6o THE POPULAR SCIENCE MONTHLY 



as possible within the group, the possible rate of this reduction has 

 been much exaggerated. In spite of all our charities 45 per cent, of 

 the present generation die before the average age of marriage, indi- 

 cating a great penalization of ignorance and immorality in the broad 

 sense. As this selection is especially active among the physically unfit, 

 these need not give so much concern to the eugenicist as the mentally 

 and morally deficient. While we have no assurance that the children 

 of the criminal and the imbecile will not live to hand down the curse, 

 the weak and diseased are more likely to die out unless vitalized with 

 fresh blood. The one exception is in the case of defectives in special 

 senses, the deaf and blind, for example, being quite capable of perpetu- 

 ating their defects through generations. 



On the whole, lethal selection is attended with too much suffering 

 and social sacrifice to be deliberately retained, but can never wholly dis- 

 appear. We may always rely upon it to some extent as a weeder of the 

 physically unfit, but the mentally and morally infirm are left to be dealt 

 with chiefly by the projects of artificial selection previously mentioned. 



Chapter V. Sexual Selection 



While lethal selection shows a gradually decreasing action as we 

 rise in the scale of evolution, and works by means generally opposed to 

 civilization, the second great form of natural selection, that which acts 

 not by premature death but by differential success in leaving progeny, 

 reaches its greatest importance in man. Its first mode, sexual selection, 

 has always been valuable in developing human aspects which lethal 

 selection is powerless to invoke, including many of the esthetic and 

 moral characteristics. Since it is not, like lethal selection, inextricably 

 bound up with human suffering, it can be looked to whole-heartedly for 

 progress. However, as this is a factor lying wholly outside the province 

 of social control and within the bounds nearly universally left sacred to 

 the individual, little has hitherto been attempted in the way of utilizing 

 it in human evolution. 



The influence of sexual selection is often belittled on the grounds 

 that almost any man can marry and that love is often aroused by 

 trivialities rather than worthiness. However badly it may work, how- 

 ever, its existence is proved by the fact that there are many people pre- 

 cluded from marriage by some obvious defects. Another very large 

 group of inferiors, the criminals, tramps, paupers and prostitutes, 

 largely substitute promiscuity for marriage, which leads to few births 

 because of the consequent frequency of sterility and abortion. Those 

 who marry are usually conscious of having made a selection from sev- 

 eral, in spite of the fatalistic impression current in this field and finding 

 voice in the proverbs " Marriage is a lottery " and " Love is blind." 



Sexual selection, then, is an active force. The question is, Does this 



