Positive selection on the human genome.

Positive selection has undoubtedly played a critical role in the evolution of Homo sapiens. Of the many phenotypic traits that define our species--notably the enormous brain, advanced cognitive abilities, complex vocal organs, bipedalism and opposable thumbs--most (if not all) are likely the product of strong positive selection. Many other aspects of human biology not necessarily related to the 'branding' of our species, such as host-pathogen interactions, reproduction, dietary adaptation and physical appearance, have also been the substrate of varying levels of positive selection. Comparative genetics/genomics studies in recent years have uncovered a growing list of genes that might have experienced positive selection during the evolution of human and/or primates. These genes offer valuable inroads into understanding the biological processes specific to humans, and the evolutionary forces that gave rise to them. Here, we present a comprehensive review of these genes, and their implications for human evolution.