Australopithecus afarensis appeared earlier in the hominid evolutionary timeline, dating back 3.9-2.9 million years ago. Homo habilis evolved around 2.4-1.4 million years ago, Homo erectus appeared around 1.9 million years ago, and Neanderthals are much more recent at 400,000-40,000 years ago. Australopithecus represents an earlier stage of human evolution before the Homo genus emerged.