Using Pliocene palaeoclimatic data to postulate dispersal pathways of early hominins

A Geographic Information System (GIS) simulation is used here to test postulated early hominin expansions into Eurasia. To understand fully Plio–Pleistocene hominin dispersals, that is the increasing geographic range of hominins, a number of interacting factors must be examined. The most important variables affecting the first hominin dispersals would have been environmental, and it is thus imperative that appropriate climatic and geographical factors are included in analyses of possible Plio–Pleistocene hominin expansions. As the Late Pliocene climate was substantially different from that of today the present model utilises the Pliocene Research Interpretation and Synoptic Mapping Middle Pliocene Paleoenvironmental Reconstruction: PRISM2 [Dowsett, H.J., Barron, J.A., Poore, R.Z., Thompson, R.S., Cronin, T.M., Ishman, S.E., Willard, D.A., 1999. Middle Pliocene Paleoenvironmental Reconstruction: PRISM2. U.S. Geological Survey. http://pubs.usgs.gov/of/1999/of99-535/ (Accessed 3/02/00)]. The combination of data from palaeoclimate reconstructions and existing archaeological and palaeontological sites sheds light on the ‘Out of Africa 1’ problem, suggesting that expansion of hominins out of Africa would have been most feasible from a palaeoclimatic perspective at and around the Plio–Pleistocene boundary. The model predicts that the most likely dispersal route out of Africa would have been through the Levantine region, but a lack of research in the region of the Bab el Mandeb Straits means that this alternative pathway should not be ignored. There is also a small possibility of dispersals across the Mediterranean Sea, but with expansion limited to the northern coastline. Further easterly expansion of the hominin range is likely to have occurred through the more northerly countries of central Asia: specifically Georgia, Ukraine, Russia and Kazakhstan. A hominin dispersal route thus existed from Africa, through central Asia, to China during the Plio–Pleistocene period following the grassland vegetation belt that was present in this region at the time.