North Africa was a patchwork of human populations around the time our species trekked out of the continent.

Previous studies have proposed that the Sahara Desert was transformed into lush grassland during a wet spell between around 130,000 years and 75,000 years ago, offering few barriers to Homo sapiens expanding its range. However, researchers led by Eleanor Scerri at the University of Bordeaux, France, modelled the climate of northern Africa during this period and found that the Sahara, although much greener than today, still contained tracts of uninhabitable desert.

Comparisons of artefacts from 17 archaeological sites revealed geographic variability in the types of stone tool and techniques used to make them. The most similar tool assemblages tended to be those found closest to one another or those linked by green passageways.

Human populations in North Africa, including those that eventually colonized Europe and Asia, lived in semi-isolated groups that rarely mixed, the authors say.

Quat. Sci. Rev. 101, 207–216 (2014)