Lamarck, Jean Baptiste Pierre Antoine de Monet, Chevalier de (1744–1829) A French naturalist who, in 1809, proposed the first formal theory of evolution. He advanced the theory that evolutionary change may occur by the inheritance of characteristics acquired during the lifetime of the individual. For example, fossil evidence suggests that the ancestors of the giraffe had short necks: Lamarck proposed that competition for food encouraged them to stretch upward in order to browse among higher vegetation, causing their necks to lengthen, and that this lengthening was passed on to their descendants. Over millions of years the minute increases from each generation to the next culminated in the long-necked form. It is interesting to note that the theory of the inheritance of acquired characteristics did not hold a central position in Lamarck's own writings. His cardinal point was that evolution is a directional, creative process in which life climbs a ladder from simple to complex organisms. He believed the inheritance of acquired characteristics provided a mechanism for this evolution. Lamarck explained that this progress of life up the ladder of complexity is complicated by organisms being diverted by the requirements of local environments; thus cacti have reduced leaves (and giraffes have long necks). Compare DARWIN, CHARLES ROBERT.

Lamarck, Jean Baptiste Pierre Antoine de Monet, Chevalier de (1744–1829) A French naturalist who, in 1809, proposed the first formal theory of evolution. He advanced the theory that evolutionary change may occur by the inheritance of characteristics acquired during the lifetime of the individual. For example, fossil evidence suggests that the ancestors of the giraffe had short necks: Lamarck proposed that competition for food encouraged them to stretch upward in order to browse among higher vegetation, causing their necks to lengthen, and that this lengthening was passed on to their descendants. Over millions of years the minute increases from each generation to the next culminated in the long-necked form. It is interesting to note that the theory of the inheritance of acquired characteristics did not hold a central position in Lamarck's own writings. His cardinal point was that evolution is a directional, creative process in which life climbs a ladder from simple to complex organisms. He believed the inheritance of acquired characteristics provided a mechanism for this evolution. Lamarck explained that this progress of life up the ladder of complexity is complicated by organisms being diverted by the requirements of local environments; thus cacti have reduced leaves (and giraffes have long necks). Compare DARWIN, CHARLES ROBERT.

Lamarck, Jean Baptiste Pierre Antoine de Monet, chevalier de (1744–1829) A French naturalist who, in 1809, advanced the theory that evolutionary change may occur by the inheritance of characteristics acquired during the lifetime of the individual. This theory was also the basis for Lysenko's arguments on the inheritance of acquired plant characteristics. It is interesting to note that the theory of the inheritance of acquired characteristics did not hold a central position in Lamarck's own writings. His cardinal point was that evolution is a directional, creative process in which life climbs a ladder from simple to complex organisms. He believed the inheritance of acquired characteristics provided a mechanism for this evolution. Lamarck explained that this progress of life up the ladder of complexity is complicated by organisms being diverted by the requirements of local environments; thus, cacti have reduced leaves (and giraffes have long necks). Compare DARWIN, CHARLES ROBERT.

Lamarck, Jean Baptiste Pierre Antoine de Monet, Chevalier de (1744–1829) French natural historian. In 1778 he published a flora of France, which included a dichotomous identification key, and later worked on the classification of invertebrates, published in a seven-volume natural history (1815–22). In 1809 he put forward a theory of evolution that has become known as Lamarckism (later rejected in favour of Darwinism).

Lamarck, Jean Baptiste Pierre Antoine de Monet, Chevalier de (1744–1829) French biologist. His theories of evolution, according to which acquired characteristics are inherited by offspring, influenced evolutionary thought throughout the 19th century, until they were disproved by Darwin. One of his major works is Philosophie zoologique (1809).