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.”— 
Waitman, Animal Behavior. 
“Tnstinct 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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