EVOLUTION'S HOPEFUL PROMISE FOR A HEALTHIER RACE.
Given before the Greenacre Conference of Evolutionists.
We have most of us in the past looked upon health as a matter of inheritance, or temperance and moderation in working, in eating and drinking; or as depending on climate; or exercise, or plenty of sleep, pure water and a morning bath, or some other secret, one or more of which is pretty sure to be in the possession of most persons who have lived long enough to have had some experience with those things that do them good or harm. All these agencies have great value; but I think few of us realize that nature, through the laws of evolution, has long been working to produce a brave and strong, healthy and hardy race of men and women by other methods than those health habits which most of us value so highly.
Nature has been doing this chiefly by two methods, and it seems necessary that I should say something about them in order to present my subject as I wish to present it. The methods to which I refer are those of sexual and natural selection. It is to these two processes that we are largely indebted for race improvements—more perfect bodies, more active brains, and the high degree of health which a considerable portion of the race enjoys.
Sexual Selection.—By sexual selection is meant that preference which the male or the female has for certain characteristics of the other sex. It also includes the advantages which the stronger and more capable male has over the weaker one in obtaining a choice, or, among polygamous animals, a larger number of females, thus allowing offspring to be generated by the most capable, and preventing the most incapable from procuring mates.
The first principle of sexual selection, that of preference, would imply a considerable development of the intellect, and some taste, but I do not think it has had great influence on the lower forms of life. It is difficult to study the preferences of insects, for instance; but I have studied the moth of the silkworm, and could never observe that either male or female had a choice for any particular mate. They always appear to take the first one that comes along. I think this is the conclusion come to by those entomologists who have had opportunities for studying other insects. The spider might perhaps be studied in this relation to advantage, as the female is ferocious, often eating her male suitors while they are trying to woo her. Nor do I believe that it is a very important matter in many other animals. Certainly among the domestic ones—the sheep, the horse, the bull and the cow—a superior male and female will mate with inferior ones of the opposite sex, apparently without the slightest objection. I have sometimes thought I had observed in pigeons a preference, having occasionally seen a male leave his mate for a more attractive female; at least one that seemed more attractive to me.
When it comes to sexual selection through struggle, no doubt there has been great advantage, and it has produced important effects. This occurs among polygamous and also among non-polygamous animals, and the strong males are certain to secure the largest number of females and, consequently, leave the largest number of offspring. This would, no doubt, through the laws of inheritance, be beneficial in producing animals of greater vigor and more perfect health. But even in this case, the males seem to have little preference for any particular female; and so while the least vigorous ones would leave few, and many no offspring, the least vigorous females would leave nearly as many as the more vigorous ones. Still, through pure-blooded males alone, stockbreeders tell us, herds of cattle can be brought up to a high degree of perfection in three or four generations, even if the females, at the beginning of the experiment, are inferior. The first generation would be half pure blood; the second three-fourths; the third, seven-eighths, and the fourth fifteen-sixteenths, or almost thoroughbred.
When it comes to man, however, the case is different. With him sexual selection is more important, and the preference shown by both sexes is very marked. Many women have strong prejudices against marrying men with certain characteristics, and nothing will induce them to such a union. So strong are the desires many of them have for mates with particular qualities, that they prefer to remain single rather than marry one not possessing these qualities. Through this preference, on the whole, the better and those most adapted mate with those most suited to them, and a considerably larger class of physically and mentally inferior ones do not mate at all, or, if they do, leave few offspring. The idiot would stand no chance of securing a mate, although, if left free, he would unite with another idiot, like an animal. Such things have happened, and the offspring were not idiots, as might have been expected; but they were not superior beings. The most deformed in body would, in most cases, unless they had mental traits of a high order to counterbalance them, rarely find mates. Thus, through this agency, some of the poorest specimens of both sexes do not produce offspring, and this raises the standard of the health and ability of the race.
There are many characters which have come into existence, it is believed, through sexual selection. One is beauty in women, greater beauty of form, of hair, of eyes, of grace, fidelity, chastity, power of love, etc. These all give pleasure to the opposite sex, and have an element of usefulness in them. Whenever these characters have appeared in women they have given the possessors a better chance to find a partner with superior characters. The same is true of men. Woman being debarred from the hardest labor through maternity has found it useful, even in early times, to choose men who were strong, brave, courageous and capable of defending and caring for her, so far as was possible, and thus by sexual selection she has indirectly promoted health and vigor in man, for these qualities are inseparable from it.
But the results of sexual selection are by no means perfect. The sexes are nearly equally divided, and as polygamy is not to any great extent practiced among human beings, with the exception of those already named, most men and women can find mates if they wish, even though they may have many serious imperfections of body and mind, and from them many children will be born physically and mentally incompetent.