The genus Homo ( humans ) , appears about 2.4 million years ago with Homo habilis . They may be descended from australopithecine ancestors , more precisely from Kenyanthropus platyops branching off Australopithecus some 3.5 million years ago . The Homo genus ( humans , appear about 2.4 million years ago with Homo habilis ) appear to be descended from australopithecine ancestors , more precisely from Kenyanthropus platyops branching off Australopithecus some 3.5 million years ago .