1040 EVOLUTIONAL MODIFICATIONS 



they IouikI it aiul k-l't little Ix-hiiul to change its appearance as a result ol 

 their own efl'orts. Their expansions in neokini'sis, Hke their cle\eIopntents in 

 beha\ior, were strictl.x hmited b>- the handicaps of highly restrictive special- 

 izations in their instruments of externalization. 



The Mosr Profitable Advance in Neokinesis Okiginating w i rii 

 THE Prim vn;s. With the appearance of the primates, the first really ]:)ront- 

 able acKances in neokinesis were actually made. It is probable that the 

 quadrumanal dilferentiation may have led the early prosimia toward the 

 realm in which the I'liII promise of this motor capacity became possible. I n 

 any case, the long awaited instrument, the ready servant of neokinesis, had 

 at length made its appearance. Even with its possession the primates had as 

 yet a long distance to travel, many experimental trials to experience belore 

 this new instrument was so adapted as to give its maximum degree ol serx'ice. 

 The specialization in connection w ith the upper extremity was a real decisive 

 step forward; but where it extended to the low er extremities and produced 

 feet w ith many hand-like characters, it immediately imposed serious limita- 

 tions and creatt'd those disadxantages which result from the possession of 

 too man\ hands. The c|uadrumanal tendency of the primates positively 

 prohibited the full dexelopment of manual dilferentiation lor two reasons: 

 First, it committed the animals to an almost exclusi\el\ arl)ort-al hie. in the 

 second place, it. created a field of psychological indecision which had a i)ro- 

 found elfect by causing a c|uandary as to whetlu'r tlu' hand should be used 

 as a foot or the loot as a hand. It thus left in indeterminate state an instru- 

 ment which ri'c[uired aboxe all else the most exact discrimination lor its fullest 

 functional dilferentiation. 



Pakmng Ol ruE Ways between An rnROPOiD and Hlm an. In spite ol 

 their early embarrassment due to over-endow nunt ol hand-like characters, 

 the primates had come upon tin- right trail. It reciuirttl but one lurther 

 modification to set them on the track w hich would lead to the ultimate goal. 



