Slow-twitch version of ACTN-3 positively selected in Europeans and Asians

Razib has the abstract of a new paper in Nature Genetics about a study examining phenotypic effects in mice and signatures of selection around ACTN-3 in humans. One variant shows major differences between sub-Saharan Africans and others, and it has a pretty well documented role in muscle fiber composition (fast twitch vs. slow twitch) and the ability to be good at sprinting vs. endurance activity. see here, here, and here for related posts.