Let us beware how we foster the spirit of caste. Charles Darwin pronounced the Patagonians (South end of Argentina and Chile) the missing link between man and the monkey, and thought that not even the lever of Christian missions could uplift them…
But…

Darwin thought the Fuegian peoples to be one of the links between man and monkey, and thought they could never be civilized. He later confessed he was wrong. (Picture modified slightly for modesty's sake.)

Admiral Sulivan, who lived on the Falkland Islands for a time, attended the annual meeting of the South American Missionary Society in 1881. While there, he stated that he had informed Darwin of the great changes that had taken place in his Patagonian “human monkeys”: of kindness shown to shipwrecked crews by the converted natives, and how chicken houses remained unlocked, without even the theft of an egg. He stated that in reply, Darwin had candidly confessed: “I could not have believed that all the missionaries in the world could ever have made the Fuegians honest.”
So remarkable is the testimony of this great naturalist—who was, however, no “supernaturalist,”—that with his oft-quoted testimony we close this brief sketch. He had said after his visit to Patagonia, “Nothing can be done by means of mission work; all the pains bestowed on the natives will be thrown away; they never can be civilized.” This was Darwin’s opinion until proofs of the facts confronted him. Then he candidly admitted he was wrong, and added: “I had always thought that the civilization of the Japanese is the most wonderful thing in history; but I am now convinced that what the missionaries have done in Tierra del Fuego, in civilizing the natives, is at least as wonderful.” From that time, Darwin himself regularly donated to the mission society’s funds.
-Taken from the book The New Acts of the Apostles by A.T. Pierson