THE HUMAN SIDE OF APES 



approach to deliberate and formal reasoning; yet her mental 

 adjustments to complex and varying situations were far 

 beyond the capacity of the lower mammals. For life in a 

 tropical forest, where she had to be ever watchful, active, 

 and resourceful, she was an admirably adapted piece of anl 

 mal mechanism, but her attempts to solve problems requiring 

 deliberation or reflection showed that she was not equal to 

 such tasks. When an apple v/as placed on a small piece of 

 board outside her cage, she first tried to reach the apple 

 directly, but failing in this she seized the edge of the board 

 and with some difficulty drew it toward her and obtained 

 the prize. When I drove a nail in the board to serve as a 

 sort of handle she reached directly for the nail, drew in the 

 board, and seized the apple. I then substituted a longer 

 board, on which the apple was too far out to be reached 

 even when the near end was pulled against the cage. Lizzie 

 then first pulled the board in by the nail, then drew it side- 

 wise until the apple was sufficiently near to be seized. The 

 appropriate acts were done at the first trial, apparently as 

 a result of inspecting the situation and judging what must 

 be done to get the food. When an apple was placed not 

 on the board but near it, Lizzie drew the board in repeatedly 

 and seemed disappointed because the apple did not come 

 also. She could clearly see that the apple was not on the 

 board, but she did not perceive the futility of her usual 

 performance. When given a nut inside a Mason jar, with 

 the cover screwed on, she would bite and work at the cover, 

 turning it this way and that until it finally came loose. Even 

 after making numerous trials she never learned that the top 

 could be unscrewed by continuously turning it in one direc- 

 tion. When food was placed in a box having a lid fastened 

 by a button or a hook, she could open the box only by work- 

 ing at the fastenings with her hands and teeth until the lid 



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