38 HEREDITY AND SOCIETY 



in defective offspring ; or, to put it in another form, we 

 have no right, for the sake of relieving our own present 

 feelings, to make it possible for one man to do such 

 an infinity of harm and sow the seeds of so much 

 unnecessary suffering in the future. 



Among the factors in the process of natural selection 

 in civilized nations must be put the pressure of eco- 

 nomic causes. Statistics show that in old days in 

 England the number of marriages decreased in years 

 of bad harvests, which used to affect the general 

 economic condition of the whole nation much more 

 than they do now when the industrial population is 

 chiefly fed on foreign food. The decrease in the 

 marriage-rate would affect first the least efficient, and 

 the prudential motive would therefore have a selective 

 value in the right direction. As long as the relative 

 incomes of different families in the same social class is 

 roughly proportional to their industrial efficiency, and 

 as long as people marry and have children as they can 

 afford to do so, the prudential motive tends in selection 

 to breed a more efficient race. But, as we shall see 

 later, the modern habit of restricting the birth-rate 

 modifies profoundly this conclusion ; moreover, the 

 recent growth of taxation on the more efficient in 

 order to support in increased comfort the inefficient, 

 and to provide free education and maintenance for their 

 offspring, gives an artificial selective action to modern 

 economic pressure which tends to reproduce the least 

 efficient strains at the expense of the more efficient. 

 To these points we shall return later. 



Thus it will be seen that some of the most effective 



