A BEAVER’S REASON 
and flexibility of instinct which all animals show, 
some more and some less, is not reason, though it 
is doubtless the first step toward it. Out of it the 
conscious reason and intelligence of man probably 
have been evolved. I do not object to hearing this 
variability and plasticity of instinct called the twi- 
light of mind or rudimentary mentality. It is that, 
or something like that. What I object to is hearing 
those things in animal life ascribed to reason that 
can be easier accounted for on the theory of instinct. 
I must differ from the ornithologist of the New 
York Zoological Park when he says in a recent 
paper that a bird’s affection for her young is not 
an instinct, an uncontrollable emotion, but I quite 
agree with him that it does not differ, in kind at 
least, from the emotion of the human mother. In 
both cases the affection is instinctive, and not a 
matter of reason, or forethought, or afterthought at 
all. The two affections differ in this: that one is 
brief and transient, and the other is deep and last- 
ing. Under stress of circumstances the bird will 
abandon her helpless young, while the human 
mother will not. When the food supply fails, the 
lower animal will not share the last morsel with its 
young; its fierce hunger makes it forget them. Dur- 
ing the cold, wet summer of 1903 a vast number of 
half-fledged birds — orioles, finches, warblers — per- 
ished in the nest, probably from scarcity of insect 
food and the neglect of the mothers to hover them. 
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