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The Eighth Lesson: The Ascent of Man.837
slightest differences of structure or constitution may- well turn the nicely
balanced scale in the struggle for life, and so be preserved. How fleeting are
the wishes and efforts of man! how short his time! and consequently how
poor will be his results, compared with those accumulated by nature during
whole geological periods! Can we wonder, then, that Nature’s productions
should be far ‘truer’ in character than man’s productions; that they should
be infinitely better adapted to the most complex conditions of life, and
should plainly bear the stamp of far higher workmanship?”
Darwin’s theory of survival of the fittest is begun by the statement of the
fact that the number of organisms that survive are very small compared with
the number that are born. To quote his own words, “There is no exception
to the rule that every organic being naturally increases at so high a rate that,
if not destroyed, the earth would soon be covered by the progeny of a
single pair. Even slow-breeding man has doubled in twenty-five years, and
at this rate in less than a thousand years there would literally not be standing
room for the progeny.” It has been computed that if the offspring of the
elephant, which is believed to be the slowest breeding animal known, were
to survive, there would be about 20,000,000 elephants on the earth in 750
years. The roe of a single cod contains eight or nine millions of eggs, and if
each egg were to hatch, and the fish survive, the sea would shortly become a
solid mass of codfish. The house fly is said to have 20,000,000 descendants
in a season, counting several generations of progeny, from its several broods.
And some scientist has computed that the aphis, or plant-louse, breeds so
rapidly, and in such enormous quantity, that the tenth generation of one
set of parents would be so large that it would contain more ponderable
animal matter than would the population of China, which is estimated at
500,000,000! And this without counting the progeny preceding the tenth
generation!
The result of the above conditions is very plain. There must ensue a
Struggle for Existence, which necessitates the Survival of the Fittest. The
weak are crushed out by the strong; the swift out-distance the slow. The