At the beginning of the nineteenth century it was almost universally believed that all living beings on earth were immutable divine creations. In bold contrast, the French naturalist, Jean Baptiste Lamarck argued that life could change continuously on a grand scale. Moreover, he provided for the first time an appealing, easily understood process by which such changes could occur. Lamarck published his book entitled Philosophie Zoologique in 1809 propounding this idea when he was already sixty-five years old. Apparently the book attracted little attention when it appeared. It is said that, in his old age, he was neglected by his contemporaries, became blind, and died miserably. His fame came only long after his death when evolution became a heated subject following the publication of Darwin's The Origin of Species. Some of Darwin's opponents drew from Lamarck a theory called neo-Lamarckism, emphasizing the direct effect of environment as the prime factor for evolution. (For an authoritative account of the nineteenth-century approaches to evolution, readers may refer to Simpson, 1964.)

Here our main interest in Lamarck is that he proposed, probably for the first time in biology, a general theory to explain how evolution occurred. As is well known, he assumed that the effect of use and disuse, which in animals is induced by their living conditions, is inherited by offspring and this causes a perfecting tendency in evolution.