What level of melanin denotes a "black" person? What of a white? What of a "white" person who tans enough to get above this arbitrary threshold? Are they now "black"? What of "black" people who are light skinned and fall below this arbitrary threshold? Are they now white?You answered your own question there, black people have black skin, white people have white skin.
Are you now going to try to be the first person in history to finally define the distinctions between races, here on this message board, where thousands - perhaps millions - of others have tried and failed?
Except it's not similar at all. The fact that you'd dredge up this tired old pseudo-argument is telling of your complete lack of knowledge on what you're attempting to discuss.Race in humans is exactly the same concept as breeds in dogs