io ARE THE EFFECTS OF USE INHERITED ? 



the upper jaw-bone to form part of a more 

 prominent nose, while drawing back the savagely 

 obtrusive teeth and lips to a more pleasing 

 and subdued position of retirement and of 

 humanized beauty. /If human preference and 

 natural selection caused some of these differences, 

 why are they incompetent to effect changes in 

 the direction of a diminution of the jaw or teeth ? 

 And if use and disuse are the sole modifying 

 agents in the case of the human jaw, why 

 should men have any more chin than a gorilla 

 or a dog ? 



The excessive weight of the West African jaws 

 at the College of Surgeons is partly Against 

 Mr. Spencer's contention, unless he assumes that 

 Guinea Negroes use their jaws far more than the 

 Australians, a supposition which seems extremely 

 improbable. The heavier skull and narrower 

 molar teeth point however to other factors than 

 increased use. 



