There were two different and partially successive attempts of geneticists to associate genes with a definition of life. The first has its origin in the theoretical considerations elaborated at the end of the 19th century by biologists such as Hugo de Vries and August Weismann, looking for the molecular bases of biological processes and the mechanisms of their reproduction. It reached its most elaborate form in Hermann Muller's contributions, and pervaded genetics during the first part of the century. The second was the paradoxical result of the program of gene reification endorsed by molecular biologists, which progressively ruined the previous ambitions. This gave way to a less naive vision of the relation between genes and the definition of life, focused no longer on the materialistic description of the gene, but on its power to control the adaptation of organisms to their environment. It is interesting that the link between life and death that has remained a constant of philosophical investigations from Aristotle to Bichat has kept its place in this genetic approach to life. Definitions of life by both the molecular and population genetics have tried - with less success for the former - to justify the place of death in the economy of nature. Models, derived from genetics, are now used to describe the transmission of behaviors and beliefs between humans. They give genetic models a strong visibility in contemporary thinking
