I am informed by Mr. Jenner Weir, that the fowl-catchers assert that that is invariably the case with the nightingale and blackcap, and with respect to the latter he can himself affirm the statement. There are many different buildings and instincts which must have been developed through sexual selection-such because the weapons of offence and the technique of defence of the males for combating with and driving away their rivals-their courage and pugnacity-their varied ornaments-their contrivances for producing vocal or instrumental music-and their glands for emitting odours, most of these latter buildings serving solely to allure or excite the feminine. But I must confess, that, with all my faith in natural selection, I should never have anticipated that this principle could have been environment friendly in so high a degree, had not the case of those neuter insects led me to this conclusion. Since in such circumstances the males have acquired their current construction, not from being better fitted to outlive in the wrestle for existence, but from having gained an advantage over different males, and from having transmitted this advantage to their male offspring alone, sexual selection should here have come into motion. So once more the primary sexual organs, and people for nourishing or defending the younger, come below the same affect; for these people which generated or nourished their offspring finest, would depart, cæteris paribus, the best number to inherit their superiority; while these which generated or nourished their offspring badly, would go away but few to inherit their weaker powers.
In lots of circumstances habit or use and disuse have most likely come into play. You play as Aois, a directionless younger lady cloistered away in a convent. The case, also, could be very attention-grabbing, because it proves that with animals, as with plants, any quantity of modification may be effected by the accumulation of numerous, slight, spontaneous variations, that are in any means worthwhile, with out train or habit having been brought into play. I’ve, therefore, discussed this case, at some little however wholly insufficient length, in order to indicate the power of natural selection, and likewise as a result of that is by far essentially the most severe particular problem which my idea has encountered. As the male has to find the feminine, he requires organs of sense and locomotion, but when these organs are crucial for the other functions of life, as is usually the case, they will have been developed by natural choice. So again, if the chief service rendered to the male by his prehensile organs is to forestall the escape of the female earlier than the arrival of other males, or when assaulted by them, these organs could have been perfected by means of sexual selection, that’s by the benefit acquired by certain individuals over their rivals.
When the male has found the feminine, he sometimes absolutely requires prehensile organs to carry her; thus Dr. Wallace informs me that the males of sure moths can not unite with the females if their tarsi or ft are damaged. Thus the males of our migratory birds generally arrive at their locations of breeding earlier than the females, so that many males are able to contend for every female. For peculiar habits, confined to the workers of sterile females, nonetheless lengthy they could be followed, couldn’t presumably have an effect on the males and fertile females, which alone depart descendants. The female, on the other hand, may safely lose her organs for flying, swimming, or strolling, if she regularly acquired habits which rendered such powers useless. A male animal, which lives for a very quick time, may lose its organs for procuring food by way of disuse, with out detriment; however he would retain his locomotive organs in an ideal state, in order that he may attain the female. When the two sexes follow precisely the identical habits of life, and the male has the sensory or locomotive organs extra extremely developed than those of the female, it could also be that the perfection of those is indispensable to the male for finding the female; however within the overwhelming majority of circumstances, they serve only to give one male a bonus over one other, for with adequate time, the much less effectively-endowed males would achieve pairing with the females; and judging from the construction of the feminine, they could be in all other respects equally well tailored for their peculiar habits of life.