Editor's Note: This is the final installment in the series on sex-based differences in the biology of males and females. Past articles are: "The Inequality of Drug Metabolism","Sex-based Differences Continue to Mount"," "X and Y Chromosomes Concern More Than Reproduction", "Deciphering How the Sexes Think", and "Yes, Biologically Speaking, Sex Does Matter".
For as long as demographic records have existed in the United States, women have outlived men. When flappers were big, a woman's life expectancy at birth was about two years more than a man's. Some 50 years later, when disco started taking over the land, the gap had expanded three-fold, to more than seven years.
The widening of last century's life expectancy gap between the sexes has been attributed mostly to smoking—men more than women. But in the last few decades, the number of female smokers...