8 ARE THE EFFECTS OF USE INHERITED ? 



Sexual selection powerfully affects the human 

 face, and so must affect the jaws as is shown by 

 the differences between male and female jaws, 

 and by the relative lightness and smallness of 

 the latter, especially in the higher races. Human 

 preference, both sexual and social, would tend 

 to eliminate huge jaws and ferocious teeth when 

 these were no longer needed as weapons of war 

 or organs of prehension, &c. We can hardly 

 assume that the lower half of the face is specially 

 exempt from the influence of natural and sexual 

 selection ; and the effects of these undoubted 

 factors of evolution must be fully considered 

 before we are entitled to call in the aid of a 

 factor whose existence is questioned. 



After allowing for lost teeth and the conse- 

 quent alveolar absorption, and for a reduction 

 proportional to that shown in the rest of the 

 skull, the difference in average weight in fifty 

 European and fourteen Australian male jaws 



