One of the earliest superficially plausible theories of inheritance proposed by Jean-Baptiste de Lamarck in 1809. He suggested that changes in an individual are acquired during its lifetime, chiefly by increased use or disuse of organs in response to “a need that continues to make itself felt”, and that these changes are inherited by its offspring. Thus the long neck and limbs of a giraffe are explained as having evolved by the animal stretching its neck to browse on the foliage of trees. This so-called inheritance of acquired characteristics has never unquestionably been demonstrated to occur and the theory was largely displaced by the genetic theories of Mendel and his successors (see Mendelism). See also Lysenkoism.
Subjects: Biological Sciences.