Because ergaster was adapted to living in dry places, it could survive in many environments. This adaptability made possible a momentous step, the first spread of human lineages to the lands beyond Africa. A close relative and presumably descendant of ergaster, known as Homo erectus, had reached Asia by at least 1 million years ago and maybe much earlier —stone tools recently found in northern China have been dated to 1.66 23
million years ago. By 1 million years ago, ergaster itself had reached both the northern and southern extremities of Africa. And by at least 500,000 years ago a human lineage had reached Europe, perhaps through a second migration from Africa of another ergaster descendant known as Homo heidelbergensis. In Europe, under the glacial conditions that prevailed from 400,000 to 300,000 years ago, these new migrants evolved into Homo neanderthalensis, the Neanderthals, broad-boned, thickset people who were adapted to the cold.
Erectus and the Neanderthals are referred to as archaic humans in distinction to the human lineage that remained in Africa and ultimately became modern. With the departure of the archaics from Africa, the human gene pool was split into three main branches, in Africa, Asia and Europe, and each now followed a separate evolutionary path. In Africa, it was not until 500,000 years ago, more than a million years after ergaster's first appearance on the scene, that brain size relative to body size increased significantly, and not until 200,000 years ago that it reached the contemporary standard.
Yet a curious feature of the steadily increasing brain size of the human lineage is that it was not accompanied by any significant change in behavior that is visible in the archaeological record. Just as the Olduwan stone tool kit remained unchanged from 2.5 million to 1.7 million years ago, the Acheulean tool kit that succeeded it was also almost unvaried from its emergence 1.7 million years ago until its disappearance about 250,000 years ago. Erectus in Asia may have varied the formula by using bamboo, which is hard but perishable, in place of stone. This would explain the strange absence of Acheulean hand axes in the Far East. The Neanderthals in Europe used the same tool kit as the human lineage in Africa. "The technologies of these archaic creatures were homogeneous across and even between whole continents. The Acheulean, for example, although varying in minor form, is known from Cape Town to Cardiff,"
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