Biogeography and evolution of the genus Homo.

The debate about the origins of modern humans has traditionally focussed on two contrasting views. Multi-regional evolution proposes that present-day populations worldwide are the descendants of in situ evolution after an initial dispersal of Homo erectus from Africa during the Lower Pleistocene. The alternative, Out-of-Africa 2, proposes that all present-day populations are descended from a recent common ancestor that lived in East Africa approximately 150 000 years ago, the population of which replaced all regional populations. The weight of the evidence is now in favour of Out-of-Africa 2, and discussion is now dominated by the causes of the dispersal of modern humans out of Africa and the outcome of contact with other populations. Fresh approaches, from disciplines hitherto peripheral to the debate, such as evolutionary ecology, and new discoveries are challenging established views, particularly the prevalent idea that biologically superior modern humans were the cause of the demise of all other populations of Homo worldwide. Climate-driven ecological change has been, as with many other taxa, the driving force in the geographical range dynamics of the genus Homo.