Last point: Our ancestors who discriminated their mates based on skin color were naturally selected over those who did not (i.e. preference for black skin helped their offspring survive the intense sun exposure around the equator; preference for white skin helped their offspring survive the lack of sun-derived vitamin D in the northern areas like Europe). While this is not applicable today, and it is probably not genetically coded in us to prefer a black skin tone or a white skin tone, there IS a strong probability that it's genetically coded in us to view skin tone generally as a major factor for consideration in mate selection, and how we view that factor is probably largely societally-influenced (e.g. In the USA white-controlled media, "fair skin" was preferred, but then later replaced by a preference for "tan skin" rather than fair skin, which then was pejoratively termed "pasty").
