Adolescence and sexuality
The sexual development of adolescents has been exploited throughout history to encourage consumption of all sorts of material items and ideological messages. The images above were used to sell fragrances and shoes. Despite the use and abuse of teenage sexuality, adolescence became part of the human life cycle because it conferred significant reproductive advantages to our species, in part, by allowing the adolescent to learn and practice adult economic, social, and sexual behaviors before reproducing. In equal measure, adolescents in traditional and modern societies contribute much physical labor in terms of food production or financial earnings to their family and larger social group. This enhances the survival of individuals younger and older than themselves. As shown in the previous text and figures «The adolescent growth spurt», young women do not achieve an adult ovulation frequency until four to five years after Peak height velocity (PHV), on average age 16 to 17 years. Until then, adolescent girls may look like women and try to behave as women, but they have a low probability of conception.
In contrast, boys become biologically fertile early in adolescence, about one year before PHV, but they still look like juvenile boys due to their short stature and lack of body hair and musculature. Despite their fertility and the interest in adult behavior provoked by the reproductive hormones, the juvenile look of the adolescent boy excludes them from serious consideration as a sexual partner by fertile young women. Consequently, teenage boys are unlikely to become fathers.
The basic argument for the evolution and value of human adolescence is this: Girls best learn their adult social roles while they are infertile but perceived by adults as mature; whereas, boys best learn their adult social roles while they are sexually mature but not yet perceived as such by adults. Without the adolescent growth spurt, and the sex-specific timing of maturation events around the spurt, the unique style of human social and cultural learning could not occur. Over the course of time and space, the styles of learning these behaviors have come to vary considerably cross-culturally. [Barry Bogin]