Sir Peter Brian Medawar OMCBEFRS (/ˈmɛdəwər/; 28 February 1915 – 2 October 1987) was a British biologist born in Brazil, whose work on graft rejection and the discovery of acquired immune tolerance was fundamental to the practice of tissue and organ transplants. For his works in immunology he is regarded as the "father of transplantation". He is remembered for his wit in real life and popular writings. Famous zoologists such as Richard Dawkins, referred to him as "the wittiest of all scientific writers", and Stephen Jay Gould, as "the cleverest man I have ever known".