One of the most important problems in the whole range of science is the question as to what causes offspring to differ in this inborn, natural way from their parents. Many theories have been formulated, and the subject is still to some extent under discussion; but the evidence is overwhelming that variations—natural differences—are not generally caused, as most people believe, by anything that happens to the parent before the birth of the child, but are “spontaneous.” The subject is a large and intricate one, and we have not space to discuss it at length. One or two facts, however, may be mentioned. The members of a litter of puppies, kittens, or pigs, may differ naturally amongst themselves and from their parents in all sorts of ways—in colour, shape, size, hairiness, disposition, and so on. One puppy may present points of resemblance to the father, another to the mother, a third to some ancestor, while a fourth may be unlike any of its predecessors. Since, practically speaking, the puppies were all conditioned alike before birth, it is evident that these great differences must be “spontaneous.” They cannot have been caused by such things as the good or ill health of the parents, their food, or the life they led, for, in that case, the puppies would all have varied in the same way.
Again, malaria is, in effect, a universal disease on the West Coast of Africa. Individuals differ naturally in their powers of resisting it, some taking it lightly and some severely; but almost every negro suffers, and many children perish of it. If the sufferings of the parents caused children to be born weaker “by nature,” it is evident that every individual would start life inferior to his predecessor at the start, and the race would thus degenerate and ultimately become extinct. On the other hand, if variations are “spontaneous,” if, quite unaffected by the sufferings of the parents, some children are born naturally different, naturally more or less resistant to malaria than their predecessors, it is plain that the weeding out of the unfittest, the weak against the disease, would ultimately make the race resistant to it. In the one case the race would drift to destruction; in the other it would undergo protective evolution. Obviously, the latter is what has happened. Negroes show no signs of any kind of degeneration, but they are of all races the most resistant to malaria.
Suffering Produces Strength
Similarly, Englishmen who have been much exposed to consumption and measles, natives of India who have been much afflicted by enteric fever and dysentery, Esquimaux who have suffered from cold, Arabs who have endured heat, Chinamen and Jews who have long dwelt under that complex of ill conditions found in slums and ghettos, are none of them degenerate, but, on the contrary, have become resistant, each race to its own particular ill-conditions in proportion to its sufferings in the past. In fact, it may be laid down as a general rule that races strengthen only when exposed to ill conditions, and deteriorate only when the conditions are so favourable that the unfit are not eliminated. An example of the latter is seen when prize breeds of animals and plants, however well nourished and cared for, are no longer bred with care. It follows that races, if not exterminated, are not injured but strengthened by ill conditions, by the elimination of the unfittest, as gold is refined by fire.
Survival of the Fittest
It is a remarkable fact that many people are able to accomplish the surprising feat of knowing that races have become inured to ill conditions, and of believing at the same time that the offspring of people exposed to such conditions tend, as a rule, to be degenerate. It is as if they believed that two and two make four, and two more six, but that if a great number of two’s are added together the total result is a minus quantity. Obviously the two beliefs are incompatible. A race cannot degenerate in every generation and yet emerge in the end strengthened from the struggle. The confusion has arisen because the two diametrically opposite propositions are seldom considered together, and in part also from a mistaken interpretation of what is observed in such situations as the slums of cities. Here puny children are seen to be derived from puny parents, and it is assumed that the children are degenerate because the parents have suffered.
As a fact we have no reason to doubt that the children are affected in precisely the same way as the parents. On the one hand, slums are sinks into which descend people naturally inferior, people who have varied spontaneously from their ancestors in such a way as to be feeble, physically or mentally, and who reproduce their like. On the other hand, the conditions are such that even the naturally strong, both parents and children, develop badly. Doubtless, owing to the constant elimination of the unfit, the latter—the naturally strong—are by far the more numerous. There is nothing to show that, if they were removed in early life to better surroundings, they would not develop just as well as the offspring of country folk.
An Evolution that has now Ceased
The fact that races grow resistant to the ill conditions to which they are exposed, and degenerate when placed under particularly good conditions, is decisive proof that offspring are not, as a rule, innately affected by the surroundings of their parents. No doubt exceptions occur, but these are amongst the most unfit, and the race is soon purged of them. Thus European dogs are said to degenerate when taken to India. But the existence of old-established native races of dogs is proof that the degenerative process is not perpetual. Malaria and many other ill conditions are quite normal parts of the environment of the races exposed to them, and have been so for thousands of years. Except for occasional unfavourable variations, which are quickly eliminated, they have long purged the races of those strains that tended to become degenerate under their influence.