THE BERINGIAN BARRIER TO HUMAN DISPERSAL DURING THE LATE PLEISTOCENE

The occupation of Beringia remains one of the most complex problems in human paleoecology. The archaeological evidence suggests that human occupation of Beringia did not begin until at least 18,000-15,500 cal BP, and firmly documented sites are not present until the Late Glacial (14,000-13,000 cal BP). Hoffecker and Elias (2003) address the question of why humans did not occupy Beringia before this time.

Beringian climates during the LGM were cold and dry, but temperatures in many regions were not significantly lower modern levels. Increased aridity seems to have been the chief difference between LGM and modern climates. During the warmer phases of OIS 3, climates and forest cover in western Beringia were similar to today. Modern humans successfully occupied very cold, dry, and treeless regions of Eastern Europe and southern Siberia during late OIS 3 and the early LGM, using technologies similar to those of recent Arctic peoples. The latter inhabit areas such as the “Pole of Cold” (i.e., Yukaghir) where temperatures are lower than they were in many parts of Beringia during the LGM. Therefore environmental conditions alone seem insufficient barriers to human dispersal through Beringia.

We believe that the principal barrier to human dispersal across Beringia was their warm-climate morphology, derived from their recent African ancestors. The humans who first colonized northern Eurasia retained this morphology until the later phases of OIS 2. Skeletal remains from Europe dating to 40,000-24,000 cal BP exhibit high brachial and crural indices, lengthened extremities, and other features found in present-day populations of the equatorial zone. People living at the Sungir’ site (56º N) in Russia had skeletal features indicating that this warm-climate morphology was still present in subarctic Asia during the early LGM. Despite the use of technology broadly comparable to that of recent subarctic and arctic peoples, modern humans were unable to occupy areas of Northeast Asia above latitude 60o N prior to 24,000 cal BP. Moreover, as LGM climates reached their peak intensity at 24,000-21,000 cal BP, they abandoned the coldest parts of Europe and Siberia for several thousand years.