Australopithecus afarensis is an extinct homini which lived between 3.9 and 2.9 million years ago. In common with the younger Australopithecus africanus, A. afarensis was slenderly built. From analysis it has been thought that A. afarensis was ancestral to both the genus Australopithecus and the genus Homo, which includes the modern human species, Homo sapiens..