he world with each new generation that
there is not sufficient room for all. No organism can escape the struggle
for existence except by an unconditional surrender that results in death.
Everywhere we turn to examine the happenings of organic life we can find
nothing but a wearisome warfare in which it is the ultimate and cruel lot
of every contestant to admit defeat.

* * * * *

What now are the results of variation, over-multiplication, and
competition? Since some must die because nature cannot support all that
she produces, since only a small proportion of those that enter upon life
can find a foothold or successfully meet the hordes of their enemies,
which will be the ones to survive? Surely those that have even the
slightest advantage over their fellows will live when their companions
perish. It is impossible that the result could be otherwise; it must
follow inevitably from what has been described before. The whole process
has its positive and its negative aspects: the survival of the fittest and
the elimination of the unfit. Perhaps it would be more correct to say the
more real element is the negative one, for those which are least capable
of meeting their living foes and the decimating conditions of inorganic
nature are the first to die, while the others will be able to prolong the
struggle for a longer or shorter period before they too succumb. Thus the
destruction of the unfit leaves the field to the better adapted, that is,
to those that vary in such a way as to be completely or at least partially
adapted to carry on an efficient life. In this way Darwinism explains the
universal condition of organic adjustment, showing that it exists because
there is no place in nature for the incompetent.

* * * * *

Finally we come to the process of inheritance as viewed by Darwin, and its
part in the production and perfection of new species. In every case,
Darwin said, the efficiency or inefficiency of an animal depends upon its
characteristics of an inherited or congenital nature. Variations in these
qualities provide the array of more or less different individuals from
which impersonal nature selects the better by throwing out first the
inferior ones. An organism can certainly change in direct response to
environmental influence or by the indirect results of use and disuse, but
not unless it is so constituted by heredity as to be able to change
adaptively.