HISTORICAL ACCOUNT OF EVOLUTION THEORY 17 



basis. He lived at a time when it was dangerous to express views that 

 might be interpreted as unorthodox, and this may account for the 

 apparent lack of conviction in his own ideas; for he wavered between 

 special creation and evolution. His^chief contribution is the idea of 

 the direct influence of the environment in the modification of the 

 structure of animals and plants and the conservation of these modifi- 

 cations through heredity. This seems to imply that he believed in 

 the inheritance of acquired characters. He expressed himself as 

 believing that climate has had a direct effect in the production of 

 various races of man, that new varieties of animals have been formed 

 through human intervention (an idea implying artificial selection), 

 that similar results are produced by geographic migration and through 

 isolation. He expressed the view that there is a great struggle for 

 existence among animals and plants to prevent overcrowding and 

 to maintain the balance of Nature. This appears to be an anticipation 

 of Malthus' ideas on population, which were so influential in shaping 

 the theories of Charles Darwin and of Wallace. 



While many of his ideas appear to be highly advanced for his time, 

 his special applications are open to serious criticism. He reasons, 

 for example, that the pig as it exists at present could not have been 

 formed on any original complete and perfect plan, but seems to have 

 been formed as a compound from other animals. It has useless parts 

 which could hardly have been a part of a perfect plan as originally 

 conceived. He thought that "the ass is a degenerate horse, and the 

 ape a degenerate man. " 



On the whole Buff on was not a strong advocate of evolution and 

 his influence was far from being as important as some recent writers 

 appear to believe. 



Erasmus Darwin (1731-1802), grandfather of Charles Darwin, 

 was a physician, a naturalist, and a minor poet. Undoubtedly he 

 transmitted to his grandson his thoughtful habit and love of science 

 and was influential hi shaping his ideas on evolution. The elder 

 Darwin's theories as to the causes of evolution closely paralleled 

 those of Lamarck, his distinguished contemporary hi France, but it 

 is now very generally conceded that the ideas of the two men were 

 independently derived from similar materials. Erasmus Darwin laid 

 little emphasis on the direct action of the environment, which had been 

 Buffon's main dependence, and dwelt on the internal origin of adap- 

 tive characters. "All animals," he said, "undergo transformations 

 which are hi part produced by their own exertions, in response to 



