Humanity from African Naissance to Coming Millennia

Abstract

The first 2.5 million years of hominid history is characterized by limited dispersals similar to those of the living great apes whose home range sizes very little between years. Unlike our closest relative Pan, who are particulary vulnerable during dispersal because the distribution of their resources is highly habitat specific and predation takes a relatively higher toll than it does in r-selected animals, hominids are widely dispersed after 1.8 Ma. Hominid dispersal must have entailed either a shift in the types of resources exploited or a technological advance to ensure resource availability or both. Using data from ecology, geochronology, morphology, and paleontology we assess the initial hominid dispersal from Africa and the relationship to patterns of dispersal in nonhuman primates and large mammals of both 'widely dispersing' and 'non-dispersing' species. The dispersal rates of Plio/Pleistocene hominids differ from those of nonhuman primates and are typical of widely-dispersing large mammals. In fact, H. erectus first appears in Java almost immediately after its appearence in Africa, yet its first appearence in Java is contemporaneous with that of Colobus, Macaca, and Pongo that had already inhabited mainland Asia for millions of years. Although the timing of the first hominid dispersal pre-dates significant technological advances, the energy required by larger hominid body/brain sizes suggest a shift to exploitation of highprotein packages that, according to correlation between faunal and chronometric sequences, is itself dispersing. These data suggest that it is at the origin of H. erectus (sensu lato) that our uniquely human dispersal capabilities began to emerge and that this dispersal is not primarily due to the technological innovation of the Acheulean tradition. IntroductionThe global distribution of Homo sapiens contrasts with the restricted ranges of our closest living primate relative, Pan. Yet for some three million years after our lineages diverged, both were apparently exclusively African phenomena, as Pan remains today. These current biogeographic differences are reflected in home range (HR) sizes that are some 15 to 100 times greater in recent human huntergatherers than in Pan. (23 hectares in Pan, 330-2600 in humans; Leonard and Robertson, 2000). Although an extensive literature considers the significance of the behavioral repertoire that allows the final, relatively late, dispersal of Homo sapiens into Australasia, North and South America, and Siberia (e.g., Lindly & Clark, 1990;Roberts et al., 1991; Davidson & Noble, 1992; Jelinek, 1994; Waters et al., 1997), the origin of this difference in dispersal patterns is not well understood.The original hominid dispersal from Africa has been viewed as a largely hominid (technologically) driven rather than ecologically driven phenomenon. Such scenarios are based on the idea that widely dispersed ex-African hominids are not found before 1.0 ma (Pope, 1983) or are not found before the development of the Acheulean (Wolpoff, 1999), and thus that th...