Because the French Revolution and its major thinkers had much influence in Europe, including Germany and Heinrich Mann, I had a look at Voltaire and Rousseau.
There I came across a term I had not heard: Polygenists.
Voltaire, according the Wikipedia paragraph (currently under dispute), was also a "polygenist". If we go to the polygenist entry we can find many more interesting connections.
Basically, a polygenist does not believe that mankind came down from one original pair of human beings, but rather different races arose separately. Thus different races could be seen in this "voelkisch" kind of National Socialist view, that they were of different traits and quality. You can now proclaim the black person ugly and inferior. You can claim the white person softer, more beautiful and more "spiritual". This hardly seems to fit in with the ideas of the Rights of Man espoused by the Revolution. How did Voltaire really understand this question of the so-called races?
One of the other questions I have is: how did the eugenics movement develop and become a world-wide phenomenon? This polygenetic idea would just fit into their program.
Here, in Canada, too, we have home-grown intellectuals with liberal ideas who were firmly in the eugenics camp. In my home province we had eugenics programs until fairly recently. The government has been compensating victims of forced sterilization until not long ago. But here it did not have so much to do with race.
From Wikipedia. / Polygenism
Sermon: Gaudete (Advent 3) - 2017
3 hours ago