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 Buffon 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 in shaping his ideas on evolution. The elder 
Darwin’s theories as to the causes of evolution closely paralleled 
those of Lamarck, his distinguished contemporary in 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 in part produced by their own exertions, in response to 
