On the other hand, the periodical increase of conceptions cannot be explained by the opposite hypothesis, entertained by some physiologists, that the power of reproduction is increased by want and distress. Among the Western Australians and Californians,[171] for instance, the season of love is accompanied by a surplus of food, and in the land of the Bakongo, among whom Mr. Ingham believes most conceptions to take place in December and January, food is, according to him, most abundant precisely in these months and in February.
It seems, therefore, a reasonable presumption that the increase of the sexual instinct at the end of spring or in the beginning of summer, is a survival of an ancient pairing season, depending upon the same law that rules in the rest of the animal kingdom. Since spring is rather a time of want than a time of abundance for a frugivorous species, it is impossible to believe that our early ancestors, as long as they fed upon fruits, gave birth to their young at the beginning of that period. From the statements of Sir Richard Burton and Mr. A. R. Wallace, already quoted,[172] we know that the man-like apes breed early in the season when fruits begin to be plentiful. But when man began to feed on herbs, roots, and animal food, the conditions were changed. Spring is the season of the re-awakening of life, when there are plenty of vegetables and prey. Hence those children whose infancy fell in this period survived more frequently than those born at any other. Considering that the parents of at least a few of them must have had an innate tendency to the increase of the power of reproduction at the beginning of summer, and considering, further, that this tendency must have been transmitted to some of the offspring, like many other characteristics which occur periodically at certain seasons,[173] we can readily understand that gradually, through the influence of natural selection, a race would emerge whose pairing time would be exclusively or predominantly restricted to the season most favourable to its subsistence. To judge from the period when most children are born among existing peoples, the pairing season of our prehistoric ancestors occurred, indeed, somewhat earlier in the year than is the case with the majority of mammalian species. But we must remember that the infancy of man is unusually long; and, with regard to the time most favourable to the subsistence of children, we must take into consideration not only the first days of their existence, but the first period of their infancy in general. Besides food and warmth, several other factors affect the welfare of the offspring, and it is often difficult to find out all of them. We do not know the particular circumstances that make the badger breed at the end of February or the beginning of March,[174] and the reindeer of the Norwegian mountains as early as April;[175] but there can be no doubt that these breeding seasons are adapted to the requirements of the respective species.
The cause of the winter maximum of conceptions, especially considerable among the peoples of Northern Europe, is generally sought in social influences, as the quiet ensuing on the harvest time, the better food, and the amusements of Christmas.[176] But the people certainly recover before December from the labours of the field, and Christmas amusements, as Wargentin remarks, take place at the end of that month and far into January, without any particular influence upon the number of births in October being observable.[177] It has, further, been proved that the unequal distribution of marriages over the different months exercises hardly any influence upon the distribution of births.[178] Again, among the Hindus the December and January maximum of conceptions seems from the lascivious festivities of several Indian peoples to be due to an increase of the sexual instinct. According to Mr. Hill, this increase depends upon healthy conditions with an abundant food supply. But, as I have already said, it is not proved that a strengthened power of reproduction and abundance of food are connected with one another.
I am far from venturing to express any definite opinion as to the cause of these particular phenomena, but it is not impossible that they also are effects of natural selection, although of a comparatively recent date. Considering that the September maximum of births (or December maximum of conceptions) in Europe becomes larger the farther north we go; that the agricultural peoples of Northern Europe have plenty of food in autumn and during the first part of winter, but often suffer a certain degree of want in spring; and, finally, that the winter cold does not affect the health of infants, the woods giving sufficient material for fuel,—it has occurred to me that children born in September may have a better chance of surviving than others. Indeed, Dr. Beukemann states that the number of still-born births is largest in winter or at the beginning of spring, and that “the children born in autumn possess the greatest vitality and resisting power against the dangers of earliest infancy.”[179] This would perhaps be an adequate explanation either of an increase of the sexual instinct or of greater disposition to impregnation in December. It is not impossible either, that the increase of the power of reproduction among the Hindus in December and January, which causes an increase of births in September and October—i.e., the end of the hot season and the beginning of winter—owes its origin to the fact that during the winter the granaries get filled and some of the conditions of life become more healthy. But it should be remarked that September itself, according to Mr. Hill, is a very unhealthy month.[180]
Now it can be explained, I believe for the first time, how it happens that man, unlike the lower animals, is not limited to a particular period of the year in which to court the female.[181] The Darwinian theory of natural selection can, as it seems to me, account for the periodicity of the sexual instinct in such a rude race as the Western Australians, among whom the mortality of children is so enormous that the greater number of them do not survive even the first month after birth,[182] and who inhabit a land pre-eminently unproductive of animals and vegetables fitted to sustain human life, a land where, “during the summer seasons, the black man riots in comparative abundance, but during the rest of the year ... the struggle for existence becomes very severe.”[183] The more progress man makes in arts and inventions; the more he acquires the power of resisting injurious external influences; the more he rids himself of the necessity of freezing when it is cold, and starving when nature is less lavish with food; in short, the more independent he becomes of the changes of the seasons—the greater is the probability that children born at one time of the year will survive as well, or almost as well, as those born at any other. Variations as regards the pairing time, always likely to occur occasionally, will do so the more frequently on account of changed conditions of life, which directly or indirectly cause variability of every kind;[184] and these variations will be preserved and transmitted to following generations. Thus we can understand how a race has arisen, endowed with the ability to procreate children in any season. We can also understand how, even in such a rude race as the Yahgans in Tierra del Fuego, the seasonable distribution of births seems to be pretty equal, as there is, according to the Rev. T. Bridges, “such a variety of food in the various seasons that there is strictly no period of hardship, save such as is caused by accidents of weather.” We can explain, too, why the periodical fluctuation in the number of births, though comparatively inconsiderable in every civilized society, is greater in countries predominantly agricultural, such as Chili, than in countries predominantly industrial, as Saxony;[185] why it is greater in rural districts than in towns;[186] and why it was greater in Sweden in the middle of the last century than it is now.[187] For the more man has abandoned natural life out of doors, the more luxury has increased and his habits have got refined, the greater is the variability to which his sexual life has become subject, and the smaller has been the influence exerted upon it by the changes of the seasons.
Man has thus gone through the same transition as certain domestic animals. The he-goat[188] and the ass in southern countries,[189] for instance, rut throughout the whole year. The domestic pig pairs generally twice a year, while its wild ancestors had but one rutting season.[190] Dr. Hermann Müller has even observed a canary that laid eggs in autumn and winter.[191] Natural selection cannot, of course, account for such alterations: they fall under the law of variation. It is the limited pairing season that is a product of this powerful process, which acts with full force only under conditions free from civilization and domestication.
If the hypothesis set forth in this chapter holds good, it must be admitted that the continued excitement of the sexual instinct could not have played a part in the origin of human marriage—provided that this institution did exist among primitive men. Whether this was the case I shall examine in the following chapters.
[CHAPTER III]
THE ANTIQUITY OF HUMAN MARRIAGE
If it be admitted that marriage, as a necessary requirement for the existence of certain species, is connected with some peculiarities in their organism, and, more particularly among the highest monkeys, with the paucity of their progeny and their long period of infancy,—it must at the same time be admitted that, among primitive men, from the same causes as among these animals, the sexes in all probability kept together till after the birth of the offspring. Later on, when the human race passed beyond its frugivorous stage and spread over the earth, living chiefly on animal food, the assistance of an adult male became still more necessary for the subsistence of the children. Everywhere the chase devolves on the man, it being a rare exception among savage peoples for a woman to engage in it.[192] Under such conditions a family consisting of mother and young only, would probably, as a rule, have succumbed.