"Women live longer in almost every country, and the sex difference in lifespan has been recognised since at least the mid-18th century," said Daniel J. Kruger, a research scientist in the U-M School of Public Health and the Institute for Social Research. "It is not a recent trend; it originates from our deep evolutionary history."

Kruger argues that the difference in life expectancy stems from the biological imperative of attracting mates: "This whole pattern is a result of sexual selection and the roles that males and females play in reproduction," Kruger said, "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." For example, in common chimps, the greatest difference in mortality rates for males and females occurs at about 13 years of age, when the males are just entering the breeding scene and competing aggressively for social status and females.

Males compete aggressively for female attention, and that costs them something. In nature, it means riskier physiology and behaviour for the males, such as putting more resources into flashy plumage or engaging in physical sparring. And even in modern life, where most duelling is a form of entertainment, male behaviour and physiology is shortening their lifespans relative to women, Kruger said. In fact, modern lifestyles are actually exacerbating the gap between male and female life expectancies.

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, Kruger said. Behavioural causes - smoking, overeating, reckless driving, violence - set men apart from most women.

MEDICA.de; Source: University of Michigan