Here's a piece in today's Guardian that touches on some of the issues raised in this thread - In Brazil I glimpsed a possible future in which there is only one race:

"Some time ago, Brazil's census takers asked people to describe their skin colour. Brazilians came up with 134 terms, including alva-rosada (white with pink highlights), branca-sardenta (white with brown spots), café com leite (coffee with milk), morena-canelada (cinammon-like brunette), polaca (Polish), quase-negra (almost black) and tostada (toasted)...