Neoteny

Neoteny is a type of heterochrony. It is a change in the timing of development in an animal. It is where bodily development is slowed, but sexual development goes on at the same rate. At the extreme, this results in a sexually mature juvenile or larval form. A classic example of that is the Axolotl salamander.
It has often been suggested that the human species is an example of neoteny. There are features of adult humans that are more like those of juvenile apes than adult apes. 
These are some of the neotenous traits in humans: 
In some texts these differences may be called paedomorphosis, meaning "like a child". The term "K-selection" is sometimes used to describe this evolutionary process. The process is all part of a situation where the species benefits from the longer-lasting of juvenile features into adult life.
If we continue the list into physiology and behaviour, we find:
This second list shows how the first list becomes the basis for the larger groups of modern man and their better transmission of experiences to later generations.