Figure 1.

Principal Component Analysis

(A) Map showing the sampling locations for Indian groups in our study (except central_mix1_nihali⁷).

(B) Principal component analysis (PCA) of 70 of 73 groups with non-Indians (European Americans [CEU], Georgian, Iranian, Basque, and Han Chinese [CHB]) highlights the “Indian cline,” a gradient of West Eurasian relatedness. Great Andamanese and Siddi are not included because of their evidence of relatively recent admixture with non-Indian groups, and central_mix1_nihali⁷ is not included because it includes multiple ethno-linguistic groups under one label. To aid visualization, we represent each group by the average PCA coordinates of all the individuals in it. Footnote a indicates groups from Metspalu et al.⁷ and footnote b indicates groups from HGDP.