Atlantic Monthly, Vol. VI.,October, 1860. No. XXXVI. - Various
Finally, it is worth noticing, that, though natural selection is
scientifically explicable, variation is not. Thus far the cause of
variation, or the reason why the offspring is sometimes unlike the
parents, is just as mysterious as the reason why it is generally like
the parents. It is now as inexplicable as any other origination; and
if ever explained, the explanation will only carry up the sequence of
secondary causes one step farther, and bring us in face of a somewhat
different problem, which will have the same element of mystery that
the problem of variation has now. Circumstances may preserve or may
destroy the variations; man may use or direct them; but selection,
whether artificial or natural, no more originates them than man
originates the power which turns a wheel, when he dams a stream and
lets the water fall upon it. The origination of this power is a
question about efficient cause. The tendency of science in respect to
this obviously is not towards the omnipotence of matter, as some
suppose, but towards the omnipotence of spirit.
So the real question we come to is as to the way in which we are to
conceive intelligent and efficient cause to be exerted, and upon what
exerted. Are we bound to suppose efficient cause in all cases exerted
upon nothing to evoke something into existence,--and this thousands of
times repeated, when a slight change in the details would make all the
difference between successive species? Why may not the new species, or
some of them, be designed diversifications of the old?
There are, perhaps, only three views of efficient cause which may
claim to be both philosophical and theistic.
1. The view of its exertion at the beginning of time, endowing matter
and created things with forces which do the work and produce the
phenomena.
2. This same view, with the theory of insulated interpositions, or
occasional direct action, engrafted upon it,--the view that events and
operations in general go on in virtue simply of forces communicated at
the first, but that now and then, and only now and then, the Deity
puts his hand directly to the work.
3. The theory of the immediate, orderly, and constant, however
infinitely diversified, action of the intelligent efficient Cause.
It must be allowed, that, while the third is preeminently the
Christian view, all three are philosophically compatible with design
in Nature. The second is probably the popular conception. Perhaps most
thoughtful people oscillate from the middle view towards the first or
the third,--adopting the first on some occasions, the third on others.
Those philosophers who like and expect to settle all mooted questions
will take one or the other extreme. The "Examiner" inclines towards,
the "North American" reviewer fully adopts, the third view, to the
logical extent of maintaining that "_the origin of an individual_, as
well as the origin of a species or a genus, can be explained only by
the _direct_ action of an intelligent creative cause." This is the
line for Mr. Darwin to take; for it at once and completely relieves
his scientific theory from every theological objection which his
reviewers have urged against it.
At present we suspect that our author prefers the first conception,
though he might contend that his hypothesis is compatible with either
of the three. That it is also compatible with an atheistic or
pantheistic conception of the universe is an objection which, being
shared by all physical science, and some ethical or moral, cannot
specially be urged against Darwin's system. As he rejects spontaneous
generation, and admits of intervention at the beginning of organic
life, and probably in more than one instance, he is not wholly
excluded from adopting the middle view, although the interventions he
would allow are few and far back. Yet one interposition admits the
principle as well as more. Interposition presupposes particular
necessity or reason for it, and raises the question, When and how
often it may have been necessary. It would be the natural supposition,
if we had only one set of species to account for, or if the successive
inhabitants of the earth had no other connections or resemblances than
those which adaptation to similar conditions might explain. But if
this explanation of organic Nature requires one to "believe, that, at
innumerable periods in the earth's history, certain elemental atoms
have been commanded suddenly to flash into living tissues," and when
the results are seen to be all orderly, according to a few types, we
cannot wonder that such interventions should at length be considered,
not as interpositions or interferences, but rather as "exertions so
frequent and beneficent that we come to regard them as the ordinary
action of Him who laid the foundations of the earth, and without whom
not a sparrow falleth to the ground."[7]
What does the difference between Mr. Darwin and his reviewer now
amount to? If we say that according to one view the origination of
species is _natural_, according to the other _miraculous_, Mr. Darwin
agrees that "what is natural as much requires and presupposes an
intelligent mind to render it so,--that is, to effect it continually
or at stated times,--as what is supernatural does to effect it for
once."[8] He merely inquires into the form of the miracle, may remind
us that all recorded miracles (except the primal creation of matter)
were transformations or actions in and upon natural things, and will
ask how many times and how frequently may the origination of
successive species be repeated before the supernatural merges in the
natural.
In short, Darwin maintains that the origination of a species, no less
than that of an individual, is natural. The reviewer, that the natural
origination of an individual, no less than the origination of a
species, requires and presupposes Divine power. _A fortiori_, then,
the origination of a variety requires and presupposes Divine power.
And so between the scientific hypothesis of the one and the
philosophical conception of the other no contrariety remains. "A
proper view of the nature of causation.... places the vital doctrine
of the being and the providence of a God on ground that can never be
shaken."[9] A true and worthy conclusion, and a sufficient answer to
the denunciations and arguments of the rest of the article, so far as
philosophy and natural theology are concerned. If a writer must needs
use his own favorite dogma as a weapon with which to give _coup de
grace_ to a pernicious theory, he should be careful to seize it by the
handle, and not by the blade.
We can barely glance at a subsidiary philosophical objection of the
"North American" reviewer, which the "Examiner" also raises, though
less explicitly. Like all geologists, Mr. Darwin draws upon time in
the most unlimited manner. He is not peculiar in this regard. Mr.
Agassiz tells us that the conviction is "now universal among
well-informed naturalists, that this globe has been in existence for
innumerable ages, and that the length of time elapsed since it first
became inhabited cannot be counted in years." Pictet, that the
imagination refuses to calculate the immense number of years and of
ages during which the faunas of thirty or more epochs have succeeded
one another, and developed their long succession of generations. Now
the reviewer declares that such indefinite succession of ages is
"virtually infinite," "lacks no characteristic of eternity except its
name,"--at least, that "the difference between such a conception and
that of the strictly infinite, if any, is not appreciable." But
infinity belongs to metaphysics. Therefore, he concludes, Darwin
supports his theory, not by scientific, but by metaphysical evidence;
his theory is "essentially and completely metaphysical in character,
resting altogether upon that idea of 'the infinite' which the human
mind can neither put aside nor comprehend."[10] And so a theory which
will be generally objected to as much too physical is transposed by a
single syllogism to metaphysics.
Well, physical geology must go with it: for, even on the soberest
view, it demands an indefinitely long time antecedent to the
introduction of organic life upon our earth. _A fortiori_ is physical
astronomy a branch of metaphysics, demanding, as it does, still larger
"instalments of infinity," as the reviewer calls them, both as to time
and number. Moreover, far the greater part of physical inquiries now
relate to molecular actions, which, a distinguished natural
philosopher informs us, "we have to regard as the results of an
infinite number of infinitely small material particles, acting on each
other at infinitely small distances,"--a triad of infinites,--and so
_physics_ becomes the most _metaphysical_ of sciences.
Verily, on this view,
"Thinking is but an idle waste of thought,
And nought is everything, and everything is
nought."
The leading objection of Mr. Agassiz is likewise of a philosophical
character. It is, that species exist only "as categories of
thought,"--that, having no material existence, they can have had no
material variation, and no material community of origin. Here the
predication is of species in the subjective sense, while the inference
is applied to them in the objective sense. Reduced to plain terms, the
argument seems to be: Species are ideas; therefore the objects from
which the idea is derived cannot vary or blend, cannot have had a
genealogical connection.
The common view of species is, that, although they are
generalizations, yet they have a direct objective ground in Nature,
which genera, orders, etc., have not. According to the succinct
definition of Jussieu,--and that of Linnaeus is identical in
meaning,--a species is the perennial succession of similar individuals
in continued generations. The species is the chain of which the
individuals are the links. The sum of the genealogically connected
similar individuals constitutes the species, which thus has an
actuality and ground of distinction not shared by genera and other
groups which were not supposed to be genealogically connected. How a
derivative hypothesis would modify this view, in assigning to species
only a temporary fixity, is obvious. Yet, if naturalists adopt this
hypothesis, they will still retain Jussieu's definition, which leaves
untouched the question as to how and when the "perennial successions"
were established. The practical question will only be, How much
difference between two sets of individuals entitles them to rank under
distinct species; and that is the practical question now, on whatever
theory. The theoretical question is--as stated at the beginning of
this long article--whether these specific lines were always as
distinct as now.
Mr. Agassiz has "lost no opportunity of urging the idea, that, while
species have no material existence, they yet exist as categories of
thought in the same way [and only in the same way] as genera,
families, orders, classes," etc. He "has taken the ground, that all
the natural divisions in the animal kingdom are primarily distinct,
founded upon different categories of characters, and that all exist in
the same way, that is, as categories of thought, embodied in
individual living forms. I have attempted to show that branches in the
animal kingdom are founded upon different plans of structure, and for
that very reason have embraced from the beginning representatives
between which there could be no community of origin; that classes are
founded upon different modes of execution of these plans, and
therefore they also embrace representatives which could have no
community of origin; that orders represent the different degrees of
complication in the mode of execution of each class, and therefore
embrace representatives which could not have a community of origin any
more than the members of different classes or branches; that families
are founded upon different patterns of form, and embrace
representatives equally independent in their origin; that genera are
founded upon ultimate peculiarities of structure, embracing
representatives which, from the very nature of their peculiarities,
could have no community of origin; and that, finally, species are
based upon relations and proportions that exclude, as much as all the
preceding distinctions, the idea of a common descent.
"As the community of characters among the beings belonging to these
different categories arises from the intellectual connection which
shows them to be categories of thought, they cannot be the result of a
gradual material differentiation of the objects themselves. The
argument on which these views are founded may be summed up in the
following few words: Species, genera, families, etc., exist as
thoughts, individuals as facts."[11]
An ingenious dilemma caps the argument:--
"It seems to me that there is much confusion of ideas in the general
statement of the variability of species so often repeated lately. If
species do not exist at all, as the supporters of the transmutation
theory maintain, how can they vary? and if individuals alone exist,
how can the differences which may be observed among them prove the
variability of species?"
Now we imagine that Mr. Darwin need not be dangerously gored by either
horn of this curious dilemma. Although we ourselves cherish
old-fashioned prejudices in favor of the probable permanence, and
therefore of a more stable objective ground of species, yet we
agree--and Mr. Darwin will agree fully with Mr. Agassiz--that species,
and he will add varieties, "exist as categories of thought," that is,
as cognizable distinctions,--which is all that we can make of the
phrase here, whatever it may mean in the Aristotelian metaphysics.
Admitting that species are only categories of thought, and not facts
or things, how does this prevent the individuals, which are material
things, from having varied in the course of time, so as to exemplify
the present almost innumerable categories of thought, or embodiments
of Divine thoughts in material forms, or--viewed on the human side--in
forms marked with such orderly and graduated resemblances and
differences as to suggest to our minds the idea of species, genera,
orders, etc., and to our reason the inference of a Divine original? We
have no clear idea how Mr. Agassiz intends to answer this question, in
saying that branches are founded upon different plans of structure,
classes upon different modes of execution of these plans, orders on
different degrees of complication in the mode of execution, families
upon different patterns of form, genera upon ultimate peculiarities of
structure, and species upon relations and proportions. That is, we do
not perceive how these several "categories of thought" exclude the
possibility or the probability that the individuals which manifest or
suggest the thoughts had an ultimate community of origin. Moreover,
Mr. Darwin would insinuate that the particular philosophy of
classification upon which this whole argument reposes is as purely
hypothetical and as little accepted as his own doctrine. If both are
pure hypotheses, it is hardly fair or satisfactory to extinguish the
one by the other. If there is no real contradiction between them,
there is no use in making the attempt.
As to the dilemma propounded, suppose we try it upon that category of
thought which we call _chair_. This is a genus, comprising the common
chair, (_Sella vulgaris_,) the arm or easy chair, (_S. cathedra_,) the
rocking chair, (_S. oscillans_,) widely distributed in the United
States, and some others,--each of which has _sported_, as the
gardeners say, into many varieties. But now, as the genus and the
_species_ have no material existence, how can they vary? If
individuals alone exist, how can the differences which may be observed
among them prove the variability of the species? To which we reply by
asking, Which does the question refer to, the category of thought, or
the individual embodiment? If the former, then we would remark that
our categories of thought vary from time to time in the readiest
manner. And, although the Divine thoughts are eternal, yet they are
manifested in time and succession, and by their manifestation only can
we know them, how imperfectly! Allowing that what has no material
existence can have had no material connection and no material
variation, we should yet infer that what had intellectual existence
and connection might have intellectual variation; and, turning to the
individuals which represent the species, we do not see how all this
shows that they may not vary. Observation shows us that they do.
Wherefore, taught by fact that successive individuals do vary, we
safely infer that the idea or intention must have varied, and that
this variation of the individual representatives proves the
variability of the species, whether subjectively or objectively
regarded.
Each species or sort of chair, as we have said, has its varieties, and
one species shades off by gradations into another. And--note it
well--these numerous and successively slight variations and
gradations, far from suggesting an accidental origin to chairs and to
their forms, are very proofs of design.
Again, _edifice_ is a generic category of thought. Egyptian, Grecian,
Byzantine, and Gothic buildings are well-marked species, of which each
individual building of the sort is a material embodiment. Now the
question is, whether these categories of thought may not have been
evolved, one from another, in succession, or from some primal, less
specialized, edificial category. What better evidence for such
hypothesis could we have than the variations and grades which connect
one of these species with another? We might extend the parallel, and
get some good illustrations of natural selection from the history of
architecture, the probable origin of the different styles, and their
adaptation to different climates and conditions. Two qualifying
considerations are noticeable. One, that houses do not propagate, so
as to produce continuing lines of each sort and variety; but this is
of small moment on Agassiz's view, he holding that genealogical
connection is not of the essence of species at all. The other, that
the formation and development of the ideas upon which human works
proceed is gradual; or, as the same great naturalist well states it,
"while human thought is consecutive, Divine thought is simultaneous."
But we have no right to affirm this of Divine action.
We must close here. We meant to review some of the more general
scientific objections which we thought not altogether tenable. But,
after all, we are not so anxious just now to know whether the new
theory is well founded on facts as whether it would be harmless, if it
were. Besides, we feel quite unable to answer some of these
objections, and it is pleasanter to take up those which one thinks he
can.
Among the unanswerable, perhaps the weightiest of the objections, is
that of the absence, in geological deposits, of vestiges of the
intermediate forms which the theory requires to have existed. Here all
that Mr. Darwin can do is to insist upon the extreme imperfection of
the geological record and the uncertainty of negative evidence. But,
withal, he allows the force of the objection almost as much as his
opponents urge it,--so much so, indeed, that two of his English
critics turn the concession unfairly upon him, and charge him with
actually basing his hypothesis upon these and similar
difficulties,--as if he held it because of the difficulties, and not
in spite of them;--a handsome return for his candor!
As to this imperfection of the geological record, perhaps we should
get a fair and intelligible illustration of it by imagining the
existing animals and plants of New England, with all their remains and
products since the arrival of the Mayflower, to be annihilated; and
that, in the coming time, the geologists of a new colony, dropped by
the New Zealand fleet on its way to explore the ruins of London,
undertake, after fifty years of examination, to reconstruct in a
catalogue the flora and fauna of our day, that is, from the close of
the glacial period to the present time. With all the advantages of a
surface exploration, what a beggarly account it must be! How many of
the land animals and plants which are enumerated in the Massachusetts
official reports would it be likely to contain?
Another unanswerable question asked by the Boston reviewers is, Why,
when structure and instinct or habit vary,--as they must have varied,
on Darwin's hypothesis,--they vary together and harmoniously, instead
of vaguely. We cannot tell, because we cannot tell why either should
vary at all. Yet, as they both do vary in successive generations,--as
is seen under domestication,--and are correlated, we can only adduce
the fact. Darwin may be precluded from this answer, but we may say
that they vary together because designed to do so. A reviewer says
that the chance of their varying together is inconceivably small; yet,
if they do not, the variant individuals must perish. Then it is well
that it is not left to chance. As to the fact: before we were born,
nourishment and the equivalent to respiration took place in a certain
way. But the moment we were ushered into this breathing world, our
actions promptly conformed, both as to respiration and nourishment, to
the before unused structure and to the new surroundings.
"Now," says the "Examiner," "suppose, for instance, the gills of an
aquatic animal converted into lungs, while instinct still compelled a
continuance under water, would not drowning ensue?" No doubt.
But--simply contemplating the facts, instead of theorizing--we notice
that young frogs do not keep their heads under water after ceasing to
be tadpoles. The instinct promptly changes with the structure, without
supernatural interposition,--just as Darwin would have it, if the
development of a variety or incipient species, though rare, were as
natural as a metamorphosis.
"Or if a quadruped, not yet furnished with wings, were suddenly
inspired with the instinct of a bird, and precipitated itself from a
cliff, would not the descent be hazardously rapid?" Doubtless the
animal would be no better supported than the objection. Darwin makes
very little indeed of voluntary efforts as a cause of change, and even
poor Lamarck need not be caricatured. He never supposed that an
elephant would take such a notion into his wise head, or that a
squirrel would begin with other than short and easy leaps; but might
not the length of the leap be increased by practice?
The "North American" reviewer's position, that the higher brute
animals have comparatively little instinct and no intelligence, is a
heavy blow and great discouragement to dogs, horses, elephants, and
monkeys. Stripped of their all, and left to shift for themselves as
they can in this hard world, their pursuit and seeming attainment of
knowledge under such peculiar difficulties is interesting to
contemplate. However, we are not so sure as is the critic that
instinct regularly increases downward and decreases upward in the
scale of being. Now that the case of the bee is reduced to moderate
proportions,[12] we know of nothing in instinct surpassing that of an
animal so high as a bird, the Talegal, the male of which plumes
himself upon making a hot-bed in which to hatch his partner's
eggs,--which he tends and regulates the heat of about as carefully and
skilfully as the unplumed biped does an eccaleobion.[13] As to the
real intelligence of the higher brutes, it has been ably defended by a
far more competent observer, Mr. Agassiz, to whose conclusions we
yield a general assent, although we cannot quite place the best of
dogs "in that respect upon a level with a considerable portion of poor
humanity," nor indulge the hope, or, indeed, the desire, of a renewed
acquaintance with the whole animal kingdom in a future life.[14]
The assertion, that acquired habitudes or instincts, and acquired
structures, are not heritable, any breeder or good observer can
refute.
That "the human mind has become what it is out of a developed
instinct"[15] is a statement which Mr. Darwin nowhere makes, and, we
presume, would not accept. As to his having us believe that individual
animals acquire their instincts gradually,[16] this statement must
have been penned in inadvertence both of the very definition of
instinct, and of everything we know of in Mr. Darwin's book.
It has been attempted to destroy the very foundation of Darwin's
hypothesis by denying that there are any wild varieties, to speak of,
for natural selection to operate upon. We cannot gravely sit down to
prove that wild varieties abound. We should think it just as necessary
to prove that snow falls in winter. That variation among plants cannot
be largely due to hybridism, and that their variation in Nature is not
essentially different from much that occurs in domestication, we could
show, if our space permitted.
As to the sterility of hybrids, that can no longer be insisted upon as
absolutely true, nor be practically used as a test between species and
varieties, unless we allow that hares and rabbits are of one species.
That it subserves a purpose in keeping species apart, and was so
designed, we do not doubt. But the critics fail to perceive that this
sterility proves nothing against the derivative origin of the actual
species; for it may as well have been intended to keep separate those
forms which have reached a certain amount of divergence as those which
were always thus distinct.