Ancient climate change and human migration - a link?

Posted at 3:03 PM on November 16, 2007 by Mark Seeley (1 Comments)

Every now and then a piece of significant research falls through the cracks and is not noticed by the wider community. Such may be the case of a paper released earlier this year by Christopher Scholz and 18 other co-authors. It appeared in Proceedings of the National Academy of Science.

Many anthropological studies of early humans (Homo sapiens) trace maternal lineages back to South and East Africa. Using DNA techniques, modern human ancestry is clearly traceable to this area before 130,000 years ago.

Climate studies from African lake sediments (Tanganyika, Malawi, and Bosumtwi) reveal that climate variability and especially aridity were quite severe during the period from 135,000 to 75,000 years ago. Maintenance of a sizable population of human beings on the African continent would have been a formidable task in such a harsh and highly variable climate. Severe droughts that were decades long severely limited the terrestrial and aquatic food supplies, as well as fresh water supplies.

But a climatic shift away from these highly variable and arid conditions took place about 70,000 years ago, and the African continent became much wetter and a good deal more stable from year to year. This is coincident with detected rapid expansion of early modern human populations, not only across Africa but out of Africa.

Blessed with more abundant food supplies and waterways to travel, it seems that climate change at that time opened the door of opportunity for the human race to explore new territory, and thus began the spread to the Mediterranean, then Asia and Europe. The hypothesis proposed by the authors is that climate change was the trigger for this!

You can read more on megadroughts and early human origins here

Comments (1)

And going back even earlier, I've read in a book on human evolution, I wish I remember which one, the theory is posited that climate change ~30 MYA is partially responsible for our ancestors "coming down out of the trees".

Around this time, what is now the Indian subcontinent, formerly a separate landmass in the ocean, slammed into Eurasia, starting the process of the formation of the Himalayas, which has had a drastic change on the long term climate of the Earth. Its even been suggested that this change has set up conditions that, later, would allow Ice Ages to be possible.

Posted by Paul | November 17, 2007 10:37 AM

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