given, are fully accounted for by the "Law of Variation" as laid down at
the commencement of this paper. Universal variability--small in amount
but in every direction, ever fluctuating about a mean condition until
made to advance in a given direction by "election," natural or
artificial,--is the simple basis for the indefinite modification of the
forms of life;--partial, unbalanced, and consequently unstable
modifications being produced by man, while those developed under the
unrestrained action of natural laws, are at every step self-adjusted to
external conditions by the dying out of all unadjusted forms, and are
therefore stable and comparatively permanent. To be consistent in their
views, our opponents must maintain that every one of the variations that
have rendered possible the changes produced by man, have been determined
at the right time and place by the will of the Creator. Every race
produced by the florist or the breeder, the dog or the pigeon fancier,
the ratcatcher, the sporting man, or the slave-hunter, must have been
provided for by varieties occurring when wanted; and as these variations
were never withheld, it would prove, that the sanction of an all-wise
and all-powerful Being, has been given to that which the highest human
minds consider to be trivial, mean, or debasing.
This appears to be a complete answer to the theory, that variation
sufficient in amount to be accumulated in a given direction must be the
direct act of the Creative Mind, but it is also sufficiently condemned
by being so entirely unnecessary. The facility with which man obtains
new races, depends chiefly upon the number of individuals he can procure
to select from. When hundreds of florists or breeders are all aiming at
the same object, the work of change goes on rapidly. But a common
species in nature contains a thousand-or a million-fold more individuals
than any domestic race; and survival of the fittest must unerringly
preserve all that vary in the right direction, not only in obvious
characters but in minute details, not only in external but in internal
organs; so that if the materials are sufficient for the needs of man,
there can be no want of them to fulfil the grand purpose of keeping up a
supply of modified organisms, exactly adapted to the changed conditions
that are always occurring in the inorganic world.
_The Objection that there are Limits to Variation._
Having now, I believe, fairly answered the chief objections of the Duke
of Argyll, I proceed to notice one or two of those adduced in an able
and argumentative essay on the "Origin of Species" in the _North British
Review_ for July, 1867. The writer first attempts to prove that there
are strict limits to variation. When we begin to select variations in
any one direction, the process is comparatively rapid, but after a
considerable amount of change has been effected it becomes slower and
slower, till at length its limits are reached and no care in breeding
and selection can produce any further advance. The race-horse is chosen
as an example. It is admitted that, with any ordinary lot of horses to
begin with, careful selection would in a few years make a great
improvement, and in a comparatively short time the standard of our best
racers might be reached. But that standard has not for many years been
materially raised, although unlimited wealth and energy are expended in
the attempt. This is held to prove that there are definite limits to
variation in any special direction, and that we have no reason to
suppose that mere time, and the selective process being carried on by
natural law, could make any material difference. But the writer does not
perceive that this argument fails to meet the real question, which is,
not whether indefinite and unlimited change in any or all directions is
possible, but whether such differences as do occur in nature could have
been produced by the accumulation of variations by selection. In the
matter of speed, a limit of a definite kind as regards land animals does
exist in nature. All the swiftest animals--deer, antelopes, hares,
foxes, lions, leopards, horses, zebras, and many others, have reached
very nearly the same degree of speed. Although the swiftest of each must
have been for ages preserved, and the slowest must have perished, we
have no reason to believe there is any advance of speed. The possible
limit under existing conditions, and perhaps under possible terrestrial
conditions, has been long ago reached. In cases, however, where this
limit had not been so nearly reached as in the horse, we have been
enabled to make a more marked advance and to produce a greater
difference of form. The wild dog is an animal that hunts much in
company, and trusts more to endurance than to speed. Man has produced
the greyhound, which differs much more from the wolf or the dingo than
the racer does from the wild Arabian. Domestic dogs, again, have varied
more in size and in form than the whole family of Canidae in a state of
nature. No wild dog, fox, or wolf, is either so small as some of the
smallest terriers and spaniels, or so large as the largest varieties of
hound or Newfoundland dog. And, certainly, no two wild animals of the
family differ so widely in form and proportions as the Chinese pug and
the Italian greyhound, or the bulldog and the common greyhound. The
known range of variation is, therefore, more than enough for the
derivation of all the forms of Dogs, Wolves, and Foxes from a common
ancestor.
Again, it is objected that the Pouter or the Fan-tail pigeon cannot be
further developed in the same direction. Variation seems to have reached
its limits in these birds. But so it has in nature. The Fan-tail has not
only more tail feathers than any of the three hundred and forty existing
species of pigeons, but more than any of the eight thousand known
species of birds. There is, of course, some limit to the number of
feathers of which a tail useful for flight can consist, and in the
Fan-tail we have probably reached that limit. Many birds have the
oesophagus or the skin of the neck more or less dilatable, but in no
known bird is it so dilatable as in the Pouter pigeon. Here again the
possible limit, compatible with a healthy existence, has probably been
reached. In like manner the differences in the size and form of the beak
in the various breeds of the domestic Pigeon, is greater than that
between the extreme forms of beak in the various genera and sub-families
of the whole Pigeon tribe. From these facts, and many others of the same
nature, we may fairly infer, that if rigid selection were applied to any
organ, we could in a comparatively short time produce a much greater
amount of change than that which occurs between species and species in a
state of nature, since the differences which we do produce are often
comparable with those which exist between distinct genera or distinct
families. The facts adduced by the writer of the article referred to, of
the definite limits to variability in certain directions in domesticated
animals, are, therefore, no objection whatever to the view, that all the
modifications which exist in nature have been produced by the
accumulation, by natural selection, of small and useful variations,
since those very modifications have equally definite and very similar
limits.
_Objection to the Argument from Classification._
To another of this writer's objections--that by Professor Thomson's
calculations the sun can only have existed in a solid state 500,000,000
of years, and that therefore _time_ would not suffice for the slow
process of development of all living organisms--it is hardly necessary
to reply, as it cannot be seriously contended, even if this calculation
has claims to approximate accuracy, that the process of change and
development may not have been sufficiently rapid to have occurred within
that period. His objection to the Classification argument is, however,
more plausible. The uncertainty of opinion among Naturalists as to which
are species and which varieties, is one of Mr. Darwin's very strong
arguments that these two names cannot belong to things quite distinct in
nature and origin. The Reviewer says that this argument is of no weight,
because the works of man present exactly the same phenomena; and he
instances patent inventions, and the excessive difficulty of determining
whether they are new or old. I accept the analogy though it is a very
imperfect one, and maintain that such as it is, it is all in favour of
Mr. Darwin's views. For are not all inventions of the same kind directly
affiliated to a common ancestor? Are not improved Steam Engines or
Clocks the lineal descendants of some existing Steam Engine or Clock? Is
there ever a new Creation in Art or Science any more than in Nature? Did
ever patentee absolutely originate any complete and entire invention, no
portion of which was derived from anything that had been made or
described before? It is therefore clear that the difficulty of
distinguishing the various classes of inventions which claim to be new,
is of the same nature as the difficulty of distinguishing varieties and
species, because neither are absolute new creations, but both are alike
descendants of pre-existing forms, from which and from each other they
differ by varying and often imperceptible degrees. It appears, then,
that however plausible this writer's objections may seem, whenever he
descends from generalities to any specific statement, his supposed
difficulties turn out to be in reality strongly confirmatory of Mr.
Darwin's view.
_The "Times," on Natural Selection._
The extraordinary misconception of the whole subject by popular writers
and reviewers, is well shown by an article which appeared in the _Times_
newspaper on "The Reign of Law." Alluding to the supposed economy of
nature, in the adaptation of each species to its own place and its
special use, the reviewer remarks: "To this universal law of the
greatest economy, the law of natural selection stands in direct
antagonism as the law of 'greatest possible waste' of time and of
creative power. To conceive a duck with webbed feet and a spoon-shaped
bill, living by suction, to pass naturally into a gull with webbed feet
and a knife-like bill, living on flesh, in the longest possible time and
in the most laborious possible way, we may conceive it to pass from the
one to the other state by natural selection. The battle of life the
ducks will have to fight will increase in peril continually as they
cease (with the change of their bill) to be ducks, and attain a
_maximum_ of danger in the condition in which they begin to be gulls;
and ages must elapse and whole generations must perish, and countless
generations of the one species be created and sacrificed, to arrive at
one single pair of the other."
In this passage the theory of natural selection is so absurdly
misrepresented that it would be amusing, did we not consider the
misleading effect likely to be produced by this kind of teaching in so
popular a journal. It is assumed that the duck and the gull are
essential parts of nature, each well fitted for its place, and that if
one had been produced from the other by a gradual metamorphosis, the
intermediate forms would have been useless, unmeaning, and unfitted for
any place, in the system of the universe. Now, this idea can only exist
in a mind ignorant of the very foundation and essence of the theory of
natural selection, which is, the preservation of _useful_ variations
only, or, as has been well expressed, in other words, the "survival of
the fittest." Every intermediate form which could possibly have arisen
during the transition from the duck to the gull, so far from having an
unusually severe battle to fight for existence, or incurring any
"_maximum_ of danger," would necessarily have been as accurately
adjusted to the rest of nature, and as well fitted to maintain and to
enjoy its existence, as the duck or the gull actually are. If it were
not so, it never could have been produced under the law of natural
selection.
_Intermediate or generalized Forms of extinct Animals, an indication of
Transmutation or Development._
The misconception of this writer illustrates another point very
frequently overlooked. It is an essential part of Mr. Darwin's theory,
that one existing animal has not been derived from any other existing
animal, but that both are the descendants of a common ancestor, which
was at once different from either, but, in essential characters,
intermediate between them both. The illustration of the duck and the
gull is therefore misleading; one of these birds has not been derived
from the other, but both from a common ancestor. This is not a mere
supposition invented to support the theory of natural selection, but is
founded on a variety of indisputable facts. As we go back into past
time, and meet with the fossil remains of more and more ancient races of
extinct animals, we find that many of them actually are intermediate
between distinct groups of existing animals. Professor Owen continually
dwells on this fact: he says in his "Palaeontology," p. 284: "A more
generalized vertebrate structure is illustrated, in the extinct
reptiles, by the affinities to ganoid fishes, shown by Ganocephala,
Labyrinthodontia, and Icthyopterygia; by the affinities of the
Pterosauria to Birds, and by the approximation of the Dinosauria to
Mammals. (These have been recently shown by Professor Huxley to have
more affinity to Birds.) It is manifested by the combination of modern
crocodilian, chelonian, and lacertian characters in the Cryptodontia
and the Dicnyodontia, and by the combined lacertian and crocodilian
characters in the Thecodontia and Sauropterygia." In the same work he
tells us that, "the Anoplotherium, in several important characters
resembled the embryo Ruminant, but retained throughout life those marks
of adhesion to a generalized mammalian type;"--and assures us that he
has "never omitted a proper opportunity for impressing the results of
observations showing the more generalized structures of extinct as
compared with the more specialized forms of recent animals." Modern
palaeontologists have discovered hundreds of examples of these more
generalized or ancestral types. In the time of Cuvier, the Ruminants and
the Pachyderms were looked upon as two of the most distinct orders of
animals; but it is now demonstrated that there once existed a variety of
genera and species, connecting by almost imperceptible grades such
widely different animals as the pig and the camel. Among living
quadrupeds we can scarcely find a more isolated group than the genus
Equus, comprising the horses, asses, and Zebras; but through many
species of Paloplotherium, Hippotherium, and Hipparion, and numbers of
extinct forms of Equus found in Europe, India, and America, an almost
complete transition is established with the Eocene Anoplothorium and
Paleotherium, which are also generalized or ancestral types of the Tapir
and Rhinoceros. The recent researches of M. Gaudry in Greece have
furnished much new evidence of the same character. In the Miocene beds
of Pikermi he has discovered the group of the Simocyonidae intermediate
between bears and wolves; the genus Hyaenictis which connects the hyaenas
with the civets; the Ancylotherium, which is allied both to the extinct
mastodon and to the living pangolin or scaly ant-eater; and the
Helladotherium, which connects the now isolated giraffe with the deer
and antelopes.
Between reptiles and fishes an intermediate type has been found in the
Archegosaurus of the Coal formation; while the Labyrinthodon of the
Trias combined characters of the Batrachia with those of crocodiles,
lizards, and ganoid fishes. Even birds, the most apparently isolated of
all living forms, and the most rarely preserved in a fossil state, have
been shown to possess undoubted affinities with reptiles; and in the
Oolitic Archaeopteryx, with its lengthened tail, feathered on each side,
we have one of the connecting links from the side of birds; while
Professor Huxley has recently shown that the entire order of
Dinosaurians have remarkable affinities to birds, and that one of them,
the Compsognathus, makes a nearer approach to bird organisation than
does Archaeopteryx to that of reptiles.
Analogous facts to those occur in other classes of animals, as
an example of which we have the authority of a distinguished
paleontologist, M. Barande, quoted by Mr. Darwin, for the statement,
that although the Palaeozoic Invertebrata can certainly be classed under
existing groups, yet at this ancient period the groups were not so
distinctly separated from each other as they are now; while Mr. Scudder
tells us, that some of the fossil insects discovered in the Coal
formation of America offer characters intermediate between those of
existing orders. Agassiz, again, insists strongly that the more ancient
animals resemble the embryonic forms of existing species; but as the
embryos of distinct groups are known to resemble each other more than
the adult animals (and in fact to be undistinguishable at a very early
age), this is the same as saying that the ancient animals are exactly
what, on Darwin's theory, the ancestors of existing animals ought to be;
and this, it must be remembered, is the evidence of one of the strongest
opponents of the theory of natural selection.
_Conclusion._
I have thus endeavoured to meet fairly, and to answer plainly, a few of
the most common objections to the theory of natural selection, and I
have done so in every case by referring to admitted facts and to logical
deductions from those facts.
As an indication and general summary of the line of argument I have
adopted, I here give a brief demonstration in a tabular form of the
Origin of Species by means of Natural Selection, referring for the
_facts_ to Mr. Darwin's works, and to the pages in this volume, where
they are more or less fully treated.
_A Demonstration of the Origin of Species by Natural Selection_.
___________________________________________________________________
| | |
|_PROVED FACTS_. |_NECESSARY CONSEQUENCES_ |
| |(_afterwards taken as Proved |
| |Facts_). |
|_________________________________|_________________________________|
| | |
|RAPID INCREASE OF ORGANISMS, | |
|pp. 29, 265; ("Origin |STRUGGLE FOR EXISTENCE, |
|of Species," p. 75, 5th Ed.) |the deaths equalling the |
| |births on the average, p. 30; |
|TOTAL NUMBER OF INDIVIDUALS |("Origin of Species," chap. |
|STATIONARY, pp. 30, |III.) |
|266. | |
|_________________________________|_________________________________|
| | |
|STRUGGLE FOR EXISTENCE. |SURVIVAL OF THE FITTEST, |
| |or Natural Selection; meaning |
|HEREDITY WITH VARIATION, |simply, that on the |
|or general likeness with |whole those die who are |
|individual differences of parents|least fitted to maintain their |
|and offspring, pp. |existence; ("Origin of Species," |
|266, 287-291, 308; ("Origin |chap. IV.) |
|of Species," chap. I., II., V.) | |
|_________________________________|_________________________________|
| | |
|SURVIVAL OF THE FITTEST. |CHANGES OF ORGANIC FORMS, |
| |to keep them in harmony |
|CHANGE OF EXTERNAL CONDITIONS, |with the Changed Conditions; |
|universal and unceasing.--See |and as the changes |
|"Lyell's |of conditions are permanent |
|Principles of Geology." |changes, in the sense |
| |of not reverting back to |
| |identical previous conditions, |
| |the changes of organic |
| |forms must be in the |
| |same sense permanent, and |
| |thus originate SPECIES. |
|_________________________________|_________________________________|
IX.
THE DEVELOPMENT OF HUMAN RACES UNDER THE LAW OF NATURAL SELECTION.
Among the most advanced students of man, there exists a wide difference
of opinion on some of the most vital questions respecting his nature and
origin. Anthropologists are now, indeed, pretty well agreed that man is
not a recent introduction into the earth. All who have studied the
question, now admit that his antiquity is very great; and that, though
we have to some extent ascertained the minimum of time during which he
_must_ have existed, we have made no approximation towards determining
that far greater period during which he _may_ have, and probably _has_
existed. We can with tolerable certainty affirm that man must have
inhabited the earth a thousand centuries ago, but we cannot assert that
he positively did not exist, or that there is any good evidence against
his having existed, for a period of ten thousand centuries. We know
positively, that he was contemporaneous with many now extinct animals,
and has survived changes of the earth's surface fifty or a hundred times
greater than any that have occurred during the historical period; but we
cannot place any definite limit to the number of species he may have
outlived, or to the amount of terrestrial change he may have witnessed.
_Wide differences of opinion as to Man's Origin._
But while on this question of man's antiquity there is a very general
agreement,--and all are waiting eagerly for fresh evidence to clear up
those points which all admit to be full of doubt,--on other, and not
less obscure and difficult questions, a considerable amount of dogmatism
is exhibited; doctrines are put forward as established truths, no doubt
or hesitation is admitted, and it seems to be supposed that no further
evidence is required, or that any new facts can modify our convictions.
This is especially the case when we inquire,--Are the various forms
under which man now exists primitive, or derived from pre-existing
forms; in other words, is man of one or many species? To this question
we immediately obtain distinct answers diametrically opposed to each
other: the one party positively maintaining, that man is a _species_ and
is essentially _one_--that all differences are but local and temporary
variations, produced by the different physical and moral conditions by
which he is surrounded; the other party maintaining with equal
confidence, that man is a genus of _many species_, each of which is
practically unchangeable, and has ever been as distinct, or even more
distinct, than we now behold them. This difference of opinion is
somewhat remarkable, when we consider that both parties are well
acquainted with the subject; both use the same vast accumulation of
facts; both reject those early traditions of mankind which profess to
give an account of his origin; and both declare that they are seeking
fearlessly after truth alone; yet each will persist in looking only at
the portion of truth on his own side of the question, and at the error
which is mingled with his opponent's doctrine. It is my wish to show how
the two opposing views can be combined, so as to eliminate the error and
retain the truth in each, and it is by means of Mr. Darwin's celebrated
theory of "Natural Selection" that I hope to do this, and thus to
harmonise the conflicting theories of modern anthropologists.
Let us first see what each party has to say for itself. In favour of the
unity of mankind it is argued, that there are no races without
transitions to others; that every race exhibits within itself variations
of colour, of hair, of feature, and of form, to such a degree as to
bridge over, to a large extent, the gap that separates it from other
races. It is asserted that no race is homogeneous; that there is a
tendency to vary; that climate, food, and habits produce, and render
permanent, physical peculiarities, which, though slight in the limited
periods allowed to our observation, would, in the long ages during which
the human race has existed, have sufficed to produce all the differences
that now appear. It is further asserted that the advocates of the
opposite theory do not agree among themselves; that some would make
three, some five, some fifty or a hundred and fifty species of man; some
would have had each species created in pairs, while others require
nations to have at once sprung into existence, and that there is no
stability or consistency in any doctrine but that of one primitive
stock.