DEVELOPMENT OF MODERN COMPARATIVE PSYCHOLOGY 



489 



creator. Man, as the sole possessor of the 

 faculty of reason, was sharply marked off 

 .from even the higher animals on the 

 .mental side. This view was, of course, 

 nothing more or less than the qualitative 

 dichotomy between man and brute that 

 had survived from the middle ages. The 

 Darwinian assumption of physical and 

 mental continuity within the organic 

 world, and the serious attempt to account 

 .for both along broad genetic lines aroused 

 [bitter and determined opposition on all 

 isides. 



1 The evolutionary conception, regardless 

 of its specific formulation, brought with 

 it several problems of great interest to 

 comparative psychology. First, there 

 was the question as to the origin of mind 

 comparable to that regarding the origin 

 of life in biology. On this point Darwin 

 had nothing to say on the positive side. 

 l"'I have nothing to do with the origin of 

 the mental powers," he writes, "any 

 more than I have with life itself. We 

 are concerned only with the diversities 

 of instinct and of the other mental 

 faculties of animals of the same class." 

 (2.9, 1:319). Given life and mind, or living 

 organisms with a mental endowment, 

 he concerned himself with the evolu- 

 tion of complex and varied types from 

 the simple and unitary. A second prob- 

 lem, and the fundamental one, for Dar- 

 win, related to the factors which may 

 have operated in the several stages of 

 organic, including mental evolution. And 

 since instinct and intelligence were 

 generally considered to be essentially 

 different mental types the development of 

 both had to be accounted for. 



A half century previous to the publica- 

 tion of The Origin of Species, Lamarck (63) 

 had attempted to show the modus operandi 

 of the development of the instincts on a 

 naturalistic basis. The explanatory prin- 

 ciple of Lamarck was later elaborated by 



Spencer, among others, and called by 

 him the "lapsed intelligence theory." 

 Lamarck held, in brief, that use and disuse 

 of various parts, or members of the 

 organism brought about more or less 

 definite, local changes which were trans- 

 mitted from generation to generation. 

 He did not deny the influence of the direct 

 effect of environment (Buffon's principle) 

 but stressed functioning (use and disuse of 

 parts) as the all-important factor, and he 

 included conscious as well as purely 

 physiological functioning. It is the desire 

 of the giraffe to feed on higher foliage, 

 accompanied by the stretching of the 

 neck, for countless generations, as the 

 expression of that desire, that finally 

 brought about the development of the 

 unusually long neck. Instinctive patterns 

 have been developed pari passu with 

 morphological change; habitual responses 

 initiated by conscious desire, or some 

 form of internal or psychic urge, have 

 been passed on as a cumulative heritage 

 and finally fixated in the species as in- 

 stincts. Lamarck's view is obviously 

 meaningless apart from the generally 

 discarded theory of the heritability of 

 acquired morphological and functional 

 changes in the organism. 



Darwin appealed in the main to the 

 principle of natural selection to account 

 for the evolution of instincts and of 

 mental life in general. He did not deny 

 the operation of other factors, such as 

 those previously applied by Buffon and 

 Lamarck, but he considered these rela- 

 tively unimportant, and as merely supple- 

 mentary to his own principle of selection. 

 Functional types, like structural types, 

 had been evolved by the gradual accumu- 

 lation of favorable variations in the 

 struggle of the organism to survive. The 

 more complex and elaborate instincts had 

 developed gradually out of the less com- 

 plex, and these in turn out of still simpler. 





