There are many different beliefs about what the dominant forces are in the process of human development. One of these forces is maturation, a biological process in which developmental changes are controlled by internal factors. Behaviors that result from maturation, such as walking or secondary sex changes at puberty, are characteristic of the species and are never the result of specific practice or exercise—that is, they are not learned.

Maturation is usually aligned with a belief that heredity is a dominant influence upon development, and the most popular developmental theorist to put forth this belief is Arnold Gesell. Gesell was influenced by G. Stanley Hall's interest in recapitulation theory, which held that the development of the individual recapitulates (or repeats) the evolutionary history of the species' ...