Credit: Ian Beatty
Apparently there’s a new paper on Bushmen genetic diversity coming out in PNAS. It reports that this group is the most diverse in the world in terms of intra-population variance. This is not a great surprise after the much heralded Nature paper from last year. But the bigger point seems to be that modern humans may derive from a southern African populations, not an eastern African one, as has been the predominant assumption for the past few generations. The reasoning is that the most diverse population has had the greatest amount of time to accumulate genetic variation since the emergence of modern humanity, other groups having been periodically purged of variance because of population bottlenecks during the process of migration. African populations are the most diverse of all, and of African populations the Bushmen are among the most diverse.
I think Sarah Tishkoff has the right of it: “African populations have had complex demographic histories and there is no a priori reason to believe that populations evolved in situ in the regions where they exist today. Some could have migrated from other regions.” In plain English …