iew here
set forth. Natural selection, as we have seen in our earlier chapters,
acts perpetually and on an enormous scale in weeding out the "unfit" at
every stage of existence, and preserving only those which are in all
respects the very best. Each year, only a small percentage of young
birds survive to take the place of the old birds which die; and the
survivors will be those which are best able to maintain existence from
the egg onwards, an important factor being that their parents should be
well able to feed and protect them, while they themselves must in turn
be equally able to feed and protect their own offspring. Now this
extremely rigid action of natural selection must render any attempt to
select mere ornament utterly nugatory, unless the most ornamented always
coincide with "the fittest" in every other respect; while, if they do so
coincide, then any selection of ornament is altogether superfluous. If
the most brightly coloured and fullest plumaged males are _not_ the most
healthy and vigorous, have _not_ the best instincts for the proper
construction and concealment of the nest, and for the care and
protection of the young, they are certainly not the fittest, and will
not survive, or be the parents of survivors. If, on the other hand,
there _is_ generally this correlation--if, as has been here argued,
ornament is the natural product and direct outcome of superabundant
health and vigour, then no other mode of selection is needed to account
for the presence of such ornament. The action of natural selection does
not indeed disprove the existence of female selection of ornament as
ornament, but it renders it entirely ineffective; and as the direct
evidence for any such female selection is almost _nil_, while the
objections to it are certainly weighty, there can be no longer any
reason for upholding a theory which was provisionally useful in calling
attention to a most curious and suggestive body of facts, but which is
now no longer tenable. The term "sexual selection" must, therefore, be
restricted to the direct results of male struggle and combat. This is
really a form of natural selection, and is a matter of direct
observation; while its results are as clearly deducible as those of any
of the other modes in which selection acts. And if this restriction of
the term is needful in the case of the higher animals it is much more so
with the lower. In butterflies the weeding out by natural selection
takes place to an