Darwin and Descent with Modification (_continued_)
I HAVE said enough to show that Mr. Darwin claimed I to have been the
originator of the theory of descent with modification as distinctly as
any writer usually claims any theory; but it will probably save the
reader trouble in the end if I bring together a good many, though not,
probably, all (for I much disliked the task, and discharged it
perfunctorily), of the passages in the “Origin of Species” in which the
theory of descent with modification in its widest sense is claimed
expressly or by implication. I shall quote from the original edition,
which, it should be remembered, consisted of the very unusually large
number of four thousand copies, and from which no important deviation was
made either by addition or otherwise until a second edition of two
thousand further copies had been sold; the “Historical Sketch,” &c.,
being first given with the third edition. The italics, which I have
employed so as to catch the reader’s eye, are mine, not Mr. Darwin’s.
Mr. Darwin writes:—
“Although much remains obscure, and will long remain obscure, _I can
entertain no doubt_, _after the most deliberate study and dispassionate
judgment of which I am capable_, _that the view which most naturalists
entertain_, _and which I formerly entertained—namely that each species
has been independently created—is erroneous_. I am fully convinced that
species are not immutable, but that those belonging to what are called
the same genera are lineal descendants of some other and generally
extinct species, in the same manner as the acknowledged varieties of any
one species are the descendants of that species. Furthermore, I am
convinced that natural selection” (or the preservation of fortunate
races) “has been the main but not exclusive means of modification” (p.
6).
It is not here expressly stated that the theory of the mutability of
species is Mr. Darwin’s own; this, nevertheless, is the inference which
the great majority of his readers were likely to draw, and did draw, from
Mr. Darwin’s words.
Again:—
“It is not that all large genera are now varying much, and are thus
increasing in the number of their species, or that no small genera are
now multiplying and increasing; for if this had been so it would have
been fatal to _my theory_; inasmuch as geology,” &c. (p. 56).
The words “my theory” stand in all the editions. Again:—
“This relation has a clear meaning _on my view_ of the subject; I look
upon all the species of any genus as having as certainly descended from
the same progenitor, as have the two sexes of any one of the species” (p.
157).
“My view” here, especially in the absence of reference to any other
writer as having held the same opinion, implies as its most natural
interpretation that descent pure and simple is Mr. Darwin’s view.
Substitute “the theory of descent” for “my view,” and we do not feel that
we are misinterpreting the author’s meaning. The words “my view” remain
in all editions.
Again:—
“Long before having arrived at this part of my work, a crowd of
difficulties will have occurred to the reader. Some of them are so grave
that to this day I can never reflect on them without being staggered; but
to the best of my belief the greater number are only apparent, and those
that are real are not, I think, _fatal to my theory_.
“These difficulties and objections may be classed under the following
heads:—Firstly, if species have descended from other species by
insensibly fine gradations, why do we not everywhere see?” &c. (p. 171).
We infer from this that “my theory” is the theory “that species have
descended from other species by insensibly fine gradations”—that is to
say, that it is the theory of descent with modification; for the theory
that is being objected to is obviously the theory of descent _in toto_,
and not a mere detail in connection with that theory.
The words “my theory” were altered in 1872, with the sixth edition of the
“Origin of species,” into “the theory;” but I am chiefly concerned with
the first edition of the work, my object being to show that Mr. Darwin
was led into his false position as regards natural selection by a desire
to claim the theory of descent with modification; if he claimed it in the
first edition, this is enough to give colour to the view which I take;
but it must be remembered that descent with modification remained, by the
passage just quoted “my theory,” for thirteen years, and even when in
1869 and 1872, for a reason that I can only guess at, “my theory” became
generally “the theory,” this did not make it become any one else’s
theory. It is hard to say whose or what it became, if the words are to
be construed technically; practically, however, with all ingenuous
readers, “the theory” remained as much Mr. Darwin’s theory as though the
words “my theory” had been retained, and Mr. Darwin cannot be supposed so
simple-minded as not to have known this would be the case. Moreover, it
appears, from the next page but one to the one last quoted, that Mr.
Darwin claimed the theory of descent with modification generally, even to
the last, for we there read, “_By my theory_ these allied species have
descended from a common parent,” and the “my” has been allowed, for some
reason not quite obvious, to survive the general massacre of Mr. Darwin’s
“my’s” which occurred in 1869 and 1872.
Again:—
“He who believes that each being has been created as we now see it, must
occasionally have felt surprise when he has met,” &c. (p. 185).
Here the argument evidently lies between descent and independent acts of
creation. This appears from the paragraph immediately following, which
begins, “He who believes in separate and innumerable acts of creation,”
&c. We therefore understand descent to be the theory so frequently
spoken of by Mr. Darwin as “my.”
Again:—
“He who will go thus far, if he find on finishing this treatise that
large bodies of facts, otherwise inexplicable, can be explained _by the
theory of descent_, ought not to hesitate to go farther, and to admit
that a structure even as perfect as an eagle’s eye might be formed _by
natural selection_, although in this case he does not know any of the
transitional grades” (p. 188).
The natural inference from this is that descent and natural selection are
one and the same thing.
Again:—
“If it could be demonstrated that any complex organ existed which could
not possibly have been formed by numerous, successive, slight
modifications, _my theory_ would absolutely break down. But I can find
out no such case. No doubt many organs exist of which we do not know the
transitional grades, more especially if we look to much-isolated species,
round which, according to my _theory_, there has been much extinction”
(p. 189).
This makes “my theory” to be “the theory that complex organs have arisen
by numerous, successive, slight modifications;” that is to say, to be the
theory of descent with modification. The first of the two “my theory’s”
in the passage last quoted has been allowed to stand. The second became
“the theory” in 1872. It is obvious, therefore, that “the theory” means
“my theory;” it is not so obvious why the change should have been made at
all, nor why the one “my theory” should have been taken and the other
left, but I will return to this question.
Again, Mr. Darwin writes:—
“Although we must be extremely cautious in concluding that any organ
could not possibly have been produced by small successive transitional
gradations, yet, undoubtedly grave cases of difficulty occur, some of
which will be discussed in my future work” (p. 192).
This, as usual, implies descent with modification to be the theory that
Mr. Darwin is trying to make good.
Again:—
“I have been astonished how rarely an organ can be named towards which no
transitional variety is known to lead . . . Why, _on the theory of
creation_, should this be so? Why should not nature have taken a leap
from structure to structure? _On the theory of natural selection_ we can
clearly understand why she should not; for natural selection can act only
by taking advantage of slight successive variations; she can never take a
leap, but must advance by the slowest and shortest steps” (p. 194).
Here “the theory of natural selection” is opposed to “the theory of
creation;” we took it, therefore, to be another way of saying “the theory
of descent with modification.”
Again:—
“We have in this chapter discussed some of the difficulties and
objections which may be urged against _my theory_. Many of them are very
grave, but I think that in the discussion light has been thrown on
several facts which, _on the theory of independent acts of creation_, are
utterly obscure” (p. 203).
Here we have, on the one hand, “my theory,” on the other, “independent
acts of creation.” The natural antithesis to independent acts of
creation is descent, and we assumed with reason that Mr. Darwin was
claiming this when he spoke of “my theory.” “My theory” became “the
theory” in 1869.
Again:—
“On the theory of natural selection we can clearly understand the full
meaning of that old canon in natural history, ‘_Natura non facit
saltum_.’ This canon, if we look only to the present inhabitants of the
world is not strictly correct, but if we include all those of past times,
it must _by my theory_ be strictly true” (p. 206).
Here the natural interpretation of “by my theory” is “by the theory of
descent with modification;” the words “on the theory of natural
selection,” with which the sentence opens, lead us to suppose that Mr.
Darwin regarded natural selection and descent as convertible terms. “My
theory” was altered to “this theory” in 1872. Six lines lower down we
read, “_On my theory_ unity of type is explained by unity of descent.”
The “my” here has been allowed to stand.
Again:—
“Again, as in the case of corporeal structure, and conformably with _my
theory_, the instinct of each species is good for itself, but has never,”
&c. (p. 210).
Who was to see that “my theory” did not include descent with
modification? The “my” here has been allowed to stand.
Again:—
“The fact that instincts . . . are liable to make mistakes;—that no
instinct has been produced for the exclusive good of other animals, but
that each animal takes advantage of the instincts of others;—that the
canon of natural history, ‘_Natura non facit saltum_,’ is applicable to
instincts as well as to corporeal structure, and is plainly explicable on
the foregoing views, but is otherwise inexplicable,—_all tend to
corroborate the theory of natural selection_” (p. 243).
We feel that it is the theory of evolution, or descent with modification,
that is here corroborated, and that it is this which Mr. Darwin is mainly
trying to establish; the sentence should have ended “all tend to
corroborate the theory of descent with modification;” the substitution of
“natural selection” for descent tends to make us think that these
conceptions are identical. That they are so regarded, or at any rate
that it is the theory of descent in full which Mr. Darwin has in his
mind, appears from the immediately succeeding paragraph, which begins
“_This theory_,” and continues six lines lower, “For instance, we can
understand, on the _principle of inheritance_, how it is that,” &c.
Again:—
“In the first place, it should always be borne in mind what sort of
intermediate forms must, _on my theory_, formerly have existed” (p. 280).
“My theory” became “the theory” in 1869. No reader who read in good
faith could doubt that the theory of descent with modification was being
here intended.
“It is just possible _by my theory_, that one of two living forms might
have descended from the other; for instance, a horse from a tapir; but in
this case _direct_ intermediate links will have existed between them” (p.
281).
“My theory” became “the theory” in 1869.
Again:—
“_By the theory of natural selection_ all living species have been
connected with the parent species of each genus,” &c. We took this to
mean, “By the theory of descent with modification all living species,”
&c. (p. 281).
Again:—
“Some experienced conchologists are now sinking many of the very fine
species of D’Orbigny and others into the rank of varieties; and on this
view we do find the kind of evidence of change which _on my theory_ we
ought to find” (p. 297).
“My theory” became “the theory” in 1869.
In the fourth edition (1866), in a passage which is not in either of the
two first editions, we read (p. 359), “So that here again we have
undoubted evidence of change in the direction required by _my theory_.”
“My theory” became “the theory” in 1869; the theory of descent with
modification is unquestionably intended.
Again:—
“Geological research has done scarcely anything in breaking down the
distinction between species, by connecting them together by numerous,
fine, intermediate varieties; and this not having been effected, is
probably the gravest and most obvious of all the many objections which
may be urged against _my views_” (p. 299).
We naturally took “my views” to mean descent with modification. The “my”
has been allowed to stand.
Again:—
“If, then, there be some degree of truth in these remarks, we have no
right to expect to find in our geological formations an infinite number
of those transitional forms which _on my theory_ assuredly have connected
all the past and present species of the same group in one long and
branching chain of life . . . But I do not pretend that I should ever
have suspected how poor was the record in the best preserved geological
sections, had not the absence of innumerable transitional links between
the species which lived at the commencement and at the close of each
formation pressed so hardly _on my theory_” (pp. 301, 302).
Substitute “descent with modification” for “my theory” and the meaning
does not suffer. The first of the two “my theories” in the passage last
quoted was altered in 1869 into “our theory;” the second has been allowed
to stand.
Again:—
“The abrupt manner in which whole groups of species suddenly appear in
some formations, has been urged by several palæontologists . . . as a
fatal objection _to the belief in the transmutation of species_. If
numerous species, belonging to the same genera or families, have really
started into life all at once, the fact would be fatal _to the theory of
descent with slow modification through natural selection_” (p. 302).
Here “the belief in the transmutation of species,” or descent with
modification, is treated as synonymous with “the theory of descent with
slow modification through natural selection;” but it has nowhere been
explained that there are two widely different “theories of descent with
slow modification through natural selection,” the one of which may be
true enough for all practical purposes, while the other is seen to be
absurd as soon as it is examined closely. The theory of descent with
modification is not properly convertible with either of these two views,
for descent with modification deals with the question whether species are
transmutable or no, and dispute as to the respective merits of the two
natural selections deals with the question how it comes to be transmuted;
nevertheless, the words “the theory of descent with slow modification
through the ordinary course of things” (which is what “descent with
modification through natural selection” comes to) may be considered as
expressing the facts with practical accuracy, if the ordinary course of
nature is supposed to be that modification is mainly consequent on the
discharge of some correlated function, and that modification, if
favourable, will tend to accumulate so long as the given function
continues important to the wellbeing of the organism; the words, however,
have no correspondence with reality if they are supposed to imply that
variations which are mainly matters of pure chance and unconnected in any
way with function will accumulate and result in specific difference, no
matter how much each one of them may be preserved in the generation in
which it appears. In the one case, therefore, the expression natural
selection may be loosely used as a synonym for descent with modification,
and in the other it may not. Unfortunately with Mr. Charles Darwin the
variations are mainly accidental. The words “through natural selection,”
therefore, in the passage last quoted carry no weight, for it is the
wrong natural selection that is, or ought to be, intended; practically,
however, they derived a weight from Mr. Darwin’s name to which they had
no title of their own, and we understood that “the theory of descent with
slow modification” through the kind of natural selection ostensibly
intended by Mr. Darwin was a quasi-synonymous expression for the
transmutation of species. We understood—so far as we understood anything
beyond that we were to believe in descent with modification—that natural
selection was Mr. Darwin’s theory; we therefore concluded, since Mr.
Darwin seemed to say so, that the theory of the transmutation of species
generally was so also. At any rate we felt as regards the passage last
quoted that the theory of descent with modification was the point of
attack and defence, and we supposed it to be the theory so often referred
to by Mr. Darwin as “my.”
Again:—
“Some of the most ancient Silurian animals, as the Nautilus, Lingula,
&c., do not differ much from the living species; and it cannot _on my
theory_ be supposed that these old species were the progenitors,” &c. (p.
306) . . . “Consequently _if my theory be true_, it is indisputable,” &c.
(p. 307).
Here the two “my theories” have been altered, the first into “our
theory,” and the second into “the theory,” both in 1869; but, as usual,
the thing that remains with the reader is the theory of descent, and it
remains morally and practically as much claimed when called “the
theory”—as during the many years throughout which the more open “my”
distinctly claimed it.
Again:—
“All the most eminent palæontologists, namely, Cuvier, Owen, Agassiz,
Barrande, E. Forbes, &c., and all our greatest geologists, as Lyell,
Murchison, Sedgwick, &c., have unanimously, often vehemently, maintained
_the immutability of species_. . . . I feel how rash it is to differ from
these great authorities . . . Those who think the natural geological
record in any degree perfect, and who do not attach much weight to the
facts and arguments of other kinds brought forward in this volume, will
undoubtedly at once _reject my theory_” (p. 310).
What is “my theory” here, if not that of the mutability of species, or
the theory of descent with modification? “My theory” became “the theory”
in 1869.
Again:—
“Let us now see whether the several facts and rules relating to the
geological succession of organic beings, better accord with the common
view of the immutability of species, or with that of their _slow and
gradual modification_, _through descent and natural selection_” (p. 312).
The words “natural selection” are indeed here, but they might as well be
omitted for all the effect they produce. The argument is felt to be
about the two opposed theories of descent, and independent creative
efforts.
Again:—
“These several facts accord well with _my theory_” (p. 314). That “my
theory” is the theory of descent is the conclusion most naturally drawn
from the context. “My theory” became “our theory” in 1869.
Again:—
“This gradual increase in the number of the species of a group is
strictly conformable _with my theory_; for the process of modification
and the production of a number of allied forms must be slow and gradual,
. . . like the branching of a great tree from a single stem, till the
group becomes large” (p. 314).
“My theory” became “the theory” in 1869. We took “my theory” to be the
theory of descent; that Mr. Darwin treats this as synonymous with the
theory of natural selection appears from the next paragraph, on the third
line of which we read, “On _the theory of natural selection_ the
extinction of old forms,” &c.
Again:—
“_The theory of natural selection_ is grounded on the belief that each
new variety and ultimately each new species, is produced and maintained
by having some advantage over those with which it comes into competition;
and the consequent extinction of less favoured forms almost inevitably
follows” (p. 320). Sense and consistency cannot be made of this passage.
Substitute “The theory of the preservation of favoured races in the
struggle for life” for “The theory of natural selection” (to do this is
only taking Mr. Darwin’s own synonym for natural selection) and see what
the passage comes to. “The preservation of favoured races” is not a
theory, it is a commonly observed fact; it is not “grounded on the belief
that each new variety,” &c., it is one of the ultimate and most
elementary principles in the world of life. When we try to take the
passage seriously and think it out, we soon give it up, and pass on,
substituting “the theory of descent” for “the theory of natural
selection,” and concluding that in some way these two things must be
identical.
Again:—
“The manner in which single species and whole groups of species become
extinct accords well with _the theory of natural selection_” (p. 322).
Again:—
“This great fact of the parallel succession of the forms of life
throughout the world, is explicable _on the theory of natural selection_”
(p. 325).
Again:—
“Let us now look to the mutual affinities of extinct and living species.
They all fall into one grand natural system; and this is at once
explained _on the principle of descent_” (p. 329).
Putting the three preceding passages together, we naturally inferred that
“the theory of natural selection” and “the principle of descent” were the
same things. We knew Mr. Darwin claimed the first, and therefore
unhesitatingly gave him the second at the same time.
Again:—
“Let us see how far these several facts and inferences accord with _the
theory of descent with modification_” (p. 331)
Again:—
“Thus, _on the theory of descent with modification_, the main facts with
regard to the mutual affinities of the extinct forms of life to each
other and to living forms, seem to me explained in a satisfactory manner.
And they are wholly inexplicable _on any other view_” (p. 333).
The words “seem to me” involve a claim in the absence of so much as a
hint in any part of the book concerning indebtedness to earlier writers.
Again:—
“_On the theory of descent_, the full meaning of the fossil remains,” &c.
(p. 336).
In the following paragraph we read:—
“But in one particular sense the more recent forms must, _on my theory_,
be higher than the more ancient.”
Again:—
“Agassiz insists that ancient animals resemble to a certain extent the
embryos of recent animals of the same classes; or that the geological
succession of extinct forms is in some degree parallel to the
embryological development of recent forms. . . . This doctrine of Agassiz
accords well with _the theory of natural selection_” (p. 338).
“The theory of natural selection” became “our theory” in 1869. The
opinion of Agassiz accords excellently with the theory of descent with
modification, but it is not easy to see how it bears upon the fact that
lucky races are preserved in the struggle for life—which, according to
Mr. Darwin’s title-page, is what is meant by natural selection.
Again:—
“_On the theory of descent with modification_, the great law of the
long-enduring but not immutable succession of the same types within the
same areas, is at once explained” (p. 340).
Again:—
“It must not be forgotten that, _on my theory_, all the species of the
same genus have descended from some one species” (p. 341).
“My theory” became “our theory” in 1869.
Again:—
“He who rejects these views on the nature of the geological record, will
rightly reject _my whole theory_” (p. 342).
“My” became “our” in 1869.
Again:—
“Passing from these difficulties, the other great leading facts in
palæontology agree admirably with _the theory of descent with
modification through variation and natural selection_” (p. 343).
Again:—
The succession of the same types of structure within the same areas
during the later geological periods _ceases to be mysterious_, and _is
simply explained by inheritance_ (p. 345).
I suppose inheritance was not when Mr. Darwin wrote considered
mysterious. The last few words have been altered to “and is intelligible
on the principle of inheritance.” It seems as though Mr. Darwin did not
like saying that inheritance was not mysterious, but had no objection to
implying that it was intelligible.
The next paragraph begins—“If, then, the geological record be as
imperfect as I believe it to be, . . . the main objections _to the theory
of natural selection_ are greatly diminished or disappear. On the other
hand, all the chief laws of palæontology plainly proclaim, _as it seems
to me_, _that species have been produced by ordinary generation_.”
Here again the claim to the theory of descent with modification is
unmistakable; it cannot, moreover, but occur to us that if species “have
been produced by ordinary generation,” then ordinary generation has as
good a claim to be the main means of originating species as natural
selection has. It is hardly necessary to point out that ordinary
generation involves descent with modification, for all known offspring
differ from their parents, so far, at any rate, as that practised judges
can generally tell them apart.
Again:—
“We see in these facts some deep organic bond, prevailing throughout
space and time, over the same areas of land and water, and independent of
their physical condition. The naturalist must feel little curiosity who
is not led to inquire what this bond is.
“This bond, _on my theory_, _is simply inheritance_, that cause which
alone,” &c. (p. 350).
This passage was altered in 1869 to “The bond is simply inheritance.”
The paragraph concludes, “_On this principle of inheritance with
modification_, we can understand how it is that sections of genera . . .
are confined to the same areas,” &c.
Again:—
“He who rejects it rejects the _vera causa of ordinary_ generation,” &c.
(p. 352).
We naturally ask, Why call natural selection the “main means of
modification,” if “ordinary generation” is a _vera causa_?
Again:—
“In discussing this subject, we shall be enabled at the same time to
consider a point equally important for us, namely, whether the several
distinct species of a genus, _which on my theory have all descended from
a common ancestor_, can have migrated (undergoing modification during
some part of their migration) from the area inhabited by their
progenitor” (p. 354).
The words “on my theory” became “on our theory” in 1869.
Again:—
“With those organic beings which never intercross (if such exist) _the
species_, _on my theory_, _must have descended from a succession of
improved varieties_,” &c. (p. 355).
The words “on my theory” were cut out in 1869.
Again:—
“A slow southern migration of a marine fauna will account, _on the theory
of modification_, for many closely allied forms,” &c. (p. 372).
Again:—
“But the existence of several quite distinct species, belonging to genera
exclusively confined to the southern hemisphere, is, _on my theory of
descent with modification_, a far more remarkable case of difficulty” (p.
381).
“My” became “the” in 1866 with the fourth edition. This was the most
categorical claim to the theory of descent with modification in the
“Origin of Species.” The “my” here is the only one that was taken out
before 1869. I suppose Mr. Darwin thought that with the removal of this
“my” he had ceased to claim the theory of descent with modification.
Nothing, however, could be gained by calling the reader’s attention to
what had been done, so nothing was said about it.
Again:—
“Some species of fresh-water shells have a very wide range, _and allied
species_, _which_, _on my theory_, _are descended from a single source_,
prevail throughout the world” (p. 385).
“My theory” became “our theory” in 1869.
Again:—
“In the following remarks I shall not confine myself to the mere question
of dispersal, but shall consider some other facts which bear upon the
truth of _the two theories of independent creation and of descent with
modification_” (p. 389). What can be plainer than that the theory which
Mr. Darwin espouses, and has so frequently called “my,” is descent with
modification?
Again:—
“But as these animals and their spawn are known to be immediately killed
by sea-water, _on my view_, we can see that there would be great
difficulty in their transportal across the sea, and therefore why they do
not exist on any oceanic island. But why, _on the theory of creation_,
they should not have been created there, it would be very difficult to
explain” (p. 393).
“On my view” was cut out in 1869.
On the following page we read—“On my view this question can easily be
answered.” “On my view” is retained in the latest edition.
Again:—
“Yet there must be, _on my view_, some unknown but highly efficient means
for their transportation” (p. 397).
“On my view” became “according to our view” in 1869.
Again:—
“I believe this grand fact can receive no sort of explanation _on the
ordinary view of independent creation_; whereas, _on the view here
maintained_, it is obvious that the Galapagos Islands would be likely to
receive colonists . . . from America, and the Cape de Verde Islands from
Africa; and that such colonists would be liable to modification; the
principle of inheritance still betraying their original birth-place” (p.
399).
Again:—
“With respect to the distinct species of the same genus which, _on my
theory_, must have spread from one parent source, if we make the same
allowances as before,” &c.
“On my theory” became “on our theory” in 1869.
Again:—
“_On my theory_ these several relations throughout time and space are
intelligible; . . . the forms within each class have been connected by
the same bond of ordinary generation; . . . in both cases the laws of
variation have been the same, and modifications have been accumulated by
the same power of natural selection” (p. 410).
“On my theory” became “according to our theory” in 1869, and natural
selection is no longer a power, but has become a means.
Again:—
“_I believe that something more is included_, and that propinquity of
descent—the only known cause of the similarity of organic beings—is the
bond, hidden as it is by various degrees of modification, which is
partially revealed to us by our classification” (p. 418).
Again:—
“_Thus_, _on the view which I hold_, the natural system is genealogical
in its arrangement, like a pedigree” (p. 422).
“On the view which I hold” was cut out in 1872.
Again:—
“We may feel almost sure, _on the theory of descent_, that these
characters have been inherited from a common ancestor” (p. 426).
Again:—
“_On my view of characters being of real importance for classification
only in so far as they reveal descent_, we can clearly understand,” &c.
(p. 427).
“On my view” became “on the view” in 1872.
Again:—
“The more aberrant any form is, the greater must be the number of
connecting forms which, _on my theory_, have been exterminated and
utterly lost” (p. 429).
The words “on my theory” were excised in 1869.
Again:—
“Finally, we have seen that _natural selection_ _. . . explains_ that
great and universal feature in the affinities of all organic beings,
namely, their subordination in group under group. _We use the element of
descent_ in classing the individuals of both sexes, &c.; . . . _we use
descent_ in classing acknowledged varieties; . . . and I believe this
element of descent is the hidden bond of connection which naturalists
have sought under the term of the natural system” (p. 433).
Lamarck was of much the same opinion, as I showed in “Evolution Old and
New.” He wrote:—“An arrangement should be considered systematic, or
arbitrary, when it does not conform to the genealogical order taken by
nature in the development of the things arranged, and when, by
consequence, it is not founded on well-considered analogies. There is a
natural order in every department of nature; it is the order in which its
several component items have been successively developed.” {195a} The
point, however, which should more particularly engage our attention is
that Mr. Darwin in the passage last quoted uses “natural selection” and
“descent” as though they were convertible terms.
Again:—
“Nothing can be more hopeless than to attempt to explain this similarity
of pattern in members of the same class by utility or the doctrine of
final causes . . . _On the ordinary view of the independent creation of
each being_, we can only say that so it is . . . _The explanation is
manifest on the theory of the natural selection of successive slight_
modifications,” &c. (p. 435).
This now stands—“The explanation is to a large extent simple, on the
theory of the selection of successive, slight modifications.” I do not
like “a large extent” of simplicity; but, waiving this, the point at
issue is not whether the ordinary course of things ensures a
quasi-selection of the types that are best adapted to their surroundings,
with accumulation of modification in various directions, and hence wide
eventual difference between species descended from common progenitors—no
evolutionist since 1750 has doubted this—but whether a general principle
underlies the modifications from among which the quasi-selection is made,
or whether they are destitute of such principle and referable, as far as
we are concerned, to chance only. Waiving this again, we note that the
theories of independent creation and of natural selection are contrasted,
as though they were the only two alternatives; knowing the two
alternatives to be independent creation and descent with modification, we
naturally took natural selection to mean descent with modification.
Again:—
“_On the theory of natural selection_ we can satisfactorily answer these
questions” (p. 437).
“Satisfactorily” now stands “to a certain extent.”
Again:—
“_On my view_ these terms may be used literally” (pp. 438, 439).
“On my view” became “according to the views here maintained such language
may be,” &c., in 1869.
Again:—
“I believe all these facts can be explained as follows, _on the view of
descent with modification_” (p. 443).
This sentence now ends at “follows.”
Again:—
“Let us take a genus of birds, _descended_, _on my theory_, _from some
one parent species_, and of which the several new species _have become
modified through natural selection_ in accordance with their divers
habits” (p. 446).
The words “on my theory” were cut out in 1869, and the passage now
stands, “Let us take a group of birds, descended from some ancient form
and modified through natural selection for different habits.”
Again:—
“_On my view of descent with modification_, the origin of rudimentary
organs is simple” (p. 454).
“On my view” became “_on the view_” in 1869.
Again:—
“_On the view of descent with modification_,” &c. (p. 455).
Again:—
“_On this same view of descent with modification_ all the great facts of
morphology become intelligible” (p. 456).
Again:—
“That many and grave objections may be advanced against _the theory of
descent with modification through natural selection_, I do not deny” (p.
459).
This now stands, “That many and serious objections may be advanced
against _the theory of descent with modification through variation and
natural selection_, I do not deny.”
Again:—
“There are, it must be admitted, cases of special difficulty _on the
theory of natural selection_” (p. 460).
“On” has become “opposed to;” it is not easy to see why this alteration
was made, unless because “opposed to” is longer.
Again:—
“Turning to geographical distribution, the difficulties encountered _on
the theory of descent with modification_ are grave enough.”
“Grave” has become “serious,” but there is no other change (p. 461).
Again:—
“As _on the theory of natural selection_ an interminable number of
intermediate forms must have existed,” &c.
“On” has become “according to”—which is certainly longer, but does not
appear to possess any other advantage over “on.” It is not easy to
understand why Mr. Darwin should have strained at such a gnat as “on,”
though feeling no discomfort in such an expression as “an interminable
number.”
Again:—
“This is the most forcible of the many objections which may be urged
_against my theory_ . . . For certainly, _on my theory_,” &c. (p. 463).
The “my” in each case became “the” in 1869.
Again:—
“Such is the sum of the several chief objections and difficulties which
may be justly urged _against my theory_” (p. 465).
“My” became “the” in 1869.
Again:—
“Grave as these several difficulties are, _in my judgment_ they do not
overthrow _the theory of descent with modifications_” (p. 466).
This now stands, “Serious as these several objections are, in my judgment
they are by no means sufficient to overthrow _the theory of descent with
subsequent modification_;” which, again, is longer, and shows at what
little, little gnats Mr. Darwin could strain, but is no material
amendment on the original passage.
Again:—
“_The theory of natural selection_, even if we looked no further than
this, _seems to me to be in itself probable_” (p. 469).
This now stands, “The theory of natural selection, even if we look no
further than this, _seems to be in the highest degree probable_.” It is
not only probable, but was very sufficiently proved long before Mr.
Darwin was born, only it must be the right natural selection and not Mr.
Charles Darwin’s.
Again:—
“It is inexplicable, _on the theory of creation_, why a part developed,
&c., . . . _but_, _on my view_, this part has undergone,” &c. (p. 474).
“On my view” became “on our view” in 1869.
Again:—
“Glancing at instincts, marvellous as some are, they offer no greater
difficulty than does corporeal structure _on the theory of the natural
selection of successive_, _slight_, _but profitable modifications_” (p.
474).
Again:—
“_On the view of all the species of the same genus having descended from
a common parent_, and having inherited much in common, we can understand
how it is,” &c. (p. 474).
Again:—
“If we admit that the geological record is imperfect in an extreme
degree, then such facts as the record gives, support _the theory of
descent with modification_.
“ . . . The extinction of species . . . almost inevitably follows on _the
principle of natural selection_” (p. 475).
The word “almost” has got a great deal to answer for.
Again:—
“We can understand, _on the theory of descent with modification_, most of
the great leading facts in Distribution” (p. 476).
Again:—
“The existence of closely allied or representative species in any two
areas, implies, _on the theory of descent with modification_, that the
same parents formerly inhabited both areas . . . It must be admitted that
these facts receive no explanation _on the theory of creation_ . . . The
fact . . . is intelligible _on the theory of natural selection_, with its
contingencies of extinction and divergence of character” (p. 478).
Again:—
“Innumerable other such facts at once explain themselves _on the theory
of descent with slow and slight successive modifications_” (p. 479).
“Any one whose disposition leads him to attach more weight to unexplained
difficulties than to the explanation of a certain number of facts, _will
certainly reject my theory_” (p. 482).
“My theory” became “the theory” in 1869.
* * * * *
From this point to the end of the book the claim is so ubiquitous, either
expressly or by implication, that it is difficult to know what not to
quote. I must, however, content myself with only a few more extracts.
Mr. Darwin says:—
“It may be asked _how far I extend the doctrine of the modification of
species_” (p. 482).
Again:—
“Analogy would lead me one step further, namely, to the belief that all
animals and plants have descended from some one prototype . . . Therefore
I should infer from analogy that probably all the organic beings which
have ever lived on this earth have descended from some one primordial
form, into which life was first breathed.”
From an amœba—Adam, in fact, though not in name. This last sentence is
now completely altered, as well it might be.
Again:—
“When _the views entertained in this volume on the origin of species_,
_or when analogous views are generally admitted_, we can dimly foresee
that there will be a considerable revolution in natural history” (p.
434).
Possibly. This now stands, “When the views advanced by me in this
volume, and by Mr. Wallace, or when analogous views on the origin of
species are generally admitted, we can dimly foresee,” &c. When the
“Origin of Species” came out we knew nothing of any analogous views, and
Mr. Darwin’s words passed unnoticed. I do not say that he knew they
would, but he certainly ought to have known.
Again:—
“_A grand and almost untrodden field of inquiry will be opened_, on the
causes and laws of variation, on correlation of growth, on the effects of
use and disuse, on the direct action of external conditions, and so
forth” (p. 486).
Buffon and Lamarck had trodden this field to some purpose, but not a hint
to this effect is vouchsafed to us. Again;—
“_When I view all beings not as special creations_, _but as the lineal
descendants of some few beings which lived long before_ the first bed of
the Silurian system was deposited, they seem to me to become ennobled . . .
We can so far take a prophetic glance into futurity as to foretell that
it will be the common and widely spread species, belonging to the larger
and dominant groups, which will ultimately prevail and procreate new and
dominant species.”
There is no alteration in this except that “Silurian” has become
“Cambrian.”
The idyllic paragraph with which Mr. Darwin concludes his book contains
no more special claim to the theory of descent _en bloc_ than many
another which I have allowed to pass unnoticed; it has been, moreover,
dealt with in an earlier chapter (Chapter XII.)