Jean-Baptiste Lamarck is the researcher who developed the theory of use or disuse, also called the theory of acquired characteristics. Jean-Baptiste Lamarck is a French biologist, Lamarck founded a school of French Transformationism which included Étienne Geoffroy Saint-Hilaire, and which corresponded with a radical British school of anatomy based in the extramural anatomy schools in Edinburgh, Scotland, which included the surgeon Robert Knox and the comparative anatomist Robert Edmond Grant.