HOLMES'S "THE EVOLUTION OF ANIMAL 

 INTELLIGENCE" « 



GEORGES BOHN 



Paris, France 



Professor S. J. Holmes, a biologist whose work is highly 

 esteemed in France, has recently published a very interesting 

 work on comparative psychology, entitled "The Evolution of 

 Animal Intelligence." In order to demonstrate this evolution, 

 Holmes studies a certain number of types, chosen in such a way 

 as to bring into evidence the activities from which intelligence 

 is derived ; certain groups of the animal kingdom are left entirely 

 out of account, because they are hardly adapted to furnish use- 

 ful data towards the solution of the problem which the author 

 has set himself. 



From the outset, Holmes clearly shows what his guiding ideas 

 are. The ingenious theory wherein he makes pleasure and pain 

 play an important role is already familiar to us: these are the 

 powerful agents of inhibition and reinforcement, and conse- 

 quently of adaptation and evolution; the development of pleas- 

 ure-pain reactions constitutes the most important stage in the 

 evolution of "behavior," for the development of intelligence 

 itself is, according to the theory, based on these reactions. 



But to speak of pleasure-pain means to raise at once the 

 question of consciousness and sensations in the lower animals, 

 questions which have already given rise to so much controversy. 

 We have certainly no means of knowing states of consciousness 

 outside of ourselves. Holmes does not conceal this fact from 

 himself, but it does not prevent him from continuing the dis- 

 cussion. The analogies between man and the higher animals 

 are so evident as to make it certain that the latter are conscious 

 of some of their acts. In the case of lower forms, we are re- 

 duced to probabilities. Certain writers, among whom the author 

 is mistaken in citing me (for to me there is no objective mark 

 of consciousness), have regarded ability to learn, or associative 



1 Holmes, S. J. The Evolution of Animal Intelligence. New York, Henry Holt 

 and Company, 1911, pp. v+296. 



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