Also, please, can we stop equating "race" and "skin color"? Haven't you ever seen an African albino? Being white in skin color doesn't make him white racially.

Or consider the famous golfer Vijay Singh, who of South Asian origin and was born on Fiji. He is darker than the average African-American (but has Caucasian features). He is never, ever considered to be racially black or African-American in America. Never. You can make up a list of other dark-skinned people who aren't considered black in America, such as pundits Dinesh D'Souza and Ramesh Ponnuru.

Race is about ancestry.

Different societies have different ways to deal with the inevitable complexities of genealogy in assigning people to races, but they are genealogy-based, not skin color based.