134 THE DESCENT OP MAN. 



settled countries, where they prove useful pioneers. Intemper- 

 ance is so highly destructive, that the expectation of life of the 

 intemperate, at the age of thirty for instance, is only 13.8 years; 

 whilst for the rural laborers of England at the same age it is 

 40.59 years." Profligate women bear few children, and profligate 

 men rarely marry; both suffer from disease. In the breeding of 

 domestic animals, the elimination of those individuals, though 

 few in number, which are in any marked manner inferior, is by 

 no means an unimportant element towards success. This espe- 

 cially holds good with injurious characters which tend to reap- 

 pear through reversion, such as blackness in sheep; and with 

 mankind some of the worst dispositions, which occasionally with- 

 out any assignable cause make their appearance in families, may 

 perhaps be reversions to a savage state, from which we are not 

 removed by very many generations. This view seems indeed 

 recognized in the common expression that such men are the black 

 sheep of the family. 



With civilized nations, as far as an advanced standard of 

 morality, and an increased number of fairly good men are con- 

 cerned, natural selection apparently effects but little; though 

 the fundamental social instincts were originally thus gained. 

 But I have already said enough, whilst treating of the lower 

 races, on the causes which lead to the advance of morality, name- 

 ly, the approbation of our fellow-men — the strengthening of our 

 sympathies by habit — example and imitation — reason — experience, 

 and even self-interest — instruction during youth, and religious 

 feelings. 



A most important obstacle in civilized countries to an increase 

 in the number of men of a superior class has been strongly in- 

 sisted on by Mr. Greg and Mr. Galton," namely, the fact that the 

 very poor and reckless, who are often degraded by vice, almost 

 invariably marry early, whilst the careful and frugal, who are 

 generally otherwise virtuous, marry late in life, so that they may 

 be able to support themselves and their children in comfort. 

 Those who marry early produce within a given period not only a 

 greater number of generations, but, as shown by Dr. Duncan,™ 



1* B. Ray Lankester, 'Comparative Longevity,' 1870, p. 115. The table 

 of the intemperate is from Nelson's 'Vital Statistics.' In regard to 

 profligacy, see Dr. Farr, 'Influence of Marriage on Mortality,' 'Nat. 

 Assoc, for the Promotion of Social Science,' 1858. 



" 'Eraser's Magazine,' Sept. 1868, p. 353. 'Macmillan's Magazine,' Aug 

 1S65, p. 318. The Rev. P. W. Parrar ('Praser's Mag.' Aug. 1870, p. 264) 

 takes a different view. 



-" 'On the Laws of the Pertility of Women," in 'Transact. Roya), 

 Soc' Edinbi/rgh, vol. xxiv. p. 287; now published separately under the 

 title of 'Fecundity, Fertility, and Sterility,' 1S71. See, also, Mr. Galtoi, 

 'Hereditary Genius,' pp. 352-357, for observations to the above effect. 



