5) I know that other species of hominids die out due to competition with better species. As a result, it is understandable how Homo erectus, heidelbergensis and neanderthals went extinct. However, Austrolopithecus and Ardipithecus, correct me if I'm wrong, still lived mostly in the forest. In fact, from what I have read, both groups of hominids seem like chimpanzees who could naturally walk upright. Why did they all die out?