Neoteny in humans Neoteny in humans Neoteny in humans is the retention of juvenile features well into adulthood. This trend is greatly amplified in humans especially when compared to non-human primates. Adult humans more closely resemble the infants of gorillas and chimpanzees than the adults. Neotenic features of the head include the globular skull thinness of skull bones; the reduction of the brow ridge; the large brain; the flattened and broadened face; the hairless face; hair on (top of) the head; larger eyes; ear shape; small nose; small teeth; and the small maxilla (upper jaw) and mandible (lower jaw). Neoteny of the human
Sex differences in humans Sex differences in humans Sex differences in humans have been studied in a variety of fields. In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome, the type of gonads, the sex hormones, the internal reproductive anatomy (such as the uterus), and the external genitalia. Genetic sex is determined solely by the presence or absence of a Y chromosome. Sex differences generally refer to traits that are sexually dimorphic. A subset of such differences is hypothesized to be the product of the evolutionary process of sexual selection. Sex differences in