118 THE DESCENT OF MAN. Part I. 



26 



is certain. But with savages, as Mr. Herbert Spencer 

 has remarked, the greater use of the jaws in chewing 

 coarse, uncooked food, would act in a direct manner on 

 the masticatory muscles and on the bones to which 

 they are attached. In infants long before birth, the 

 skin on the soles of the feet is thicker than on any 

 other part of the body; 27 and it can hardly be doubted 

 that this is due to the inherited effects of pressure 

 during a long series of generations. 



It is familiar to every one that watchmakers and en- 

 gravers are liable to be short-sighted, whilst men living 

 much out of doors, and especially savages, are generally 

 long-sighted. Short-sight and long-sight certainly tend 

 to be inherited. 28 The inferiority of Europeans, in com- 

 parison with savages, in eye-sight and in the other 

 senses, is no doubt the accumulated and transmitted 

 effect of lessened use during many generations; for 

 Eengger 29 states that he has repeatedly observed Euro- 

 peans, who had been brought up and spent their whole 

 lives with the wild Indians, who nevertheless did not 

 equal them in the sharpness of their senses. The same 

 naturalist observes that the cavities in the skull for 

 the reception of the several sense-organs are larger in 

 the American aborigines than in Europeans ; and this 

 no doubt indicates a corresponding difference in the 

 dimensions of the organs themselves. Blumenbach has 

 also remarked on the large size of the nasal cavities 



26 ( Principles of Biology,' vol. i. p. 455. 



27 Paget, ' Lectures on Surgical Pathology,' vol. ii. 1853, p. 209. 

 2S ' The Variation of Animals under Domestication,' vol. i. p. 8. 



29 ' Saugethiere von Paraguay,' s. 8, 10. I have had good oppor- 

 tunities for observing the extraordinary power of eyesight in the 

 Fuegians. See also Lawrence (' Lectures on Physiology,' &c, 1822, p. 

 404) on this same subject. M. Giraud-Teulon has recently collected 

 (' Ptevue des Cours Scientifiques,' 1870, p. 625) a large and valuable 

 body of evidence proving that the cause of short-sight, " C'est le travail 

 " assidu, de pres.' 



