Figure 3 from the paper: Saharan palaeohydrology overlaid with the spatial distribution of Ouranian and barbed bone points and Nilo-Saharan languages.
Nick A. Drake, Roger M. Blench, Simon J. Armitage, Charlie S. Bristow, and Kevin H. White
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"Evidence increasingly suggests that sub-Saharan Africa is at the center of human evolution and understanding routes of dispersal “out of Africa” is thus becoming increasingly important. The Sahara Desert is considered by many to be an obstacle to these dispersals and a Nile corridor route has been proposed to cross it. Here we provide evidence that the Sahara was not an effective barrier and indicate how both animals and humans populated it during past humid phases."