Thanks for all the guesses!
The answer is JBS Haldane.
@tnavinash.bsky.social @marekkohn.bsky.social @shikharabhat.bsky.social nailed it right away.
JBS, in turn, said of Medawar “He smiles and smiles and is a villain.”
Arvid Ågren
THURSDAY TRIVIA
Who did Peter Medawar describe as “in some ways the cleverest and in some ways the silliest man I have ever known”?