Abstract

Our species has reached virtually every corner of the globe, with human populations settling in geographic areas that are extremely different in ecological terms. The colonization was accompanied by pressure to adapt to the new environments, and I will present some of our efforts to understand these local adaptations. Analyzing the genomes of present-day and early modern humans we observe that positive selection has fundamentally influenced the (otherwise modest) genetic differences that exist among human populations today. We infer that early hunter-gatherers have contributed more genic adaptive alleles than early farmers to present-day Europeans. The ultimate origin of the adaptive alleles remains debated, with new, introgressed, and neutral standing alleles being plausible sources. I will discuss the possibility that shifts in natural selection on previously non-neutral standing alleles (e.g. slightly advantageous or under balancing selection) mediates fast adaptations to novel environments, and how these models can help understand human local adaptation.