ABSTRACT
When the life cycle of the human female is viewed from the perspective of parenthood, its major features clearly support a uniquely human pattern of high levels of long-term parental investment and the dependency of multiple young of differing ages. In developed countries menarche occurs at 12 to 13, cultural infertility breaks down in the late teens, and intercourse before marriage requires the use of contraception or abortion. Lactation is so short that birth spacing is dependent on contraception. A cross-species perspective suggests that adolescence in the human species has its own unique set of characteristics—some of which are shared with closest living relatives, the great apes, and others which may be found only in humans. For girls, the first external sign of puberty is the development of the breast bud. This is an odd and noteworthy feature of human development and one that is likely to go unnoticed without comparative mammalian data.
