Page:Popular Science Monthly Volume 76.djvu/64

60 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, indicating 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 perpetuating 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 disappear. 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.

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, however, its existence is proved by the fact that there are many people precluded 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 several, 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