Figure 1.

(A) For most great apes, the progression from birth to sexual maturation can be broken into three major stages. However, we describe human maturation as occurring over four stages (B). This has evolved by the separation of weaning and adrenarche into two distinct processes. There is significant variation in the ages at which each stage is met, but a rough estimate would be: nurseling (birth‐2.5 years), weanling (2.5‐7 years), juvenile (7 years‐13 years), adult (puberty onward) [Color figure can be viewed at http://wileyonlinelibrary.com]