CHAPTER VI 

 THE EVOLUTION OF INSTINCT 



"The primary roots of instincts reach back to the constitutional 

 properties of protoplasm, and their evolution runs, in general, parallel 

 with organogeny. As the genesis of organs takes its departure from 

 the elementary structure of protoplasm, so does the genesis of in- 

 stincts proceed from the fundamental functions of protoplasm." 

 WHITMAN, Animal Behavior. 



"Instinct precedes intelligence both in ontogeny and in phylogeny, 

 and it has furnished all the structural foundations employed by 

 intelligence." Ibid. 



" It will be universally admitted that instincts are as important as 

 corporeal structures for the welfare of each species under its present 

 conditions of life. . . . If it can be shown that instincts do vary 

 ever so little, then I can see no difficulty in natural selection preserv- 

 ing and continually accumulating variations of instinct to any extent 

 that was profitable. It is thus, as I believe, that all the most complex 

 and wonderful instincts have originated." DARWIN, Origin of 

 Species. 



Efforts to explain the origin of instinct by gradual evolu- 

 tion were made from time to time before Darwin applied 

 his theory of natural selection to the solution of the problem. 

 The most noteworthy theory was Lamarck's doctrine that 

 instinct is inherited habit. It is well known that actions 

 frequently performed come in course of time to be performed 

 automatically and unconsciously, as is illustrated by the 

 familiar example of learning to play the piano. Granting 

 that the modifications produced by habit are inherited, it 

 is evident that the repetition of an action generation after 

 generation would produce a congenital proclivity to its 

 performance which might in time develop into a true in- 

 stinct. Since habits are so frequently the result of intel- 



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