THE KEY TO ANIMAL BEHAVIOR 



wink, when you threaten its eyes with your hand, 

 until it is two months old, but its sucking instinct 

 seems to be developed when it comes into the 

 world. Its instinct of fear comes much later, and 

 the little girl's doll-baby instinct, if such it be, 

 comes later still. 



Just at this point I am reminded of a curious error 

 that John Fiske fell into in his otherwise admirable 

 paper on the helplessness of the human young as a 

 factor in human evolution. " The bird known as the 

 fly-catcher no sooner breaks the egg than it will snap 

 at and catch a fly." Of course this is absurd. When 

 the young fly-catcher first comes out of the shell it 

 can neither see nor lift its head. Its fly-catching 

 does not begin until it is fully fledged, and then it 

 begins instinctively; it is prompted to this by its 

 organization and its inherited habits. So with the 

 other forms of animal life. The young bird has 

 wings, therefore it does not have to be taught to 

 fly; the woodpeckers have bills made for drilling; 

 therefore the drilling does not depend upon ex- 

 perience; the woodcock has a beak for probing mud 

 and an inborn appetite for soft worms, therefore 

 it instinctively probes mud. Does the young skunk 

 have to be taught how to defend itself, or the young 

 porcupine, or the young rattler, or the wasp, or the 

 honey-bee on its first flight? 



Squirrels are nut-eaters; therefore they know nuts 

 the moment they see or smell them. Some species 

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