between species and well-marked varieties is, that the latter are known,
or believed to be connected at the present day by intermediate
gradations, whereas species were formerly thus connected. Hence, without
rejecting the considerations of the present existence of intermediate
gradations between any two forms, we shall be led to weigh more
carefully and to value higher the actual amount of difference between
them. It is quite possible that forms now generally acknowledged to be
merely varieties may hereafter be thought worthy of specific names; and
in this case scientific and common language will come into accordance.
In short, we shall have to treat species in the same manner as those
naturalists treat genera, who admit that genera are merely artificial
combinations made for convenience. This may not be a cheering prospect;
but we shall at least be freed from the vain search for the undiscovered
and undiscoverable essence of the term species.
The other and more general departments of natural history will rise
greatly in interest. The terms used by naturalists, of affinity,
relationship, community of type, paternity, morphology [the science of
organic form], adaptive characters, rudimentary and aborted organs,
etc., will cease to be metaphorical and will have a plain signification.
When we no longer look at an organic being as a savage looks at a ship,
as something wholly beyond his comprehension; when we regard every
production of nature as one which has had a long history; when we
contemplate every complex structure and instinct as the summing up of
many contrivances, each useful to the possessor, in the same way as any
great mechanical invention is the summing up of the labour, the
experience, the reason, and even the blunders of numerous workmen; when
we thus view each organic being, how far more interesting--I speak from
experience--does the study of natural history become!
A grand and almost untrodden field of inquiry will be opened, on the
causes and laws of variation, on correlation, on the effects of use and
disuse, on the direct action of external conditions, and so forth. The
study of domestic productions will rise immensely in value. A new
variety raised by man will be a more important and interesting subject
for study than one more species added to the infinitude of already
recorded species. Our classifications will come to be, as far as they
can be so made, genealogies; and will then truly give what may be called
the plan of creation. The rules for classifying will no doubt become
simpler when we have a definite object in view. We possess no pedigree
or armorial bearings; and we have to discover and trace the many
diverging lines of descent in our natural genealogies, by characters of
any kind which have long been inherited. Rudimentary[1] organs will
speak infallibly with respect to the nature of long-lost structures.
Species and groups of species which are called aberrant, and which may
fancifully be called living fossils, will aid us in forming a picture of
the ancient forms of life. Embryology will often reveal to us the
structure, in some degree obscured, of the prototypes of each great
class.
When we can feel assured that all the individuals of the same species,
and all the closely allied species of most genera, have, within a not
very remote period descended from one parent, and have migrated from
some one birth-place; and when we better know the many means of
migration, then, by the light which geology now throws, and will
continue to throw, on former changes of climate and of the level of the
land, we shall surely be enabled to trace in an admirable manner the
former migrations of the inhabitants of the whole world. Even at
present, by comparing the differences between the inhabitants of the sea
on the opposite sides of a continent, and the nature of the various
inhabitants on that continent in relation to their apparent means of
immigration, some light can be thrown on ancient geography.
The noble science of geology loses glory from the extreme imperfection
of the record. The crust of the earth, with its imbedded remains, must
not be looked at as a well-filled museum, but as a poor collection made
at hazard and at rare intervals. The accumulation of each great
fossiliferous formation will be recognized as having depended on an
unusual occurrence of favourable circumstances, and the blank intervals
between the successive stages as having been of vast duration. But we
shall be able to gauge with some security the duration of these
intervals by a comparison of the preceding and succeeding organic forms.
We must be cautious in attempting to correlate as strictly
contemporaneous two formations, which do not include many identical
species, by the general succession of the forms of life.
As species are produced and exterminated by slowly acting and still
existing causes, and not by miraculous acts of creation; and as the most
important of all causes of organic change is one which is almost
independent of altered and perhaps suddenly altered physical conditions,
namely, the mutual relation of organism to organism--the improvement of
one organism entailing the improvement or the extermination of others;
it follows, that the amount of organic change in the fossils of
consecutive formations probably serves as a fair measure of the
relative, though not actual lapse of time. A number of species, however,
keeping in a body might remain for a long period unchanged, while within
the same period, several of these species, by migrating into new
countries and coming into competition with foreign associates, might
become modified; so that we must not overrate the accuracy of organic
change as a measure of time.
In the future I see open fields for far more important researches.
Psychology will be securely based on the foundation already well laid by
Mr. Herbert Spencer, that of the necessary acquirement of each mental
power and capacity by gradation. Much light will be thrown on the
origin of man and his history.
Authors of the highest eminence seem to be fully satisfied with the view
that each species has been independently created. To my mind it accords
better with what we know of the laws impressed on matter by the Creator,
that the production and extinction of the past and present inhabitants
of the world should have been due to secondary causes, like those
determining the birth and death of the individual. When I view all
beings as not special creations, but as the lineal descendants of some
few beings which lived long before the first bed of the Cambrian system
was deposited, they seem to me to become ennobled. Judging from the
past, we may safely infer that not one living species will transmit its
unaltered likeness to a distant futurity. And of the species now living
very few will transmit progeny of any kind to a far distant futurity;
for the manner in which all organic beings are grouped, shows that the
greater number of species in each genus, and all the species in many
genera, have left no descendants, but have become utterly extinct. 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 within each class, which will ultimately prevail and
procreate new and dominant species. As all the living forms of life are
the lineal descendants of those which lived long before the Cambrian
epoch, we may feel certain that the ordinary succession by generation
has never once been broken, and that no cataclysm has desolated the
whole world. Hence, we may look with some confidence to a secure future
of great length. And as natural selection works solely by and for the
good of each being, all corporeal and mental endowments will tend to
progress toward perfection.
It is interesting to contemplate a tangled bank, clothed with many
plants of many kinds, with birds singing on the bushes, with various
insects flitting about, and with worms crawling through the damp earth,
and to reflect that these elaborately constructed forms, so different
from each other, and dependent upon each other in so complex a manner,
have all been produced by laws acting around us. These laws taken in the
largest sense, being growth with reproduction; Inheritance which is
almost implied by reproduction; Variability from the indirect and direct
action of the conditions of life, and from use and disuse: a Ratio of
Increase so high as to lead to a Struggle for Life, and as a consequence
to Natural Selection, entailing divergence of Character and the
Extinction of less improved forms. Thus, from the war of nature, from
famine and death, the most exalted object which we are capable of
conceiving, namely, the production of the higher animals, directly
follows. There is grandeur in this view of life, with its several
powers, having been originally breathed by the Creator into a few forms
or into one; and that, while this planet has gone circling on according
to the fixed law of gravity, from so simple a beginning endless forms
most beautiful and most wonderful have been, and are being evolved.
FOOTNOTES:
[1] _Vestigial_ is now preferred to _rudimentary_ as a term.--Ed.
HOW "THE ORIGIN OF SPECIES" CAME TO BE WRITTEN.
[An extract from the autobiography of Charles Darwin, in "The
Life and Letters of Charles Darwin," New York, D. Appleton &
Co.]
From September, 1854, I devoted my whole time to arranging my huge pile
of notes, to observing and to experimenting in relation to the
transmutation of species. During the voyage of the _Beagle_ I had been
deeply impressed by discovering in the Pampean formation great fossil
animals covered with armour like that on the existing armadillos;
secondly, by the manner in which closely allied animals replace one
another in proceeding southwards over the continent; and, thirdly, by
the South American character of most of the productions of the Galapagos
Archipelago, and more especially by the manner in which these differ
slightly on each island of the group, none of these islands appearing to
be very ancient in a geological sense.
It was evident that such facts as these, as well as many others, could
only be explained on the supposition that species gradually become
modified; and the subject haunted me. But it was equally evident that
neither the action of the surrounding conditions, nor the will of the
organisms (especially in the case of plants) could account for the
innumerable cases in which organisms of every kind are beautifully
adapted to their habits of life--for instance, a woodpecker or a
tree-frog to climb trees, or a seed for dispersal by hooks or plumes. I
had always been much struck by such adaptations, and until these could
be explained it seemed to me almost useless to endeavour to prove by
indirect evidence that species have been modified.
After my return to England it appeared to me that by following the
example of Lyell in geology,[2] and by collecting all facts that bore in
any way on the variation of animals and plants under domestication and
nature, some light might perhaps be thrown on the whole subject. My
first note-book was opened in July, 1837. I worked on true Baconian
principles, and without any theory collected facts on a wholesale scale,
more especially with respect to domesticated productions, by printed
enquiries, by conversation with skilful breeders and gardeners and by
extensive reading. When I see the list of books of all kinds which I
read and abstracted, including whole series of journals and
translations, I am surprised at my industry. I soon perceived that
selection was the keystone of man's success in making useful races of
animals and plants. But how selection could be applied to organisms
living in a state of nature remained for some time a mystery to me.
In October, 1838, that is fifteen months after I had begun my systematic
enquiry, I happened to read for amusement "Malthus on Population," and
being well prepared to appreciate the struggle for existence which
everywhere goes on from long-continued observation of the habits of
animals and plants, it at once struck me that under these circumstances
favourable variations would tend to be preserved and unfavourable ones
to be destroyed. The result of this would be the formation of a new
species. Here then I had at last got a theory by which to work; but I
was so anxious to avoid prejudice that I determined not for some time to
write even the briefest sketch of it. In June, 1842, I first allowed
myself the satisfaction of writing a very brief abstract of my theory in
pencil in 35 pages; and this was enlarged during the summer of 1844 into
one of 230 pages, which I had fairly copied out and still possess.
But at that time I overlooked one problem of great importance; and it is
astonishing to me, except on the principle of Columbus and his egg, how
I could have overlooked it and its solution. This problem is the
tendency in organic beings descended from the same stock to diverge in
character as they become, modified. That they have diverged greatly is
obvious from the manner in which species of all kinds can be classed
under genera, genera under families, families under sub-orders and so
forth; and I can remember the very spot on the road, whilst in my
carriage, when to my joy the solution occurred to me; and this was long
after I had come to Down. This solution, as I believe, is that the
modified offspring of all dominant and increasing forms tend to become
adapted to many and highly diversified places in the economy of nature.
Early in 1856 Lyell advised me to write out my views pretty fully, and I
began at once to do so on a scale three or four times as extensive as
that which was afterwards followed in my "Origin of Species;" yet it was
only an abstract of the materials which I had collected and I got
through about half the work on this scale. But my plans were overthrown,
for early in the summer of 1858 Mr. Wallace, who was then in the Malay
Archipelago, sent me an essay "On the tendency of varieties to depart
indefinitely from the original type;" and this essay contained exactly
the same theory as mine.[3] Mr. Wallace expressed the wish that if I
thought well of his essay I should send it to Lyell for perusal.
The circumstances under which I consented at the request of Lyell and
Hooker to allow of an abstract from my MS., together with a letter to
Asa Gray, dated September 5, 1857, to be published at the same time
with Wallace's essay, are given in the "Journal of the Proceedings of
the Linnean Society," 1858, p. 45. I was at first very unwilling to
consent, as I thought Mr. Wallace might consider my doing so
unjustifiable, for I did not then know how generous and noble was his
disposition. The extract from my MS. and the letter to Asa Gray had
neither been intended for publication, and were badly written. Mr.
Wallace's essay, on the other hand, was admirably expressed and quite
clear. Nevertheless, our joint productions excited very little
attention, and the only published notice of them which I can remember
was by Professor Haughton of Dublin, whose verdict was that all that was
new in them was false, and what was true was old. This shows how
necessary it is that any new idea should be explained at considerable
length in order to arouse public attention.
In September, 1858, I set to work by the strong advice of Lyell and
Hooker to prepare a volume on the transmutation of species, but was
often interrupted by ill health and short visits to Dr. Lane's
delightful hydropathic establishment at Moor Park. I abstracted the MS.
begun on a much larger scale in 1856, and completed the volume on the
same reduced scale. It cost me thirteen months and ten days' hard labor.
It was published under the title of the "Origin of Species," in
November, 1859. Though considerably added to and corrected in the later
editions, it has remained substantially the same book.
It is no doubt the chief work of my life. It was from the first highly
successful. The first small edition of 1,250 copies was sold on the day
of publication, and a second edition of 3,000 copies soon afterwards.
Sixteen thousand copies have now (1876) been sold in England; and
considering how stiff a book it is, this is a large sale. It has been
translated into almost every European tongue, even into such languages
as Spanish, Bohemian, Polish and Russian. Even an essay in Hebrew has
appeared on it, showing that the theory is contained in the Old
Testament! The reviews were very numerous; for some time all that
appeared on the "Origin" and on my related books, and these amount
(excluding newspaper reviews) to 265; but after a time I gave up the
attempt in despair. Many separate essays and books on the subject have
appeared; and in Germany a catalogue or bibliography on "Darwinismus"
has appeared every year or two.
The success of the "Origin" may, I think, be attributed in large part to
my having long before written two condensed sketches and to my having
abstracted a much larger manuscript, which was itself an abstract. By
this means I was enabled to select the more striking facts and
conclusions. I had also, during many years followed a golden rule,
namely, that whenever a published fact, a new observation or thought
came across me, which was opposed to my general results, to make a
memorandum of it without fail and at once; for I had found by experience
that such facts and thoughts were far more apt to escape from the memory
than favourable ones. Owing to this habit very few objections were
raised against my views which I had not at least noticed and attempted
to answer.
It has sometimes been said that the success of the "Origin" proved "that
the subject was in the air," or "that men's minds were prepared for it."
I do not think that this is strictly true, for I occasionally sounded
not a few naturalists, and never happened to come across a single one
who seemed to doubt about the permanence of species. Even Lyell and
Hooker, though they listened with interest to me, never seemed to agree.
I tried once or twice to explain to able men what I meant by Natural
Selection, but signally failed. What I believe was strictly true is that
innumerable well-observed facts were stored in the minds of naturalists
ready to take their proper places as soon as any theory which would
receive them was sufficiently explained. Another element in the success
of the book was its moderate size; and this I owe to the appearance of
Mr. Wallace's essay; had I published on the scale on which I began to
write in 1856, the book would have been four or five times as large as
the "Origin," and very few would have had the patience to read it.
I gained much by my delay an publishing from about, 1839, when the
theory was clearly conceived, to 1859; and I lost nothing by it, for I
cared very little whether men attributed most originality to me or
Wallace; and his essay no doubt aided in the reception of the theory. I
was forestalled in only one important point, which my vanity has always
made me regret, namely, the explanation by means of the Glacial period
of the presence of the same species of plants and of some few animals on
distant mountain summits and in the arctic regions. This view pleased me
so much that I wrote it out _in extenso_, and I believe that it was read
by Hooker some years before E. Forbes published in 1846 his celebrated
memoir on the subject. In the very few points in which we differed, I
still think that I was in the right. I have never, of course, alluded in
print to my having independently worked out this view.
Hardly any point gave me so much satisfaction when I was at work on the
"Origin," as the explanation of the wide difference in many classes
between the embryo and the adult animal, and of the close resemblance of
the embryos within the same class. No notice of this point was taken, as
far as I remember, in the early reviews of the "Origin," and I recollect
expressing my surprise on this head in a letter to Asa Gray. Within late
years several reviewers have given the whole credit to Fritz Muller and
Haeckel, who undoubtedly have worked it out much more fully and in some
respects more correctly than I did. I had materials for a whole chapter
on the subject, and I ought to have made the discussion longer; for it
is clear that I failed to impress my readers; and he who succeeds in
doing so deserves, in my opinion, all the credit.
This leads me to remark that I have almost always been treated honestly
by my reviewers, passing over those without scientific knowledge as not
worthy of notice. My views have been grossly misrepresented, bitterly
opposed and ridiculed, but this has been generally done as, I believe,
in good faith. On the whole, I do not doubt that my works have been over
and over again greatly overpraised. I rejoice that I have avoided
controversies, and this I owe to Lyell, who many years ago, in reference
to my geological works, strongly advised me never to get entangled in a
controversy, as it rarely did any good and caused a miserable loss of
time and temper.
Whenever I have found out that I have blundered, or that my work has
been imperfect, and when I have been contemptuously criticised, and even
when I have been overpraised, so that I have felt mortified, it has been
my greatest comfort to say hundreds of times to myself that "I have
worked as hard and as well as I could, and no man can do more than
this." I remember when in Good Success Bay, in Tierra del Fuego,
thinking (and, I believe, that I wrote home to the effect) that I could
not employ my life better than in adding a little to Natural Science.
This I have done to the best of my abilities, and critics may say what
they like, but they can not destroy this conviction.
FOOTNOTES:
[2] See Masterpieces of Science, Vol. I, "Earth and Sky," Sir Charles
Lyell on Uniformity in geological change.
[3] The essay appears in "Natural Selection," London, 1870.
THE DESCENT OF MAN
CHARLES DARWIN
[Concluding chapter of "The Descent of Man," New York, D.
Appleton & Co.]
A brief summary will be sufficient to recall to the reader's mind the
more salient points in this work. Many of the views which have been
advanced are highly speculative, and some, no doubt, will prove
erroneous; but I have in every case given the reasons which have led me
to one view rather than to another. It seemed worth while to try how far
the principle of evolution would throw light on some of the more complex
problems in the natural history of man. False facts are highly injurious
to the progress of science, for they often endure long; but false views,
if supported by some evidence, do little harm, for every one takes a
salutary pleasure in proving their falseness; and, when this is done,
one path toward error is closed and the road to truth is often at the
same time opened.