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 of 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 j 

 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 evokition ; and yet the recession 

 of the modern jaw is not to be denied. 



