GEOGRAPHY, TIME AND SPECIATION IN PLEISTOCENE HOMO

Thirty gears ago, the pattern of human evolution seemed straightforwar d. Discoveries from Beds I and II at Olduvai Gorge had led to the intr oduction of Homo habilis as a new taxon It appeared that this species had evolved into Homo erectus, whose remains were known at the time mo stly 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 trans ition from one species to the next had occurred gradually, as trends e stablished early in the lineage were continued. More recently: this pi cture has been complicated by fresh discoveries and clouded by debate. The integrity of Homo habilis has been questioned and there is a stro ng possibility that two populations of Homo inhabited East Africa at t he close of the Pliocene. Presumably only one survived. Homo erectus h as been partitioned into distinct Asian and African components by some workers but is no longer recognized by others. The path to Homo sapie ns is now paved with uncertainties. Additional species may have flouri shed in the Middle Pleistocene, before anatomically modern people emer ged in relatively recent times, Tracing the history of our extinct rel atives is a challenge, and I comment here on several of the key questi ons surrounding Homo erectus and the relationship of this taxon to lat er humans.