"But I suppose you are all too overwhelmed with the public affairs to care for science. I never knew the newspapers so profoundly interesting. N. America does not do England Justice: I have not seen or heard of a soul who is not with the North. Some few, & I am one, even and wish to God, though at the loss of millions of lives, that the North would proclaim a crusade against Slavery. In the long run, a million horrid deaths would be amply repaid in the cause of humanity. What wonderful times we live in. Massachusetts seems to show noble enthusiasm. Great God how I should like to see the greatest curse on Earth Slavery abolished. ― Charles Darwin to Asa Gray (June 5, 1861) The Correspondence of Charles Darwin Vol. 9 1861 (1994), p.163
Fitz-Roy's temper was a most unfortunate one. ...We had several quarrels; for when out of temper he was utterly unreasonable. For instance, early in the voyage at Bahia in Brazil he defended and praised slavery, which I abominated, and told me that he had just visited a great slave-owner, who had called up many of his slaves and asked them whether they were happy, and whether they wished to be free, and all answered "No." I then asked him, perhaps with a sneer, whether he thought that the answers of slaves in the presence of their master was worth anything. This made him excessively angry, and he said that as I doubted his word, we could not live any longer together. I thought that I should have been compelled to leave the ship; but as soon as the news spread, which it did quickly, as the captain sent for the first lieutenant to assuage his anger by abusing me, I was deeply gratified by receiving an invitation from all the gun-room officers to mess with them. But after a few hours Fitz-Roy showed his usual magnanimity by sending an officer to me with an apology and a request that I would continue to live with him. ― Charles Darwin, Autobiography of Charles Darwin 1809-1882 (restored edition)(1958), Nora Barlow editor, pp. 73- 74
Opposed to Darwin was the creationist biologist Agassiz, who believed that blacks were not related to whites at all, but were created separately.
And from Henry Morris, director of the Institute for Creation Research:
Yet the prophecy again has its obverse side. Somehow they have only gone so far and no farther. The Japhethites and Semites have, sooner or later, taken over their territories, and their inventions, and then developed them and utilized them for their own enlargement. Often the Hamites, especially the Negroes, have become actual personal servants or even slaves to the others. Possessed of a genetic character concerned mainly with mundane matters, they have eventually been displaced by the intellectual and philosophical acumen of the Japhethites and the religious zeal of the Semites.
The Beginning Of the World, Second Edition (1991), pp. 147-148
Contrary to creationists and racists, evolutionary theory says there are no biological human races. Within any "race" creationists have imagined to exist, there is more variation than there is variation between those "races."
If a scientist uttered the sort of racist bilge that Morris wrote, his career would be over. It's very disturbing that Morris could write something like that and still have his job. Not that every creationist is a racist. But it's telling that no one of them made a serious effort to chastize Morris for that act.
It's no coincidence that creationism is strongest where segregation held on the longest.