> We know from observation and experimentation that testosterone
> alters people's mood and behavior. Men produce a lot, women produce
> a little. Specifically, we know that testosterone stimulates sexual
> desire in both men and women.
The average age of menopause among women is about 49.9 years in the United States; the testosterone level in men peak at about age 20 and begins to decline in their thirties: "As a result of the combined effects of a rise in SHBG and a fall in total testosterone, calculated free testosterone levels decrease by approximately 2-3% per year (Feldman et al., 2002)" ("Age-Related Changes in Testosterone and the Role of Replacement," <http://www.medscape.com/ viewarticle/479523_2>). Tying gender identities to hormone levels or other changing biological factors creates identity problems for both men and women. If people wish to retain the idea of genders, they have to develop social definitions of genders (so men and women can conceive of themselves as much men and women in their old age as in their youth) or else they will have to invent more genders than two, based on biological changes brought about by aging: e.g., four genders -- children, men, women, and the old (no longer male or female).
Yoshie Furuhashi <http://montages.blogspot.com> <http://monthlyreview.org> <http://mrzine.org>