A slight degree of variability resulting in some advantage, nevertheless slight, in reiterated deadly contests would suffice for the work of sexual choice; and it is sure that secondary sexual characters are eminently variable. Secondary sexual characters of the sort simply referred to, will be fully mentioned in the next chapters, as being in many respects attention-grabbing, however especially as depending on the desire, choice, and rivalry of the people of both intercourse. So again, if the chief service rendered to the male by his prehensile organs is to prevent the escape of the female before the arrival of other males, or when assaulted by them, these organs will have been perfected by way of sexual choice, that is by the benefit acquired by certain people over their rivals. The reason for this difference between the males and females of their intervals of arrival and maturity is sufficiently obvious. Throughout the good class of insects the males almost all the time are the primary to emerge from the pupal state, so that they generally abound for a time before any females can be seen.
Most often, differences of construction between the sexes are kind of directly related with the propagation of the species: thus a feminine, which has to nourish a mess of ova, requires extra meals than the male, and consequently requires special means for procuring it. For instance, many girls are asked in the event that they can be keen to have intercourse without using a condom for extra cash; cash which they is perhaps obliged to take after renting a window, paying taxes and in some instances, paying a pimp. When the 2 sexes follow precisely the same habits of life, and the male has the sensory or locomotive organs more extremely developed than those of the feminine, it could also be that the perfection of these is indispensable to the male for finding the female; but within the vast majority of circumstances, they serve only to offer one male an advantage over one other, for with ample time, the much less effectively-endowed males would succeed in pairing with the females; and judging from the structure of the feminine, they could be in all other respects equally properly tailored for his or her abnormal habits of life. A male animal, which lives for a really short time, might lose its organs for procuring meals by disuse, without detriment; however he would retain his locomotive organs in a perfect state, in order that he might reach the feminine.
Once we behold two males combating for the possession of the female, or a number of male birds displaying their gorgeous plumage, and performing unusual antics before an assembled physique of females, we can’t doubt that, though led by intuition, they know what they’re about, and consciously exert their mental and bodily powers. Differences of construction between the 2 sexes in relation to different habits of life are typically confined to the decrease animals; but with some few birds the beak of the male differs from that of the feminine. When, as within the cases above mentioned, the 2 sexes differ in structure in relation to totally different habits of life, they have no doubt been modified by natural choice, and by inheritance restricted to one and the identical sex. But typically of this sort it’s inconceivable to tell apart between the consequences of natural and sexual selection. We could infer that this can be the case, as a result of the females, that are unarmed and unornamented, are able to outlive and procreate their kind. As, nonetheless, these constructions are not more fascinating than others tailored for the ordinary functions of life, I shall pass them over virtually solely, giving only a few cases below every class.
The males of many oceanic crustaceans, when grownup, have their legs and antennæ modified in an extraordinary manner for the prehension of the female; therefore we might suspect that it is because these animals are washed about by the waves of the open sea, that they require these organs as a way to propagate their sort, and if so, their growth has been the results of atypical or natural selection. Because the male has to find the feminine, he requires organs of sense and locomotion, but when these organs are essential for the opposite purposes of life, as is usually the case, they will have been developed via natural selection. Just as man can enhance the breeds of his recreation-cocks by the collection of those birds which are victorious in the cockpit, so it appears that the strongest and most vigorous males, or those provided with the very best weapons, have prevailed underneath nature, and have led to the advance of the pure breed or species. Thus the males of our migratory birds typically arrive at their locations of breeding before the females, in order that many males are ready to contend for every female. Those males which yearly first migrated into any nation, or which within the spring were first ready to breed, or have been the most eager, would leave the most important variety of offspring; and these would are likely to inherit related instincts and constitutions.