Climate amelioration, abrupt vegetation recovery, and the dispersal of Homo sapiens in Baikal Siberia.

The dispersal of Homo sapiens in Siberia and Mongolia occurred by 45 to 40 thousand years (ka) ago; however, the climatic and environmental context of this event remains poorly understood. We reconstruct a detailed vegetation history for the Last Glacial period based on pollen spectra from Lake Baikal. While herb and shrub taxa including Artemisia and Alnus dominated throughout most of this period, coniferous forests rapidly expanded during Dansgaard-Oeschger (D-O) events 14 (55 ka ago) and 12 to 10 (48 to 41 ka ago), with the latter presenting the strongest signal for coniferous forest expansion and Picea trees, indicating remarkably humid conditions. These abrupt forestation events are consistent with obliquity maxima, so that we interpret last glacial vegetation changes in southern Siberia as being driven by obliquity change. Likewise, we posit that major climate amelioration and pronounced forestation precipitated H. sapiens dispersal into Baikal Siberia 45 ka ago, as chronicled by the appearance of the Initial Upper Paleolithic.