Darwinists' views about race existed not only in Nazi Germany but also in America, as it apparents from surveys of textbooks published from 1880 to around 1950. For example, Princeton biologist Edwin Conklin stated in his college text that comparison
of any modern race with the Neanderthal or Heidelberg types show... Negroid races more closely resemble the original stock than the white or yellow races. Every consideration should lead those who believe in the superiority of the white race to strive to preserve its purity and to establish and maintain the segregation of the races.32
German eugnicists relied heavily on work completed in Britain and America, especially that research related to sterilization policies. ...
[Jerry Bergman, Hitler and the Nazi Darwinian Worldview: How the Nazi Eugenic Crusade for a Superior Race Caused the Greatest Holocaust in World History (Kitchener, Ontario, Canada: Joshua Press, 2012, 2014), 83]
32 Edwin G. Conklin, The Direction of Human Evolution (New York: Scribner's, 1921), 34, 53
Conversely, German eugenicists repeatedly acknowledged their debt to the American and British researchers and periodically honoured eugenicists from British and American universities with various awards. Furthermore, many of the American eugenicists argued that the Nazis were outdoing them and were able to convince American courts (including the Supreme Court) of the validity of even some of the most outrageous eugenic claims. Some of these eugenic-based ideas became part of American law and practice until after World War II when the full horror of the German eugenics programmes became widely known
What was the prevalent understanding of race relations in the late 19th and early 20th centuries in Western countries? Was it color-blindness? If one were to read the revisionist history put up by RAAN writers such as Jarvis Williams, you would think most Westerners in the late 19th century and early 20th century held to the theory of color-blindness. But such is absolutely false. While Christians of that era hopefully should have been promoters of color-blindness, and they did when their better angels prevailed, the predominant theory concerning race relations in the late 19th and early 20th centuries was Social Darwinism. It was in Nazi Germany that Social Darwinism was applied in practice in the Holocaust, but that does not mean that only Nazi Germany held to the theory of Social Darwinism, just that they were willing to actually put it into practice regardless of how inhumane it would become.
Social Darwinism is the application of Darwinian evolutionary theory to real life. In Darwinian evolutionary theory, organizations and species evolve towards being fitter, and only the fittest survive (survival of the fittest), while the less fit slowly lose out and become extinct. Humans are also placed on the evolutionary scale as being an evolution from ancient apes, and thus are fitter and stronger than the apes. But even in a species, since everyone is struggling on the evolutionary process, the fitter specimens should survive while the weaker ones die off. Placed into the human context where latent racism was already present, some "races" were seen to be more evolved (e.g. the "Aryans") while other "races" less so and are deemed to be more "ape-like." Social Darwinism aims to apply the Darwinian process to humans and thus eliminate the "less fit" specimens. Thus, individuals and "races" deemed to be less fit are to be eliminated while fitter individuals should procreate and produce many children, leading to the evolution of humanity to become better and fitter. Of course, what does this world "elimination" mean except killing actual humans and groups of humans off, that is, genocide! Nazi Germany followed Social Darwinism to its logical conclusion, conveniently identify their enemies with the "less fit" and sought to eradicate all non-Aryans, starting with the Jews and the Slavs.
Outside of Nazi Germany, the implications of Social Darwinism was not worked out into extermination but rather sterilization, such that the "less fit" would not be able to reproduce and thus decrease the supposed "vitality" of the population gene pool. Of course, in America, it was the blacks who would bore the brunt of the label of being less fit, and I wouldn't be surprised if moves such as segregation came about because of an embrace of some form of Social Darwinism.
Social Darwinism is therefore the prevalent doctrine concerning race relations in the late 19th and early 20th centuries, not color-blindness. If one desires to deplore racism, then one should attack Social Darwinism and its parents, the theory of human evolution itself. Otherwise, attacking color-blindness is to attack the cure and cause more racism instead of less, a problem that RAAN might actually instigate.