118 
THE DESCENT OF MAN. 
Paet I. 
is certain. But with savages, as Mr. Herbert Spencer 26 
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-aighted, whilst men living 
much out of doors, and especially savages, are generally 
long-sighted. Short-sight anil long-sight certainly tend 
to be inherited. : I he inieriority ot 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 
1 lenggoi states that he has repeatedlv 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. Blumenbaek has 
also remarked on the large size of the nasal cavities 
26 c Principles 0 f Biology,’ yol. i. p. 455. 
77 Paget, ‘Lectures on Surgical Pathology, ’ vol. ii. 1853, p. 209. 
28 ‘ The Variation of Animals under Domestication,’ vol. i. p. 8 . 
28 ‘Saugethiei'o von Paraguay,’ s. 8, 10. 1 have had good oppor- 
tunities tor observing the extraordinary power of eyesight in the 
huegntns. See also Lawrence (‘ Lectures on Physiology,’ &c., 1822, p. 
404) on this samo subject. M. Giraud-Teulon has recently collected 
( Kevue des Cours Scientifiques,’ 1870, p. 625) a large and valuable 
body ot evidence proving that the cause of sliort-sight, “ C’est le travail 
“ astsidu, de pres.’ 
