A visit to a senior center or to a nursing home can easily lead to the question “Where are all the very old men?” Women’s average longevity is about 5 years more than men’s at birth (in 2004), nar­rowing to roughly 1 year by age 85 (Arias, 2006; National Center for Health Statistics, 2008a). These differences are fairly typical of most industrialized countries but not of developing countries. Indeed, the female advantage in average longevity in the United States became apparent only in the early 20th century (Hayflick, 1996). Why? Until then, so many women died in childbirth that their average longevity as a group was reduced to that of men. Death in childbirth still partially explains the lack of a female advantage in developing countries today; however, part of the difference in some countries also results from infanticide of baby girls. In industrial­ized countries, socioeconomic factors such as access to health care, work and educational opportunities, and athletics also help account for the emergence of the female advantage (Hayflick, 1998).

Many ideas have been offered to explain the sig­nificant advantage women have over men in aver­age longevity in industrialized countries (Hayflick,

1996) . Overall, men’s rates of dying from the top 15 causes of death are significantly higher than women’s at nearly every age, and men are also more suscep­tible to infectious diseases. These differences have led some to speculate that perhaps it is not just a gender-related biological difference at work in lon­gevity, but a more complex interaction of lifestyle, much greater susceptibility in men of contracting certain fatal diseases, and genetics (Hayflick, 1996).

Other researchers disagree; they argue that there are potential biological explanations. These include the fact that women have two X chromosomes, compared with one in men; men have a higher metabolic rate; women have a higher brain-to-body weight ratio; and women have lower testosterone levels. However, none of these explanations has sufficient scientific support to explain why most women in industrialized countries can expect, on average, to outlive most men (Hayflick, 1996).

Despite their longer average longevity, women do not have all the advantages. Interestingly, older men who survive beyond age 90 are the hardiest segment of their birth cohort in terms of performance on cognitive tests (Perls & Terry, 2003). Between ages 65 and 89, women score higher on cognitive tests; beyond age 90, men do much better.