Charles Darwin
(an excerpt from: "On the Origin of Species by
Means of Natural Selection, or the Preservation of Favoured Races in the
Struggle for Life")
last words in all editions with the exception of the
first printing in 1859
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, whilst this planet has gone cycling 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.
Charles Darwin
THE ORIGIN OF SPECIES
(excerpts from: "On the Origin of Species by Means
of Natural Selection, or the Preservation of Favoured Races in the Struggle for
Life")
London, John Murray 1859
"What can be more curious than that the hand of a
man, formed for grasping, that of a mole for digging, the leg of the horse, the
paddle of the porpoise, and the wing of the bat, should all be constructed on
the same pattern, and should include the same bones, in the same relative
positions? Geoffroy St Hilaire has insisted strongly on the high
importance of relative connexion in homologous organs: the parts may change to
almost any extent in form and size, and yet they always remain connected
together in the same order. We never find, for instance, the bones of the arm
and forearm, or of the thigh and leg, transposed. Hence the same names can be
given to the homologous bones in widely different animals. We see the same great
law in the construction of the mouths of insects: what can be more different
than the immensely long spiral proboscis of a sphinx-moth, the curious folded
one of a bee or bug, and the great jaws of a beetle? yet all these organs,
serving for such different purposes, are formed by infinitely numerous
modifications of an upper lip, mandibles, and two pairs of maxillae. Analogous
laws govern the construction of the mouths and limbs of crustaceans. So it is
with the flowers of plants."
"I will here only allude to what may be called correlation of growth. Any
change in the embryo or larva will almost certainly entail changes in the mature
animal. In monstrosities, the correlations between quite distinct parts are very
curious; and many instances are given in Isidore Geoffroy St Hilaire's great
work on this subject. Breeders believe that long limbs are almost always
accompanied by an elongated head. Some instances of correlation are quite
whimsical; thus cats with blue eyes are invariably deaf; colour and
constitutional peculiarities go together, of which many remarkable cases could
be given amongst animals and plants. From the facts collected by Heusinger, it
appears that white sheep and pigs are differently affected from coloured
individuals by certain vegetable poisons. Hairless dogs have imperfect teeth;
long-haired and coarse-haired animals are apt to have, as is asserted, long or
many horns; pigeons with feathered feet have skin between their outer toes;
pigeons with short beaks have small feet, and those with long beaks large feet.
Hence, if man goes on selecting, and thus augmenting, any
peculiarity, he will almost certainly unconsciously modify other parts of the
structure, owing to the mysterious laws of the correlation of
growth."
"We shall have to recur to the general subject of rudimentary and aborted
organs; and I will here only add that their variability seems to be owing to
their uselessness, and therefore to natural selection having no power to check
deviations in their structure. Thus rudimentary
parts are left to the free play of the various laws of growth, to the effects of
long-continued disuse, and to the tendency to reversion."
"A trailing bamboo in the Malay Archipelago climbs the loftiest trees by
the aid of exquisitely constructed hooks clustered around the ends of the
branches, and this contrivance, no doubt, is of the highest service to the
plant; but as we see nearly similar hooks on many trees which are not climbers
the hooks on the bamboo may have arisen from unknown laws of growth, and have
been subsequently taken advantage of by the plant undergoing further
modification and becoming a climber. The naked skin on the head of a vulture is
generally looked at as a direct adaptation for wallowing in putridity; and so it
may be, or it may possibly be due to the direct action of putrid matter; but we
should be very cautious in drawing any such inference, when we see that the skin
on the head of the clean-feeding male turkey is likewise naked. The sutures in
the skulls of young mammals have been advanced as a beautiful adaptation for
aiding parturition, and no doubt they facilitate, or may be indispensable for
this act; but as sutures occur in the skulls of young birds and reptiles, which
have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been
taken advantage of in the parturition of the higher animals."
"Therefore we may infer that these several bones might have been acquired
through natural selection, subjected formerly, as now, to the several laws of
inheritance, reversion, correlation of growth, &c. Hence every detail of structure in every living creature (making some
little allowance for the direct action of physical conditions) may be viewed,
either as having been of special use to some ancestral form, or as being now of
special use to the descendants of this form either directly, or indirectly
through the complex laws of growth."
"We are far too ignorant, in almost every case, to be enabled to assert
that any part or organ is so unimportant for the welfare of a species, that
modifications in its structure could not have been slowly accumulated by means
of natural selection. But we may confidently
believe that many modifications, wholly due to the laws of growth, and at first
in no way advantageous to a species, have been subsequently taken advantage of
by the still further modified descendants of this species. We
may, also, believe that a part formerly of high importance has often been
retained (as the tail of an aquatic animal by its terrestrial descendants),
though it has become of such small importance that it could not, in its present
state, have been acquired by natural selection, a power which acts solely by the
preservation of profitable variations in the struggle for life."
"The expression of conditions of existence, so often insisted on by the
illustrious Cuvier, is fully embraced by the principle of natural selection. For
natural selection acts by either now adapting the varying parts of each being to
its organic and inorganic conditions of life; or by having adapted them during
long-past periods of time: the adaptations being
aided in some cases by use and disuse, being slightly affected by the direct
action of the external conditions of life, and being in all cases subjected to
the several laws of growth. Hence, in fact, the law of the
Conditions of Existence is the higher law; as it includes, through the
inheritance of former adaptations, that of Unity of Type."
"The subject of instinct might have been worked into the previous
chapters; but I have thought that it would be more convenient to treat the
subject separately, especially as so wonderful an instinct as that of the
hive-bee making its cells will probably have occurred to many readers, as a
difficulty sufficient to overthrow my whole theory. I must premise, that
I have nothing to do with the origin of the primary
mental powers, any more than I have with that of life itself.
We are concerned only with the diversities of instinct and of the other
mental qualities of animals within the same class."
"As the capacity of one plant to be grafted or budded on another is so
entirely unimportant for its welfare in a state of nature, I presume that no one will suppose that this capacity is a
specially endowed quality, but will admit that it is incidental on differences
in the laws of growth of the two plants."
Charles Darwin
(an excerpt from: "The variation of animals
and plants under domestication")
London, John Murray 1875 (first publ.
1868)
"...we may infer that, when any part or organ is either greatly increased
in size or wholly suppressed through variation and continued selection,
the coordinatory power of the organization will
continually tend to bring again all the parts into harmony with each
other."
