UCLA

Key PointsRecent genomic analyses of sequence data from archaic humans have detected evidence of gene flow from the genomes of archaic humans to modern humans. Several studies have identified DNA segments within the genomes of modern humans that show strong signatures of both introgression and positive selection.Statistical analysis methods have been developed to detect surviving archaic human DNA segments and to ascertain that these introgressed segments show signatures of positive selection.There are reported examples of adaptive introgression by putative selective pressures, including pathogens, temperatures, altitude and diet. Candidate genes showing evidence for adaptive introgression have functional annotations that suggest roles in immune function, pigmentation, response to high altitude, and metabolism.Although recent studies have identified several well-supported examples of adaptive introgression in humans, we still lack a framework that jointly models the effects of introgression and positive selection. Studies of the synergistic effect of these two forces will lead to a better characterization of adaptive introgression and of its relative importance in human adaptation.