authors with respect to animals, more especially those recently made by
Professor Broca, that in the earlier editions of my Origin of Species
I perhaps attributed too much to the action of natural selection or the
survival of the fittest. I have altered the fifth edition of the
Origin so as to confine my remarks to adaptive changes of structure;
but I am convinced, from the light gained during even the last few
years, that very many structures which now appear to us useless, will
hereafter be proved to be useful, and will therefore come within the
range of natural selection. Nevertheless, I did not formerly consider
sufficiently the existence of structures, which, as far as we can at
present judge, are neither beneficial nor injurious; and this I believe
to be one of the greatest oversights as yet detected in my work. I may
be permitted to say, as some excuse, that I had two distinct objects in
view; firstly, to shew that species had not been separately created,
and secondly, that natural selection had been the chief agent of
change, though largely aided by the inherited effects of habit, and
slightly by the direct action of the surrounding conditions. I was not,
however, able to annul the influence of my former belief, then almost
universal, that each species had been purposely created; and this led
to my tacit assumption that every detail of structure, excepting
rudiments, was of some special, though unrecognised, service. Any one
with this assumption in his mind would naturally extend too far the
action of natural selection, either during past or present times. Some
of those who admit the principle of evolution, but reject natural
selection, seem to forget, when criticising my book, that I had the
above two objects in view; hence if I have erred in giving to natural
selection great power, which I am very far from admitting, or in having
exaggerated its power, which is in itself probable, I have at least, as
I hope, done good service in aiding to overthrow the dogma of separate
creations.
It is, as I can now see, probable that all organic beings, including
man, possess peculiarities of structure, which neither are now, nor
were formerly of any service to them, and which, therefore, are of no
physiological importance. We know not what produces the numberless
slight differences between the individuals of each species, for
reversion only carries the problem a few steps backwards, but each
peculiarity must have had its efficient cause. If these causes,
whatever they may be, were to act more uniformly and energetically
during a lengthened period (and against this no reason can be
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