Racial categories in the US , in particular the one-drop rule: When the supposedly defining biological notions of race stopped being a thing, race then morphed into an ascriptive "identity." Before that time, it was posited through a prism of whiteness that races had radically different genetic differences from each other which in turn dehumanized non white races, with different "scientific proofs" being adduced. Though some races, like blacks were also black, and this made classifying them a breeze, without knowing anything other things about particular individuals or groups. Later on, blacks became black, but only black. "Black" still had to mean something, though nobody actually knew precisely what that something was anymore, other than the fact that there was a group of people that easily could be identified as "black" upon visual inspection. Vitally, the one-drop rule remained and this significantly shapes "identity" in today’s...