Born in Brazil in 1915 to a Lebanese father and a British mother, Peter Medawar became one of the greatest immunologists of his day. He arrived in England as a child and studied zoology at Oxford University under John Z Young, afterwards being appointed professor of zoology at Birmingham University and, later on, University College London.
Probably his greatest contribution to science was his work on the discovery of “acquired immunological tolerance” for which he won half share of the Nobel Prize in Medicine or Physiology in 1960. It was known that the immune system protects the body against invading pathogenic micro-organisms and viruses and that it is responsible for rejecting the transplantation of foreign tissue. But how does the immune system recognise the body’s own tissues as “self” and so know not to attack it?
Medawar showed in a series of brilliant experiments how this self-discrimination is learned at the biological level rather than the level of the genes. He showed that although part of our immunity has a hereditary basis, determined completely by our genes, there is also a part that is acquired during life and is not present in the foetus. In 1951, he demonstrated this by successfully transplanting tissue between mouse foetuses without tissue rejection – they hadn’t yet learned the ability to recognise “self”.
The discovery was fundamental to organ and tissue transplants and Medawar is sometimes referred to as “the father of transplantation”. He was also a popular science writer and wit, described by the acclaimed zoologist and science writer Stephen Jay Gould as “the cleverest man I have ever known”.
One of his most influential books was Advice to a Young Scientist, published in 1979, which is an encapsulation of Medawar’s thoughts on what makes a good scientist. He deflates the myths of solitary genius or superiority, arguing instead for common sense and an inquiring mind, but not mere curiosity. “Curiosity is a nursery word,” he says, “Most able scientists I know have something for which ‘exploratory impulsion’ is not too grand a description …. A strong sense of unease and dissatisfaction always goes with lack of comprehension.”
As for whether anyone can predict whether an individual has “the right stuff” to be a scientist: “There is no certain way of telling in advance if the day-dreams of a life dedicated to the pursuit of truth will carry a novice through the frustration of seeing experiments fail and of making the dismaying discovery that some of one’s favourite ideas are groundless,” Medawar writes. “Twice in my life I have spent two weary and scientifically profitless years seeking evidence to corroborate dearly loved hypotheses that later proved to be groundless; times such as these are hard for scientists – days of leaden grey skies bringing with them a miserable sense of oppression and inadequacy. It is my recollection of these bad times that accounts for the earnestness of my advice to young scientists that they should have more than one string to their bow and should be willing to take no for an answer if the evidence points that way.”