The Role of Genetic Variation in Human Populations

There is genetic variation among human populations, I mean there's no question about that. Some of that genetic variation is linked to what biologists call phenotypic traits such as skin color. The issue is are those groups that we identify as races on the base of color mostly skin color and a few other characteristics but it's a really largely skin color. Are those groups first of all homogeneous enough to represent a biological entity of some importance? Those are the actual empirical questions, right? Which weight is claiming the answers? Yes they do.