In the most recent issue of PNAS Pickrell et al. examine the history of hunter-gatherer and pastoralist populations of southern and eastern Africa using patterns of admixture linkage disequilibrium. These populations are among the most culturally, linguistically and genetically diverse human populations. The authors found that all of these populations have some ancestry related to Europeans and Middle Easterners and infer that the presence of west Eurasian ancestry in southern Africa occurred 900-1800 y ago. They propose that a large migration of people from west Eurasia into Ethiopia occurred around 3000 y ago, which resulted in the dispersal of west Eurasian ancestry throughout eastern Africa. They then suggest that a migration of an admixed population from eastern Africa to southern Africa took place 1500 y ago, contributing to the genetic diversity seen in southern and eastern Africa today.