Population Genomics of Human Adaptation

Recent advances in genotyping technologies have facilitated genome-wide scans for natural selection. Detecting targets of natural selection sheds light on human evolution and it can help identify genetic variants that influence normal human phenotypic variation as well as disease susceptibility. Here we focus on studies of natural selection in modern humans who originated similar to 200,000 years ago in Africa and migrated across the globe similar to 50,000-100,000 years ago. Movement into new environments, as well as changes in culture and technology, including plant and animal domestication, resulted in local adaptation to diverse environments. We summarize statistical approaches for detecting targets of natural selection and for distinguishing the effects of demographic history from natural selection. On a genome-wide scale, immune-related genes are major targets of positive selection. Genes associated with reproduction and fertility also are fast evolving. Additional examples of recent human adaptation include genes associated with lactase persistence, eccrine glands, and response to hypoxia. Lastly, we emphasize the need to supplement scans of selection with functional studies to demonstrate the physiologic impact of candidate loci.