I'd probaby classify it more as human variants or sub-varients. Intially and historical origins of ancestors, blacks would've lived closer toward the equater of the earth where temperatures were warmer and more tropical and white folk lived in a bit cooler less tropical climates in the north. Our climates started off very different and we adapt to changing enviroments. I notice that american blacks are very different from african blacks. I think many american blacks are mixed or may have some italian in their genes. It's interesting the many variants in people that barely have any classification if any. It can get quite complex and confusing, so many people just lump them in with others. This holds true for people of kinds too. Trying to fit in another form of classification can also be tricky, but not just because complex variants, but also people might get too easily offended. Had some neat ideas of classification, but some people might not see in the same light and might think it meant to offend.