CREATION BY EVOLUTION 



happened to come open. She never clearly perceived why 

 a button or a hook kept her from opening the box. An 

 animal of higher intelligence would have comprehended the 

 cause of the difficulty and performed the appropriate act 

 without wasting so much time and effort in random biting 

 and clawing. Lizzie was very impatient to obtain her objec- 

 tives. If she could not see quickly and intuitively what course 

 should be followed, she did not spend time in devising new 

 methods of attack. She seemed quite incapable of exercising 

 what we might call conscious deliberation over means of 

 attaining ends. 



I have dwelt upon Lizzie's intellectual aptitudes and limi- 

 tations because they indicate a stage of mental development 

 that is in many respects intermediate between what is found 

 in ordinary mammals and the higher type of mentality pos- 

 sessed by the anthropoid apes. The recent studies of Kohler 

 and Yerkes have added much to our knowledge of the ape 

 mind. These studies had the great merit, as compared with 

 older observations, of putting the animals through experi- 

 mental tests in order to ascertain the character and extent 

 of their intellectual powers. It has been shown quite clearly 

 that the apes employ means to ends in a way that indicates 

 a faculty of inferring what will happen if the proper condi- 

 tions are fulfilled. In several experiments performed by 

 Kohler with chimpanzees a piece of fruit was suspended 

 beyond the reach of the animals (Fig. 2). When given 

 boxes to mount upon, the apes quickly learned to pull them 

 into position and climb upon them to reach the fruit. After 

 one of the chimpanzees. Sultan, had learned to use the box 

 the fruit was suspended still higher and two boxes were 

 placed at his disposal some distance away from the objec- 

 tive. His behavior under these conditions was as follows: 

 "Sultan drags the bigger of the two boxes towards the 



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