ESSAYS ON DARWINISM.
BY
THOMAS R. R. STEBBING, M.A.
_Late Fellow and Tutor of Worcester College, Oxford._
LONDON:
LONGMANS, GREEN, AND CO.
1871.
[_All rights reserved_]
OXFORD:
BY T. COMBE, M.A., E. B. GARDNER, AND E. PICKARD HALL,
PRINTERS TO THE UNIVERSITY.
PREFACE.
The opinions of Mr. Darwin have now been for many years before the
world. His own book on ‘The Origin of Species by means of Natural
Selection,’ unfolds and supports them with admirable clearness of
argument. Far from being an abstruse and tedious work, it carries the
reader on with unflagging interest to the close. Observations and
experiments, some the most simple, some the most elaborate, notes
on natural history, as well from every quarter of the globe as from
almost every province of nature, are brought to bear upon the subject
without confusion of thought or embarrassment of style. The language
flows easily in its calm, temperate, unegotistical course. There is no
disguising of objections, no seeking of opponents. There is an evident
searching after truth. Of its form or of its shadow the author’s mind
as evidently retains a bright clear vision, and what he sees he tries
to make others see as clearly as he sees it himself. The suspicion and
dislike which are aroused in some minds by the very name of Darwinism
cannot be retained by those who read Mr. Darwin’s own description
of his theory and the grounds which slowly led him to adopt it. Few
readers can be dull enough to feel no charm at finding the most
unlooked-for results deduced from the simplest illustrations, from
old familiar facts, from every-day occurrences, or at finding what
seem examples of the most special and varied contrivance reconciled to
the simplicity of a single general law. Many readers will be inclined
to whisper to themselves at many passages, ‘we never thought of that
before,’ ‘we never looked at the matter in that light,’ ‘how curious
if after all it should be true,’ ‘it looks less wicked and silly than
we used to think it.’ Whether the theory itself be right or wrong, the
general effect of the book which describes it can only be to quicken
the minds of its readers, to enlarge for them the circle of ideas, to
open up before them new lines of thought and enquiry, to let them see
the whole face of nature teeming with mysteries and revelations, an
inexhaustible vintage for the human reason to gather in.
Such being the character of Mr. Darwin’s own Work, the handful of
Essays and Letters contained in the present volume, supporting the same
views by almost the same arguments, may seem a superfluous contribution
to the literature of the question. And so it would be if all who
condemn and ridicule Darwinism would be at the pains to study Mr.
Darwin’s Work. But opinions passed upon it and allusions made to it in
common conversation and in popular lectures often testify to nothing
except supreme ignorance of its general merits. To judge by such
hearsay, one might believe that Mr. Darwin had lived all his life shut
up in a dove-cote, and never seen or examined any other living creature
than a pigeon. Another estimate will dismiss the whole subject, scathed
with indignant laughter, by simply explaining, that, according to
this fatuous theory, man is descended from a monkey. Naturally no
well-minded persons will consent to be _pithecoid_ in origin, whether
they know what _pithecoid_ means or not; still less can a theory be
accepted as moral and good, according to which, as some will tell
you, the giraffe lengthened its neck by a series of stretchings, and
the elephant acquired a trunk by continually pulling its own nose.
A disinterested advocate will perhaps be allowed to deprecate these
burlesque and ignorant representations, and to strip from what is
merely vulgar prejudice the guise of magnanimity and fine feeling. The
range of topics embraced in the present volume, however feebly handled,
and however inaccurate that handling may in some points prove to be,
should at least teach those who are willing to learn, that the whole
subject is a great one, and worthy of attention, claiming earnest
thought and varied learning to decide upon it in all its bearings;
it cannot be disposed of by caricaturing; it cannot be settled in
deference to any religious prepossession; it must be examined with open
eyes, and with the full candour of mind which great subjects demand,
and which great subjects nobly repay.
Some of the following papers treat of matters on which no man of
scientific education can be supposed at the present day to retain even
a vestige of doubt. But thousands of persons, whom in ordinary courtesy
we must call well-educated, although they know nothing of science,
hold opinions on the Flood and the age of the world as irreconcileable
with the best-approved scientific conclusions as they are with the
Darwinian Theory. In appealing to the judgment of such persons, as well
as in considering the measure of his own powers, the present writer
has thought it expedient to confine himself, for the most part, to the
clearest and simplest arguments, leaving on one side the subtle and
intricate.
The letters collected at the end of the volume may be looked on
as short essays of a somewhat informal character. The apology for
reprinting them is this, that whereas in a regular essay the writer
assumes his own standpoint, and may be suspected of ignoring the
vantage-ground of his opponents, in replying to a correspondent he
must, at least to some extent, follow the lead of an antagonist, and
fight, if he fights at all, on the field which another has chosen. As
I cannot reprint the various able compositions which I have attempted
to answer, it will be fair, to one at least of the writers, to remark
that I have personal reason to know that he still retains the opinions
of which I attempted to disabuse him. He contrives to reconcile this
obduracy to his own intelligence by laying stress on the candid
admission made by Darwinians, that the Theory of Development is for the
present that which they call it,--a Theory, and not a demonstration.
No one pretends to answer fully every objection that has been urged
against the Theory. The evidence is as yet incomplete. By its very
nature it must perhaps always to some extent remain so. The proof
depends in part upon analogy, which leads to conclusions possible
or probable, rather than to what is demonstrably certain. But the
advocates of the Theory, remembering Bishop Butler’s maxim, that ‘to
us probability is the very guide of life,’ endeavour to maintain that
their opinions have far more than that minimum of preponderance which,
in Butler’s view, not only justifies, but imperiously exacts, the
adhesion of reasonable beings.
THOMAS R. R. STEBBING.
Torquay, Feb. 6, 1871.
CONTENTS.
PAGE
DARWINISM[1] 3
THE NOACHIAN FLOOD[1] 34
INSTINCT AND REASON[2] 62
HUMAN NATURE AND BRUTE NATURE 82
THE LAPSE OF TIME[1] 93
NOTE ON THE HYPOTHESIS OF SPONTANEOUS GENERATION[1] 126
IMPERFECTION OF THE GEOLOGICAL RECORD[1] 133
DARWINISM: THE NOACHIAN FLOOD 147
DARWINISM: SCIENCE AND RELIGION 152
DARWINISM, AND THE FIRST VERTEBRATE 156
THE FIRST VERTEBRATE, AND THE BEGINNING OF REASON 160
OYSTERS OF THE CHALK, AND THE THEORY OF DEVELOPMENT 165
THE MATHEMATICAL TEST OF NATURAL SELECTION 168
THE GENESIS OF SPECIES 173
INDEX 181
NOTES to pp. 13 and 34.
It has been kindly pointed out to me by Mr. James Parker of Oxford
that there is an error in Mr. Darwin’s calculation reproduced in page
13 of this volume. Upon the data supplied, the increase in the number
of elephants there mentioned would require 750 years instead of 500.
The further increase calculated in the same page, would in like manner
require seven or eight additional centuries instead of five.
Mr. Parker also suggests that the expressions in page 34, ‘taken for
granted,’ ‘taught for centuries,’ seem to ignore Bishop Stillingfleet
and other writers of his time, who saw good reason for believing the
Flood in the days of Noah not to have been universal. I am glad to
explain that I did not by any means intend to imply that there were no
exceptions to the general state of opinion, for I am well aware that
there are at the present day some schools, a few nurseries, and even
one or two pulpits, into which the truth on this point has been allowed
to penetrate.
DARWINISM.
DARWINISM.
The object of this lecture is to explain, with as much simplicity as
possible, the opinions of Darwin on the chain of secondary causes
which has resulted in the wonderful structures known to us as living
creatures, and including, in an almost infinite variety, lichen and
moss, mite and mildew, grass and flower and branching tree; mollusk and
reptile and fish; the swan, the petrel, the ostrich and the eagle; the
cunning ape; the faithful hound; the elephant, sagacious and mindful of
insults; the lion, capable of generosity; the horse, patient of labours
and eager for victory; and, along with a multitude of others diversely
qualified, One, without doubt partaking of the animal nature that lives
and dies, yet seeming to partake of something beyond it, seeming to
be distinguished from all the rest by its postures, by its laughing,
by its cooking its food, by its articulate language, by its powers of
reasoning; and yet linked and united to its inferiors by a multitude
of affinities and sympathies, resemblances of form and nature, and
by the very details of its superiority. So ran the Pagan legend that
Providence had compacted man’s moral nature out of particles taken from
each of the lower animals, giving him the wisdom of the serpent and
the fiery courage of the lion[3]. To this sense of an intimate union
between man and the rest of the animate creation have the writers of
fables in all ages appealed, while imparting their lessons of prudence
and virtue under the guise of transactions between birds and beasts and
trees of the forest.
It is well known that after the discovery of almost every great
truth a sort of feeling or instinct of it can be traced back in
obscure hints, in chance expressions, in vague guesses, in flights
of imagination, so that people very soon begin to fancy that they
have all along understood and maintained the very theory, which, on
its first appearance, they violently rejected as something false and
even vicious. Darwinism has this characteristic of truth, that it has
often been obscurely anticipated. It has this other characteristic,
that its fiercest opponents have already begun insensibly to adopt its
conclusions, and to speak its language, to opine, even, that the credit
of its promulgation belongs to themselves.
In Mr. Darwin’s own historical sketch of the rise and progress of his
doctrine, he does full justice to those who have preceded and who
have worked with him in bringing it to light and in establishing its
foundations. The opinion that species originate, not by successive
miraculous interpositions or acts of creation, but by birth, was
held as far back as 1794-5, by four men of distinguished genius, by
Lamarck, by Mr. Darwin’s own grandfather, Dr. Erasmus Darwin, by
Geoffroy Saint Hilaire, and by the poet Goethe. In the present day, Mr.
Wallace, Mr. Herbert Spencer, the great zoologist Van Baer, and others,
independently of Mr. Darwin, seem to have come more or less to the same
conclusions, which have been warmly espoused and powerfully vindicated
by Dr. Hooker, Professor Huxley, and Sir Charles Lyell. I mention
these names because it seems to be their due, and not for the sake of
giving weight to any argument because of the scientific renown of its
advocates; there are names, it may be, equally distinguished on the
opposite side. But one thing ought to be observed, that the progress
of scientific enquiry has achieved so much during the last hundred
years that the opinions of the older Naturalists have an importance
when they agree with modern conclusions, which they cannot have when
they differ from them, unless it can be shown that the observations,
the experiments, the discoveries of late years had all been made by,
or were known to, the earlier enquirers. For those, however, who think
the opinions of a past generation of necessity more trustworthy than
those of the present, Sir Charles Lyell has done well to point out that
Linnæus himself looked forward to a time when it should be proved that
in botany, at least, all species of a genus had descended from the same
mother[4].
This is precisely Mr. Darwin’s opinion on the origin of species at
large. He applies it to the animal as well as to the vegetable kingdom.
He extends it by considering genera themselves as species of the orders
which contain them, and orders as species of the great classes to
which they as orders respectively belong. In a word, he considers that
all living forms whatsoever are descended from a very few original
ancestors of the simplest type, and that this primæval group itself
had, probably, a common parentage. Wildly improbable, ludicrously
absurd, degrading to humanity, and irreligious, no doubt this
hypothesis has appeared to many, and will continue so to appear till
it has been studied with attention, and studied without prejudice. To
rescue it from the prejudice which would make it in the eyes of some a
pernicious and forbidden study, is the hope which underlies the object
of the present lecture.
Round Nelson’s Column in Trafalgar Square there are four colossal
statue lions, the conception of a great artist. They look unnatural,
not because of their size, or their position, or the material of which
they are made, but because they are all so exactly alike; and exact
likenesses are scarcely ever found in animate nature, unless it be
among the very simplest organisms. When we speak of a striking likeness
between two human beings, we evidently imply that a high degree of
similarity is uncommon, and, therefore, noteworthy. What is true of
even the most highly organized animals, is true, as far as observation
goes, of all below them. Horses, dogs, sheep, kine, afford familiar
illustrations of this principle. To the uneducated eye, individual
differences may be totally unapparent, which are yet perfectly
conspicuous to the trainer, the huntsman, the shepherd, and the drover.
Wild creatures know their mates; wild herds select their leaders; the
bee and the ant are capable of distinguishing the various individuals
of their own communities, for strangers of the very self-same species
with themselves they repel or destroy[5]. As each creature is, in
numberless cases, the offspring of two unlike parents, it cannot be
an exact copy of either, and the influences of the two parents may
be combined in various proportions in each of the offspring; but the
parents themselves are continually changing, with the variations of
age and food and climate, so that the very rule of resemblance between
the producers and the produced will entail another rule of unlikeness
between the several members of an offspring not born all at once.
It is a fact, which cannot be denied, that in numberless instances the
young of a creature differ more or less from the parents and likewise
among themselves. Why it should be so has been in part explained.
This is the _Variability_, without which Natural Selection could
never have been thought of, because without differences there would
have been nothing to select. But this Variability being granted, the
Darwinian theory becomes possible--becomes quite capable of referring
back the elephant and the pig, for instance, to the same ancestry. The
difference between progenitors and their immediate offspring are, it
is true, comparatively slight. It would, indeed, be a prodigious birth
if one family contained at once a young monkey, a little pig, a big
donkey, and a great goose; but it is obviously possible that any amount
of unlikeness may be found between the descendants of common ancestors,
if we are not confined to the differences of a single generation, but
are allowed to multiply them through as many thousands as we require.
Say that two race-courses differ in length by one yard; multiply that
difference 1760 times and they will then differ by a whole mile. If,
on leaving this Lecture-room, you found the trees--which half-an-hour
ago were bare and leafless--clothed with summer verdure, your gardens
blooming with a wealth of roses, your orchards laden with autumnal
fruits, you would scarcely credit your senses; and yet, when the
requisite number of half-hours, reckoned by days and months, shall
have elapsed, you will greet these wonderful changes as perfectly
natural and nothing to be wondered at. In a dissolving view that is
well managed, Alpine peak and glacier-pass melt imperceptibly into some
tall cathedral and sunshiny market-place. The two scenes are wholly
unlike, and yet it is contrived that at no moment should the passage
from one to the other be discernibly abrupt. Is it not possible then to
conceive that through an immense multitude of generations the form of
an ape might be derived from the form of a fish? We do not mean to say
that this has actually happened, but supposing the descendant of the
fish to vary continuously in the direction of the ape-like form, the
result would be intelligible enough. What, then, is there to determine
variation in any particular direction, and what limits are there,
if any, to the system of interminable change which the principle of
variation seems to involve?
Of course it is understood that the general mass of characters or
qualities belonging to any creature are inherited by one generation
from its immediate ancestors and transmitted to its immediate
descendants, so that for a long period there would be a large number
of individuals in the world united into a group by common characters,
which according to their supposed importance we might call specific
or generic. But besides this, there is the very curious principle of
_Reversion_ to be taken into account, as largely conducing to the
comparative permanence of species. In Norway, I believe, when the
father’s name is Jack, and the son’s name is Tom, Tom is called Tom
Jackson, and Tom is in the habit of giving his own eldest son the
grandfather’s name, and then Tom Jackson’s son is called Jack Tomson.
Now, in the same way, in nature it not unfrequently happens that
when a long-nosed man is father of a short-nosed son, the son of the
short-nosed man inherits by reversion the more elongated feature of
his grandsire. Under certain conditions, which however greatly limit
it, the operation of this principle of Reversion may extend, so far as
we know, to any quality whatever after an interval of any number of
generations. The tendency, therefore, is to the permanence of species,
and yet, as will be shown in the sequel, it has furnished Mr. Darwin
with an additional argument to prove that species are not permanent. It
must be borne in mind that when a character reverts from a very distant
ancestor, the creature which inherits it will have numerous other
qualities, all probably more or less differing from those originally
united to the reversionary character; just as if, in the School of Art,
a picture by Raffaelle were shown to fifty pupils, and when it had been
copied by the first, the second pupil were to make a copy of the copy,
and so on to the end, each of the copies would no doubt differ more and
more from the original, and yet in the very last, by the help of memory
or sympathetic genius, there might be some beauty not to be found in
any of the others, recalling the hand of the great master; while it
is true, that if the sketch were something exceedingly simple, the
fiftieth copy, and all the intermediate ones, might be almost exactly
like the original; and so in nature, exceedingly simple organisms are
seemingly reproduced for almost endless generations with no change, or
scarcely any.
If it be true that all living creatures on this earth spring from a
very few, extremely simple, original germs of life, we have to explain
how it is that now there is an enormous variety of highly organised
creatures, and at the same time some of extreme simplicity. For, if the
simplest forms are permanent, how can the more complex be derived from
them? On the other hand, if the simplest forms vary, how is it that we
find, as we do, the very earliest known form of life still living at
the present day? The solution is easy to suggest, that the offspring
of very simple forms are sometimes exactly like their parents,
and sometimes not exactly like. From what has been said above of
Inheritance and Variation, this is in the highest degree probable, and,
this being admitted, it will follow that according to circumstances the
progeny that are like their parents, or those that are unlike, will
have the best of it. Why this follows will now have to be explained.
All over the surface of our globe there is _a struggle for life_ going
on. The instinct of self-preservation is probably stronger than any
other, so that we may rely upon it that the creatures of every race
will strive to preserve their own existence, if need be, at the expense
of that of others. It may be horrible to the sentimentalist, but it
is true; and remember that man as well as the tiger is a carnivorous
mammal. There is no beast or bird of prey that can be compared with
man for his ravaging, destructive, butchering, remorseless dissipation
of other forms of life, to preserve his own existence and make it
comfortable. He secures his gluttony from famine, as far as he can,
by being omnivorous. Moss and fungus, grass and herb, leaf and flower
and stem and fruit, all alike find a grave in man. The lion and the
flea are the victims of his fear; many a harmless snake and toad of
his antipathy; the otter and the fox die for his sport; the ostrich
and the ermine for his vanity. For his food, like a wolf, he slays the
harmless sheep; like a hawk, he pounces on the innocent chicken; like a
wily panther, surprises the antlered stag; devours fish like a shark;
spreads nets for his prey like a spider; and in some instances acquires
a well-developed taste for the flesh of his fellow-man. Practically
with all living animals, the first consideration is food. If all
living animals could obtain abundance of pleasant and suitable food
without preying on one another, the scene of war which Nature presents
would perhaps in a great measure disappear. Yet this warfare is as
conspicuous in the vegetable as it is in the animal kingdom. There is
a certain amount of nourishment in a given piece of ground, and for
that nourishment the plants upon it will compete, some thriving and
multiplying to the hindrance and destruction of the others. Here again,
if the surface of the globe supplied nutriment for all its plants,
there would be at least no need for this destructive competition.
And how is it that this wide, wide world does not supply food enough
for all the vegetable forms that make an effort to live upon it?
The answer to this curious question has long been known, though not
sufficiently attended to. It would not be fair to say that Nature is
stingy in her supplies of food, but rather that she is too generously
prolific of forms of life. For, take the supposition that all living
creatures, whether animal or vegetable, were shielded from all enemies
and influences at present hurtful to them, and let us see to what it
would bring us. A single grain of wheat produces an ear containing ten,
twenty, or some larger number of grains. But if the ear contained
only two grains, still, at that rate of increase, a single grain would
in thirty years be represented by more than a thousand millions of
grains[6]. What, then, would be the position of the world, if, starting
with a thousand millions of grains, this rate of increase were allowed
to continue unchecked, not for thirty years, but for three thousand?
But Mr. Darwin has calculated in regard to the elephant, which is
reckoned the slowest breeder of all known animals, that, according
to the very lowest probable rate of natural increase, a single pair
would in five hundred years have a progeny of fifteen million living
elephants[7]. Now fancy an island like our own, only in a climate
suitable to elephants, into which a couple should have found their
way a thousand years back. At the end of five hundred years, if all
that were born were enabled to breed unchecked, there would be at
least fifteen millions of their huge descendants stalking about the
land; but, at the end of five hundred years more, there would be one
hundred and twelve millions of millions of elephants. Goodness! What
a stupendous menagerie! What a zoological garden! What a prospect at
the end of the next five hundred years! And all this time, remember,
according to our sentimental, philanthropic, philelephantine,
nature-improving scheme, the men and women, the donkeys with a soul
above thistles, the thistles no longer toothsome to donkeys, the mice,
the rats, the cats, the oaks, the cabbages, the toadstools, would have
been multiplying, not in the same proportion as the elephants, but very
much more rapidly. The great desideratum would be standing room. The
back of an elephant, or the branch of an oak, would no doubt command an
enormous rent, and a right of way across the heads of your neighbours
would be religiously guarded by the law of the land. Nor would the
position of affairs be better in the surrounding sea; for while these
elephants have been computed to breed at the rate of two young ones
in thirty years, a single codfish has been found to produce in one
year more than six millions of eggs, and there are other creatures
infinitely more prolific[8].
You see, then, that the struggle for existence is an absolute
necessity; and out of this all-essential strife springs what has been
well called Natural Selection. What is meant by this will more easily
be understood by looking first at Artificial Selection, which has been
practised by man, sometimes consciously, and oftener unconsciously,
in the process of domesticating a great number of plants and animals.
Dogs, sheep, bulls, pigs, horses, fowls, pigeons, cabbages, and other
culinary vegetables, strawberries, and all manner of edible fruits,
together with gay-coloured, curiously-formed, sweetly-perfumed
garden-flowers innumerable, have been, and are still being, subjected
to man’s selection. That the wonderful changes which occur are indeed
due to man’s repeated choice of the varieties which suit his purposes,
is clear from this, that all the remarkable changes have taken place
in those particular qualities which man has valued, leaving the other
qualities comparatively unaltered. Let it be speed, size, taste,
colour, form, temper, the coat, the feathers, the flesh, the muscular
strength, the powers of endurance; in a vegetable, let it be the root,
the stem, the leaf, the flower, the fruit, the seed, let it be what
it will that is of value, that part and that character have been in
each case most highly developed. To take a few examples: You are fond
of peas, and you sow in your garden what your seedsman tells you are
the finest new varieties; you like strawberries, you admire roses, you
fancy a good cabbage, you are particular about having a mealy potato;
so in each case you plant what you understand to be the best new
kinds. What will you say if it turns out that the roses have improved
in their roots but not in the bloom, and the potatoes in the bloom
but not in their tubers; that the strawberries have remarkably fine
leaves but very small fruit; that the peas and the cabbages have indeed
enormous stems, while the seed of the one and the leaf of the other
are insignificant in size and tasteless to the palate? So, too, if you
purchase a race-horse and a pig from the most noted breeders of those
animals, will you not be disgusted if it turns out that the horse has
a remarkable propensity for fattening, while the pig is distinguished
by nothing but its extreme fleetness of foot? These disappointments do
not occur, because the variations of domesticated plants and animals
are selected by competent persons. Were strawberry-leaves of as much
importance in horticulture as they are in heraldry, many fine varieties
would soon be exhibited. As soon as the most minute tendency to vary
in any particular direction has been descried in any living creature,
the fancier can exaggerate the difference to an extent inconceivable
to the inexperienced. As a popular illustration of this we may take
the Big Gooseberry, which fills so large a space in the newspapers
when Parliament is prorogued. A gooseberry has been grown weighing
more than 37 pennyweights--that is, nearly two ounces[9]. But mere
size is not a fair test of the extreme plasticity of living organisms.
You may have your trees growing stiffly upright, or with pendulous
branches and prostrate stems; you may have your cattle long-horned,
short-horned, or with no horns at all; your rabbits straight-eared or
lop-eared; your fowls with every variety of comb and crest and wattles
and plumage; and your pigeons pretty well at discretion. A type is
prefigured, and the fancier produces it; and what is done for amusement
with pigeons, is done for food, for profit, for the good of mankind at
large, by the grower of corn, by the breeder of sheep, by all the wise
produce-masters of the world[10].
Such is Artificial Selection; but man is after all but one of Nature’s
works, and one of her numerous agents. All that he does, however
miraculous it may seem, can only be done under her conditions, and
by the means which she supplies. In Artificial Selection man does
but take advantage of the natural laws of Inheritance and Variation,
and while he is seeking by means of these to produce one alteration,
Nature herself is producing perhaps a hundred others. For, by the law
of _Correlation_, when one part changes, some other or others almost
inevitably change with it. Whether it be shortening the beak of a
pigeon or lengthening the neck of a giraffe that is in question, Nature
takes care, along with the change, to make other adaptations of the
structure in the creature’s interest under its altered circumstances.
Surely, the working of this principle of Correlation indicates a
far-sighted Providence of the results, the disastrous monstrosities,
that would otherwise have sprung from the law of Variation.
Man’s efforts are considerably limited, moreover, by the law of
Reversion. Now, supposing many differing species to be descended, as
we maintain, from common ancestors, what ought to be the observable
effects of this law? Evidently, we should expect the character of one
species now and then to appear in species allied to it, or species of
kindred origin to vary in the same manner. In accordance with such
an expectation, we find the horse and the ass sometimes assuming the
stripes of the quagga and the zebra; certain varieties of the pigeon,
the fowl, the turkey, the canary-bird, the duck, and the goose, all
have top-knots or reversed feathers on their heads; one kind of melon
resembles a cucumber in everything but taste; there are purple-leaved
varieties of the beech and the hazel; and a great multitude of plants
sometimes exhibit their leaves cut, blotched, and variegated[11].
Now, from the working of Nature under, as it were, man’s guidance, we
pass to the working of Nature when left to her own discretion. The work
of Natural Selection is a very slow and secret work: the slowness of it
veils the movement. As with the hour-hand of a tiny watch travelling
but an inch in a day, there is progress which you cannot discern, there
is change that can be marked and registered at intervals, though each
successive moment and each successive movement seem to leave things
exactly as they were. You have heard of the Greek simpleton who had
been told that a raven lived three hundred years, and so bought one
to see. We might live three thousand years instead of three hundred
without being able to prove the theory of Natural Selection by actual
observing. But when a group of most important observed facts can be
explained consistently by this theory, and by none other, while no
fact has been brought forward to make it inadmissible, it ought to be
accepted till some theory can be produced equally unimpeachable and
explanatory of a larger group of facts.
Qualities are inherited; but with this peculiarity, that very
generally, and sometimes of necessity, the inheritor comes into
possession of the inherited quality at the same period of life at
which it was acquired by the parent. As, for instance, the child
of a gouty father, though it may be destined in old age to inherit
the disease, is not born with the gout, any more than a calf is born
with horns, or a cherry-tree produced covered with cherries. In the
life of every creature there is not merely growth, but development.
At every stage of life it is possible for some quality acquired by
variation to be fixed by Natural Selection. But in the embryonic and
earliest stages of development, variation is least likely to be of
service to any creature. Such variations, therefore, will less often
be selected than others, and if it be true that many species have a
common ancestry, then it ought to be found that in their embryonic
and earliest stages they resemble one another. This is precisely what
we do find. Plants, the most remote in appearance and properties when
full grown, differ but slightly in their cotyledons: the difference
between the egg of a nightingale and the egg of an ostrich bears no
proportion to the dissimilarity between the two birds when fully
developed; nor by comparing the roe of a herring with the roe of a
salmon could you possibly guess, before experience, how the full-grown
fish would differ. But in the life of every human being there is a
stage of development, at which the most sagacious physician could
not distinguish him from the embryo of a snake, a lizard, a bird, or
an ape[12]. Now, if the simplest embryonic forms of life were the
progenitors of all existing forms, this is intelligible; but how else
can it be explained?
But, again, if species do not vary, how comes it that those living at
the present day are for the most part not to be found among the fossil
creatures of the ancient rocks? Well, some will tell you there have
been many distinct creations, following after many catastrophes potent
to destroy all the previous inhabitants of the globe. Well, I will
answer, if you rest on Scripture, that view has no basis in Scripture,
but if you do not rest on Scripture, it certainly has no scientific
foundation, for though the crust of the globe has been made what it is
almost exclusively by the action of fire and water, the effect of any
sudden convulsions has been a mere nothing as compared with the results
from the steady, slow-going, ceaselessly-operating forces of those two
agents. Besides, when you look back through the rocks of different
ages, not only do you find some forms the same in all, which testifies
to the permanent unity of the living creation, but in those forms which
differ, you find the differences increasing the further you go back,
and some forms you find which have no modern representatives, forms,
that is, which have been beaten in the struggle for existence.
Travel over the globe, and every country will present you with some
new species; distant rivers, distant islands, in the ocean shallows
separated by great deeps, the opposite sides of a continent, the twin
sides of a mountain chain, the foot, the spur, the knee, the breast,
the snow-clad head of an Alpine range, will all present you with their
own peculiar forms of life. And how came they there? Created, some
will say, _in_ those regions and _for_ those regions, because of their
special adaptation to them. Yet, since the globe has been inhabited,
vast tracts of it have changed their climates from tropical heat to
frozen gloom, and again, yielded the thick-ribbed ice to genial suns
and fragrant zephyrs. Unhappy species, the creatures of a fixed idea,
created for the temperate meridian of Devonshire, and condemned by the
thoughtlessness of nature, to pass their lives in a climate like that
of Nova Zembla!
But further, had each species been assigned to its station as some
suppose, by a single act of creation, is it not reasonable, does not
reverence require us to expect, that each species would have been best
off in its own station? But this is not the case. On the contrary,
imported species of plants and animals often thrive prodigiously in
their new _habitat_, and over-run it.
Once more, we find in numberless plants and animals rudimentary organs
that are of no use to the possessors,--mammæ, that give no milk;
pistils, in male florets; in insects wings too small for flight, and
soldered to the wing cases; the fifth toe in the hind-foot of the
dog; the spur of the hen; the wing of the Apteryx; and the stunted,
ineffectual, but ever-present tail in our noble selves.
On the old theory of creation, in face of these facts, we cannot
save the admired doctrine that nature does nothing in vain; but on
the Darwinian theory of creation, that doctrine still holds good,
and wisdom is still justified by all her productions; for Natural
Selection works only for the good of a species; it does not work in
vain, or waste its efforts in getting rid of any organ simply because
it is useless, so long as it is not injurious; it leaves it as it was
and where it was, a germ, a capacity, perhaps, in the future, to be
re-developed or fitted for a new purpose.
Here we have incidentally touched upon what seems to be morally the
grandest part of the whole theory, an even sublime explanation, as
far as it goes, of that small fraction which we see in terrestrial
life of the great and manifold works of God. We noted above that it
is to death, a necessity much hated, much maligned, that we owe the
possibility of our own birth and standing-room on the face of the
globe; but the theory of Natural Selection makes it further clear
that the causes of death which we most dread and think evil of--war
and famine and pestilence--are tending continually to improve the
races of living creatures. On the whole, the wisest, the strongest,
the healthiest survive to propagate their species. In the long run,
prudence, courage, and temperance prevail, and their owners become the
parents of the later generations.
When the competition for life becomes severe, as to every race
of creatures, man included, it does at times become, the smallest
advantageous variation will give its possessor a superior chance of
surviving, while the smallest that is disadvantageous will diminish
the chance. Take the apposite instance of a number of quadrupeds
incapable of climbing, supported by browsing on the leaves of trees
during a dearth of other suitable food. When the lower leaves within
the general reach were exhausted, the famine still continuing, those
animals alone would survive which, by some peculiarity, could reach the
higher leaves. In this way, those that could spring best, those that
could assume even a climbing posture, those endowed with the longest
legs, snouts, or necks, would be selected. In some such a way, then, we
can conceive the jumping powers of the kangaroo and the antelope, the
climbing powers of the bear and the cat, the trunk of the elephant, and
the long neck of the giraffe to have been evolved by natural selection.
The keen scent of the hound, the sharp eye of the lynx, the gay colours
of the butterfly, the splendid plumage of the bird of Paradise, are all
easy to account for on this principle of natural selection. So, too,
are the dull colours of many female birds, to whom obscurity is useful
in protecting their young; so, too, the almost blindness of the mole,
which works in the dark, and to which an instrument at once delicate
and useless, would entail the risk of positive injury.
The principle explains what no other hypothesis has ever done, not
only Nature’s perfection, which, in the hour of ease, we are ready to
believe in, but what has hitherto been a much greater puzzle to those
who knew of its existence, Nature’s imperfection. The whole creation is
in constant travail to bring forth something better than its present
best. The products of man’s reason are not, you will readily admit,
always perfect, and yet man’s reason is a part of the creation, and
of nature’s work. The waste of life is prodigious, if such a term
is applicable to the circumstance that often millions of spores are
produced in order that half a dozen plants may grow; millions of eggs
in the roe of a fish, in order that the parents may be represented by
three or four individuals. The bee defends itself by its sting, but its
weapon of defence is fatal to itself. Were a merchant habitually to
send five or six million articles of merchandize across the Atlantic
on the bare possibility that five or six articles out of the number
might reach their destination; or, were a father to arm his son with
a weapon on the presumption that the first time he used it, it would
cost him his life; you would think the man mad, not wise. Yet, if the
astonishing fecundity of the braken, the mushroom, and the codfish, if
the sting of the bee with its backward serratures, be the products of
direct creation, the analogy is somewhat telling. How different, on
the other hand, must our judgment be of those contrivances, when we
trace them to the simple, primary, beneficent law of natural selection,
working always steadily for the good of each species, and so working,
that we may feel tolerably sure that when any species dies out and
disappears, it has been replaced by something better. For by this law,
we see that fertility itself is a character which will be selected as
tending to the preservation of a species, and that many creatures must
have acquired the power of what looks like wasteful reproduction in the
long-continued struggle for existence. We can see, too, how in that
same struggle, it may have proved expedient for a creature to be armed
with a weapon capable of inspiring terror, yet so contrived that its
possessor should, of necessity, be peaceful towards its neighbours.
True, this might have been done by a single act of creation, but why,
then, was it not done also in the case of the mosquito, the wasp, and
the hornet?
On the theory of sudden creation, how can we account in any but an
arbitrary manner, for the innumerable cases in which slight differences
separate various species; for the confused neutral ground between
different classes, as where, for example, a creature seems half animal
half plant; for the isolation of many forms from the stations they
are admirably fitted to occupy; for the fact that many creatures are
hideous, weak, timid, violent, and venomous; for the imperfection of an
instinct in one species found perfected in another, which Mr. Darwin
exemplifies by comparing the cells of the humble-bee, the _melipona
domestica_ of Mexico, and the hive-bee, ranging from great simplicity
to an extreme perfection[13]? But the principle of natural selection
offers a solution to every one of these enigmas. It embraces all the
various phases of life of the ancient world as well as the modern, and
gives a key to the whole grand uninterrupted plan. It carries back the
mind to a period when the earth was destitute of life; when yet, as it
were, the thought in the Divine mind was still unspoken, that of one,
and that as good as dead, should spring seed like the sand which is
upon the sea-shore for multitude. Then it came to pass that the dust
of the earth was called into life by the Life-Giver, and received the
strange command and the mysterious power to multiply, and to replenish
the earth. As soon as living creatures multiplied to any great extent,
they would spread themselves into different lands and seas and
climates; they would find different sources of nourishment, and then
variation would come into play, and close upon variation would follow
selection, not of necessity destroying the old forms, but establishing
new ones, because in some stations the form that had not varied might
thrive best, in others the variety would have an advantage[14]. As time
went on, through the constant changes that the surface of the globe is
undergoing, one variety would be isolated from another, and in such
an isolation the differences would increase. And the more a species
varied, the more fitted it might become for some _habitat_, from which
it was completely cut off by a chain of mountains, a rapid river,
or a deep sea. As the competition became more intense, variations
would become more and more valuable, enabling creatures to occupy
positions before untenable, ocean-depths, sandy shores, holes in rocks,
fresh-water lakes, tops of mountains, branches of trees, the bodies
of other living beings. Some would be taught by necessity and enabled
by favourable variations to prey, as well as take up their abode, on
other creatures. And as the strife became more and more urgent, all
sorts of qualities that from our point of view may seem noxious and
degrading might prove of the highest service and advantage to their own
possessors. Plants with sharp thorns and envenomed hairs, poisonous
snakes, trichinæ and other parasites horrible to man, would find their
advantage at our cost, or by unparalleled fertility would defy all
efforts to extirpate them. Some species would profit by minuteness,
others by size; others, in various ways, by talons, beak, thread-like
tongue, prehensile tail, or furry coat; and, just as men are said to
go through fire and water for the sake of money, so for the sake of
preservation, no habit, no locality would be too uncongenial for a
species to develope adaptation thereunto. And, accordingly, we find
that the water-ouzel, which is a species of thrush, subsists entirely
by diving; there is a tree-climbing lobster in the Mauritius; there
are fishes which ramble about on the land, and one fish, the _anabas
scandens_, can climb eight or ten feet up the trunk of a palm[15].
The choice of food, the choice of habitation, the construction of
dwelling-places for themselves or their offspring, methods of defence,
methods of attack, are variously carried out by myriads of species.
The processes employed, in man we call for the most part rational; in
the lower animals we call them instinctive; but there are processes
employed for these self-same objects by vegetables as well as by men.
For plants, in one sense stationary, travel towards water by their
roots, towards light by their branches; they assimilate the elements of
nutriment that suit them, rejecting others. The Sensitive plant shrinks
from the touch, Venus’s fly-trap closes round unwary insects and
destroys them. Tendrils fasten on the supports that are offered them.
Trees keep in their delicate blossoms till the weather is genial. Many
a corolla folds carefully round stamens and pistils when the chilly
twilight approaches.