THE INTELLIGENCE OF MONKEYS. 279 



able form. But if wc take human beings at from 6 months to 3 years of 

 iige or later, we find plenty of traits that appear in the monkeys. In 

 fact the human instinct which is perhaps of prime importance in 

 human mentality, the instinct which perhaps is the real cause of many 

 of our most boasted powers, has its clear prototype and homologue in 

 the monkey. I refer to the instinctive enjoyment of physical and men- 

 tal activity in general, to the tendencies to act and feel as much as pos- 

 sible, regardless of any ulterior practical considerations, which we some- 

 times call destructiveness or constructiveness and curiosity. 



Even the casual observer, if he has any psychological insight, will 

 be struck by the general, aimless, intrinsically valuable (to the animal's 

 feelings) physical activities of a monkey compared with the specialized, 

 definitely aroused, utilitarian activities of a dog or cat. Watch 

 the latter and he does but few things, does them in response to 

 obvious sense presentations, does them with practical consequences of 

 food, sex-indulgence, preparation for adult battles, etc. If nothing 

 that appeals to his special organization comes up, he does nothing. 

 Watch a monkey and you cannot enumerate the things he does, cannot 

 discover the stimuli to which he reacts, cannot conceive the raison 

 d'etre of his pursuits. Everything appeals to him. He likes to be 

 active for the sake of activity. 



The observer who has proper opportunities and takes proper pains 

 will find this intrinsic interest to hold true of mental activity as well. 

 No. 1 happened to hit a projecting wire so as to make it vibrate. He 

 repeated this act hundreds of times in the few days following. He 

 could not eat, make love to or get preliminary practise for the serious 

 battles of life out of that sound. But it did give him mental food, 

 mental exercise. Monkeys seem to enjoy strange places; they revel, if I 

 may be permitted an anthropomorphism, in novel objects. They like to 

 have feelings as they do to make movements. The fact of mental life 

 is to them its own reward. 



Finally in their method of learning, although monkeys do not reach 

 the human stage of a rich life of ideas, yet they carry the animal method 

 of learning by the selection of impulses and association of them with 

 different sense impressions, to a point beyond that reached by any other 

 of the lower animals. In this, too,they resemble man ; for he differs from 

 the lower animals not only in the possession of a new sort of intelligence 

 but also in the tremendous extension of that sort which he has in com- 

 mon with them. A fish learns slowly a few simple habits. Man learns 

 quickly an infinitude of habits that may be highly complex. Dogs and 

 cats learn more than the fish, while monkeys learn more than they. In 

 the number of things he learns, the complex habits he can form, the 

 variety of lines along which he can learn them, and in their permanence 

 when once formed, the monkey justifies his inclusion with man in a 

 separate mental genus. 



