Australopithecus was an early proto-hominid that evolved in Eastern Africa around 4 million years ago. It consisted of a number of sub-species: A. anamensis, A. afarensis, A. sediba, and A. africanus; and two more sub-species whose genus is disputed: A. robustus and A. boisei. Over the course of two million years or so, the various Australopithecenes ranged across Eastern and Southern Africa.
The Australopithecines evolved about 2 million years after the split between the ancestral roots of humanity and chimpanzees (our closest relative), and one or more of the various sub-species of Australopithecus is likely to have been the progenitor of the Homo Genus, to which modern humanity (homo sapiens sapiens) belongs.
As mentioned in:
The Big Bang Theory — Barenaked Ladies