82 ARBOREAL MAN 



usually falls opposite the middle of the base of the third 

 digit (see Figs. 29, 30 and 31). This line has exactly the 

 same contour in the hand, and is the typical one seen 

 in the Monkey's foot. It is the outline of the primitive 

 foot preserved in its primitive condition by arboreal life. 

 The contour of the anterior extremity of the human 

 foot has therefore not undergone much change from its 

 primitive arboreal condition, the alteration being almost 

 soirly confined to the phalanges of the free digits. 



It is the outer toes which are undergoing atrophy, 

 and this atrophy has not to any great extent affected 

 the metacarpal bones, nor altered the outline of the foot 

 itself. 



Human specializations seem to be producing a tendency 

 to depend upon, and develop especially as supporting 

 organs, the bones of the inner margin of the foot. The 

 big toe and its supporting bones are becoming the principal 

 axis of the foot. 



The imperfect efforts at walking upon the feet which 

 the higher Primates can make have not attained to thi*^ 

 human development. The human baby walks upon the 

 outer side of its feet when it first learns to walk, and the 

 bones upon this side of the foot are the first to become 

 ossified. But a typically human and later change is the 

 eversion of the foot, which brings its inner margin into 

 the line transmitting the weight of the body to the 

 ground. A whole series of finishing touches in human 

 development is brought into play in this process, but 

 since they are essentially not arboreal effects, they cannot 

 be dealt with here. 



However, without going into the details of the eversion 

 of the foot, the general facts are clear enough. Man has. 

 inherited a primitive and arboreal foot ; purely human 

 modifications are obviously at work producing a very 

 typical human type of structure which, adapted in the 

 first place for support in an arboreal habitat, is now being 

 fitted for terrestrial progression. The human foot is a 



