All human ancestors and the current day humans belong to the biological family of Hominidae.Within this family individual ancestors are recognized by the names of their genus and species.A genus is a group of similar species.Humans belong to two genera and they are Austalopithecus and Homo.
According to some anthropologists the earliest of the ancestors fall under the genus Ardipithecus.It is still debated as to whether the fossils of Ardipithecus are different enough from those of Australopithecus to constitute a separate genus.
Genus Millions of years ago
Homo Sapiens 0.5-0.0
Home Erectus 1.5-1.0
Australopithecus boeises 1.25
Australopithecus Robustus 2.0-1.5
Homo Habilis 2.5-2.3
Australopithecus Africanus 2.75-2.25
Australopithecus Afarensis 3.75-3.5
Australopithecus Anamensis About 4.0
Ardipithecus Ramidus About 4.4
Bipedal locomotion in human ancestors developed earlier than increased brain size or making of stone tools.Different species are identified on the basis of their dental characteristics.Ardipithecus Ramidus lived approximately 4.4 million years ago.It had large jaws similar to those of the chimpanzees of modern days.
Julian Steward's studies on relatively recent population showed parallel changes in socio-cultural forms and adaptive means in different parts of the world.These are known as parallels through time and they were result of convergent evolution.