Daniel J. Kruger, a U-M research scientist says, "Women live longer in almost every country, and the sex difference in lifespan has been recognized since at least the mid-18th century. It isn't a recent trend; it originates from our deep evolutionary history."
This skewed mortality isn't even unique to our species; the men come up short in common chimps and many other species, Kruger added.
Kruger and co-author Randolph Nesse, a professor of psychology and psychiatry and director of the Evolution and Human Adaptation Program, argue that the difference in life expectancy stems from the biological imperative of attracting mates.
Kruger says, "This whole pattern is a result of sexual selection and the roles that males and females play in reproduction. Females generally invest more in offspring than males and are more limited in offspring quantity, thus males typically compete with each other to attract and retain female partners."
Modern day examples can be seen in both the tail of the peacock and the "blinged" out SUV's gleaming with shiny rims.
In modern life, most dueling is in the form of entertainment, Kruger believes male behavior and physiology is actually shortening their life spans relative to women. In fact, modern lifestyles are actually exacerbating the gap between male and female life expectancies.
Researchers in the study also believe male physiology, shaped by eons of sexual competition, is putting the guys at a disadvantage in longevity. Male immune systems are somewhat weaker, and their bodies are less able to process the fat they eat. And behavioral causes---smoking, overeating, reckless driving, and violence---set men apart from most women.
