What is "lamarckism"

Lamarckism \La"marck"ism\, n. [From Lamarck, a distinguished French naturalist.] (Biol.) The theory that structural variations, characteristic of species and genera, are produced in animals and plants by the direct influence of physical environments, and esp., in the case of animals, by effort, or by use or disuse of certain organs. It is a discredited theory, not believed by modern biologists.

Lamarckism (or Lamarckian inheritance) is the idea that an organism can pass on characteristics that it has acquired during its lifetime to its offspring (also known as heritability of acquired characteristics or soft inheritance). It is 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 an inherent progressive tendency driving organisms continuously towards greater complexity, in parallel but separate lineages with no extinction. Lamarck did not originate the idea of soft inheritance, which proposes that individual efforts during the lifetime of the organisms were the main mechanism driving species to adaptation, as they supposedly would acquire adaptive changes and pass them on to offspring. When Charles Darwin published his theory of evolution by natural selection in On the Origin of Species (1859), he continued to give credence to what he called "use and disuse inheritance," but rejected other aspects of Lamarck's theories. Later, Mendelian genetics supplanted the notion of inheritance of acquired traits, eventually leading to the development of the modern evolutionary synthesis, and the general abandonment of the Lamarckian theory of evolution in biology. Despite this abandonment, interest in Lamarckism has continued as studies in the field of epigenetics have highlighted the possible inheritance of behavioral traits acquired by the previous generation. However, this remains controversial as science historians have asserted that it is inaccurate to describe transgenerational epigenetic inheritance as a form of Lamarckism.