The elaboration of a viable individual from its genes requires an amazing co-ordination of highly diverse chemical, physical and physiological events. In order to enable us to understand the medical causes and consequences, modern biology must “reinvent” life. Genetic engineering and the creation of clones and chimeras are just some of the methods used by biologists to examine and explain the proliferation or self-destruction of certain cells, and to study cellular migration, transformation and reassembly. The author believes that we are at the dawn of a new type of medicine which will no longer be concerned only with palliative measures and “repairs”, but will also be capable of regenerating diseased tissues via the introduction of embryonic cells. This major upheaval will oblige us to reconsider the meaning of the individual and of life itself.

Nicole Ledouarin teaches at the Collège de France. She is also a member of France’s Académie des Sciences, the U.S. National Academy and Britain’s Royal Society.