192 



COMPARATIVE ANATOMY 



primates to five, continues in man by a general reduction in size of all 

 the teeth and by closing the diastema, the open space next the canines. 



""^PALATINE 



palatine' 



A. CAUCASIAN B. NEGRO C. ORANG OUTAN 



Fig. 144. — Dental arcades of ape. Negro and Caucasian. The form of the Negro 

 arcade is transitional between that of the ape and white man. "With the shortening 

 of the human jaw the diastema between incisor and canine teeth seen in the ape jaw 

 is lacking. The refinement of the face is one of the most striking results of primate 

 (Redrawn after Wiedersheim.) 



evolution. 



INCISORS 



iCAN I NE 

 I 



PREMOLARS A^^^J^^l— 



'MOLARS 



/ \ ^PREMOLARS 



INCISORS ^CANINE 

 Fig. 145. — Human teeth viewed from the left side. The human dental formula is: 

 il c\, pml mi As a result of the shortening of the hvmian jaws the third molars fre- 

 quently do not erupt. The elongated root of the canine tooth suggests that as in lower 

 primates the ancestors of man may have had fangs. (Redrawn after Braus.) 



Consequently, human teeth are a continuous series and no tooth is very 

 much larger than another, for the canines ceased to be tusks at the begin- 



