HISTORY OF' THE EVOLUTION THEORY. Aristotle (me. 384-322) may be regarded as the father of the theory of descent, although Empedoeles has been credited with the conception. The latter taught in a vague way the fact of the gradual succession of life-forms from the less to the more perfect, though he did not claim any ge netic relation, but believed that they were sepa rately created. The wonderfully comprehensive mind of Aristotle, who was the first anato mist, conceived of a genetic series, of a chain of being from polyps to man; he perceived the won derful adaptation in nature, the principle of the physiological division of labor, and regarded lifo as the function of the organism, not as a sepa rate principle. He recognized the fact of hered ity atavism, and believed in the inheritance of mutilations.
The nearest approach which the didactic poet Lucretius made to the evolution idea is to he found in his account of the development of the faculties and arts among the human races.
Saint Augustine (A.D. 354-130) spoke of the creation of things by series of causes, and Thomas Aquinas (1226-74) expounded and upheld Saint Augustine's view. But the idea of special creation became the universal teaching ;roan the middle of the sixteenth to the middle of the nineteenth That broad-minded early German philosopher Leibnitz (1646-1716) gave examples of the gra dation of characters between living and extinct forms as proofs of the universal gradation or connection between species. He believed in a chain of being, and that the different classes of animals are so closely united that there are no gaps between them. He also suggested that by means of great changes of habitat 'even the species of animals are often changed;' he also taught the doctrine of the continuity of nature, and was the author of the saying, Natura 9/0/1, Tacit sultan?.
Buffon (1707-88) thoroughly read and was in fluenced by Leibnitz's writings. Whether or not he owed his evolutional views to Leibnitz, he stated, and as frequently denied, the mutability of species. He suggested that such changes were directly produced by changes in climate, food, and domestication, and he gave a few examples of the effects of disuse, and held that all ani mals were possibly derived from a single type.
A stronger, more observant and bolder reasoner than Buffon was Erasmus Darwin (q.v.), the grandfather of Charles Darwin. He was a country doctor, not a working naturalist. but a remarkably close observer, and a sound thinker. He claimed that all animals were derived from `a single filament,' insisted on the effects of changes of climate, of use, characters being pro duced by the exertion of animals. He was the first to propose the factor of sexual selection, stated the principle of the law of battle, quite fully elaborated the idea of protective mimicry, and vaguely stated the doctrine of use-inherit ance.
The true founder of evolution, however, was Lamarck (q.v.), who was the leading zoologist of the period between Linnus and Cuvier (1744 1829). In 1801 he first published his evolutionist views. He taught in his lectures (1801-1806), and in his Philosophic zoologigue (Paris, 1809), that all organisms arose from germs; that de velopment was from the simple to the complex; that the animal series was not continuous, but tree-like; and he constructed the first phylogenet ic tree. The Lamarckian factors are the changes of environment, climate, soil, food, and tempera ture, such changes being direct in plants and the lowest, animals, indirect in the higher animals. He speaks of the struggle for existence, stating that the stronger devour the weaker, and refers to competition. He discussed at length the effects of use and disuse, taught that vestigial structures are the remains of organs actively used by the ancestors of existing forms, and claimed that new wants or necessities induced by changes of climate. habitat. etc.. result in the pro duetion of new propensities, new habits, and new functions. Change of habits, he says, originate organs, change of functions create new organs, and the formation of mew habit. precedes the origin of new organs or modification of organs formed. 11e refers to the swamping effects of crossing, and to isolation as a factor. His definition of species is the most satisfactory yet stated. Lamarck's were not generally ac cepted. but misrepresented or ignored, largely through tae influence of Cuvier and his disciples. See LAMARCKISM ; XEOLAMARCKISM.