Timing of a back-migration into Africa. Reply to Forster P. & Romano V.

The principal problem with great syntheses of languages, genes, and figurines (or pots) is that they lump together different migrational and cultural processes and especially overstretch recent events of the Holocene, thereby downplaying or swamping the genetic signals that point to much earlier events of the Pleistocene (1, 2). Forster and Romano propose a recent arrival—within the last 2000 to 15,000 years—of haplogroup M1 in North Africa from western Asia, linked to the spread of Afro-Asiatic languages. This would entail a Near Eastern origin of the Afro-Asiatic language family and thus would be in agreement with Bellwood (3), provided that one subscribes to such a tight link between genes and languages. Afro-Asiatic scholarship (4), as well as the coalescence times of both M1a and M1b and the diverse basal distribution of M1a lineages especially in East Africa, however, militate against this interpretation. As we proposed in our Report, the arrival of M1 in Africa is most likely contemporary with that of U6, but if one alternatively hypothesized that only M1a originally went into the Northeast African Mediterranean coast, then 25,000 to 30,000 years ago would be the realistic time frame.