Desert speleothems reveal climatic window for African exodus

[Wayne Harrison]

The African origin of early modern humans 200,000–150,000 years ago is now well documented, with archaeological data suggesting that a major migration from tropical east Africa to the Levant took place between 130,000 and 100,000 years ago via the presently hyper-arid Saharan-Arabian desert.

This migration was dependent on the occurrence of wetter climate in the region. Whereas there is good evidence that the southern and central Saharan-Arabian desert experienced increased monsoon precipitation during this period, no unequivocal evidence has been found for a corresponding rainfall increase in the northern part of the migration corridor, including the Sinai-Negev land bridge between Africa and Asia. Passage through this “bottleneck” region would have been dependent on the development of suitable climate conditions. Vaks et al. present a reconstruction of paleoclimate in the Negev Desert based on absolute uranium series dating of carbonate cave deposits (speleothems). Speleothems only form when rainwater enters the groundwater system and vegetation grows above a cave.

<a href="http://www.huliq.com/32170/desert-speleothems-reveal-climatic-window-for-african-exodus">via Huliq.com</a>