François Jacob. 17 June 1920 — 19 April 2013

Biological research was a late vocation for François Jacob, who entered the laboratory of André Lwoff at the Institut Pasteur in Paris at the age of 30. Ten years before, in 1940, he had abruptly left France, after the German troops entered Paris, and joined the Free French Forces organized by de Gaulle in London. He served as a medic in battles against the German troops in Africa, and was severely wounded in Normandy in August 1944. He could no longer be a surgeon as he had expected, and his return to a civilian life was difficult. Fifteen years after he entered the Institut Pasteur, in 1965, he received the Nobel Prize in Physiology or Medicine, together with André Lwoff and Jacques Monod, for the discovery of the mechanisms controlling gene expression in bacteria, the operon model. The impact of this discovery was immense and triggered the conversion of molecular biologists to the study of higher organisms and their development. Jacob decided to work on mice, and his characterization of embryonal carcinoma cells and of their differentiation foreshadowed recent studies on embryonic stem cells. His comparison between evolution and the work of a tinkerer was also highly influential. Jacob wrote many books on the history and philosophy of the biological sciences. He was convinced that reflection on these issues was necessary for researchers to defend the value of scientific knowledge. He also continuously fought for an ethical use of scientific knowledge.