Jean Lamarck (1744-1829), the French naturalist who proposed early ideas on evolution and the variation of species. His theory of evolution, known as Lamarckism, was based on the idea that acquired characteristics are inherited. After 1800 he put forward general ideas on plant and animal species, which he believed were not 'fixed'. He proposed that in nature it is the environment that produces change; the length of the giraffe's neck, for example, he attributed to generations of reaching up for food. A facet of his views was that such a change could be inherited; and this attracted ridicule. Lamarckism was largely abandoned after the work of Darwin and Mendel.