Figure 3. The role of introgression in the evolution of the immune system.

A) Beneficial genetic variation can be acquired from other species or populations through admixture. Adaptive introgression from archaic humans is represented by blue arrows, while adaptive admixture between modern human populations is represented by orange arrows. B) Worldwide distribution of Neanderthal vs modern human haplotypes for the OAS1 gene – one of the most emblematic cases of adaptive introgression in humans. Specifically, we show the allele frequencies for the two alleles of rs1557866, a SNP which derived allele is of Neandertal origin (blue) and that is a strong proxy of individuals harboring the Neandertal haplotype in the OAS region. The map was generated using the tool described by (Marcus and Novembre 2017).