32 THE DESCENT OF MAN. 



with their lower extremities motionless. Other writers Have 

 come to a similar conclusion in analogous cases. According to 

 Cranz,'" who lived for a long time with the Esquimaux, "the na- 

 "tives believe that ingenuity and dexterity in seal-catching (their 

 "highest art and virtue) is hereditary; there is really something 

 "in it, for the son of a celebrated seal-catcher will distinguish 

 "himself, though he lost his father in childhood." But in this 

 case it is mental aptitude, quite as much as bodily structure, which 

 appears to be inherited. It is asserted that the hands of English 

 laborers are at birth larger than those of the gentry.-^ From the 

 correlation which exists, at least in some cases,='' between the de- 

 velopment of the extremities and of the jaws, it is possible that 

 in those classes which do not labor much with their hands and 

 feet, the jaws would be reduced in size from this cause. That they 

 are generally smaller in refined and civilized men than in hard- 

 working men or savages, 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 at- 

 tached. In infants, long before birth, the skin on the soles of 

 the feet is thicker than on any other part of the body;=» 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 engravers 

 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.'" The infe- 

 riority of Eviropeans, in comparison with savages, in eyesight and 

 in the other senses, is no doubt the accumulated and transmitted 

 effect of lessened use during many generations; for Rengger" 



2* 'History ot Greenland,' Eng. translat. 1767, vol. i. p. 230. 



2= 'Intermarriage.' By Alex. Walker, 1838, p. 377. 



=" 'The Variation of Animals under Domestication,' vol. i. p. 173. 



'" 'Principles of Biology,' vol. i. p. 455. 



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



^ It is a, singular and unexpected fact that sailors are inferior to 

 landsmen in their mean distance of distinct vision. Dr. B. A, Gould 

 ('Sanitary Memoirs of the War of the Rebellion,' 1869, p. 530), has proved 

 this to be the case: and he accounts for it by the ordinary range of 

 vision in sailors being "restricted to the length of the vessel and the 

 height of the masts." 



™ 'The variation of Animals Under Domestication,' vol. i. p. 8. 



=1 'Saugethiere von Paraguay,' s. 8, 10. I have had good opportuni- 

 ties for observing the extraordinary power of eyesight in the Fuegians. 

 See also Lawrence ('Lectures on Phj-siology,' &c., 1822, p. 404) on this 

 same subject. M. Giraud-Teulon has recentlj^ collected ('Revue des 

 Cours Scientifiques,' 1870, p. 625) a large and valuable body cf e.idence 

 proving that the cause of short-sight, "C'est le travail assidu. de pres." 



