THE VIEWS OF ERASMUS DARWIN
Erasmus Darwin, the grandfather of Charles Darwin, was born in 1731, or
twenty-four years after Buffon. He was an English country physician with
a large practice, and not only interested in philosophy, mechanics, and
natural science, but given to didactic rhyming, as evinced by _The
Botanical Garden_ and _The Loves of the Plants_, the latter of which was
translated into French in 1800, and into Italian in 1805. His "shrewd
and homely mind," his powers of keen observation and strong common sense
were revealed in his celebrated work _Zoonomia_, which was published in
two volumes in 1794, and translated into German in 1795-99. He was not a
zoölogist, published no separate scientific articles, and his striking
and original views on evolution, which were so far in advance of his
time, appear mostly in the section on "Generation," comprising 173 pages
of his _Zoonomia_,[152] which was mainly a medical work. The book was
widely read, excited much discussion, and his views decided opposition.
Samuel Butler in his _Evolution, Old and New_ (1879) remarks: "Paley's
_Natural Theology_ is written throughout at the _Zoonomia_, though he
is careful, _moro suo_, never to mention this work by name. Paley's
success was probably one of the chief causes of the neglect into which
the Buffonian and Darwinian systems fell in this country." Dr. Darwin
died in the same year (1802) as that in which the _Natural Theology_ was
published.
Krause also writes of the reception given by his contemporaries to his
"physio-philosophical ideas." "They spoke of his wild and eccentric
fancies, and the expression 'Darwinising' (as employed, for example, by
the poet Coleridge when writing on Stillingfleet) was accepted in
England nearly as the antithesis of sober biological investigation."[153]
The grandson of Erasmus Darwin had little appreciation of the views of
him of whom, through atavic heredity, he was the intellectual and
scientific child. "It is curious," he says in the 'Historical Sketch' of
the _Origin of Species_--"it is curious how largely my grandfather,
Dr. Erasmus Darwin, anticipated the views and erroneous grounds of
opinion of Lamarck in his _Zoonomia_ (vol. i., pp. 500-510), published
in 1794." It seems a little strange that Charles Darwin did not devote a
few lines to stating just what his ancestor's views were, for certain of
them, as we shall see, are anticipations of his own.
The views of Erasmus Darwin may thus be summarily stated:
1. All animals have originated "from a single living filament" (p. 230),
or, stated in other words, referring to the warm-blooded animals alone,
"one is led to conclude that they have alike been produced from a
similar living filament" (p. 236); and again he expresses the conjecture
that one and the same kind of living filament is and has been the cause
of all organic life (p. 244). It does not follow that he was a
"spermist," since he strongly argued against the incasement or
"evolution" theory of Bonnet.
2. Changes produced by differences of climate and even seasons. Thus
"the sheep of warm climates are covered with hair instead of wool, and
the hares and partridges of the latitudes which are long buried in snow
become white during the winter months" (p. 234). Only a passing
reference is made to this factor, and the effects of domestication are
but cursorily referred to. In this respect Darwin's views differed much
from Buffon's, with whom they were the primary causes in the
modification of animals.
The other factors or agencies are not referred to by Buffon, showing
that Darwin was not indebted to Buffon, but thought out the matter in
his own independent way.
3. "Fifthly, from their first rudiment or primordium to the termination
of their lives, all animals undergo perpetual transformations, which are
in part produced by their own exertions in consequence of their desires
and aversions, of their pleasures and their pains, or of irritations or
of associations; and many of these acquired forms or propensities are
transmitted to their posterity" (p. 237). The three great objects of
desire are, he says, "lust, hunger, and security" (p. 237).
4. Contests of the males for the possession of the females, or law of
battle. Under the head of desire he dwells on the desire of the male for
the exclusive possession of the female; and "these have acquired weapons
to combat each other for this purpose," as the very thick, shield-like
horny skin on the shoulders of the boar, and his tusks, the horns of the
stag, the spurs of cocks and quails. "The final cause," he says, "of
this contest among the males seems to be that the strongest and most
active animal should propagate the species, which should thence become
improved" (p. 238). This savors so strongly of sexual selection that we
wonder very much that Charles Darwin repudiated it as "erroneous." It is
not mentioned by Lamarck, nor is Dr. Darwin's statement of the exertions
and desires of animals at all similar to Lamarck's, who could not have
borrowed his ideas on appetency from Darwin or any other predecessor.
5. The transmission of characters acquired during the lifetime of the
parent. This is suggested in the following crude way:
"Thirdly, when we enumerate the great changes produced in the
species of animals before their maturity, as, for example, when the
offspring reproduces the effects produced upon the parent by
accident or cultivation; or the changes produced by the mixture of
species, as in mules; or the changes produced probably by the
exuberance of nourishment supplied to the fetus, as in monstrous
births with additional limbs, many of these enormities of shape are
propagated and continued as a variety, at least, if not as a new
species of animal. I have seen a breed of cats with an additional
claw on every foot; of poultry also with an additional claw, and
with wings to their feet, and of others without rumps. Mr. Buffon
mentions a breed of dogs without tails, which are common at Rome and
Naples, which he supposes to have been produced by a custom, long
established, of cutting their tails close off. There are many kinds
of pigeons admired for their peculiarities which are more or less
thus produced and propagated."[154]
6. The means of procuring food has, he says, "diversified the forms of
all species of animals. Thus the nose of the swine has become hard for
the purpose of turning up the soil in search of insects and of roots.
The trunk of the elephant is an elongation of the nose for the purpose
of pulling down the branches of trees for his food, and for taking up
water without bending his knees. Beasts of prey have acquired strong
jaws or talons. Cattle have acquired a rough tongue and a rough palate
to pull off the blades of grass, as cows and sheep. Some birds have
acquired harder beaks to crack nuts, as the parrot. Others have acquired
beaks to break the harder seeds, as sparrows. Others for the softer
kinds of flowers, or the buds of trees, as the finches. Other birds have
acquired long beaks to penetrate the moister soils in search of insects
or roots, as woodcocks, and others broad ones to filtrate the water of
lakes and to retain aquatic insects. All which seem to have been
gradually produced during many generations by the perpetual endeavors of
the creature to supply the want of food, and to have been delivered to
their posterity with constant improvement of them for the purpose
required" (p. 238).
7. The third great want among animals is that of security, which seems
to have diversified the forms of their bodies and the color of them;
these consist in the means of escaping other animals more powerful than
themselves.[155] Hence some animals have acquired wings instead of legs,
as the smaller birds, for purposes of escape. Others, great length of
fin or of membrane, as the flying-fish and the bat. Others have acquired
hard or armed shells, as the tortoise and the Echinus marinus (p. 239).
"The colors of insects," he says, "and many smaller animals
contribute to conceal them from the dangers which prey upon them.
Caterpillars which feed on leaves are generally green; earthworms
the color of the earth which they inhabit; butterflies, which
frequent flowers, are colored like them; small birds which frequent
hedges have greenish backs like the leaves, and light-colored
bellies like the sky, and are hence less visible to the hawk, who
passes under them or over them. Those birds which are much amongst
flowers, as the goldfinch (_Fringilla carduelis_), are furnished
with vivid colors. The lark, partridge, hare, are the color of dry
vegetables or earth on which they rest. And frogs vary their color
with the mud of the streams which they frequent; and those which
live on trees are green. Fish, which are generally suspended in
water, and swallows, which are generally suspended in air, have
their backs the color of the distant ground, and their bellies of
the sky. In the colder climates many of these become white during
the existence of the snows. Hence there is apparent design in the
colors of animals, whilst those of vegetables seem consequent to
the other properties of the materials which possess them" (_The
Loves of the Plants_, p. 38, note).
In his _Zoonomia_ (§ xxxix., vi.) Darwin also speaks of the efficient
cause of the various colors of the eggs of birds and of the hair and
feathers of animals which are adapted to the purpose of concealment.
"Thus the snake, and wild cat, and leopard are so colored as to resemble
dark leaves and their light interstices" (p. 248). The eggs of
hedge-birds are greenish, with dark spots; those of crows and magpies,
which are seen from beneath through wicker nests, are white, with dark
spots; and those of larks and partridges are russet or brown, like their
nests or situations. He adds: "The final cause of their colors is easily
understood, as they serve some purpose of the animal, but the efficient
cause would seem almost beyond conjecture." Of all this subject of
protective mimicry thus sketched out by the older Darwin, we find no
hint or trace in any of Lamarck's writings.
8. Great length of time. He speaks of the "great length of time since
the earth began to exist, perhaps millions of ages before the
commencement of the history of mankind" (p. 240).
In this connection it may be observed that Dr. Darwin emphatically
opposes the preformation views of Haller and Bonnet in these words:
"Many ingenious philosophers have found so great difficulty in
conceiving the manner of the reproduction of animals that they have
supposed all the numerous progeny to have existed in miniature in
the animal originally created, and that these infinitely minute
forms are only evolved or distended as the embryon increases in the
womb. This idea, besides being unsupported by any analogy we are
acquainted with, ascribes a greater tenuity to organized matter than
we can readily admit" (p. 317); and in another place he claims that
"we cannot but be convinced that the fetus or embryon is formed by
apposition of new parts, and not by the distention of a primordial
nest of germs included one within another like the cups of a
conjurer" (p. 235).
9. To explain instinct he suggests that the young simply imitate the
acts or example of their parents. He says that wild birds choose spring
as their building time "from the acquired knowledge that the mild
temperature of the air is more convenient for hatching their eggs;" and
further on, referring to the fact that seed-eating animals generally
produce their young in spring, he suggests that it is "part of the
traditional knowledge which they learn from the example of their
parents."[156]
10. Hybridity. He refers in a cursory way to the changes produced by the
mixture of species, as in mules.
Of these ten factors or principles, and other views of Dr. Darwin, some
are similar to those of Lamarck, while others are directly opposed.
There are therefore no good grounds for supposing that Lamarck was
indebted to Darwin for his views. Thus Erasmus Darwin supposes that the
formation of organs precedes their use. As he says, "The lungs must be
previously formed before their exertions to obtain fresh air can exist;
the throat or oesophagus must be formed previous to the sensation or
appetites of hunger and thirst" (_Zoonomia_, p. 222). Again (_Zoonomia_,
i., p. 498), "From hence I conclude that with the acquisition of new
parts, new sensations and new desires, as well as new powers, are
produced" (p. 226). Lamarck does not carry his doctrine of
use-inheritance so far as Erasmus Darwin, who claimed, what some still
maintain at the present day, that the offspring reproduces "the effects
produced upon the parent by accident or cultivation."
The idea that all animals have descended from a similar living filament
is expressed in a more modern and scientific way by Lamarck, who derived
them from monads.
The Erasmus Darwin way of stating that the transformations of animals
are in part produced by their own exertions in consequence of their
desires and aversions, etc., is stated in a quite different way by
Lamarck.
Finally the principle of law of battle, or the combat between the males
for the possession of the females, with the result "that the strongest
and most active animal should propagate the species," is not hinted at
by Lamarck. This view, on the contrary, is one of the fundamental
principles of the doctrine of natural selection, and was made use of by
Charles Darwin and others. So also Erasmus anticipated Charles Darwin in
the third great want of "security," in seeking which the forms and
colors of animals have been modified. This is an anticipation of the
principle of protective mimicry, so much discussed in these days by
Darwin, Wallace, and others, and which was not even mentioned by
Lamarck. From the internal evidence of Lamarck's writings we therefore
infer that he was in no way indebted to Erasmus Darwin for any hints or
ideas.[157]
FOOTNOTES:
[152] Vol. ii., 3d edition. Our references are to this edition.
[153] Krause, _The Scientific Works of Erasmus Darwin_, footnote on
p. 134: "See 'Athenæum,' March, 1875, p. 423."
[154] _Zoonomia_, i., p. 505 (3d edition, p. 335).
[155] The subject of protective mimicry is more explicitly stated by
Dr. Darwin in his earlier book, _The Loves of the Plants_, and, as
Krause states, though Rösel von Rosenhof in his _Insekten-Belustigungen_
(Nurnberg, 1746) describes the resemblance which geometric caterpillars,
and also certain moths when in repose, present to dry twigs, and thus
conceal themselves, "this group of phenomena seems to have been first
regarded from a more general point of view by Dr. Darwin."
[156] _Zoonomia_, vol. i., p. 170.
[157] Mr. Samuel Butler, in his _Evolution, Old and New_, taking it for
granted that Lamarck was "a partisan of immutability till 1801,"
intimates that "the secret of this sudden conversion must be found in a
French translation by M. Deleuze of Dr. Darwin's poem, _The Loves of the
Plants_, which appeared in 1800. Lamarck--the most eminent botanist of
his time--was sure to have heard of and seen this, and would probably
know the translator, who would be able to give him a fair idea of the
_Zoonomia_" (p. 258).
But this notion seems disproved by the fact that Lamarck delivered his
famous lecture, published in 1801, during the last of April or in the
first half of May, 1800. The views then presented must have been formed
in his mind at least for some time--perhaps a year or more--previous,
and were the result of no sudden inspiration, least of all from any
information given him by Deleuze, whom he probably never met. If Lamarck
had actually seen and read the _Zoonomia_ he would have been manly
enough to have given him credit for any novel ideas. Besides that, as we
have already seen, the internal evidence shows that Lamarck's views were
in some important points entirely different from those of Erasmus
Darwin, and were conceptions original with the French zoölogist.
Krause in his excellent essay on the scientific works of Erasmus Darwin
(1879) refers to Lamarck as "evidently a disciple of Darwin," stating
that Lamarck worked out "in all directions" Erasmus Darwin's principles
of "will and active efforts" (p. 212).