The natural process of weeding out
the inferior or least adapted through early death, or through failure to
reproduce, Darwin called "natural selection", and likened it in its
effect upon organisms to the artificial selection which breeders
consciously use to secure types of plants or animals that they desire.
The only great addition to Darwin's theories which has been made since
he wrote is that of the Dutch botanist, Hugo de Vries, who has shown
that the variations which are fruitful for the production of new species
are probably great or discontinuous variations, which he terms
"mutations," instead of the small fluctuating variations which Darwin
thought were probably most important in the production of new species.
De Vries' theory in no way affects the doctrine of descent, nor does it
take away from the importance of natural selection in fixing the
variations. Darwin's theory, therefore, stands in all of its essentials
to-day unquestioned by men of science, and it must be assumed by the
student of sociology in any attempt to explain social evolution.
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