UK: Fish appeared to have swam across the Sahara during its last wet phase sometime between 10,000 and 6,000 years ago, claimed researcher Nick Drake, a geographer at King’s College London. In conversation with LiveScience, Drake said, “The Sahara is not a barrier to the migrations of animals and people. Thus it is possible that early modern humans did so, and this could explain how we got out of Africa.”
Using satellite imagery and digital maps of the landscape, researchers found the Sahara was once covered by a dense network of rivers, lakes and inland deltas. This large waterway channelled water and animals into and across the Sahara during wet, “green” times.
In their analysis, Drake and his colleagues found evidence that many creatures, including aquatic ones, dispersed across the Sahara recently. For example, 25 North African animal species have populations both north and south of the Sahara with small refuges within the desert. Indeed, more animals may have once crossed over the Sahara than over the Nile corridor, the researchers said — only nine animal species that occupy the Nile corridor today are also found both north and south of the Sahara.
If fish could have crossed the Sahara, it is hard to imagine that humans didn’t. Analysis of African languages and artifacts suggest that ancient waterways recently affected how humans occupied the Sahara. In addition, ancient lake sediments suggest the Sahara was green roughly 125,000 years ago, back when anatomically modern humans might have begun migrating out of Africa.
The scientists detailed their findings online December 27, 2010, in the journal Proceedings of the National Academy of Sciences.