(A) Sharing of derived alleles among present-day humans, Denisovans and Neandertals. We compare all possible pairs of 11 present-day humans {H1, H2} in their “D-statistics”, which measure the rate at which they share derived alleles with Denisovans (x-axis) and Neandertals (y-axis). Each point reports ±1 standard error bars from a Block Jackknife. D-statistics are color-coded by geographic region. The D-statistic is not the same as the mixture proportion; it is also affected by quantities like the amount of shared genetic drift between the samples being compared. (B) Sharing of derived alleles that are absent in Africans among present-day humans, Denisovans and Neandertals. We enhance the power of the D-statistics by restricting to sites where 35 sub-Saharan African samples have the ancestral allele, and pooling modern humans by region to increase resolution (bars again give one standard error). Eastern non-African populations have significantly more archaic ancestry than European populations (Z=5.3 and Z=4.8 for the tests based on the Denisovan and Neandertal D-statistics, respectively).