Lamarck, Jean Baptiste Pierre Antoine de Monet, chevalier de [key], 1744–1829, French naturalist. He is noted for his study and classification of invertebrates and for his introduction of evolutionary theories. After varied careers he turned his attention to botany, and recognition of his skill followed upon publication of Flore françoise (3 vol., 1778). He was elected to the Academy of Sciences, and, aided by Buffon, he traveled over Europe, under the title of royal botanist, visiting museums and collecting material for the museum of the academy. From 1793 he was professor of zoology at the Museum of Natural History. His ideas concerning the origin of species were first made public in his Système des animaux sans vertèbres (1801). He introduced the terms biology and Invertebrata and suggested the invertebrate classes Infusoria, Annelida, Crustacea, Arachnida, and Tunicata. He is also considered the founder of invertebrate paleontology. His later works were Philosophie zoologique (2 vol., 1809; tr. Zoological Philosophy, 1963) and Histoire naturelle des animaux sans vertèbres (7 vol. in 8, 1815–22). Blindness and poverty marred his later years.
Lamarck's theory of evolution, or Lamarckism, asserts that all life forms have arisen by a continuous process of gradual modification throughout geologic history. To explain this process he cited the then generally accepted theory of acquired characteristics, which held that new traits in an organism develop because of a need created by the environment and that they are transmitted to its offspring. Although the latter hypothesis was disputed during Lamarck's lifetime by Cuvier and others and was rejected altogether as the principles of heredity were established, Lamarck's theory of evolution was an important forerunner of the work of Charles Darwin, who recognized a modified influence of environment in evolutionary processes.
See studies by R. W. Burkhart (1977) and P. Corsi (tr. 1988).
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