On the contrary, there has been extensive writing on the history of the ideas concerning evolution, from pre-Darwinian theories such as those of Lamarck, through the rejection of natural selection in the late 19th century and the later reconciliation of natural selection with genetics in the 1930s and 40s (the modern synthesis) and on up to the present day.
The opinion that blacks were inferior to whites predates the idea of evolution by quite a long stretch and was prevalent, up until the very past, in many of the parts of America where Darwin was most vehemently rejected. Some racists may have tapped evolutionary biology to justify their bigotry, but that doesn't mean that evolutionary biology is wrong, any more than some bigot finding their justification in a bible passage makes the bible wrong. Just about anything can be twisted to serve the needs of twisted people.