After the sale, he said: “I’m very pleased. It’s more money than I expected to give to charity.”

The sale also became symbolic of a quest for redemption after he became what he called an “unperson” in the scientific community seven years ago; he had told The Sunday Times of London Magazine in an interview that he was pessimistic about Africa because “all our social policies are based on the fact that their intelligence is the same as ours, whereas all the testing says not really.”

Dr. Watson apologized at the time for those remarks: “To those who have drawn the inference from my words that Africa, as a continent, is somehow genetically inferior, I can only apologize unreservedly. That is not what I meant. More importantly from my point of view, there is no scientific basis for such a belief.”

The medal belonging to Dr. Watson’s main partner in the discovery, Francis Crick, sold posthumously last year for $2.27 million to Jack Wang, chief executive of a Chinese biotech company.

Christie’s also auctioned Dr. Watson’s notes for his Nobel acceptance speech for $365,000, and the manuscript for the lecture he gave the day after he received the medal went for $245,000; both amounts were in line with presale estimates. A single anonymous bidder, different from the Nobel medal buyer, took both documents.

Dr. Watson said most of the money would go to support institutions that had nurtured him, like the University of Chicago, which he entered as a 15-year-old undergraduate; Indiana University, where he received his Ph.D.; Cambridge, where he worked with Dr. Crick; and the Cold Spring Harbor Laboratory on Long Island, where he has worked for many years.