All modern humans belong to the same species. When and how did we evolve? Some scholars ('lumpers') believe that we all derive from ancient Homo erectus whose descendants moved out of Africa into Asia and Europe well before 500,000 BC.
There they developed regional characteristics, but these scholars claim that there was interbreeding between adjacent groups, spreading genetic developments and evolutionary modifications right across the inhabited area, as we gradually became modern humans.
Most scholars today, however, favour the alternative theory, that African descendants of Homo erectus developed into modern humans who then spread out across the globe, eventually replacing all other types of hominid.
The evidence supporting this view is persuasive. Some African sites, notably Klasies River Mouth, contain fossil bones of modern humans by 120,000 BC, if not earlier: this is considerably earlier than modern humans elsewhere.
Recent microbiological work on blood proteins has demonstrated that Asian and European populations diverged from African ones and from each other relatively recently, whereas African groups had been evolving for a much longer time.
This supports the fossil evidence of an African origin for Homo sapiens sapiens by 120,000 BC.
