Neoteny - Biological

Neoteny is a type of heterochrony (variation in the timing of onset or termination of the stages of growth and development) that results in the retention of infantile or juvenile traits into adulthood. This is achieved by having sexual maturation take place while the individual is still in a pre-adult stage of phenotypic development. There are hypotheses that human evolution is a case of neoteny, with humans maturing sexually while in a stage of development equivalent to chimpanzee juvenility. These hypotheses use neoteny to explain human adult playfulness, language, and some juvenile-like physical traits. However, the anatomical, physiological, neurological, and cognitive evidence does not support the neoteny hypothesis and, rather favors addition of new life history stages and/or the extension of the timing of life history stages common to the apes.