A number of hypotheses have been proposed to explain the evolution of modern humans. When on the ground they walked upright, but they were active in trees.
Experts recognize two species of Australopithecus.
A. africanus that occupied southern Africa and A. afarensis which occupied northeastern Africa. These groups of animals did not evolve directly from the apes but they were intermediate in form between apes and humans. Australopithecus resembled apes in having front teeth that were large in relation to the size of their molars. The animal fed largely on coarse food, probably fruits an seed pods. A general cooling and drying over the last 20 Myr 2.