The Colonization of “Savannahstan”: Issues of Timing(s) and Patterns of Dispersal Across Asia in the Late Pliocene and Early Pleistocene

Abstract

This paper examines current weaknesses in the Out of Africa 1 model concerning the earliest hominin dispersals into Asia. It proposes first that the development of grasslands in Late Pliocene East Africa was the final part of a process of eastward expansion of grasslands across Asia that began in the Miocene; and secondly that early H. erectus in East Africa was not particularly distinctive relative to its contemporaries. It then reviews assessments that the Dmanisi hominins may have been ancestral to H. erectus in both East Africa and East Asia, and argues that the current fossil vertebrate record of Southwest Asia cannot demonstrate that hominins were absent before 1.8 Ma. Some alternatives are explored, of which the most parsimonious is that hominins may have dispersed into Southwest Asia before 2.0 Ma, and perhaps shortly after 2.6 Ma when stone tool-making became routine. Regarding the direction of dispersal, hominins probably dispersed southwards towards Java, and northwards via Central Asia to North China. Because of the climatic and vegetational changes that affected Asia during the Pliocene and Pleistocene, hominin populations would have expanded and contracted in tune with these fluctuations. Out of Africa 1 was therefore not an isolated, continental-level colonization event shortly after 1.8 Ma, but probably a process of numerous, small-scale latitudinal and longitudinal dispersals that began before 2 Ma.