THE BRAIN OF PREHISTORIC MAN 889 



THE PARIETAL LOBE OF THE DAWN \L\N 



The j)ariftal lobe, although it lacks any impression of lissurcs or con- 

 \()lutions, lias c'\ickntl\ nicreased in size. This is especially noticeable in 

 the parietal eminence and m the prommenee ol the arc of the \erte\. Both 

 of these mcrcments siij;nily accessions to general bocl\ sense and are incident 

 to specific expansions in the area pertaining to the uppir extremity, more 

 especiall\ the hand. Such augmentation of the parietal lobe justiiies the 

 interpretation of further extension in manual attainments. There is reason 

 to lx'lie\-e that the Dawn man had accjuired increased capacitx in the use of 

 his hand as a sensory organ. He could emplo\- it to much ad\antage in 

 exploring the world about him, and in analyzing the objects in his cnviron- 

 nunt b\ actual contact with them. Thus he learned the consistency, the 

 shape and the texture of things he touched. The weight and mobilitv of 

 objects gave him added information concerning their utility and application. 

 The relative resistance of wood and st(jne, their respective projectile and 

 penetrating powers, the acKantages of sharp edges as compared with blunt 

 surlaces, the pliability ol llexible substances, the tensile strength of various 

 tissues, all came to him as re\elations called forth by these new perceptions 

 of the world, liut such revelation did not limit itself to inere sensing. The 

 sensory impressions found externalization in new actions. They doubtless 

 guided his hand to utilize the serviceable qualities of objects with which 

 nature surrounded him. In a word, they led him to make use of stick and 

 stone, Irom which advance it was but a step to fashion his materials into 

 implements better suited to his purposes. 



W hile the increase in the parietal arc and in the parietal eminence 

 denotes new capacities of sensation, it is quite as insistent concerning the 

 motor powers added to the human hand. There may be a question whether 

 the earlier ape-man of Java had learned the secret of making implements 

 for himself, but it is becoming more clear that the crude flints found in the 



