Although Many Human Characteristics Are Neotenous Compared to a Chimpanzee

Essay

Although many human characteristics are neotenous compared to a chimpanzee, head growth is not. In the fetus of both species, brain and head growth start at approximately the same developmental stage and progress at the same rate. Soon after birth, chimpanzee brain and head growth stops. Human brain and head growth continues for several years after birth. Thus, relative to head growth, reproduction is occurring at a later stage. Assuming that chimpanzees represent the ancestral condition, explain what type of heterochrony humans have in brain development.