monogensis v. polygenesis and fair treatment

Our discussion of monogenesis vs. polygenesis really got me thinking about how people could use these two different theories of human origin to justify different treatment of people.

In my mind, one can interpret monogenesis in two ways. If scientists suddenly proved monogenesis unequivocally true, some treat the discovery as proof of a true human essence, and consider it ground to relate to and be charitable towards all humans. In my opinion, others might treat it as some proof of "equality of opportunity" and say that because we descended from the same (wo)man, we all have had the same opportunity for advancement. They may then draw the conclusion that those races who dominate economics and politics were able to do so only through their sheer superiority of intellect and work ethic.

Conversely, If polygenesis were suddenly ratified by the sciences, I think people could interpret that in two diametrically opposed ways. I think some might use polygenesis to help explain and celebrate cultural differences. Others, however, might use it as further proof for white supremacy and the need for segregation (a sort of, if God/nature made us separately then we should remain separate).

What do you all think about these interpretations? Do you agree or think certain alternatives are more likely than others? Or do you think people would react totally differently?