ANTHROPOLOGICAL SOCIETY. 69 



Chimpanzee, the short arms and man-like hands and feet of 

 the gorilla, the size of brain of the orang-outang, and the 

 features of S&nnopithicits, Cercopithicas, or Mormon. That 

 such a form once existed was as reasonable as that the orang- 

 outang should exist. Increase of brain an accompanying 

 increases of intelligence was due to two causes : 1. Efforts 

 to evade enemies through the exercise of sagacity or cun- 

 ning ; 2. Efforts to obtain food by skill and strategy. The 

 first of these was rendered necessary to a greater degree than 

 in the case of other animals in consequence of a notable 

 absence of the means of defence with which most animals 

 are endowed. The second was also due in great part to the 

 lack of offensive weapons and other specialized means of 

 pursuing any one peculiar mode of life. To understand 

 this better, however, another important fact must be con- 

 sidered. Nearly or qiiite all the animals of the family from 

 which man has descended are strictly arboreal. They are 

 usually light and supple creatures, adapted to life in trees, 

 subsisting chiefly upon the nuts and fruits which they yield. 

 But some of the anthropoids, the gorilla, for example, have 

 attained so large a size and so great a weight that arboreal 

 existence has become difficult and the)' have descended to 

 the ground. The ancestor of man must have belonged to 

 this class and early become at least a partially terrestrial 

 animal. The effect of this was both to increase the number 

 and character of his enemies and to diminish his supply of 

 natural food. Both these circumstances combined in in- 

 creasing the necessity for mental exertion which in turn was 

 the immediate cause of his rapid brain development. 



Two causes likewise, operated to produce the erect posture, 

 namely: 1st, life on the ground, and, 2d, increased brain 

 mass. 



The conformation of the limbs of the ape family is such 

 that life on the ground would naturally cause the fore limbs 

 to be used more and more exclusively as hands, and the hind 

 ones as the only means of locomotion. The enlarged brain 

 accompanied by a still greater increase in the weight of the 



