Early human expansions into Eurasia: The Atapuerca evidence

Abstract

Abstract The first humans to have migrated out of Africa were the ancestors of the Pithecanthropines — Homo erectus — of Java. Different sources point to ca. 1.9 Ma as the date of their exodus. Although the demographic success of early species of genus Homo preceded the 1.9 Ma date, a period of severe environmental crises ensued. A second dispersal was that of the Dmanisi population — H. ergaster, or H. sp. cf. Ergaster — these hominids came out of Africa most probably around 1.7 (earlier than 1.6 Ma BP), a time of continental uplift, aridification, the radiation of the Paranthropines, and the evolution of humans, all of which preceded the development of Paleolithic Mode 2 industries. The third movement of humans from Africa is attested to by the finds of Ubeidiya, with an Acheulean (Mode 2) artifactual assemblage, and a combination of faunal elements from East Africa and Eurasia that indicates an age of no more than 1.4 and barely less than 1.3 Ma. That interval is characterized by warm and humid climatic conditions, and vegetation improvement. The migration of mammals to the north may coincide with an inflection in environmental conditions dated to 1.3 Ma, or later. The record of fossil humans in Africa declines markedly at around 1.3 Ma BP, and recovers only slightly half a million years later, with a few localities between 800 and 600 ka BP. The evaluation of effects on human populations is impeded by physiographic changes globally adverse to sedimentary conditions for fossilization and the preservation of occupation floors. Archaeological and paleoanthropological sites in Eurasia, particularly the Atapuerca-Gran Dolina site, with findings in the “Aurora” Bed, testify to the successful expansion of a deme with modern asiatic traits, descendants of an ancient, not a new out-of-Africa exodus (that is, related neither to Gesher Benot Ya’aqov nor to Ubeidiya). More recent movements, at about 0.6 Ma, may correspond to the African origins of the European preneandertals — H. heidelbergensis — and Neandertals, as can be inferred from studies of the large fossil human sample of the Atapuerca-Sima de los Huesos site. Evidence points to several population movements between Africa and Eurasia in the past, and to a complex origin of modern mankind — Homo sapiens.