GEOGRAPHY, TIME AND SPECIATION IN PLEISTOCENE HOMO

Thirty gears ago, the pattern of human evolution seemed straightforward. Discoveries from Beds I and II at Olduvai Gorge had led to the introduction of Homo habilis as a new taxon It appeared that this species had evolved into Homo erectus, whose remains were known at the time mostly from the famous sites bz Java and China. With its expanded brain and tool-making capabilities, Homo erectus was accepted by nearly all authorities as the link to Homo sapiens. It was assumed that the transition from one species to the next had occurred gradually, as trends established early in the lineage were continued. More recently: this picture has been complicated by fresh discoveries and clouded by debate. The integrity of Homo habilis has been questioned and there is a strong possibility that two populations of Homo inhabited East Africa at the close of the Pliocene. Presumably only one survived. Homo erectus has been partitioned into distinct Asian and African components by some workers but is no longer recognized by others. The path to Homo sapiens is now paved with uncertainties. Additional species may have flourished in the Middle Pleistocene, before anatomically modern people emerged in relatively recent times, Tracing the history of our extinct relatives is a challenge, and I comment here on several of the key questions surrounding Homo erectus and the relationship of this taxon to later humans.