Darwinism and Race Progress

by John Berry Haycraft

[The Reproductive Cells are as a Rule unaffected by them.]

A short study of these diseases should well repay us, showing as it will do that in by far the greater number of cases these severe constitutional derangements produce no effect upon the reproductive cells; that they are in fact incapable of producing a change that will be hereditarily transmitted. We shall learn, moreover, the part that they have played, and can play, in producing racial change by selection. The micro-organisms of disease are of many varieties, and each variety is capable of setting up its own peculiar disturbance. The disturbance set up by one kind we call small-pox, that arising from another kind, cholera, and so on. Now, the very curious point comes out that in most of these diseases, although the composition of the blood is profoundly altered, and many of the tissues undergo marked change, this change, fortunately for us, is quite of a temporary character, and when the attack is over there is only one test which will enable us to say that the body is not just in the same condition as it was before. This test is that it cannot be infected again for a long time, if at all, by the same micro-organism.

This induced immunity from further attacks has received in the hands of Metschnikoff a curious and very interesting explanation. He has shown that an army of small cells, called phagocytes, which wander through the blood and tissues, are able to attack the microbes of disease, and that after a struggle they are able in many cases to kill these voracious invaders. In so doing, however, the weaker phagocytes succumb to the struggle, while those which are left alive within the body of the convalescent patient possess the power of resisting and destroying the particular microbe which had undertaken the invasion. These resisting phagocytes, selected from the rest, together with their descendants, who share their resisting qualities, are able to prevent fresh inroads of the same enemy. We need not, therefore, assume that this acquired immunity, the sole relic of the attack, indicates any change in the ordinary muscle or brain cells of the body, or that the reproductive cells are in any way altered, for the immunity is due only to a change in the phagocytic army.

The germ cells in almost every case get off scot-free, and there is nothing in the organisation of a child to indicate whether or not his father or mother suffered from measles, or scarlet fever. It might at first sight be urged, in opposition to this fact, that, although we cannot recognise the child of a man who suffered from measles or scarlet fever by any visible sign, yet the child is in some way different, inasmuch as he is to some extent immune to those diseases. In favour of this belief, the many instances in which a fever has been brought to a country never before accessible to the germ (for instance, the introduction of measles and small-pox to newly discovered America, where fearful ravages were caused thereby), may be brought up as evidence to prove that those habitually living among the germs must have become immune and have transmitted this immunity to their progeny. Again, the black population of Sierra Leone have only a mortality of 24 per cent. from malaria, while the mortality of the white settlers is 47 per cent.;[12] and, in this case, it may be urged that the black race has become by transmission of immunity partially immune. But these cases which appear to be examples of transmitted immunity may receive another, and a much more simple, explanation. No two children of the same parents are alike in colour of hair, shape of limb, temperament, etc., and they also differ widely in their capacity to receive and combat infection. An epidemic of fever, therefore, will always select to kill those organically most liable to fall a prey to it, while the remnant, having by nature greater power of resistance, not only survive, but may also be calculated upon to produce progeny, on the whole, as resistant as they are themselves.

[Man has been selected by the Action of the Microbes of Fever.]

Races, therefore, subject to epidemics of a particular fever, suffer selections in the hands of the microbe of that particular fever, and those living are survivals cast in the most resisting mould. It may not be flattering to our national vanity to look upon Englishmen as the product of the selection of the micro-organisms of measles, scarlet fever, small-pox, etc., but the reasonableness of the conclusion seems to be forced upon us when we consider his immunity from these diseases as compared with that of natives of the interior of Africa, or of the wilds of America, whose races have never been so selected, and who, when attacked for the first time by these diseases, are ravaged almost to extermination. We find, then, that an ordinary attack of measles, scarlet fever, whooping cough, erysipelas, typhoid, or typhus fever, when it has passed away, leaves the tissues of the body in as sound and healthy a condition as before; and, indeed, were it not for this fact, the human race could hardly have existed at all, continually exposed as it has been, for countless ages, to the aggressions of these microbes. By exterminating these diseases, we shall, no doubt, preserve countless lives to the community, who will in their turn become race producers, but, inasmuch as the individuals thus preserved will in many cases belong to the feebler and less resisting of the community, the race will not become more robust. In fact, it is probable that, as a race, we shall thereby suffer, for the banishment of the disease will enable the feebler members of the community to live, and in larger proportion contribute to the progeny of the future. That this is actually the case will shortly be pointed out.

[Leprosy an Exterminator of the Unhealthy.]

But there are other microbes which, in addition to the production of blood changes, have a profound and lasting effect upon many of the tissues of the body. Such are the microbes of leprosy and syphilis.

The terrible ravages that the microbe of leprosy is capable of effecting are appreciated only by those who in Norway or elsewhere have visited those death-houses now fortunately to be found in but one or two parts of Europe. Yet, even in this case, strange to say, the germ cells do not seem to be reached by this loathsome disease, and it is not transmitted from parent to child.[13] A disease of mediæval, not of modern, Europe, we need not discuss its action on racial change more than to say that, hideous as are its aspects, it must be looked upon as a friend to humanity; for, while the microbe of typhoid fever will attack a man who is healthy and living in healthy surroundings—excepting for the microbe that lurks in his well—the microbe of leprosy feeds upon those who are debilitated by conditions under which healthy and strong racial development is impossible. It is a depopulator of starved, ill-nourished districts, and the race recruits to its advantage from those more favourably placed.