STRUCTURAL CUL.MUNATION 97" 



performances near to the body. These impediments are also pronounced for 

 projectile activities, for the wielding of weapons or the manipulation of 

 instruments. The upper extremity in the great anthropoids is preeminently 

 specialized in the interest of arboreal life. Its enormous musculature and 

 great length favor the exigencies of locomotion determined by tree climbing. 

 Some other factor, therefore, over and above the actual specialization of 

 the hand, must serve as an important incentrve for the expansion of the 

 cerebral cortex, which led to its ultimate expression as seen in the human 

 brain. Were this not the case, it is probable that some of the lower simians 

 would possess brains more closely in harmony with that of man than the 

 great anthropoids. It is probable that this primary- factor is to be found in 

 the foot rather than in the hand. 



The lower extremity, which specializes a foot of preeminent hand- 

 like character, has manifested this differentiation essentially in the 

 interest of arboreal life. Such life definitely restricts the motor capaci- 

 ties of the animal by consigning it to a type of locomotion for which the 

 use of both hands and feet is indispensable. Under the circumstances, 

 however much the proportions of the arm, forearm, hand and fmgers 

 may correspond to human standards, complete manual differentiation is 

 impossible. The hand, to be the freest for the purposes of manual manipula- 

 tion, must be permitted to operate on a basis far more secure than that offered 

 by arboreal life. In other words, the animal, to make the most perfect use of 

 the hand, must, so to speak, stand with both feet upon the ground, and from 

 this point of vantage, be able to traverse and utilize at will all of the habitat 

 zones of life. The adequate structure for securing such a basis of operation is 

 not to be found in the hand-like specialization of the foot. None of the apes, 

 for example, could in any wise adjust itself to life upon the earth so that it 

 might effectively take advantage of other habitat zones. It is undoubtedly the 

 hand-like specialization of the foot in the great anthropoids and in all of the 



