FACTORS OF ORGANIC EVOLUTION 43 



the relation of the theory of sexual selection to 

 certain statistical facts of human marriage. 



Married men live longer on the average than 

 bachelors. The wholly unjustifiable inference still 

 continues to be drawn, despite Spencer's exposure 

 of it in the "Study of Sociology," in 1873, that 

 marriage is conducive to longevity. The truth is 

 that married men are selected ; and, as they are 

 the fathers of nearly all of the younger generation, 

 it is well that they should be selected. In some 

 degree they are selected by their mates, who tend 

 to prefer energy, health, and the good looks bred 

 of health. Furthermore, it is the robust man who, 

 in greater degree than the weakling, has the inclina- 

 tion towards that which marriage satisfies ; and it is 

 the healthy man who is more able, on the average, 

 to earn the means which permit him to marry. In 

 these various ways, then, marriage tends to health ; 

 and the superior longevity of married men is thus a 

 consequence of a certain mode of sexual selection, 

 not a consequence of the married state. 



Lastly, we must consider an aspect of sexual 

 selection which has recently been emphasised by 

 the work of the biometricians — the new school of 

 biologists who employ the methods of mathematics 

 in studying the problems of life. Professor Karl 

 Pearson and his co-worker, Professor Weldon, have 

 recently made a most comprehensive research into 

 the facts of human marriage, by studying, for in- 

 stance, the tombstones of rural Oxfordshire, the 

 dales of Yorkshire, and the London cemeteries, and 

 by inquiries into pedigrees', such as those furnished 

 by the records of the Society of Friends. They 



