In the 1970s, the development of molecular phylogeny led to a profound overhaul of Primate classification, particularly that of the Hominoid super-family in which the genus Homo is rooted . Our species is the sole survivor of a bush of forms that represent the sister taxon of today's chimpanzees; gorillas, orangutans and gibbons form lineages that are more distantly related.
Since the separation of the human and chimpanzee lineages at least 7 million years ago, the hominin branch has produced a wide variety of forms. Today, there are more than twenty paleontological species in this group. The genus Homo is rooted in the older australopithecine group. Until around 1.9 million years ago, traces of man can only be found in Africa. Historically, however, man's origins were first sought outside Africa, and particularly in Europe.
While Homo habilis was the first species attributed to our genus, since its discovery, several other forms of primitiveHomo have been recognized in East and Southern Africa. Under the pressure of the environmental changes that affected the australopithecines' habitat from 3 million years before the present, representatives of the Homo genus diverged from the so-called "robust" forms of australopithecines. In fact, both lineages have been documented as early as 2.8-2.6 million years ago.
The first representatives of the Homo genus show changes to the masticatory system, generally interpreted as a sign of more pronounced carnivorous tendencies than in australopithecines, followed by an increase in brain volume. However, the anatomical and behavioral changes associated with the emergence of our genus seem to have taken place separately from one another and over a fairly long period of time. What's more, a high degree of homoplasy is consistently observed among hominins. Some late australopithecines show unmistakable convergences with early Homo. From 1.6 million years ago, only Homo erectus survived the first diversification of the Homo genus; and it does not appear thatHomo habilis can be considered its direct ancestor.
