Evolution of the Human Genome: Adaptive Changes

Abstract

Abstract The study of human evolution is of interest to many both for the potential it has to improve our understanding of heritable disease, as well as for the possibility of illuminating evidence for adaptations that may help to tell the story of our origin. But uncovering evidence of positive selection at the genetic level has been a challenge. It remains unclear how much of the human genome has been affected by positive selection, what the main mechanism of selection is, and what types of patterns we should be looking for to identify adaptations. With whole‐genome sequencing and high performance computation, we are quickly shifting to a field in which data is no longer a limiting factor. Here we will discuss the progress that has been made towards these ends, explore the best examples of human‐specific adaptations to date, and discuss the implications of these findings within the context of classical population genetic theory. Key Concepts: An abundance of genomic data allows for a genotype‐first approach to discover selection in humans. Ancient hominin genomic sequences provide a nearer outgroup to humans than chimpanzee, and therefore can help elucidate selective targets in humans. Hard sweeps may have been rare in human evolution, whereas soft sweeps are a much more likely mechanism of selection. The genomic signatures of sweeps, background selection, and demography all look similar and can be difficult to distinguish. Genomic scans for selection make use of various signatures of selection and they rarely identify overlapping targets. More accurate modelling of selection in humans is needed to find true signals of selection.