We find, in short, such evidence of the slow and scarcely sensible
mutations of specific forms, as we have the right to expect.
ON THE STATE OF DEVELOPMENT OF ANCIENT COMPARED WITH LIVING FORMS.
We have seen in the fourth chapter that the degree of differentiation and
specialisation of the parts in organic beings, when arrived at maturity, is
the best standard, as yet suggested, of their degree of perfection or
highness. We have also seen that, as the specialisation of parts is an
advantage to each being, so natural selection will tend to render the
organisation of each being more specialised and perfect, and in this sense
higher; not but that it may leave many creatures with simple and unimproved
structures fitted for simple conditions of life, and in some cases will
even degrade or simplify the organisation, yet leaving such degraded beings
better fitted for their new walks of life. In another and more general
manner, new species become superior to their predecessors; for they have to
beat in the struggle for life all the older forms, with which they come
into close competition. We may therefore conclude that if under a nearly
similar climate the eocene inhabitants of the world could be put into
competition with the existing inhabitants, the former would be beaten and
exterminated by the latter, as would the secondary by the eocene, and the
palaeozoic by the secondary forms.
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