In referring to the remarkable patterns displayed on the male Argus pheasant, designs which have been developed through Sexual Selection, Mr. Darwin says:
Many will declare that it is utterly incredible that a female bird should be able to appreciate fine shading and exquisite patterns. It is undoubtedly a marvellous fact that she should possess this almost human degree of taste. He who thinks that he can safely gauge the discrimination and taste of the lower animals may deny that the female Argus pheasant can appreciate such refined beauty; but he will then be compelled to admit that the extraordinary attitudes assumed by the male during the act of courtship, by which the wonderful beauty of his plumage is fully displayed, are purposeless; and this is a conclusion which I, for one, will never admit.[17]
Here, then, in the female bird we see developed in a remarkable degree the power of discrimination, the exercise of taste, a sense of beauty, and the ability to choose—qualities which the facts brought forward by scientists show conclusively to have been acquired by the female and by her transmitted to her offspring. Regarding males, outside the instinct for self-preservation, which, by the way, is often overshadowed by their great sexual eagerness, no distinguishing characters have been acquired and transmitted, other than those which have been the result of passion, namely, pugnacity and perseverance. This excessive eagerness which prompts them to parade their charms whenever such display is likely to aid them in the gratification of their desires is developed only in the male line.
According to the law of heredity, those modifications of the male which have been the result of Sexual Selection appear only in the sex in which they originated. It will be well for us to remember that according to Mr. Darwin’s theory of pangenesis, sexes do not differ much in constitution before the power of reproduction is reached, but that after this time the undeveloped atoms or
gemmules which are cast off from each varying part in the one sex would be much more likely to possess the proper affinities for uniting with the tissues of the same sex, and thus becoming developed, than with those of the opposite sex.[18]
We are given to understand that secondary sexual characters are extremely variable, also that variability denotes low organization; secondary sexual characters indicate that the various organs of the structure have not become specialized for the performance of their legitimate functions. Highly specialized forms are not variable.
To sum up the argument thus far: It has been observed that through the separation of the sexes, and the consequent division of labour, there have been established two diverging lines of development. While the male pheasant has been inheriting from his male progenitors fantastic ball-and-socket ornaments, and huge wings which are utterly useless for their legitimate purpose, the female, in the meantime, has been receiving as her inheritance only those peculiarities of structure which tend toward uninterrupted development. Within her have been stored or conserved all the gain which has been effected through Natural Selection, and as a result of greater specialization of parts, there have been developed certain peculiarities in her brain nerve-cells, by which she is enabled to exercise functions requiring a considerable degree of intelligence.
Although this power of choice, which we are given to understand is exercised by the female throughout the various departments of the vertebrate kingdom (evidences of it having been observed among creatures even as low in the organic scale as fishes), implies a degree of intelligence far in advance of that manifested by males, it is admitted that the qualities which bespeak this superiority, namely, the power to exercise taste and discrimination, constitute a “law almost as general as the eagerness of the male.”[19]
We are assured by Mr. Darwin that in the economy of nature those ornaments of the male Argus pheasant which serve no other purpose than to please the female and secure her favours, and which have been acquired at great expense of vital force, are of the “highest importance to him,” and that his success in captivating the female “has more than compensated him for his greatly impeded power of flight and his lessened capacity for running.” Yet it is plain that his compensation for this immense expenditure of vital force has not lain in the direction of higher specialization, but that while by the acquirement of these characters the processes of reproduction have doubtless been aided, the injury to the male constitution has been deep and lasting.
Upon this subject Mr. Darwin himself says: