biological influences (Carnegie Corporation of New York, 1989). The actual evidence for this suggestion is minimal due to paucity of relevant research (see Buchanan et al., 1992). But this suggestion is consistent with evidence that many of the mood and behavioral changes most often hypothesized to be related to the hormonal changes associated with puberty are most marked during the early adolescent years (Carnegie Corporation of New York, 1989; Moffitt, 1993).
Equally critical for this report is the issue of individual and group differences in both the rates and types of changes in these hormonal systems and individual differences in the reactions to these changes. Both current and previous life events and genetically linked vulnerabilities and propensities affect adolescents’ reactions to the hormonal changes occurring particularly during early and middle adolescence (Caspi and Moffitt, 1991; Graber and Brooks-Gunn, in press; Gubba et al., 2000; Rutter et al., 1997; Silberg et al., in press). The nature of these interactions suggests that early adolescents living in high-risk settings may be more prone to the problematic effects of changes in the gonadol and adrenal hormone systems associated with late childhood and early adolescence.
There are, of course, also sex differences in the nature of pubertal change. The hormonal changes associated with puberty are different for girls and boys: levels of testosterone increase more in boys, while levels of estrogen and progesterone increase more in girls. In addition, girls develop a monthly cycle of gonadol hormones; for the most part, boys do not. It has been suggested that the sex differences associated with the emergence of depression, eating disorders, and aggression may be linked to these differences in patterns of hormonal changes associated with pubertal development. But evidence suggests that the origins of both sex differences and individual differences more generally in these mood and behaviors patterns lie in complex interactions between experience, life events, intensified gender role socialization, genetically linked vulnerabilities, and changes in hormonal systems (Buchanan et al., 1992; Goodyer, 1995; Graber and Brooks-Gunn, in press b; Keel et al., 1997; Kendler and Karkowski-Shuman, 1997; Kessler et al., 1993; Petersen et al., 1991; Rutter et al., 1997; Silberg et al., in press; Wichstrom, 1999; Zahn-Waxler et al., in press). Each of these authors stresses that we are just beginning to understand the nature of these interactions and therefore encourages cautious interpretation of simplistic models of the role of hormones in accounting for sex differences in moods or behaviors.
There are also sex and ethnic group differences in the timing of puberty. In general, pubertal changes begin 12 to 18 months earlier for