Theoretical background1At the end of the 9th century and the beginning of the 20th century, the theory of biological evolution had a wide influence. At that time, it was found in biology that the history of human embryo development was the repetition of animal evolution. Hall accepted this theory of evolution and complex speech and applied it to the theory of individual psychological development.
The basic idea is that the development of individual psychology should be regarded as a series of more or less repeated phylogeny. He believes that from the perspective of phylogeny evolution, it is manifested in the early stage of individual life.
The present genetic characteristics are older than the later ones, so they are not as stable and powerful as the former. The earliest activities in the history of human evolution are first manifested in individual development. They are all advanced, voluntary activities, and they are only available when they are older.