EVOLUTION 311 



onslaughts and to bend to his own uses phenomena exhibited by 

 it. Man's superiority over other animals rests upon his greater 

 success in controlling the forces of environment. 



Pre-Darwinian Theories. — The essential features of evolution 

 as a process were understood by the ancient Greek philosophers, 

 but prior to the time of Charles Darwin theories advanced to 

 explain the process were too feebly supported by facts to carry 

 much conviction. Several of Darwin's immediate predecessors 

 contributed ideas which were important in the later development 

 of the subject. Comte de Buffon (1707-1788), supported the 

 teaching of the Greek philosopher Aristotle (384-322 B.C.), 

 that species form a single ascending series from the lowest to 

 the highest, and that higher forms evolved from lower ones. 

 He emphasized the importance of variations as the basis of 

 evolutionary change and believed that the larger differences 

 between species resulted from the building up of smaller differ- 

 ences or variations between the members of the same species, 

 under the direction or guidance of environment. He accepted the 

 principle of the inheritance of acquired characters, a principle 

 that was stressed by his successors, particularly Lamarck. 

 Buffon pointed to the results achieved by animal and plant 

 breeders in developing new varieties from a common wild stock 

 as an example of the effect of environmental conditions or stimuli 

 on the plastic nature of organisms. This idea was also supported 

 by Erasmus Darwin (1731-1803), poet and physician, and the 

 grandfather of Charles Darwin. In connection with the question 

 of the effects produced by environment, Erasmus Darwin 

 emphasized the importance of the inheritance of functional 

 responses of the organism to external stimuli. 



The French biologist, Jean Baptiste Lamarck (1744-1829), 

 discarded the idea of a single evolutionary series from the lowest 

 to the highest forms and formulated instead the modern concept 

 of the origin of all forms of life from a common stock by diverging 

 lines of ascent, similar to the formation of limbs and smaller 

 branches from the trunk of a tree. Thus the treelike arrange- 

 ment of the scheme of classification was originated by Lamarck. 

 In his later years Lamarck was a staunch evolutionist, yet he 

 failed to produce a completely worked-out theory to explain the 

 process. His ideas may be summarized as follows: (1) The 

 environment has a direct effect in modifying plants and an 



