INTERSEXUAL SELECTION
I
IN all the birds which I have enumerated as having a bright or pleasingly coloured mouth cavity, acquired, as I believe, through the agency of sexual selection, the sexes are alike, both in regard to this special feature, and also in their plumage and general appearance. They are alike also in their habit of opening and shutting the bill, as it were, at one another, and in their other nuptial actions or antics. The first of these two identities involves no difficulty. In many birds of bright plumage the female is as gaudy, or almost as gaudy, as the male, and it is then assumed (by those, at least, who follow Darwin) that each successive variation in the hue and markings of the latter has, by the laws of inheritance, been transmitted in an equal or only slightly less degree to the former. As far, therefore, as the particular kind of beauty which I am here considering is, in itself, concerned, the arguments for or against its acquirement by the male, through the choice of the female, are the same as in regard to that of any other kind, nor do they extend any farther; but in the display of it by the female as well as by the male a fresh element enters into the problem, as it does also in the case of any other nuptial display common to the two sexes. The brilliant mouth cavity can, of course, only be exhibited by the opening of the bill, and in doing this—in the particular way, and with the accompaniments described in each case—both sexes act alike. In other words, if there is really a conscious display in the matter then each sex displays to the other. What conclusion are we to draw from this? Either, as it appears to me, we must assume that both the male and female equally strive to please one another, or that, while the actions of the male mean something, those of the female mean nothing, or nothing in particular, having been transmitted to her, through him, by those same laws of inheritance which have given her, in these and other cases, his own ornamental plumage, and not in accordance with any principle by virtue of which she has been rendered more and more attractive to him. For, except in some special cases where the female is larger and handsomer than the male, the Darwinian theory does not suppose that the hen bird has been modified to please the taste of the cock, whose eagerness, it is assumed, has made this quite unnecessary.
But any uniformly repeated action is a habit, and habits must bear a relation to the psychology of the being practising them, from which it would seem to follow that whatever be the mental state of the male bird through whom any habit has been transmitted to the female, such mental state, being the cause of such habit, must have been transmitted to her along with it. To suppose, however, that the female acts in a certain way in order to please the male, but that since she has not learnt to do so under the true laws of sexual selection, but has acquired her character incidentally, merely, by transmission from the male, and that, therefore, her conduct has no effect upon the male, since it has not been brought about in relation to his disposition, which is so eager as to make it indifferent to him what hen he gets, as long as he gets one—to suppose all this is—well, for me it is very difficult. The plain common sense of the thing seems to be that if the female displays her charms to the male in the same way that he displays his to her, she must do it for the same purpose, and is no more likely to be wasting labour, or expending it unnecessarily, than is he. If we do not give the same value to actions identical in either sex—if we will not allow "sauce for the gander" to be "sauce for the goose"—we become involved, as it appears to me, in inextricable confusion; and, moreover, can it be supposed that a habit which bore no fruit would remain fixed, or be governed by times and seasons, even if it did not cease on account of its inutility? Assuming, then, as I feel bound to assume, that the languishing actions of two fulmar petrels when sitting together on a ledge, or the throwing up of the head and opening the bill at each other of a pair of shags, each during the breeding season, are equally pleasing to one sex as to the other, may we not, or are we not rather compelled to think that such special adornments as we admit in the male to have been acquired through the agency of sexual selection (whether we include amongst these the bright colouring of the mouth or not), have been acquired by the female also in the same way—that there has been, in fact, a double process of sexual selection instead of a single one only; that the male, as well as the female, has been capable of exercising choice?
Great stress has been laid upon the eagerness of the male, as contrasted with the coyness of the female, in courtship, throughout nature; but were the latter to possess some eagerness also, her share of it need not be so great as the male's, so that we should not, by supposing her to, be contravening this principle: she might even fly, or seem to fly, from his pursuit. How, then, might her own ardour become valid to the extent of influencing the choice of the cock? As it appears to me, this might be brought about through the jealousy inspired in one hen bird by the sight of attentions paid to another. She, the jealous one, might have behaved coyly had the same, or another, male wooed her, but her feelings become inflamed and her modesty is lost when she sees that which, for all her seeming, she would have wished for herself, bestowed upon another. She interposes, let us say, at first, by attacking the favoured female, but if this one is as strong and as determined as herself, there will be now a series of indecisive combats, of which the cock will be the spectator; and why should not these combats be varied with displays, or something of that nature, on the part of either combatant, with the view of attracting him? If so, the cock who has previously, we will suppose, been chosen for his good looks, becomes in his turn—for how, under such circumstances, can he help it?—the chooser between those of others; and thus there will be a double process of selection carried on between the two sexes.
But may we not go a step farther in our suppositions?—for which, as I believe, there is a considerable body of evidence, in spite of the frequent great difficulty and consequent absence of proper observation. The theory of sexual selection is based upon the assumption that choice is exercised by the female, and this exercise of choice must go hand-in-hand with a corresponding development of the critical faculty in regard to the comparative merits of different males, which again would involve a power of taking a liking, or a dislike, to any one of them. How are we to reconcile all this with that quiescent, waiting-to-be-spoken-to frame of mind which we assume to be that of the hen bird in regard to the cock, during the season of courtship? A decided preference should show itself in actions. Why should she never exercise her critical faculty except as between such males as are rivals for her favour? If, for instance, she is courted by two or more males, why should she not declare in favour of a third or fourth that is either indifferent or courting another hen, on the ground of his superior beauty alone?
Why, in fact, should it not be with birds as it is with men and women? Women, to casual observation, seem at least as coy and modest as do hen birds, in whom, however, there can be no idea of modesty. They are supposed to be wooed, and not to woo; but they both can, and, to a considerable extent, do exercise the latter power. If they cannot ask, they can demand to be asked; and to think that the latter is a less powerful agency than the former is to think very naively. If women were not often, in reality, very active wooers, such common expressions as "setting her cap at him," "drawing him on," "throwing herself at his head," etc., etc., could hardly have arisen, and it must not be forgotten that the same thing can be done both coarsely and refinedly, visibly and so as to be hardly perceptible. No doubt there is something called modesty amongst civilised women, but there are also jealousy and prudential considerations—very powerful solvents of anything of the sort. Yet with all this we have the prevailing idea that (even in a civilised state of things) it is man who woos and woman who is won; man who advances and woman who retires; man who seeks and woman who shuns. The reason probably is that the actions of man are of a more downright nature, and easier to observe and follow, than those of woman—who, as a clever writer has remarked, approaches her object obliquely—and, secondly, that it is man mostly, and not woman, who has given his opinion on this and other matters through the most authoritative channels—for it is man who, by virtue of his intellect and his selfishness, holds the chief places of authority.
May not these factors have affected in some degree, also, our conclusions in regard to the lower animals? Here, too, the actions of the female may be often more subtle and difficult to follow than those of the male, though in many cases, as I believe, they are seen plainly enough, but, for a reason shortly to be mentioned, attributed to the male. Yet in the case of birds, at any rate, it is very noticeable in some species that the females, after the couples have once paired off, are extremely eager in their enticements of the males to hymeneal pleasures, and it seems difficult to reconcile this eagerness after marriage with any very real coldness before it—especially as the supposed coy sweetheart of one spring has been the forward wife of the spring before. But there is another point, in this connection, which it is of the utmost importance for us to bear in mind. Birds in which, if in any, we might expect to find the courting actions alike or similar in the male and female (and this would imply an active wooing on the part of each) are of two classes—viz. (1) those in which the sexes are alike or nearly so, and (2) those in which, though they may differ conspicuously, the one is as handsome, or nearly as handsome, as the other. In the first case, the colours of the hen must either be due to the selective agency of the cock, or they must have been transmitted to her through the latter (as being prepotent), in which case they can have no significance as far as the theory of sexual selection is concerned—two possibilities which equally require proving. In the second case—but examples of this nature are not, I believe, numerous—a double process of sexual selection seems the only available explanation. Only when the female is plain and unadorned, and the male gaudy, does it seem primâ facie evident that the latter, alone, has been selected for his beauty. But it is just this last class of cases that has attracted the largest amount of notice, for, as might have been expected, it is precisely here that we find the males—often the most ornate of birds—indulging in the most extraordinary antics, which, of course, arrest attention. In observing these birds, however, the sexes are at once, and without difficulty, distinguished, and as the females do not share in such antics, we assume, when we see similar ones on the part of birds, the sexes of which are indistinguishable, that here, also, the same law holds good, though there is by no means the same presumption that this should be the case. Confronted with a certain effect, which implies a corresponding causal process, in one case, we assume this same process in another, though we cannot there see the effect. We see, for instance, one stock-dove manifestly court another, and at once assume that the courting bird is the male. The courtship, as is often the case, ends in a pretty severe battle, where blows with the wing are given and received on either side. We may be surprised to see the female so belligerent, but we do not yet doubt the fact of her being the female. The courting bird is, at last, repelled, and a fight of much the same description takes place between him and another stock-dove. This one might just as well be a female as the first, but in the midst of the strife both birds bow, several times, according to their custom, and we then feel sure that both are males. Meanwhile, however, our assured female, who has been left where she was, is seen to bow to another bird who has alighted near her, upon which we change our minds, conclude that she is a male after all, and that what we, at first, thought to be courtship, was only a fight between two cocks. And thus we go on, correcting and correcting our opinion—until in a gathering of perhaps a dozen or more stock-doves there would seem to be no female at all—because if they were pheasants or blackcocks the hens would not behave in this way. Again, when one first sees a shag throw itself down before another one, and go through a variety of strange gestures to which the latter makes no response—if not by a caress of the bill—it is impossible not to feel sure that the bird thus acting is the male shag, and the other the female. But when one afterwards sees two birds at the nest—male and female beyond a doubt—mutually or alternately performing some portion of these antics, though without the primary prostration,[13] what is one to think then? In such cases as these, where the sexes are not to be distinguished except by dissection, or having the bird in one's hands, we cannot be sure that it is always the male we see displaying to the female, and never the female to the male. I believe, however, that we have tacitly assumed this to be the case.
[13] I instance only what I have actually seen, and go no farther.