164 THE DESCENT OF MAN. [Part I. 



the contiiiuecl preservation of the same line of descent, 

 without any selection, are checked by men of rank always 

 wishing to increase their wealth and power ; and this they 

 ciFect by marrying heiresses. But the daughters of parents 

 who have produced single children, are themselves, aS 

 Mr. Galton has shown," apt to be sterile ; and thus noble 

 families are continually cut off in the direct line, and their 

 wealth flows into some side-channel ; but unfortunately 

 this channel is not determined by superiority of any kind. 



Although civilization thus checks in many ways the 

 action of natural selection, it apparently favors, by means 

 of improved food and the freedom from occasional hard- 

 ships, the better development of the body. This may be 

 inferred from civilized men having been found, wherever 

 compared, to be physically stronger than savages. They 

 appear also to have equal powers of endurance, as has 

 been proved in many adventurous expeditions. Even the 

 gi'cat luxury of the rich can be but little detrimental ; for 

 the expectation of life of our aristocracy, at all ages and 

 of both sexes, is very little inferior to that of healthy Eng- 

 lish lives in the lower classes." 



We will now look to the intellectual faculties alone. 

 If in each grade of society the members Avere divided 

 into two equal bodies, the one including the intellectually 

 superior and the other the inferior, there can be little 

 doubt tliat the former would succeed best in all occupa- 

 tions and rear a greater number of children. Even in the 

 lowest walks of life, skill and ability must be of some ad- 

 vantage, though in many occupations, owing to the great 

 division of labor, a very small one. Hence in civilized 

 nations there will be some tendency to an increase both 



'2 'Ilereditary Genius,' 1810, pp. 132-140. 



'^ See the fifth and sLsth columns, compiled from good authorities, in 

 the table given in Mr. E. R. Lankcster's 'Comparative Longevity,' 1870, 

 p. 116. 



