Lamarckism (or Lamarckian evolution) is the once widely accepted idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring. It is named for the French biologist Jean-Baptiste Lamarck, who incorporated the action of soft inheritance into his evolutionary theories.
After publication of Charles Darwin‘s theory of natural selection, the importance of individual efforts in the generation of adaptation was considerably diminished. 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.
Between 1794 and 1796 Erasmus Darwin wrote “Zoönomia” suggesting “that all warm-blooded animals have arisen from one living filament… with the power of acquiring new parts” in response to stimuli, with each round of “improvements” being inherited by successive generations. Subsequently Jean-Baptiste Lamarck repeated in his “Philosophie Zoologique” of 1809 the folk wisdom that characteristics which were “needed” were acquired (or diminished) during the lifetime of an organism then passed on to the offspring.
Darwin’s “Origin of Species” proposed natural selection as the main mechanism for development of species, but did not rule out a variant of Lamarckism as a supplementary mechanism. Darwin’s half-cousin, Francis Galton carried out experiments on rabbits, with Darwin’s cooperation, in which he transfused the blood of one variety of rabbit into another variety in the expectation that its offspring would show some characteristics of the first. They did not, and Galton declared that he had disproved Darwin’s hypothesis of Pangenesis, but Darwin objected, in a letter to Nature that he had done nothing of the sort, since he had never mentioned blood in his writings.
A form of Lamarckism was revived in the Soviet Union of the 1930s when Trofim Lysenko promoted Lysenkoism which suited the ideological opposition of Joseph Stalin to Genetics. This ideologically driven research influenced Soviet agricultural policy which in turn was later blamed for crop failures.
Neo-Lamarckism is a theory of inheritance based on a modification and extension of Lamarckism, essentially maintaining the principle that genetic changes can be influenced and directed by environmental factors.