· E. Patin et al., Inferring the Demographic History of African Farmers and Pygmy Hunter–Gatherers Using a Multilocus Resequencing Data Set. PLoS Genetics, 2009.
The autors analyzed autosomal DNA samples from Western and Eastern Pygmies, as well as of a variety of agriculturalist peoples of Tropical Africa. They conclude that Pygmies separated from other Tropical Africans as a single population at the estimated time of some 60,000 BP and that they split into two groups, Eastern and Western, c. 20,000 BP.
Fig. 2. A is regular K-means clustering and B represents "filtered" populations after exclusion of individuals with more than 20% admixture at K=4.