Within a single population, increasing the sequenced sample size yields diminishing returns of new SNPs. Figure 3 quantifies the number of SNPs discovered by resequencing as a function of sample size; it demonstrates the expected partitioning between populations with genetic proximity to Africa, and therefore higher diversity, and the rest of the populations. The new SNPs are mostly of lower frequency, and account for the majority of the discovered variant sites as the number of interrogated samples is increased (Supplementary Fig. 5).
