Hence every type which is best adapted to its conditions, (and this on the average means every higher type), has a rate of multiplication that insures a tendency to predominate. Survival of the fittest, acting alone, is ever replacing inferior species by superior species. But beyond the longer survival, and therefore greater chance of leaving offspring, which superiority gives, we see here another way in which the spread of the superior is insured. Though the more-evolved organism is the less fertile absolutely, it is the more fertile relatively.
CHAPTER XII.
MULTIPLICATION OF THE HUMAN RACE.
§ 365. The relative fertility of Man considered as a species, and those changes in Man’s fertility which occur under changed conditions, must conform to the laws which we have traced thus far. As a matter of course, the inverse variation between Individuation and Genesis holds of him as of all other organized beings. His extremely low rate of multiplication—far below that of all terrestrial Mammals except the Elephant, (which though otherwise less evolved is, in extent of integration, more evolved)—we shall recognize as the necessary concomitant of his much higher evolution. And the causes of increase or decrease in his fertility, special or general, temporary or permanent, we shall expect to find in those changes of bulk, of structure, or of expenditure, which we have in all other cases seen associated with such effects.
In the absence of detailed proof that these parallelisms exist, it might suffice to contemplate the several communities between the reproductive function in human beings and other beings. I do not refer simply to the fact that genesis proceeds in a similar manner; but I refer to the similarity of the relation between the generative function and the functions which have for their joint end the preservation of the individual. In Man, as in other creatures that expend much, genesis commences only when growth and development are declining in rapidity and approaching their termination. Among the higher organisms in general, the reproductive activity, continuing during the prime of life, ceases when the vigour declines, leaving a closing period of infertility; and in like manner among ourselves, barrenness supervenes when middle age brings the surplus vitality to an end. So, too, it is found that in Man, as in beings of lower orders, there is a period at which fecundity culminates. In [§ 341], facts were cited showing that at the commencement of the reproductive period, animals bear fewer offspring than afterwards; and that towards the close of the reproductive period, there is a decrease in the number produced. In like manner it is shown by the tables of Dr. Duncan’s recent work, that the fecundity of women increases up to the age of about 25 years, and continuing high with but slight diminution till after 30, then gradually wanes. It is the same with the sizes and weights of offspring. Infants born of women from 25 to 29 years of age, are both longer and heavier than infants born of younger or older women; and this difference has the same implication as the greater total weight of the offspring produced at a birth, during the most fecund age of a pluriparous animal. Once more, there is the fact that a too-early bearing of young produces on a woman the same injurious effects as on an inferior creature—an arrest of growth and an enfeeblement of constitution.
Considering these general and special parallelisms, we might safely infer that variations of human fertility conform to the same laws as do variations of fertility in general. But it is not needful to content ourselves with an implication. Evidence is assignable that what causes increase or decrease of genesis in other creatures, causes increase or decrease of genesis in Man. It is true that, even more than hitherto, our reasonings are beset by difficulties. So numerous are the inequalities in the conditions, that but few unobjectionable comparisons can be made. The human races differ considerably in their sizes, and notably in their degrees of cerebral development. The countries they inhabit entail on them widely different consumptions of matter for maintenance of temperature. Both in their qualities and quantities the foods they live on are unlike; and the supply is here regular and there very irregular. Their expenditures in bodily action are extremely unequal; and even still more unequal are their expenditures in mental action. Hence the factors, varying so much in their amounts and combinations, can scarcely ever have their respective effects identified. Nevertheless there are a few comparisons the results of which may withstand criticism.
§ 366. The increase of fertility caused by a nutrition that is greatly in excess of the expenditure, is to be detected by contrasting populations of the same race, or allied races, one of which obtains good and abundant sustenance much more easily than the other. Three cases may here be set down.
The traveller Barrow, describing the Cape-Boers, says:—“Unwilling to work and unable to think,” ... “indulging to excess in the gratification of every sensual appetite, the African peasant grows to an unwieldy size;” and respecting the other sex, he adds—“the women of the African peasantry lead a life of the most listless inactivity,” Then, after illustrating these statements, he goes on to note “the prolific tendency of all the African peasantry. Six or seven children in a family are considered as very few; from a dozen to twenty are not uncommon.” The native races of this region yield evidence to the same effect. Speaking of the cruelly-used Hottentots (he is writing a century ago), who, while they are poor and ill-fed, have to do all the work for the idle Boers, Barrow says that they “seldom have more than two or three children; and many of the women are barren.” This unusual infertility stands in remarkable contrast with the unusual fertility of the Kaffirs, of whom he afterwards gives an account. Rich in cattle, leading easy lives, and living almost exclusively on animal food (chiefly milk with occasional flesh), these people were then reputed to have a very high rate of multiplication. Barrow writes:—“They are said to be exceedingly prolific; that twins are almost as frequent as single births, and that it is no uncommon thing for a woman to have three at a time.” Probably both these statements are in excess of the truth; but there is room for large discounts without destroying the extreme difference. A third instance is that of the French-Canadians. “Nous sommes terribles pour les enfants!” observed one of them to Prof. Johnston, who tells us that the man who said this “was one of fourteen children—was himself the father of fourteen, and assured me that from eight to sixteen was the usual number of the farmers’ families. He even named one or two women who had brought their husbands five-and-twenty, and threatened ‘le vingt-sixième pour le prêtre.’” From these large families, joined with the early marriages and low rate of mortality, it results that, by natural increase, “there are added to the French-Canadian population of Lower Canada four persons for every one that is added to the population of England.” Now these French-Canadians are described by Prof. Johnston as home-loving, contented, unenterprising; and as living in a region where “land and subsistence are easily obtained.” Very moderate industry brings to them liberal supplies of necessaries; and they pass a considerable portion of the year in idleness. Hence the cost of Individuation being much reduced, the rate of Genesis is much increased. That this uncommon fertility is not due to any direct influence of the locality, is implied by the fact that along with the “restless, discontented, striving, burning energy of their Saxon neighbours,” no such rate of multiplication is observed; while further south, where the physical circumstances are more favourable if anything, the Anglo-Saxons, leading lives of excessive activity, have a fertility below the average. And that the peculiarity is not a direct effect of race, is proved by the fact that in Europe, the rural French are certainly not more prolific than the rural English.
To every reader there will probably occur the seemingly-adverse evidence furnished by the Irish; who, though not well fed, multiply fast. Part of this more rapid increase is due to the earlier marriages common among them, and consequent quicker succession of generations—a factor which, as we have seen, has a larger effect than any other on the rate of multiplication. Part of it is due to the greater generality of marriage—to the comparative smallness of the number who die without having had the opportunity of producing offspring. The effects of these causes having been deducted, we may doubt whether the Irish, individually considered, would be found more prolific than the English. Perhaps, however, it will be said that, considering their diet, they ought to be less prolific. This is by no means obvious. It is not simply a question of nutriment absorbed. It is a question of how much remains after the expenditure in self-maintenance. Now a notorious peculiarity in the life of the Irish peasant is, that he obtains a return of food which is large in proportion to his outlay in labour. The cultivation of his potatoe-ground occupies each cottager but a small part of the year; and the domestic economy of his wife is not of a kind to entail on her much daily exertion. Consequently the crop, tolerably abundant in quantity though innutritive in quality, possibly suffices to meet the comparatively-low expenditure, and to leave a good surplus for genesis—perhaps a greater surplus than remains to the males and females of the English peasantry, who, though fed on better food, are harder worked.
We conclude, then, that in the human race, as in all other races, such absolute or relative abundance of nutriment as leaves a large excess after defraying the cost of carrying on parental life, is accompanied by a high rate of genesis.[66]
§ 367. Evidence of the converse truth, that relative increase of expenditure, leaving a diminished surplus, reduces the degree of fertility, is not wanting. Some of it has been set down for the sake of antithesis in the foregoing section. Here may be grouped a few facts of a more special kind having the same implication.