Here is a direct quote from Darwin’s writings:
And the black man—what of him?
As he was known to the ancient Egyptians, to the Greek and to the Roman, even so is he found in his African home today. At the dawn of history he was fully developed, and during the past three thousand years he has not made one step of progress. Independently, he has shown no power to advance. The superiority of the American n—-o to his African brother, who is a savage and cannibal, is due to slavery, and could have been acquired in no other way. Men who ascribe debased characteristics of the negro to slavery show a short-sightedness that is pitiable. The present attainment of the American n—-o has been solely the result of his close personal contact with the white man.
Nor should it be forgotten that most of the leaders in the n—-o race are men with Anglo-Saxon blood in their veins who partake more of their Caucasian than of their Ethiopian lineage. Some of these are splendid men, who are making heroic efforts to elevate the n—-o race. Others of mixed blood are vicious and turbulent. These are the men who create trouble.
Left to itself, a n—-o population lapses into barbarism….The negro has been domesticated, but the question is, will he ever become an integral part of Anglo-American civilization….The black man has never been a competitor, but has always been subservient to the white race. And just so long as he remains subservient his position is secure, and just so soon as he becomes a competitor his fate is sealed.