| ↑ 1 blocks not present in 1859 1860 1861 1866 1872; present in 1869 |
| In some instances, however, the acquirement of conspicuous colours by the female may have been checked through natural selection, on account of the danger to which she would thus have been exposed during incubation.
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| → any structure more injurious than beneficial to that being, 1872 |
| anything injurious to itself, 1866 1869 |
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When the female is as beautifully coloured as the male, which is not rarely the case with birds and butterflies, the cause
lies in the colours acquired through sexual selection having been
both sexes, instead of
the males alone. ↑
How the sense of beauty in its simplest form— that is, the reception of a peculiar kind of pleasure from certain colours, forms, and sounds— was first developed in the mind of man and of the lower animals, is a very obscure subject. The same sort of difficulty is presented, if we enquire how it is that certain flavours and odours give pleasure, and others displeasure. Habit in all these cases appears to have come to a certain extent into play; but there must be some fundamental cause in the constitution of the nervous system in each species.
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| Natural selection cannot possibly produce any modification in
species exclusively for the good of another species; though throughout nature one species incessantly takes advantage of, and profits by, the
of
But natural selection can and does often produce structures for the direct injury of other
as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are
in the living bodies of other insects. If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection. Although many statements may be found in works on natural history to this effect, I cannot find even one which seems to me of any weight. It is admitted that the rattlesnake has a poison-fang for its own
and for the destruction of its prey; but some authors suppose that at the same time
is furnished with a rattle for its own injury, namely, to warn its
I would almost as soon believe that the cat curls the end of its tail when preparing to spring, in order to warn the doomed mouse. It is a much more probable view that the rattlesnake uses its rattle, the cobra expands its frill, and the puff-adder swells whilst hissing so loudly and harshly, in order to alarm the many birds and beasts which are known to attack even the most venomous species. Snakes act on the same principle which makes the hen ruffle her feathers and expand her wings when a dog approaches her chickens; but I have not space here to enlarge on the many ways by which animals endeavour to frighten away their enemies.
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| Natural selection will never produce in a being
→any structure more injurious than beneficial to that being,
for natural selection acts solely by and for
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