THE RECESSION OF THE JAWS 95 



arrived at its highest Anthropoid stage, the still relatively 

 large tooth-bearing (alveolar) margin of the jaws is well 

 in advance of the rest of the jaws. The tooth-bearing 

 surfaces and the teeth project. The upper jaw is prog- 

 nathous, and the lower jaw has a very receding chin. 

 With the abbreviation of the alveolar margin in Man, the 

 prognathism disappears and the chin makes its appear- 

 ance. The gradations in this change are very beautifully 

 seen in the remains of ancient Man and also in the jaws 

 of existing primitive Man (see Fig. 32). The mandible 



A B 



FIG. 32. ONE HALF OP THE LOWER JAW OF (A) HOMO AND (B) 

 A MONKEY, TO SHOW THE PROMINENCE OF THE TOOTH- 

 BEARING MARGIN IN B AND OF THE CHIN IN A. 



of the " Piltdown individual " is notorious, with its 

 advanced alveolar margin and receding chin. The 

 prognathous savage is proverbial. Man developed a chin 

 by the shrinkage of the alveolar margin of his jaw, con- 

 sequent upon the diminishing demands made upon the 

 teeth, the functions of which were so largely usurped by 

 the hands. ^Modern and civilized Man seems to be in 

 some danger of losing even his chin as the whole mandible 

 becomes reduced. First, the recession of the tooth- 

 bearing margin makes the lower margin conspicuous, 

 and a chin is developed ; and now the lower margin seems 

 to be disposed to follow in the train of the upper. The 

 dawn of a chinless aristocracy is no pleasing picture in 

 the later stages of human evolution; and yet the recession 

 of the modern jaw is not to be denied. 



