Skin-Related Survival and Adaptation: The Functional Implications of Archaic Introgression in the BNC2 locus of Modern non-Africans

Abstract

The cohort of anatomically modern humans (AMHs) that migrated out of Africa were able to adapt more quickly to the new environments they encountered, in part, because of the DNA they acquired from their archaic cousins. This concept, known as introgression, occurred in AMHs when the derived alleles that originated in archaic humans were introduced into the modern human genome via admixture. Some of these derived alleles proved beneficial for the survival of AMHs in conditions outside of Africa and were subsequently swept to high frequencies by evolutionary selection. The purpose of this research is to characterize the adaptive advantages of the archaic haplotypes in the Basonuclin 2 (BNC2) locus. The BNC2 gene is generally associated with skin pigmentation and skin color saturation, traits that are highly involved in the adaptation of AMHs to new environmental conditions such as changes in sunlight and temperature. Additionally, we hope to elucidate the selection pressures that swept these haplotypes to high frequencies in modern non-Africans, particularly in Europeans. In order to assess what genomic advantages these introgressed sites gave to modern Eurasians, we explored the functional elements within the BNC2 locus that intersect with Neanderthal- and Denisovan- derived sites. We found that in addition to affecting skin phenotypes, the archaic haplotypes in the BNC2 locus seem to be responsible for the tight regulation of the gene.