At www.upenn.edu/pennnews/news/penn-researchers-add-genetic-data-archaeology.html there is a report, or news flash, about genetic research they hope will shed light on the demographic history of Africa as it is now known from anthropology, archaeology, and linguistic studies, and it is being published in the Proceedings of the National Academy of Sciences. It is nice to read some research which does not mention global warming. For the moment some parameters are being laid as genetic variation in Africa is structured geographically and to a lesser extent, linguistically. Populations in close geographical communities and speaking a related language are more likely to exchange genes. Hence, genetic variation is consistent with natural geographical barriers which limit gene flow. Patterns will emerge as geneticists further analyse a mountain of genetic data from these understudied populations (for further details go to www.nasonline,org/SACKLER_Human_Condition and see also www.physorg.com/print194115309.html ). We may expect some interesting results.