Recent research has cast doubt on the line of ape-human development as once considered. Ardipethicus ramidus (taken to be the earliest human like type) and Australopithecus anamensis were considered to have a common unnamed ancestor in the ape in Africa. The given story was that this ape inhabited the jungle in wet dense conditions. After the rift valley rose and the east dried and vegetation changed, walking became important, and forced a change in survival and adaptation, although the first human types had both long arms and were bipedal.
But now the Orrorin Tugenensis of the Locano Basin in Eastern Africa has been dated from 5.8 to 6.1 million years old. This dating has taken place using association and magnetic field techniques. The hip bone shows that like the Australopithecus anamensis it walked upright, but its hands were adapted to live in the trees. Also it had back teeth for grinding in an ombnivore diet like the Australopithecus anamensis. The argument now is that this creature became highly mobile just like the Orang Utan today within its trees setting, therefore starting the line of development which would end up as homo sapiens. This line may bypass the next stage and run directly to Australopithecus anamensis. Subsequently the complexity of development is far more plural and species run back in time further than was once considered with the key bipedal development.