Climate, African and Beringian subaerial continental shelves, and migration of early peoples

The impacts of rapid climate change likely influenced human behaviour during the last glacial cycle, potentially stimulating habitation of, and migration along, continental shelves exposed during periods of lowered sea level. Last glacial maximum (LGM) climate model simulation shows cooler surface air temperatures in Eastern Beringia than Western and Central Beringia. Central Beringia was slightly wetter than present day (PD), whereas Eastern and Western Beringia were drier than PD. However Eastern Beringia was wetter than either Central or Western Beringia. Increased C3 grass coverage is shown in Eastern and Western Beringia, but increased C3 grass net primary productivity (NPP) appears only in Western Beringia; needleleaf trees and many shrubs disappear, replaced by barren soil and C3 grass. Such change would have squeezed species dependant on needleleaf trees out of Western and Eastern Beringia and potentially initiated their migration to more southerly parts of East Asia where a diminishing needleleaf tree environment remained. Shrub-reliant species in Eastern and Western Beringia, and C3 grass-dependant species in East Asia and Eastern Beringia would have found additional and productive habitat on the subaerial continental shelf. The LGM simulation identifies cooler LGM temperatures and increased aridity in South and particularly Central Africa, and associated large reductions in LGM broadleaf tree NPP and coverage in Africa, reduced C3 grass NPP particularly in Central Africa, decreased needleleaf tree NPP in South Africa, reduced shrub coverage in North and Central Africa, and greater barren ground coverage in Central and South Africa. Reduced productivity and shifting vegetation during the LGM may have squeezed flora, fauna, and human Populations onto the potentially more productive and proximally located exposed continental shelf. (C) 2007 Elsevier Ltd and INQUA. All rights reserved.