investigation than another, it is, that the vast series of extinct
animals and plants is not divisible, as it was once supposed to be, into
distinct groups, separated by sharply-marked boundaries. There are no
great gulfs between epochs and formations--no successive periods marked
by the appearance of plants, of water animals, and of land animals,
'en masse'. Every year adds to the list of links between what the older
geologists supposed to be widely separated epochs: witness the crags
linking the drift with older tertiaries; the Maestricht beds linking the
tertiaries with the chalk; the St. Cassian beds exhibiting an abundant
fauna of mixed mesozoic and palaeozoic types, in rocks of an epoch once
supposed to be eminently poor in life; witness, lastly, the incessant
disputes as to whether a given stratum shall be reckoned devonian or
carboniferous, silurian or devonian, cambrian or silurian.
This truth is further illustrated in a most interesting manner by
the impartial and highly competent testimony of M. Pictet, from whose
calculations of what percentage of the genera of animals, existing in
any formation, lived during the preceding formation, it results that in
no case is the proportion less than 'one-third', or 33 per cent. It is
the triassic formation, or the commencement of the mesozoic epoch, which
has received the smallest inheritance from preceding ages. The other
formations not uncommonly exhibit 60, 80, or even 94 per cent. of genera
in common with those whose remains are imbedded in their predecessor.
Not only is this true, but the subdivisions of each formation exhibit
new species characteristic of, and found only in, them; and, in
many cases, as in the lias for example, the separate beds of these
subdivisions are distinguished by well-marked and peculiar forms of
life. A section, a hundred feet thick, will exhibit, at different
heights, a dozen species of ammonite, none of which passes beyond its
particular zone of limestone, or clay, into the zone below it or into
that above it; so that those who adopt the doctrine of special creation
must be prepared to admit, that at intervals of time, corresponding with
the thickness of these beds, the Creator thought fit to interfere with
the natural course of events for the purpose of making a new ammonite.
It is not easy to transplant oneself into the frame of mind of those who
can accept such a conclusion as this, on any evidence short of absolute
demonstration; and it is difficult to see what is to be gained by so
doing, since, as we have said, it is obvious that such a view of the
origin of living beings is utterly opposed to the Hebrew cosmogony.
Deserving no aid from the powerful arm of Bibliolatry, then, does the
received form of the hypothesis of special creation derive any support
from science or sound logic? Assuredly not much. The arguments
brought forward in its favour all take one form: If species were not
supernaturally created, we cannot understand the facts 'x' or 'y', or
'z'; we cannot understand the structure of animals or plants, unless we
suppose they were contrived for special ends; we cannot understand the
structure of the eye, except by supposing it to have been made to see
with; we cannot understand instincts, unless we suppose animals to have
been miraculously endowed with them.
As a question of dialectics, it must be admitted that this sort of
reasoning is not very formidable to those who are not to be frightened
by consequences. It is an 'argumentum ad ignorantiam'--take this
explanation or be ignorant.
But suppose we prefer to admit our ignorance rather than adopt a
hypothesis at variance with all the teachings of Nature? Or, suppose for
a moment we admit the explanation, and then seriously ask ourselves how
much the wiser are we; what does the explanation explain? Is it any more
than a grandiloquent way of announcing the fact, that we really know
nothing about the matter? A phenomenon is explained when it is shown
to be a case of some general law of Nature; but the supernatural
interposition of the Creator can, by the nature of the case, exemplify
no law, and if species have really arisen in this way, it is absurd to
attempt to discuss their origin.
Or, lastly, let us ask ourselves whether any amount of evidence which
the nature of our faculties permits us to attain, can justify us in
asserting that any phenomenon is out of the reach of natural causation.
To this end it is obviously necessary that we should know all the
consequences to which all possible combinations, continued through
unlimited time, can give rise. If we knew these, and found none
competent to originate species, we should have good ground for denying
their origin by natural causation. Till we know them, any hypothesis is
better than one which involves us in such miserable presumption.
But the hypothesis of special creation is not only a mere specious
mask for our ignorance; its existence in Biology marks the youth and
imperfection of the science. For what is the history of every science
but the history of the elimination of the notion of creative, or other
interferences, with the natural order of the phenomena which are the
subject-matter of that science? When Astronomy was young "the morning
stars sang together for joy," and the planets were guided in their
courses by celestial hands. Now, the harmony of the stars has resolved
itself into gravitation according to the inverse squares of the
distances, and the orbits of the planets are deducible from the laws
of the forces which allow a schoolboy's stone to break a window. The
lightning was the angel of the Lord; but it has pleased Providence, in
these modern times, that science should make it the humble messenger of
man, and we know that every flash that shimmers about the horizon on a
summer's evening is determined by ascertainable conditions, and that
its direction and brightness might, if our knowledge of these were great
enough, have been calculated.
The solvency of great mercantile companies rests on the validity of the
laws which have been ascertained to govern the seeming irregularity
of that human life which the moralist bewails as the most uncertain of
things; plague, pestilence, and famine are admitted, by all but fools,
to be the natural result of causes for the most part fully within
human control, and not the unavoidable tortures inflicted by wrathful
Omnipotence upon His helpless handiwork.
Harmonious order governing eternally continuous progress--the web and
woof of matter and force interweaving by slow degrees, without a broken
thread, that veil which lies between us and the Infinite--that universe
which alone we know or can know; such is the picture which science draws
of the world, and in proportion as any part of that picture is in unison
with the rest, so may we feel sure that it is rightly painted. Shall
Biology alone remain out of harmony with her sister sciences?
Such arguments against the hypothesis of the direct creation of species
as these are plainly enough deducible from general considerations; but
there are, in addition, phenomena exhibited by species themselves, and
yet not so much a part of their very essence as to have required earlier
mention, which are in the highest degree perplexing, if we adopt the
popularly accepted hypothesis. Such are the facts of distribution in
space and in time; the singular phenomena brought to light by the study
of development; the structural relations of species upon which
our systems of classification are founded; the great doctrines of
philosophical anatomy, such as that of homology, or of the community
of structural plan exhibited by large groups of species differing very
widely in their habits and functions.
The species of animals which inhabit the sea on opposite sides of the
isthmus of Panama are wholly distinct [4] the animals and plants which
inhabit islands are commonly distinct from those of the neighbouring
mainlands, and yet have a similarity of aspect.
The mammals of the latest tertiary epoch in the Old and New Worlds
belong to the same genera, or family groups, as those which now inhabit
the same great geographical area. The crocodilian reptiles which existed
in the earliest secondary epoch were similar in general structure to
those now living, but exhibit slight differences in their vertebrae,
nasal passages, and one or two other points. The guinea-pig has teeth
which are shed before it is born, and hence can never subserve the
masticatory purpose for which they seem contrived, and, in like manner,
the female dugong has tusks which never cut the gum. All the members
of the same great group run through similar conditions in their
development, and all their parts, in the adult state, are arranged
according to the same plan. Man is more like a gorilla than a gorilla is
like a lemur. Such are a few, taken at random, among the multitudes
of similar facts which modern research has established; but when the
student seeks for an explanation of them from the supporters of the
received hypothesis of the origin of species, the reply he receives
is, in substance, of Oriental simplicity and brevity--"Mashallah! it
so pleases God!" There are different species on opposite sides of the
isthmus of Panama, because they were created different on the two sides.
The pliocene mammals are like the existing ones, because such was the
plan of creation; and we find rudimental organs and similarity of plan,
because it has pleased the Creator to set before Himself a "divine
exemplar or archetype," and to copy it in His works; and somewhat
ill, those who hold this view imply, in some of them. That such verbal
hocus-pocus should be received as science will one day be regarded as
evidence of the low state of intelligence in the nineteenth century,
just as we amuse ourselves with the phraseology about Nature's
abhorrence of a vacuum, wherewith Torricelli's compatriots were
satisfied to explain the rise of water in a pump. And be it recollected
that this sort of satisfaction works not only negative but positive ill,
by discouraging inquiry, and so depriving man of the usufruct of one of
the most fertile fields of his great patrimony, Nature.
The objections to the doctrine of the origin of species by special
creation which have been detailed, must have occurred, with more or
less force, to the mind of every one who has seriously and independently
considered the subject. It is therefore no wonder that, from time to
time, this hypothesis should have been met by counter hypotheses, all as
well, and some better founded than itself; and it is curious to remark
that the inventors of the opposing views seem to have been led into them
as much by their knowledge of geology, as by their acquaintance with
biology. In fact, when the mind has once admitted the conception of
the gradual production of the present physical state of our globe, by
natural causes operating through long ages of time, it will be little
disposed to allow that living beings have made their appearance in
another way, and the speculations of De Maillet and his successors are
the natural complement of Scilla's demonstration of the true nature of
fossils.
A contemporary of Newton and of Leibnitz, sharing therefore in the
intellectual activity of the remarkable age which witnessed the birth
of modern physical science, Benoit de Maillet spent a long life as a
consular agent of the French Government in various Mediterranean ports.
For sixteen years, in fact, he held the office of Consul-General in
Egypt, and the wonderful phenomena offered by the valley of the Nile
appear to have strongly impressed his mind, to have directed his
attention to all facts of a similar order which came within his
observation, and to have led him to speculate on the origin of the
present condition of our globe and of its inhabitants. But, with all his
ardour for science, De Maillet seems to have hesitated to publish views
which, notwithstanding the ingenious attempts to reconcile them with the
Hebrew hypothesis contained in the preface to "Telliamed," were hardly
likely to be received with favour by his contemporaries.
But a short time had elapsed since more than one of the great anatomists
and physicists of the Italian school had paid dearly for their
endeavours to dissipate some of the prevalent errors; and their
illustrious pupil, Harvey, the founder of modern physiology, had not
fared so well, in a country less oppressed by the benumbing influences
of theology, as to tempt any man to follow his example. Probably
not uninfluenced by these considerations, his Catholic majesty's
Consul-General for Egypt kept his theories to himself throughout a long
life, for 'Telliamed,' the only scientific work which is known to have
proceeded from his pen, was not printed till 1735, when its author had
reached the ripe age of seventy-nine; and though De Maillet lived three
years longer, his book was not given to the world before 1748. Even then
it was anonymous to those who were not in the secret of the anagrammatic
character of its title; and the preface and dedication are so worded as,
in case of necessity, to give the printer a fair chance of falling back
on the excuse that the work was intended for a mere 'jeu d'esprit'.
The speculations of the suppositious Indian sage, though quite as sound
as those of many a "Mosaic Geology," which sells exceedingly well, have
no great value if we consider them by the light of modern science. The
waters are supposed to have originally covered the whole globe; to have
deposited the rocky masses which compose its mountains by processes
comparable to those which are now forming mud, sand, and shingle; and
then to have gradually lowered their level, leaving the spoils of their
animal and vegetable inhabitants embedded in the strata. As the dry land
appeared, certain of the aquatic animals are supposed to have taken to
it, and to have become gradually adapted to terrestrial and aerial
modes of existence. But if we regard the general tenor and style of
the reasoning in relation to the state of knowledge of the day, two
circumstances appear very well worthy of remark. The first, that De
Maillet had a notion of the modifiability of living forms (though
without any precise information on the subject), and how such
modifiability might account for the origin of species; the second, that
he very clearly apprehended the great modern geological doctrine,
so strongly insisted upon by Hutton, and so ably and comprehensively
expounded by Lyell, that we must look to existing causes for the
explanation of past geological events. Indeed, the following passage
of the preface, in which De Maillet is supposed to speak of the Indian
philosopher Telliamed, his 'alter ego', might have been written by the
most philosophical uniformitarian of the present day:--
"Ce qu'il y a d'etonnant, est que pour arriver a ces connoissances il
semble avoir perverti l'ordre naturel, puisqu'au lieu de s'attacher
d'abord a rechercher l'origine de notre globe il a commence par
travailler a s'instruire de la nature. Mais a l'entendre, ce
renversement de l'ordre a ete pour lui l'effet d'un genie favorable
qui l'a conduit pas a pas et comme par la main aux decouvertes les plus
sublimes. C'est en decomposant la substance de ce globe par une anatomie
exacte de toutes ses parties qu'il a premierement appris de quelles
matieres il etait compose et quels arrangemens ces memes matieres
observaient entre elles. Ces lumieres jointes a l'esprit de comparaison
toujours necessaire a quiconque entreprend de percer les voiles dont
la nature aime a se cacher, ont servi de guide a notre philosophe pour
parvenir a des connoissances plus interessantes. Par la matiere et
l'arrangement de ces compositions il pretend avoir reconnu quelle est la
veritable origine de ce globe que nous habitons, comment et par qui il a
ete forme."--Pp. xix. xx.
But De Maillet was before his age, and as could hardly fail to happen
to one who speculated on a zoological and botanical question before
Linnaeus, and on a physiological problem before Haller, he fell into
great errors here and there; and hence, perhaps, the general neglect of
his work. Robinet's speculations are rather behind, than in advance
of, those of De Maillet; and though Linnaeus may have played with
the hypothesis of transmutation, it obtained no serious support
until Lamarck adopted it, and advocated it with great ability in his
'Philosophie Zoologique.'
Impelled towards the hypothesis of the transmutation of species,
partly by his general cosmological and geological views; partly by the
conception of a graduated, though irregularly branching, scale of being,
which had arisen out of his profound study of plants and of the lower
forms of animal life, Lamarck, whose general line of thought often
closely resembles that of De Maillet, made a great advance upon the
crude and merely speculative manner in which that writer deals with
the question of the origin of living beings, by endeavouring to find
physical causes competent to effect that change of one species into
another, which De Maillet had only supposed to occur. And Lamarck
conceived that he had found in Nature such causes, amply sufficient for
the purpose in view. It is a physiological fact, he says, that organs
are increased in size by action, atrophied by inaction; it is another
physiological fact that modifications produced are transmissible to
offspring. Change the actions of an animal, therefore, and you will
change its structure, by increasing the development of the parts newly
brought into use and by the diminution of those less used; but by
altering the circumstances which surround it you will alter its actions,
and hence, in the long run, change of circumstance must produce
change of organization. All the species of animals, therefore, are,
in Lamarck's view, the result of the indirect action of changes of
circumstance, upon those primitive germs which he considered to have
originally arisen, by spontaneous generation, within the waters of the
globe. It is curious, however, that Lamarck should insist so strongly
[5] as he has done, that circumstances never in any degree directly
modify the form or the organization of animals, but only operate by
changing their wants and consequently their actions; for he thereby
brings upon himself the obvious question, how, then, do plants, which
cannot be said to have wants or actions, become modified? To this
he replies, that they are modified by the changes in their nutritive
processes, which are effected by changing circumstances; and it does not
seem to have occurred to him that such changes might be as well supposed
to take place among animals.
When we have said that Lamarck felt that mere speculation was not the
way to arrive at the origin of species, but that it was necessary,
in order to the establishment of any sound theory on the subject, to
discover by observation or otherwise, some 'vera causa', competent to
give rise to them; that he affirmed the true order of classification to
coincide with the order of their development one from another; that he
insisted on the necessity of allowing sufficient time, very strongly;
and that all the varieties of instinct and reason were traced back by
him to the same cause as that which has given rise to species, we have
enumerated his chief contributions to the advance of the question. On
the other hand, from his ignorance of any power in Nature competent to
modify the structure of animals, except the development of parts, or
atrophy of them, in consequence of a change of needs, Lamarck was led
to attach infinitely greater weight than it deserves to this agency,
and the absurdities into which he was led have met with deserved
condemnation. Of the struggle for existence, on which, as we shall see,
Mr. Darwin lays such great stress, he had no conception; indeed, he
doubts whether there really are such things as extinct species, unless
they be such large animals as may have met their death at the hands of
man; and so little does he dream of there being any other destructive
causes at work, that, in discussing the possible existence of fossil
shells, he asks, "Pourquoi d'ailleurs seroient-ils perdues des que
l'homme n'a pu operer leur destruction?" ('Phil. Zool.,' vol. i. p. 77.)
Of the influence of selection Lamarck has as little notion, and he makes
no use of the wonderful phenomena which are exhibited by domesticated
animals, and illustrate its powers. The vast influence of Cuvier was
employed against the Lamarckian views, and, as the untenability of
some of his conclusions was easily shown, his doctrines sank under the
opprobrium of scientific, as well as of theological, heterodoxy.
Nor have the efforts made of late years to revive them tended to
re-establish their credit in the minds of sound thinkers acquainted with
the facts of the case; indeed it may be doubted whether Lamarck has not
suffered more from his friends than from his foes.
Two years ago, in fact, though we venture to question if even the
strongest supporters of the special creation hypothesis had not, now
and then, an uneasy consciousness that all was not right, their position
seemed more impregnable than ever, if not by its own inherent strength,
at any rate by the obvious failure of all the attempts which had been
made to carry it. On the other hand, however much the few, who thought
deeply on the question of species, might be repelled by the generally
received dogmas, they saw no way of escaping from them save by the
adoption of suppositions so little justified by experiment or by
observation as to be at least equally distasteful.
The choice lay between two absurdities and a middle condition of uneasy
scepticism; which last, however unpleasant and unsatisfactory, was
obviously the only justifiable state of mind under the circumstances.
Such being the general ferment in the minds of naturalists, it is no
wonder that they mustered strong in the rooms of the Linnaean Society,
on the 1st of July of the year 1858, to hear two papers by authors
living on opposite sides of the globe, working out their results
independently, and yet professing to have discovered one and the same
solution of all the problems connected with species. The one of these
authors was an able naturalist, Mr. Wallace, who had been employed for
some years in studying the productions of the islands of the Indian
Archipelago, and who had forwarded a memoir embodying his views to
Mr. Darwin, for communication to the Linnaean Society. On perusing the
essay, Mr. Darwin was not a little surprised to find that it embodied
some of the leading ideas of a great work which he had been preparing
for twenty years, and parts of which, containing a development of the
very same views, had been perused by his private friends fifteen or
sixteen years before. Perplexed in what manner to do full justice both
to his friend and to himself, Mr. Darwin placed the matter in the hands
of Dr. Hooker and Sir Charles Lyell, by whose advice he communicated
a brief abstract of his own views to the Linnaean Society, at the same
time that Mr. Wallace's paper was read. Of that abstract, the work on
the 'Origin of Species' is an enlargement; but a complete statement of
Mr. Darwin's doctrine is looked for in the large and well-illustrated
work which he is said to be preparing for publication.
The Darwinian hypothesis has the merit of being eminently simple and
comprehensible in principle, and its essential positions may be stated
in a very few words: all species have been produced by the development
of varieties from common stocks; by the conversion of these, first into
permanent races and then into new species, by the process of 'natural
selection', which process is essentially identical with that artificial
selection by which man has originated the races of domestic animals--the
'struggle for existence' taking the place of man, and exerting, in the
case of natural selection, that selective action which he performs in
artificial selection.