Jean-Baptiste Lamarck was a French scientist who developed an alternative theory to Darwin's theory of natural selection in the 19th century. The theory stipulated that a characteristic used by an organism often is made more effective the more it's used. A characteristic that is not used eventually disappears. Any characteristic that has improved is passed onto offspring. (New World Encyclopedia, 2008).

Lamarck's theory of acquired characteristics significantly contrasts with Darwin's theory of natural selection and is now widely viewed as incorrect.