The Darwinian Hypothesis | Page 9

duly reflected upon all the consequences of the
marvellous struggle for existence which is daily and hourly going on
among living beings? Not only does every animal live at the expense of
some other animal or plant, but the very plants are at war. The ground
is full of seeds that cannot rise into seedlings; the seedlings rob one
another of air, light and water, the strongest robber winning the day,
and extinguishing his competitors. Year after year, the wild animals
with which man never interferes are, on the average, neither more nor
less numerous than they were; and yet we know that the annual produce
of every pair is from one to perhaps a million young,--so that it is
mathematically certain that, on the average, as many are killed by
natural causes as are born every year, and those only escape which
happen to be a little better fitted to resist destruction than those which
die. The individuals of a species are like the crew of a foundered ship,
and none but good swimmers have a chance of reaching the land.
Such being unquestionably the necessary conditions under which living
creatures exist, Mr. Darwin discovers in them the instrument of natural
selection. Suppose that in the midst of this incessant competition some
individuals of a species (A) present accidental variations which happen
to fit them a little better than their fellows for the struggle in which they
are engaged, then the chances are in favour, not only of these
individuals being better nourished than the others, but of their
predominating over their fellows in other ways, and of having a better
chance of leaving offspring, which will of course tend to reproduce the
peculiarities of their parents. Their offspring will, by a parity of
reasoning, tend to predominate over their contemporaries, and there
being (suppose) no room for more than one species such as A, the
weaker variety will eventually be destroyed by the new destructive
influence which is thrown into the scale, and the stronger will take its

place. Surrounding conditions remaining unchanged, the new variety
(which we may call B)--supposed, for argument's sake, to be the best
adapted for these conditions which can be got out of the original
stock--will remain unchanged, all accidental deviations from the type
becoming at once extinguished, as less fit for their post than B itself.
The tendency of B to persist will grow with its persistence through
successive generations, and it will acquire all the characters of a new
species.
But, on the other hand, if the conditions of life change in any degree,
however slight, B may no longer be that form which is best adapted to
withstand their destructive, and profit by their sustaining, influence; in
which case if it should give rise to a more competent variety (C), this
will take its place and become a new species; and thus, by 'natural
selection', the species B and C will be successively derived from A.
That this most ingenious hypothesis enables us to give a reason for
many apparent anomalies in the distribution of living beings in time
and space, and that it is not contradicted by the main phenomena of life
and organization appear to us to be unquestionable; and so far it must
be admitted to have an immense advantage over any of its predecessors.
But it is quite another matter to affirm absolutely either the truth or
falsehood of Mr. Darwin's views at the present stage of the inquiry.
Goethe has an excellent aphorism defining that state of mind which he
calls 'Thatige Skepsis'a--active doubt. It is doubt which so loves truth
that it neither dares rest in doubting, nor extinguish itself by unjustified
belief; and we commend this state of mind to students of species, with
respect to Mr. Darwin's or any other hypothesis, as to their origin. The
combined investigations of another 20 years may, perhaps, enable
naturalists to say whether the modifying causes and the selective power,
which Mr. Darwin has satisfactorily shown to exist in nature, are
competent to produce all the effects he ascribes to them, or whether, on
the other hand, he has been led to over-estimate the value of his
principle of natural selection, as greatly as Lamarck overestimated his
vera causa of modification by exercise.
But there is, at all events, one advantage possessed by the more recent
writer over his predecessor. Mr. Darwin abhors mere speculation as
nature abhors a vacuum. He is as greedy of cases and precedents as any
constitutional lawyer, and all the principles he lays down are capable of

being brought to the test of observation and experiment. The path he
bids us follow professes to be, not a mere airy track, fabricated of ideal
cobwebs, but a solid and broad bridge of facts. If