Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

SELECTION ON MAN. 307
seems that the best of the argument is on the side of
those who maintain the primitive diversity of man.
Their opponents have not been able to refute the permanence of existing races as far back as we can trace
them, and have failed to show, in a single case, that
at any former epoch the well marked varieties of mankind approximated more closely than they do at the
present day. At the same time this is but negative
evidence. A condition of immobility for four or five
thousand years, does not preclude an advance at an
earlier epoch, and-if we can show that there are
causes in nature which would check any further physical change when certain conditions were fulfilleddoes not even render such an advance improbable, if
there are any general arguments to be adduced in its
favour. Such a cause, I believe, does exist; and I
shall now endeavour to point out its nature and its
mode of operation.
Outline of the Theory of Nlatural Selection.
In order to make my argument intelligible, it is
necessary for me to explain very briefly the theory of
"Natural Selection" promulgated by Mr. Darwin,
and the power which it possesses of modifying the
forms of animals and plants. The grand feature in
the multiplication of organic life is, that close general
resemblance is combined with more or less individual
variation. The child resembles its parents or ancestors
more or less closely in all its peculiarities, deformities,
or beauties; it resembles them in general more than it
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