The only thinker to whom Darwin was directly indebted, so far as the
theory of Natural Selection is concerned, was Malthus, and we may once
more quote the well-known passage in the Autobiography: "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 new species."
("The Life and Letters of Charles Darwin", Vol. 1. page 83. London,
1887.)
Although Malthus gives no adumbration of the idea of Natural Selection
in his exposition of the eliminative processes which go on in mankind,
the suggestive value of his essay is undeniable, as is strikingly
borne out by the fact that it gave to Alfred Russel Wallace also "the
long-sought clue to the effective agent in the evolution of organic
species." (A.R. Wallace, "My Life, A Record of Events and Opinions",
London, 1905, Vol. 1. page 232.) One day in Ternate when he was resting
between fits of fever, something brought to his recollection the work of
Malthus which he had read twelve years before. "I thought of his clear
exposition of 'the positive checks to increase'--disease, accidents,
war, and famine--which keep down the population of savage races to
so much lower an average than that of more civilized peoples. It then
occurred to me that these causes or their equivalents are continually
acting in the case of animals also; and as animals usually breed much
more rapidly than does mankind, the destruction every year from these
causes must be enormous in order to keep down the numbers of each
species, since they evidently do not increase regularly from year to
year, as otherwise the world would long ago have been densely crowded
with those that breed most quickly. Vaguely thinking over the enormous
and constant destruction which this implied, it occurred to me to ask
the question, Why do some die and some live? And the answer was clearly,
that on the whole the best fitted live. From the effects of disease the
most healthy escaped; from enemies the strongest, the swiftest, or
the most cunning; from famine the best hunters or those with the
best digestion; and so on. Then it suddenly flashed upon me that this
self-acting process would necessarily IMPROVE THE RACE, because in every
generation the inferior would inevitably be killed off and the superior
would remain--that is, THE FITTEST WOULD SURVIVE." (Ibid. Vol. 1. page
361.) We need not apologise for this long quotation, it is a tribute
to Darwin's magnanimous colleague, the Nestor of the evolutionist
camp,--and it probably indicates the line of thought which Darwin
himself followed. It is interesting also to recall the fact that in
1852, when Herbert Spencer wrote his famous "Leader" article on "The
Development Hypothesis" in which he argued powerfully for the thesis
that the whole animate world is the result of an age-long process of
natural transformation, he wrote for "The Westminster Review" another
important essay, "A Theory of Population deduced from the General Law of
Animal Fertility", towards the close of which he came within an ace
of recognising that the struggle for existence was a factor in organic
evolution. At a time when pressure of population was practically
interesting men's minds, Darwin, Wallace, and Spencer were being
independently led from a social problem to a biological theory. There
could be no better illustration, as Prof. Patrick Geddes has pointed
out, of the Comtian thesis that science is a "social phenomenon."
Therefore, as far more important than any further ferreting out of vague
hints of Natural Selection in books which Darwin never read, we would
indicate by a quotation the view that the central idea in Darwinism
is correlated with contemporary social evolution. "The substitution
of Darwin for Paley as the chief interpreter of the order of nature is
currently regarded as the displacement of an anthropomorphic view by a
purely scientific one: a little reflection, however, will show that
what has actually happened has been merely the replacement of the
anthropomorphism of the eighteenth century by that of the nineteenth.
For the place vacated by Paley's theological and metaphysical
explanation has simply been occupied by that suggested to Darwin and
Wallace by Malthus in terms of the prevalent severity of industrial
competition, and those phenomena of the struggle for existence which the
light of contemporary economic theory has enabled us to discern, have
thus come to be temporarily exalted into a complete explanation
of organic progress." (P. Geddes, article "Biology", "Chambers's
Encyclopaedia".) It goes without saying that the idea suggested by
Malthus was developed by Darwin into a biological theory which was then
painstakingly verified by being used as an interpretative formula, and
that the validity of a theory so established is not affected by what
suggested it, but the practical question which this line of thought
raises in the mind is this: if Biology did thus borrow with such
splendid results from social theory, why should we not more deliberately
repeat the experiment?
Darwin was characteristically frank and generous in admitting that the
principle of Natural Selection had been independently recognised by
Dr W.C. Wells in 1813 and by Mr Patrick Matthew in 1831, but he had no
knowledge of these anticipations when he published the first edition
of "The Origin of Species". Wells, whose "Essay on Dew" is still
remembered, read in 1813 before the Royal Society a short paper entitled
"An account of a White Female, part of whose skin resembles that of a
Negro" (published in 1818). In this communication, as Darwin said, "he
observes, firstly, that all animals tend to vary in some degree, and,
secondly, that agriculturists improve their domesticated animals by
selection; and then, he adds, but what is done in this latter case
'by art, seems to be done with equal efficacy, though more slowly, by
nature, in the formation of varieties of mankind, fitted for the country
which they inhabit.'" ("Origin of Species" (6th edition) page xv.)
Thus Wells had the clear idea of survival dependent upon a favourable
variation, but he makes no more use of the idea and applies it only
to man. There is not in the paper the least hint that the author ever
thought of generalising the remarkable sentence quoted above.
Of Mr Patrick Matthew, who buried his treasure in an appendix to a work
on "Naval Timber and Arboriculture", Darwin said that "he clearly saw
the full force of the principle of natural selection." In 1860 Darwin
wrote--very characteristically--about this to Lyell: "Mr Patrick
Matthew publishes a long extract from his work on "Naval Timber and
Arboriculture", published in 1831, in which he briefly but completely
anticipates the theory of Natural Selection. I have ordered the book,
as some passages are rather obscure, but it is certainly, I think, a
complete but not developed anticipation. Erasmus always said that surely
this would be shown to be the case some day. Anyhow, one may be excused
in not having discovered the fact in a work on Naval Timber." ("Life and
Letters" II. page 301.)
De Quatrefages and De Varigny have maintained that the botanist Naudin
stated the theory of evolution by natural selection in 1852. He explains
very clearly the process of artificial selection, and says that in the
garden we are following Nature's method. "We do not think that Nature
has made her species in a different fashion from that in which we
proceed ourselves in order to make our variations." But, as Darwin said,
"he does not show how selection acts under nature." Similarly it must
be noted in regard to several pre-Darwinian pictures of the struggle
for existence (such as Herder's, who wrote in 1790 "All is in
struggle... each one for himself" and so on), that a recognition of this
is only the first step in Darwinism.
Profs. E. Perrier and H.F. Osborn have called attention to a remarkable
anticipation of the selection-idea which is to be found in the
speculations of Etienne Geoffroy St Hilaire (1825-1828) on the evolution
of modern Crocodilians from the ancient Teleosaurs. Changing environment
induced changes in the respiratory system and far-reaching consequences
followed. The atmosphere, acting upon the pulmonary cells, brings about
"modifications which are favourable or destructive ('funestes'); these
are inherited, and they influence all the rest of the organisation of
the animal because if these modifications lead to injurious effects,
the animals which exhibit them perish and are replaced by others of a
somewhat different form, a form changed so as to be adapted to (a la
convenance) the new environment."
Prof. E.B. Poulton ("Science Progress", New Series, Vol. I. 1897. "A
Remarkable Anticipation of Modern Views on Evolution". See also
Chap. VI. in "Essays on Evolution", Oxford, 1908.) has shown that the
anthropologist James Cowles Prichard (1786-1848) must be included, even
in spite of himself, among the precursors of Darwin. In some passages
of the second edition of his "Researches into the Physical History of
Mankind" (1826), he certainly talks evolution and anticipates Prof.
Weismann in denying the transmission of acquired characters. He is,
however, sadly self-contradictory and his evolutionism weakens in
subsequent editions--the only ones that Darwin saw. Prof. Poulton finds
in Prichard's work a recognition of the operation of Natural Selection.
"After enquiring how it is that 'these varieties are developed and
preserved in connection with particular climates and differences of
local situation,' he gives the following very significant answer: 'One
cause which tends to maintain this relation is obvious. Individuals and
families, and even whole colonies, perish and disappear in climates for
which they are, by peculiarity of constitution, not adapted. Of this
fact proofs have been already mentioned.'" Mr Francis Darwin and Prof.
A.C. Seward discuss Prichard's "anticipations" in "More Letters of
Charles Darwin", Vol. I. page 43, and come to the conclusion that the
evolutionary passages are entirely neutralised by others of an opposite
trend. There is the same difficulty with Buffon.
Hints of the idea of Natural Selection have been detected elsewhere.
James Watt (See Prof. Patrick Geddes's article "Variation and
Selection", "Encyclopaedia Britannica (9th edition) 1888.), for
instance, has been reported as one of the anticipators (1851). But we
need not prolong the inquiry further, since Darwin did not know of any
anticipations until after he had published the immortal work of 1859,
and since none of those who got hold of the idea made any use of it.
What Darwin did was to follow the clue which Malthus gave him, to
realise, first by genius and afterwards by patience, how the complex
and subtle struggle for existence works out a natural selection of
those organisms which vary in the direction of fitter adaptation to the
conditions of their life. So much success attended his application of
the Selection-formula that for a time he regarded Natural Selection
as almost the sole factor in evolution, variations being pre-supposed;
gradually, however, he came to recognise that there was some validity in
the factors which had been emphasized by Lamarck and by Buffon, and in
his well-known summing up in the sixth edition of the "Origin" he
says of the transformation of species: "This has been effected chiefly
through the natural selection of numerous successive, slight, favourable
variations; aided in an important manner by the inherited effects of
the use and disuse of parts; and in an unimportant manner, that is, in
relation to adaptive structures, whether past or present, by the direct
action of external conditions, and by variations which seem to us in our
ignorance to arise spontaneously."
To sum up: the idea of organic evolution, older than Aristotle, slowly
developed from the stage of suggestion to the stage of verification, and
the first convincing verification was Darwin's; from being an a priori
anticipation it has become an interpretation of nature, and Darwin is
still the chief interpreter; from being a modal interpretation it has
advanced to the rank of a causal theory, the most convincing part of
which men will never cease to call Darwinism.