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Conceptions of Evolution
There remain one or two conceptions of evolution which we have
not hitherto noticed, as it was advisable to see the facts first.
One of these is the view--chiefly represented in this country by
Professor Henslow--that natural selection has had no part in the
creation of species; that the only two factors are the
environment and the organism which responds to its changes. This
is true enough in the sense that, as we saw, natural selection is
not an action of nature on the "fit," but on the unfit or less
fit. But this does not in the least lessen the importance of
natural selection. If there were not in nature this body of
destructive agencies, to which we apply the name natural
selection, there would be little--we cannot say no--evolution.
But the rising carnivores, the falls of temperature, etc., that
we have studied, have had so real, if indirect, an influence on
the development of life that we need not dwell on this.
Another school, or several schools, while admitting the action of
natural selection, maintain that earlier evolutionists have made
nature much too red in tooth and claw. Dr. Russel Wallace from
one motive, and Prince Krapotkin from another, have insisted that
the triumphs of war have been exaggerated, and the triumphs of
peace, or of social co-operation, far too little appreciated. It
will be found that such writers usually base their theory on life
as we find it in nature to-day, where the social principle is
highly developed in many groups of animals. This is most
misleading, since social co-operation among animals, as an
instrument of progress, is (geologically speaking) quite a recent
phenomenon. Nearly every group of animals in which it is found
belongs, to put it moderately, to the last tenth of the story of
life, and in some of the chief instances the animals have only
gradually developed social life.* The first nine-tenths of the
chronicle of evolution contain no indication of social life,
except--curiously enough--in such groups as the Sponges, Corals,
and Bryozoa, which are amongst the least progressive in nature.
We have seen plainly that during the overwhelmingly greater part
of the story of life the predominant agencies of evolution were
struggle against adverse conditions and devouring carnivores; and
we shall find them the predominant agencies throughout the
Tertiary Era.
* Thus the social nature of man is sometimes quoted as one of the
chief causes of his development. It is true that it has much to
do with his later development, but we shall see that the
statement that man was from the start a social being is not at
all warranted by the facts. On the other hand, it may be pointed
out that the ants and termites had appeared in the Mesozoic. We
shall see some evidence that the remarkable division of labour
which now characterises their life did not begin until a much
later period, so that we have no evidence of social life in the
early stages.
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