French tradition and the rise of Evo-devo.

The limited value most French biologists attributed to Darwinism and Mendelism in the first half of the twentieth century, and their conviction that these theories were at best insufficient to explain evolution and development, probably created conditions propitious to the development of Evo-devo at the end of the century. The separation between embryology and evolution did not exist in French biology as it did in American genetics: explanations for these two phenomena were sought equally in the "organization" of the egg. The major contribution of French biologists to Evo-devo was clearly the invention of the notion of the regulatory gene by Jacob and Monod; not the operon model per se, but the introduction of a hierarchy between two different kinds of genes. The consequence, the rise of the developmental gene concept, was not immediate, and required the active role of other biologists such as Antonio Garcia-Bellido, Allan Wilson and Stephen Jay Gould. Various obstacles had to be overcome for this concept of developmental gene to be fully accepted.