Population structure of worldwide human populations. Individual ancestry proportions are shown for 1112 individuals from 42 different populations globally distributed (from left to right: 114 Africans, 100 African-Americans, 255 Europeans, 108 South Asians, 100 East Asians, 36 Oceanians, 186 Native Americans and 212 Hispanic/Latinos). Each individual is represented by a vertical line on each barplot and sorted in the same order across panels. A clustering algorithm (implemented in ADMIXTURE) was used to infer global genome estimates from K = 5 up to K = 9 ancestral populations per individual. At K = 5 clusters roughly correspond to continental regions and at K = 9 fine-scale subcontinental structure can be detected (note the South–North gradient in Europeans and the light blue component decreasing from North to South in Native Americans). Admixed populations such as African-Americans and Hispanic/Latinos show dramatic variation in admixture proportions between individuals within populations and among populations. The plot was generated using 73 901 autosomal SNP markers by intersecting genome-wide genotype data from four publicly available data sets [i.e. HGDP (7), POPRES (26), data from Mao et al. (55) and data from Bryc et al. (21)].

Local ancestry assigned along the genome for a South African individual. Using SNPs from the Illumina 550K array platform, we use a principal component-based method to assign different ancestries to segments of a genome (21). We assumed three possible ancestral source populations for an admixed South African individual: indigenous southern KhoeSan ancestry, Bantu ancestry represented by the Kenyan Luhya and recent European (Italian) ancestry (data from HapMap3 and Henn et al., in preparation). Data were phased and the distance from each admixed haplotype to the nearest ancestral source population was measured in 40 SNP windows. Only one phase for each chromosome is plotted (for ease of visualization), and chromosome X is not shown. Ancestry with a low posterior probability is plotted in gray.