Hominid family tree with uncertain relationships

The oldest identified hominid skeletal remains
have been found in Eastern Africa. They are attributed
to an extinct genus, Australopithecus.
Several different species originated about 4.5 to
2 million years ago during the Pliocene epoch
(5.3 to 1.6 million years ago). During this time
fundamental changes in morphology and behavior
occurred, presumably to adapt to changing
the habitat from the forest to the plains:
bipedalism, a dramatic increase of brain
volume, and anatomic changes in the pharynx
to allow speech were accompanied by tool
making and other complex behavior.
The earliest fossils of Homo sapiens are from
100000 years ago. Modern humans as they
exist today date back about 30000–40000
years.