Darwin
The Origin of Species
Species, Uniformity, Naturalism, Secondary
Causes, God the Creator
I have called this
principle, by which each slight variation, if useful, is preserved, by the term
Natural Selection, in order to mark its relation to man's power of
selection. But the expression often used by Mr. Herbert Spencer of the Survival
of the Fittest is more accurate, and is sometimes equally convenient. We have
seen that man by selection can certainly produce great results, and can adapt
organic beings to his own uses, through the accumulation of slight but useful
variations, given to him by the hand of Nature. But Natural Selection, as we
shall hereafter see, is a power incessantly ready for action, and is as
immeasurably superior to man's feeble efforts, as the works of Nature are to
those of Art.
Nothing is easier
than to admit in words the truth of the universal struggle for life, or more
difficult — at least, I have found it so — than constantly to bear this
conclusion in mind. Yet unless it be thoroughly engrained in the mind, the
whole economy of nature, with every fact on distribution, rarity, abundance,
extinction, and variation, will be dimly seen or quite misunderstood. We behold
the face of nature bright with gladness, we often see superabundance of food;
we do not see, or we forget, that the birds which are idly singing round us
mostly live on insects or seeds, and are thus constantly destroying life; or we
forget how largely these songsters, or their eggs, or their nestlings, are
destroyed by birds and beasts of prey; we do not always bear in mind, that,
though food may be now superabundant, it is not so at all seasons of
each recurring year.
A struggle for
existence inevitably follows from the high rate at which all organic beings
tend to increase. Every being, which during its natural lifetime produces
several eggs or seeds, must suffer destruction during some period of its life,
and during some season or occasional year, otherwise, on the principle of
geometrical increase, its numbers would quickly become so
inordinately great that no country could support the product. Hence,
as more individuals are produced than can possibly survive, there must in every
case be a struggle for existence, either one individual with another of the
same species, or with the individuals of distinct species, or with the physical
conditions of life. It is the doctrine of Malthus applied with manifold force
to the whole animal and vegetable kingdoms; for in this case there can be no
artificial increase of food, and no prudential restraint from marriage.
Although some species may be now increasing, more or less rapidly, in numbers,
all cannot do so, for the world would not hold them. There is
no exception to the rule that every organic being naturally increases at so
high a rate, that, if not destroyed, the earth would soon be covered by the
progeny of a single pair.
It has been said
that I speak of natural selection as an active power or Deity; but who objects
to an author speaking of the attraction of gravity as ruling the movements of
the planets? Every one knows what is meant and is implied by such metaphorical
expressions; and they are almost necessary for brevity. So again it is
difficult to avoid personifying the word Nature; but I mean by Nature, only the
aggregate action and product of many natural laws, and by laws the sequence of
events as ascertained by us.
It may
metaphorically be said that natural selection is daily and hourly scrutinizing,
throughout the world, the slightest variations; rejecting those that are bad,
preserving and adding up all that are good; silently and insensibly working,
whenever and wherever opportunity offers, at the improvement of each organic
being in relation to its organic and inorganic conditions of life. We see nothing
of these slow changes in progress, until the hand of time has marked the lapse
of ages, and then so imperfect is our view into long past geological ages, that
we see only that the forms of life are now different from what they
formerly were.
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It may be asked how far I extend the doctrine of
the modification of species. The question is difficult to answer because the
more distinct the forms are which we consider, by so much the
arguments in favour of community of descent become fewer in number
and less in force. But some arguments of the greatest weight extend
very far. All the members of whole classes are connected together
by a chain of affinities, and all can be classed on the same principle,
in groups subordinate to groups. Fossil remains sometimes tend to
fill up very wide intervals between existing orders.
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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 that there will be a
considerable revolution in natural history. Systematists will be able to pursue
their labours as at present; but they will not be incessantly haunted by
the shadowy doubt whether this or that form be a true species. This,
I feel sure and I speak after experience, will be no slight re-
lief. The endless disputes whether or not some fifty species of British
brambles are good species will cease. Systematists will have only to
decide (not that this will be easy) whether any form be sufficiently
constant and distinct from other forms, to be capable of definition; and
if definable, whether the differences be sufficiently important to deserve
a specific name. This latter point will become a far more essential
consideration than it is at present; for differences, however slight,
between any two forms, if not blended by intermediate gradations, are looked at
by most naturalists as sufficient to raise both forms to the rank of
species.
Hereafter we shall be compelled to acknowledge
that the only distinction 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 consideration 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, adaptive characters, rudimentary and aborted organs, &c.,
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 pedigrees 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 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 having 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 be-
tween 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 recognised as having
depended on an unusual concurrence 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 exist- ing 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, whilst 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 not as 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 towards perfection.
Study Questions:
1. Has there always been struggle and suffering? How can we know?
2. Does natural selection require natural evil?
3. Can variation occur without natural evil?
4. When does variation lead to a new species as opposed to continued variation within a species?
5. What does it mean for the Creator to impose laws on nature?
6. What are secondary causes? What is the primary cause?
7. Has the Creator acted to change creation after the beginning?
8. Why is there natural evil and struggle for life?
9. What did Malthus say about the growth of populations? Must this be true?
10. What is uniformity (uniformitarianism) and how does it apply to explaining origins? (Charles Lyell)
11. What methods are used to explain the age of the earth?
12. Do these dating methods have philosophical presuppositions?
