Juvenile Stage

Juvenile: A life history stage of growth and development of some mammals that occurs between the end of infancy and the onset of adulthood. Juvenile mammals are weaned from maternal lactation and must forage for and process their own food as well as protect themselves from predators. Juvenile mammals are either sexually immature or so physically and socially immature that they have low breeding success. The juvenile stage is most commonly found in the social mammals, such as wolves, hyenas, lions, wild dogs, most primates, especially monkeys and apes, and probably many of the cetaceans (porpoises and whales). Hypotheses for the evolution of the juvenile stage inclue 1) inhibition of sexual development due to competitive dominance by older same-sex adults, 2) risk-aversion to predation and starvation by remaining relatively small, and 3) additional time for learning and practice of behaviours essential for adult reproductive success. In humans the juvenile stage ends with puberty and the adolescent stage quickly follows. In the apes and other primate species, puberty and reproduction may begin before the end of their juvenile stage. This is especially so for female non-human primates, who often have first birth before their own body growth terminates.