Giliomee in his book on Afrikaners opines that WHITE woman were an important factor in creating an apartheid society. He suggests that they contrived to take black women out of the white mating pool to improve their own breeding success - ie they helped to create a society of separate ethnic groups (or races if you will)
The following seems to provide some support for that idea:
Studies have shown being physically attractive puts women at risk of being indirectly victimised by other females. In addition, there is evidence females are intolerant of same sex peers who are perceived as too sexually available [or of foreigners who increase the mating pool - my comment].