If you want to be technical, we're all Black, If we spent most of our evolutionary lives outside like much of the people in Africa, we'd have skin as dark as them. It's a reaction to exposure of the sun. Europeans stayed inside a lot since they migrated to the area thousands of years ago due to harsher weather extremes, which caused their lack of sun exposure, hence our lack of pigmentation.
Of course some believe this is simply a theory, which I won't doubt. But the strong evidence, your tan.
