§ 3. Minor and Secondary Consequences
(1) The extensive adoption by Man of a flesh-diet many hundreds of thousands of years ago might be expected to have shortened his alimentary canal in comparison with that of the anthropoids; but not much evidence of it is obtainable. Topinard, giving a proportionate estimate, says that in Man it is about six times the length of the body, in the gibbon about eight times. Dr. Arthur Keith, in a private communication with which he has favoured me, says that the adult chimpanzee’s intestine is slightly longer than the adult man’s, but that the measurements are for certain reasons unsatisfactory, and that there have not been enough measurements of adult chimpanzees. We must remember that, on the one hand, the chimpanzee is not exclusively frugivorous, and that, on the other hand, it is not likely that Man has been at any time exclusively carnivorous; though the return of large populations to a vegetarian diet by means of agriculture is recent.
(2) Man has lost the restraint of seasonal marriage, common to the anthropoids with other animals, as determined by food-supply and other conditions of infantile welfare; though, according to Prof. Westermarck, traces of it may still be found in a few tribes.[13] That our domestic carnivores have also lost this wholesome restraint on passion and population points, probably, to some condition of a steadier food-supply as determining or permitting the change amongst ourselves. No growth of prudence, however, or habit of laying up stores can explain the steadier supply of food; since the lower savages have no prudence and no stores. On the whole, the change may be attributed (a) to an omnivorous habit being more steadily gratified than one entirely frugivorous or carnivorous; (b) to our ancestors having wandered in quest of game from country to country in which the seasons varied, so that the original correspondence of birth-time with favourable conditions of welfare was thrown out. There may also have been causes that kept down the normal numbers of the pack, so as to be equivalent, in scarce seasons, to more abundant food: the hunter’s life, whilst securing a richer normal diet, involved many destructive incidents. And this (by the way) was favourable to rapid selection and adaptation; though if the destruction had been great enough to counterbalance the advantages of animal food, it must have frustrated the whole experiment.
(3) There is one characteristic difference of Man from the anthropoids which his hunting habits do not clearly explain—his relatively naked skin. Darwin attributed this condition to sexual selection.[14] He argued that, on the one hand, so far as Man has had the power of choice, women have been chosen for their beauty; and that, on the other hand, women have had more power of selection, even in the savage state, than is usually supposed, and “would generally choose not merely the handsomest men, according to their standard of taste, but those who were at the same time best able to defend and support them.” Hence, if a partial loss of hair was esteemed ornamental by our ape-like progenitors, sexual selection, operating age after age, might result in relative nakedness. “The faces of several species of monkey and large surfaces at the posterior end of the body have been denuded of hair; and this we may safely attribute to sexual selection.” The beard of the male, and the great length of the hair of the head in some races, especially seem due to this cause. The greater hairiness of Europeans, compared with other races, may be a case of reversion to remote ancestral conditions. But as all races are nearly naked, the common character was probably acquired before the several races had diverged from the common stock.
The species of monkey that have lost the hair on various parts of their bodies, and the beard of males (together with the longer head-hair of women) of our own race are cases that strongly support the ascription of such secondary sexual characters to sexual selection. Yet, going back to the time before the division of modern Man into races (say, 600,000 years), it seems incredible that any women then went unmarried, hair or no hair, if they were healthy (and the unhealthy soon ceased to exist); or that any man went unmarried, if he could do his share in the hunting-field (and, if not, he also soon ceased to exist). No facts observed amongst extant savages—the choice exerted by women, or the polygamy of chiefs—throw much light upon that ancient state of affairs. There were then no chiefs: the hunt-leader of pack or clan had no authority but his personal prowess, no tradition of ancestry or religion, nor probably the prestige of magic, to give him command of women. Unless, at that time, relative nakedness was strongly correlated with personal prowess in the male and efficiency in the female, it is difficult to understand how it can have been preserved and increased by sexual selection. Forgive me for adding an unkind remark: if the selection of women for their beauty has gone on for hundreds of thousands of years, and has had a cumulative effect upon the race, is not the result disappointing? Go into the street and look. That “women have become more beautiful, according to the general opinion, than men,” is not an objective, truly æsthetic judgment, but one determined by causes of which “general opinion” is falsely unconscious. Schopenhauer[15] thought that men are better looking than women; and of average specimens this seems to be true; though, to be sure, he was a sort of misogynist.
Another explanation of Man’s nakedness was suggested by Thomas Belt, based on the parallel case of certain races of naked dogs, namely, that he is the better able to free himself from parasites.[16] Darwin mentions this hypothesis and, in a footnote, cites in its favour “a practice with the Australians, when the vermin get troublesome, to singe themselves”; but he says, in the text, “whether this evil is of sufficient magnitude to have led to the denudation of the body through natural selection, may be doubted, since none of the many quadrupeds inhabiting the tropics have, as far as I know, acquired any specialised means of relief.”[17] It appears, too, that against the probability of such a result must be set the actual disadvantage of nakedness, as insisted upon by Wallace, who says that savages feel the want of protection and try to cover their backs and shoulders.[18] Still, the disadvantage implied in occasionally feeling the want of protection would not prevent the loss of hair, if this would deliver the race from serious dangers from vermin; and the force of the argument from the condition of other tropical quadrupeds depends, at least in some measure, upon whether or not there is something peculiar in the case of naked dogs and men.
Belt argues that the naked dogs with dark, shining skins, found in Central America and also in Peru,[19] and which were found there at the Spanish conquest, have probably acquired their peculiar condition by natural selection, because they are despised by the natives, and no care is taken of their breeding, and yet they do not interbreed with the common hairy varieties, as usually happens with artificial stocks. The advantage of a naked skin being the greater freedom it gives from ticks, lice and other vermin, the advantage is especially great for a domestic animal living in the huts of savages, where, because they are inhabited year after year, vermin are extraordinarily abundant. The naked dog, then, differs from tropical quadrupeds which are adapted from a dateless antiquity to such vermin as infest them, by having been thrown by human companionship amongst not only strange vermin, but vermin in extraordinarily dense aggregation. Belt would have guarded a weak point in his case, had he explained why naked races of dogs are so scarce. Hairy races may have been more recently domesticated, or bred for their hairiness, or less addicted to an indoor life.
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