October 14, 2008

Out of Africa via Libya and not the Nile?

Which way 'out of Africa'?
New evidence provides an alternative route 'out of Africa' for early humans
The widely held belief that the Nile valley was the most likely route out of sub-Saharan Africa for early modern humans 120,000 year ago is challenged in a paper published this week in the Proceedings of the National Academy of Sciences.

A team led by the University of Bristol shows that wetter conditions reached a lot further north than previously thought, providing a wet 'corridor' through Libya for early human migrations. The results also help explain inconsistencies between archaeological finds.


Anne Osborne, lead author on the paper said: "Space-born radar images showed fossil river channels crossing the Sahara in Libya, flowing north from the central Saharan watershed all the way to the Mediterranean. Using geochemical analyses, we demonstrate that these channels were active during the last interglacial period. This provides an important water course across this otherwise arid region." The critical 'central Saharan watershed' is a range of volcanic mountains formerly considered to be the limit of this wetter region.


Dr Derek Vance, senior author on the paper, added: "The study shows, for the first time, that monsoon rains fed rivers that extended from the Saharan watershed, across the northern Sahara, to the Mediterranean Sea. These corridors rivalled the Nile Valley as potential routes for early modern human migrations to the Mediterranean shores."


Maju said...

This is specially relevant, I think for the origins of the Aterian culture of North Africa, whose oldest dates (90,000 plus) fit well with this interglacial "window" for migration.

Fred Scrooby said...

"The widely held belief that the Nile valley was the most likely route out of sub-Saharan Africa for early modern humans 120,000 year ago" ( -- from the log entry)

I thought the route in question was out of northeastern Africa, not Sub-Saharan Africa.

Maju said...

It's the early route, the one used most probably by the people at Palestine (Skuhl and nearby caves) and North Africa (Aterian culture), both of which have datations of some 100,000 years, maybe more in Palestine and clearly imply "archaic" H. sapiens.

Nevertheless, as I have mentioned elsewhere, there's some uncertainty on wether modern humans might have arrived to South Asia also by that time (or later but before the Toba event).

terryt said...

Perhaps I'm simple-minded (some here would say definitely so) but this is hardly surprising to me. I've always assumed that during moister climates the Sahara would simply contract, the savanah grassland would expand into it from all around. After all the Sahara is expanding at present in both the north and the south.