ANIMAL AND RATIONAL INTELLIGENCE 255 



plate rational power in full exercise, accumulating ob 

 servations and advancing towards wider inductions, 

 animal intelligence presents no causality adequate to 

 account for its origin. Among the essential character 

 istics of a self-directing intelligence are application of 

 laws of thought, self-criticism of thought, use of prior 

 inductions, and accumulation of knowledge, sustained 

 by a living interest, practical, literary, scientific, or 

 philosophic. The powers we are agreed in assign 

 ing to the higher animals, even on the highest com 

 putations of them which have been made, offer no 

 traces of the rudiments of such rational exercise. 



This conclusion is strengthened when it is remarked 

 that the highest achievements of animal intelligence 

 observed by us are the results of human training. 

 Man s influence has been at work through successive 

 ages in development of the dog and horse. When 

 account has been made of this, difficulties for the 

 theory of evolution are multiplied. Although monkeys 

 and apes have the advantage in brain structure and 

 in powers of manipulation, they have not shown in 

 telligence coming to the level of our domesticated 

 animals. On these grounds, it is demonstrated that 

 the origin of the higher power cannot have been 

 the lower. Natural history itself fails to sustain 

 evolution of rational power. 



This conclusion is further strengthened by the 

 testimony of Geology as to traces of the presence of 

 the dog and the horse on the earth. Hitherto we 

 have included the results of domestication and train 

 ing. Now these must be excluded, retaining only 

 biological conditions, historically antecedent to man s 

 appearance in Nature. Our observations must apply 



