ABSTRACT
As the articles in this special issue demonstrate, gonadal hormones have powerful effects on the development of the brain and behavior in human beings, as in other species. Both androgens and estrogens affect behavior throughout development, from early prenatal life through adulthood, as demonstrated in studies with a variety of methods in several species. High levels of testosterone and other androgens that are present early in development are shown to facilitate the development of male-typical characteristics, and to inhibit the development of female-typical characteristics. Some of these effects are suggested to be mediated by the conversion of androgen to estradiol in the brain. Ovarian hormones are also shown to play an important role in the development and maintenance of female-typical characteristics, and their effects on the brain appear to extend beyond the prenatal and early postnatal periods. Nevertheless, there are not simple relations between the amount of hormone present and behavior. Behavioral effects of hormones are not uniform across behaviors or across individuals. Variations have been shown to relate to the timing of exposure, the organism’s sensitivity to the hormones, the specific hormone involved, and modification by the physical and social environment, although not all factors have been studied in all species, and many have not been studied directly in people. The articles in this special issue also describe attempts to identify the mechanisms—neural and basic behavioral—that mediate hormonal effects on complex human behaviors.
