From Darwin's Descent of Man and Selection in Relation to Sex:

The following case, though relating to savages, is well worth giving from its curiosity. Mr. Winwood Reade informs me that the Jollofs, a tribe of negroes on the west coast of Africa, “are remarkable for their uniformly Fine appearance.” A friend of his asked one of these men, “How is it that every one whom I meet is so fine looking, not only your men, but your women?" The Jollof answered, “It is very easily explained: it has always been our custom to pick out our worse-looking slaves and to sell them.”

It need hardly be added that, with all savages, female slaves serve as concubines. That this negro should have attributed, whether rightly or wrongly, the fine appearance of his tribe to the long-continued elimination of the ugly women is not so surprising as it may at first appear; for I have elsewhere shown that negroes fully appreciate the importance of selection in the breeding of their domestic animals, and I could give from Mr. Reade additional evidence on this head.

Descent of Man, a work of fantasy for the most part, is filled with twisted passages like this. Darwin and the best minds of this time could not resolve race; they could only complicate it, confuse it with bad and good intentions, entangle it in a language that had the authority of science but none of its content. The early part of the 20th century saw a break with this messy mind. But the war to end all wars brought this moment of improved reasoning to an end.