John Burdon Sanderson Haldane FRS (5 November 1892 – 1 December 1964), known as Jack (but who used 'J.B.S.' in his printed works), was a British-born geneticist and evolutionary biologist generally credited with a central role in the development of neo-Darwinian thinking (popularized by Richard Dawkins' 1976 work titled The Selfish Gene).