The first is that people needed to work together during a hunt. They may have learned to talk so they can outsmart or trap animals. The second is that people learned to talk while helping each other gather and share food.
Best I can offer you can be found here: http://www.scribd.com/doc/7976893/A-MATRIX-OF-HUMAN-DEVELOPMENT-THEORIES-Prepared-by-Samuel-B-Batara-
Or are looking for a matrix displaying the development...
Well, i know of Freud's theory of psycho-sexual development, which is famous, although outdated and controversial. There's also Erik Erikson's stages of psychosocial development, which are generally...
