Lamarck

Lamarckism is the hypothesis that an organism can pass on characteristics that it has acquired through use or disuse during its lifetime to its offspring. It is also known as the inheritance of acquired characteristics or soft inheritance. It is inaccurately named after the French biologist Jean-Baptiste Lamarck (1744–1829), who incorporated the action of soft inheritance into his evolutionary theories as a supplement to his concept of orthogenesis, a drive towards complexity.

The theory is cited in textbooks and popular works to contrast with Darwinian evolution. Lamarckism has been largely discredited by the majority of biologists since the advent of genetics, but it has seen a revival in the late 20th and early 21st centuries as a result of discoveries in epigenetics.

History

Lamarckism was popular in the early 19th century, before Charles Darwin's theory of evolution was published. However, it was largely ignored in the English-speaking world, where the influences of Francis Galton and August Weismann were felt strongly. Weismann's germ plasm theory stated that the hereditary material, the germ plasm, is completely separate from the rest of the body, the soma. This effectively refuted Lamarckism as it meant that changes to the soma could not affect the germ plasm and therefore could not be inherited.

Modern views

Modern biology holds that changes in the phenotype due to environmental factors do not result in corresponding changes in the genotype, except in the case of some viruses. However, the discovery of epigenetics and its role in the regulation of gene expression has led to a reevaluation of Lamarckism. Epigenetic changes can be influenced by the environment and some of these changes can be heritable. This has led to renewed interest in the idea of the inheritance of acquired characteristics, although it is not Lamarckism as originally proposed.

See also

• Epigenetics
• Evolution
• Genetics
• Jean-Baptiste Lamarck
• Orthogenesis

Lamarck Resources
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