of Homo sapiens (anatomically modern humans) and may even predate the genus Homo. The oldest undisputed evidence for hunting dates to the Early Pleistocene, consistent with the emergence and early dispersal of Homo erectus, about 1.7 million years ago (Acheulean). While it is undisputed that Homo erectus were hunters, the importance of this for the emergence of Homo erectus from its australopithecine ancestors, including the production of stone tools and eventually the control of fire, is emphasised in the so-called "hunting hypothesis" and de-emphasised in scenarios that stress omnivory and social interaction. There is no direct evidence for hunting predating Homo erectus, in either Homo habilis or in Australopithecus. The early hominid ancestors of humans were probably frugivores or omnivores, with a partially carnivore diet from scavenging rather than hunting. Evidence for australopithecine meat consumption was presented in the 1990s. It has nevertheless often been assumed that at least occasional hunting behavior may have been present well before the emergence of Homo. This can be argued on the basis of comparison with chimpanzees, the closest extant relatives of humans, who also engage in hunting, indicating that the behavioral trait may have been present in the Chimpanzee–human last common ancestor as early as 5 million years ago. The common chimpanzee (Pan troglodytes) regularly engages in troop predation behaviour where bands of beta males are led by an alpha male. Bonobos (Pan paniscus) have also been observed to occasionally engage in group hunting, although more rarely than Pan troglodytes, mainly subsisting on a frugivorous diet. Indirect evidence for Oldowan era hunting, by early Homo or late Australopithecus, has been presented in a 2009 study based on an Oldowan site in southwestern Kenya. Louis Binford (1986) criticised the idea that early hominids and early humans were hunters. On the basis of the analysis of the skeletal remains of the consumed animals, he concluded that hominids and early humans were mostly scavengers, not hunters, Blumenschine (1986) proposed the idea of confrontational scavenging, which involves challenging and scaring off other predators they have made a kill, which he suggests could have been the leading method of obtaining protein-rich meat by early humans. Stone spearheads dated as early as 500,000 years ago were found in South Africa. Wood does not preserve well, however, and Craig Stanford, a primatologist and professor of anthropology at the University of Southern California, has suggested that the discovery of spear use