Many other facts are, as it seems to me, explicable on this theory. How
strange it is that a bird, under the form of woodpecker, should have
been created to prey on insects on the ground; that upland geese, which
never or rarely swim, should have been created with webbed feet; that a
thrush should have been created to dive and feed on sub-aquatic
insects; and that a petrel should have been created with habits and
structure fitting it for the life of an auk or grebe! and so on in
endless other cases. But on the view of each
species constantly trying to increase in number, with natural selection
always ready to adapt the slowly varying descendants of each to any
unoccupied or ill-occupied place in nature, these facts cease to be
strange, or perhaps might even have been anticipated.
As natural selection acts by competition, it adapts the inhabitants of
each country only in relation to the degree of perfection of their
associates; so that we need feel no surprise at the inhabitants of any
one country, although on the ordinary view supposed to have been
specially created and adapted for that country, being beaten and
supplanted by the naturalised productions from another land. Nor ought
we to marvel if all the contrivances in nature be not, as far as we can
judge, absolutely perfect; and if some of them be abhorrent to our
ideas of fitness. We need not marvel at the sting of the bee causing
the bee s own death; at drones being produced in such vast numbers for
one single act, and being then slaughtered by their sterile sisters; at
the astonishing waste of pollen by our fir-trees; at the instinctive
hatred of the queen bee for her own fertile daughters; at ichneumonid
feeding within the live bodies of caterpillars; and at other such
cases. The wonder indeed is, on the theory of natural selection, that
more cases of the want of absolute perfection have not been observed.
The complex and little known laws governing variation are the same, as
far as we can see, with the laws which have governed the production of
so-called specific forms. In both cases physical conditions seem to
have produced but little direct effect; yet when varieties enter any
zone, they occasionally assume some of the characters of the species
proper to that zone. In both varieties and species, use and disuse seem
to have produced some effect; for it is difficult to resist this
conclusion
when we look, for instance, at the logger-headed duck, which has wings
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