On the Fact that (According to a 1992 Article by Social Scientist, Norman J. Sauer) Physical Anthropologists Can Identify the Race of a Skull's Former Owner with a Better than 80% Accuracy Rate

While facts like these don't completely destroy the social construction argument pertaining to race, they certainly don't prop it up, either (especially when you also take into consideration subtle differences in DNA, other phenotypical characteristics, etc.).