Principal components analysis of 61,000 exonic SNPs in the ≠Khomani San and other African populations. Exomes from 1000 Genomes Phase 1, Schuster et al. , and HGDP San were combined with the ≠Khomani San (related samples from Families 1 and 2 were removed). 5.76% of the variance is explained by PC1, 3.74% by PC2, 1.27% by PC3, and 1.12% by PC4. PC1 and PC2 separate Africans from Europeans, and western Africans from southern Africans, respectively (A). The three KhoeSan populations drive PC3 and PC4 (B and C), supporting prior descriptions of strong differentiation among Kalahari KhoeSan groups , and indicating even sub-structure within the ≠Khomani San samples.