking, smoking, exercise, and diet can add or subtract years from a person’s life, but women still routinely outlive men in nearly every area of the world. However, the gap has been closing over the past two decades, due in large part to an increase in the number of female smokers and a correspondent decrease among men. Over the past twenty years, the rate of lung cancer among women has tripled, to the point where the average middle-aged woman smoker will live no longer than her male counterpart.
Sadly, that means smoking may turn out to be the leveler when it comes to average life expectancy between men and women, regardless of the genetic factors that have evolved over thousands of generations.