Darwinism, which was originally a technical theory of the biological
schools, has long since become a veritable tangle of the most diverse
problems and opinions, and seems to press hardly upon the religious
conception of the world from many different sides. In its theory of blind
“natural selection” and the fortuitous play of the factors in the struggle
for existence, it appears to surrender the whole of this wonderful world
of life to the rough and ready grip of a process without method or plan.
In the general theory of evolution and the doctrine of the descent of even
the highest from the lowest, it seems to take away all special dignity
from the human mind and spirit, all the freedom and all the nobility of
pure reason and free will; it seems to reduce the higher products of
religion, morality, poetry, and the æsthetic sense to the level of an
ignoble tumult of animal impulses, desires and sensations. Purely
speculative questions relative to the evolution theory, psychological and
metaphysical, logical and epistemological, ethical, æsthetic, and finally
even historical and politico-economical questions have been drawn into the
coil, and usually receive from the Darwinians an answer at once robust and
self-assured. A zoological theory seems suddenly to have thrown light and
intelligibility into the most diverse provinces of knowledge.
But in point of fact it can be shown that Darwinism has not really done
this and cannot do it. It leaves unaffected the problem of the mind with
its peculiar and underivable laws, from the logical to the ethical.
Whether it be right or wrong in its physiological theories, its
genealogical trees and fortuitous factors, preoccupation with this theory
is a task of the second order. Nevertheless it is necessary to study it,
because the chief objections to the religious interpretation of the world
have come from it.
The Development of Darwinism.
In studying it we should like to follow a method somewhat different from
that usually observed in apologetic writings. “Darwinism,” even in its
technical, biological form, never was quite, and is to-day not at all a
unified and consistent system. It has been modified in so many ways and
presented in such different colours, that we must either refrain
altogether from attempting to get into close quarters with it, or we must
make ourselves acquainted to some extent with the phases of the theory as
it has gradually developed up to the present day. This is the more
necessary and useful since it is precisely within the circle of technical
experts that revolts from and criticisms of the Darwinian theory have in
recent years arisen; and these are so incisive, so varied, and so
instructive, that through them we can adjust our standpoint in relation to
the theory better than in any other way. And in thus letting the
biologists speak for themselves, we are spared the fatal task of entering
into the discussion of questions belonging to a region outside our own
particular studies.
We cannot, however, give more than a short sketch. But even such a sketch
may do more towards giving us a general knowledge of the question and
showing us a way out of the difficulties it raises than any of the current
“refutations.” To supplement this sketch, and facilitate a thorough
understanding of the problem, we shall give somewhat fuller references
than are usual to the relevant literature. And the same method will be
pursued in the following chapter, which deals with the mechanical theory
of life. This method throws more upon the reader, but it is probably the
most satisfactory one for the serious student.
The reactions from the Darwinism of the schools which we have just
referred to, and to which the second half of this chapter is devoted, are,
of course, of a purely scientific kind. And while we are devoting our
attention to them, we must not be unfaithful to the canon laid down in the
previous chapter, namely that with reference to the question of teleology
in the religious sense no real answer can be looked for from scientific
study, not even if it be anti-Darwinian. In this case, too, it is
impossible to read the convictions and intuitions of the religious
conception of the world out of a scientific study of nature: they precede
it. But here, too, we may find some accessory support and indirect
corroboration more or less strong and secure. This may be illustrated by a
single example. It will be shown that, on closer study, it is not
impossible to subordinate even the apparently confused tangle of
naturalistic factors of evolution which are summed up in the phrase
“struggle for existence” to interpretation from the religious point of
view. But matters will be in quite a different position if the whole
theory collapses, and instead of evolution and its paths being given over
to confusion and chance, it appears that from the very beginning and at
every point there is a predetermination of fixed and inevitable lines
along and up which it must advance. In many other connections
considerations of a like nature will reveal themselves to us in the course
of our study.
Darwinism, as popularly understood, is the theory that “men are descended
from monkeys,” and in general that the higher forms of life are descended
from the lower, and it is regarded as Darwin’s epoch-making work and his
chief merit—or fault according to the point of view—that he established
the Theory of Descent. This is only half correct, and it leaves out the
real point of Darwinism altogether. The Theory of Descent had its way
prepared by the evolutionist ideas and the speculative nature-philosophy
of Goethe, Schelling, Hegel and Oken; by the suggestions and glimmerings
of the nature-mysticism of the romanticists; by the results of comparative
anatomy and physiology; was already hinted at, at least as far as
derivation of species was concerned, in the works of Linné himself; was
worked out in the “zoological philosophies,” by the elder Darwin, by
Lamarck, Etienne Geoffrey St. Hilaire and Buffon; was in the field long
before Charles Darwin’s time; was already in active conflict with the
antagonistic theory of the “constancy of species,” and had its more or
less decided adherents. Yet undoubtedly it was through and after Darwin
that the theory grew so much more powerful and gained general acceptance.
Darwinism and Teleology.
But the essential and most characteristic importance of Darwin and his
work, the reason for which he was called the Newton of biology, and which
makes Darwinism at once interesting and dangerous to the religious
conception of the world, is something quite special and new. It is its
radical opposition to teleology. Du Bois-Reymond, in his witty lecture
“Darwin versus Galiani,”(4) explains the gist of the matter. “Les dés de
la nature sont pipés” (nature’s dice are loaded). Nature is almost always
throwing aces. She brings forth not what is meaningless and purposeless,
but in great preponderance what is full of meaning and purpose. What
“loaded” her dice like this? Even if the theory of descent be true, in
what way does it directly help the purely scientific interpretation of the
world? Would not this evolution from the lowest to the highest simply be a
series of the most astonishing lucky throws of the dice by which in
perplexing “endeavour after an aim,” the increasingly perfect, and
ultimately the most perfect is produced? And, on the other hand, every
individual organism, from the Amœba up to the most complex vertebrate, is,
in its structure, its form, its functions, a stupendous marvel of
adaptation to its end and of co-ordination of the parts to the whole, and
of the whole and its parts to the functions of the organism, the functions
of nutrition, self-maintenance, reproduction, maintenance of the species,
and so on. How account for the adaptiveness, both general and special,
without _causæ finales_, without intention and purposes, without guidance
towards a conscious aim? How can it be explained as the necessary result
solely of _causæ efficientes_, of blindly working causes without a
definite aim? Darwinism attempts to answer this question. And its answer
is: “What appears to us ‘purposeful’ and ‘perfect’ is in truth only the
manifold adaptation of the forms of life to the conditions of their
existence. And this adaptation is brought about solely by means of these
conditions themselves. Without choice, without aim, without conscious
purpose nature offers a wealth of possibilities. The conditions of
existence act as a sieve. What chances to correspond to them maintains
itself, gliding through the meshes of the sieve, what does not perishes.”
It is an old idea of the naturalistic philosophies, dating from
Empedocles, which Darwin worked up into the theory of “natural selection”
through “the survival of the fittest” “in the struggle for existence.” Of
course the assumption necessary to his idea is that the forms of life are
capable of variation, and of continually offering in ceaseless flux new
properties and characters to the sieve of selection, and of being raised
thereby from the originally homogeneous to the heterogeneous, from the
simple to the complex, from the lower to the higher. This is the theory of
descent, and it is, of course, an essential part and the very foundation
of Darwin’s theory. But it is _the doctrine of descent based upon natural
selection_ that is Darwinism itself.
The Characteristic Features of Darwinism.
We do not propose to expound the Darwinian theory for the hundredth time;
a knowledge of it must be taken for granted. We need only briefly call to
mind the characteristic features and catchwords of the theory as Darwin
founded it, which have also been the starting points of subsequent
modifications and controversies.
All living creatures are bound together in genetic solidarity. Everything
has evolved through endless deviations, gradations, and differentiations,
but at the same time by a perfectly continuous process. Variation
continually produced a crop of heterogeneous novelties. The struggle for
existence sifted these out. Heredity fixed and established them. Without
method or plan variations continue to occur (indefinite variations). They
manifest themselves in all manner of minute changes (“fluctuating”
variations). Every part, every function of an organism may be subject
individually to variation and selection. The world is strictly governed by
what is useful. The whole organisation as well as the individual organs
and functions bear the stamp of utility, at least, they must bear it if
the theory is correct. In the general continuity the transitions are
always easy; there are no fundamentally distinct “types,” architectural
plans, or groups of forms. Where gaps yawn the intermediate links have
gone amissing. There is no fundamental difference between _genus_,
_species_, and _variety_. Even the most complicated organ such as the eye,
the most puzzling function such as the instinct of the bee, may be
explained as the outcome of many more primitive stages.
The chief evidences of the theory of descent are to be found in
homologies, in the correspondences of organs and functions, as revealed by
comparative anatomy and physiology, in the recapitulation revealed by
embryology, in the structure of parasites, in rudimentary organs and
reversions to earlier stages, in the distribution of animals and plants,
and in the possibility of still transforming, at least to a slight extent,
one species into another, by experimental breeding.
Transformation and differentiation go on in nature as a vast, ceaseless,
but blind process of selection. In artificial selection evolution is
secured by choosing the most fit for breeding purposes; so it is secured
in natural selection by the favouring and survival of those forms which
are the most fit among the many unfit or less fit, which happened to be
exposed to the struggle for existence, that is, to the competition for the
means of subsistence, to the struggle with enemies, to hostile
environment, and to dangers of every kind. The adaptation thus brought
about is of a purely “passive” kind. The variations arise fortuitously out
of the organism, and present themselves for selection in the struggle for
existence; they are not actively acquired by means of the struggle. The
secondary factors of evolution recognised are: correlation in the growth
and in the development of parts, the origin of new characters through use,
their disappearance through disuse (Lamarck), the transmission of
characters thus acquired, the influence of environment and sexual
selection.(5)
The Darwinian theory, the interpretation of the teleological in the
animate world by means of the theory of descent based upon natural
selection, entered like a ferment into the scientific thought-movement,
and in a space of forty years it has itself passed through a series of
stages, differentiations, and transformations which have in part resulted
in the present state of the theory, and have in part anticipated it. These
are represented by the names of workers belonging to a generation which
has for the most part already passed away: Darwin’s collaborateurs, such
as Alfred Russel Wallace, who independently and simultaneously expounded
the theory of natural selection, Haeckel and Fritz Müller, Nägeli and
Askenasy, von Kölliker, Mivart, Romanes and others. The differentiation
and elaboration of Darwin’s theories has gone ever farther and farther;
the grades and shades of doctrine held by his disciples are now almost
beyond reckoning.
Various Forms of Darwinism.
The great majority of these express what may be called popular Darwinism
[“Darwinismus vulgaris”], theoretically worthless, but practically
possessed of great powers of attraction and propagandism. It expresses in
the main a conviction, usually left unexplained, that everything “happens
naturally,” that man is really descended from monkeys, and that life has
“evolved from lower stages” of itself, that dualism is wrong, and that
monism is the truth. It is exactly the standpoint of the popular
naturalism we have already described, which here mingles unsuspectingly
and without scruple Lamarckian and other principles with the Darwinian,
which is enthusiastic on the one hand over the “purely mechanical”
interpretation of nature, and on the other drags in directly psychical
motives, unconscious consciousness, impulses, spontaneous
self-differentiation of organisms, which nevertheless adheres to “monism”
and possibly even professes to share Goethe’s conception of nature!
Above this stratum we come to that of the real experts, the only one which
concerns us in the least. Here too we find an ever-growing distance
between divergent views, the most manifold differences amounting sometimes
to mutual exclusion. These differences occur even with reference to the
fundamental doctrine generally adhered to, the doctrine of descent. To one
party it is a proved fact, to another a probable, scientific working
hypothesis, to a third a “rescuing plank.” One party is always finding
fresh corroborations, another new difficulties. And within the same group
we find the contrasts of believers in monophyletic and believers in
polyphyletic evolution, the mechanists and the half-confessed or
thoroughgoing vitalists, the preformationists and the believers in
epigenesis. Opinions differ even more widely in regard to the _rôle_ of
the “struggle for existence” in the production of species. On the one hand
we have the Darwinism of Darwin freed from inconsequent additions and
formulated as orthodox “neo-Darwinism”; on the other hand we have
heterodox Lamarckism. The “all-sufficiency” of natural selection is
proclaimed by some, its impotence by others. Indefinite variation is
opposed by orthogenesis, fluctuating variation by saltatory mutation
(Halmatogenesis in “Greek”), passive adaptation by the spontaneous
activity and self-regulation of the living organism. The struggle for
existence is variously regarded as the chief factor, or as a co-operating
factor, or as an indifferent, or even an inimical factor in the
origination of new species.
And among the representatives of these different standpoints there are
most interesting personal differences: in some, like Weismann, we find a
great loyalty to, and persistence in the position once arrived at, in
others the most surprising transitions and changes of opinion. Thus
Fleischmann, a pupil of Selenka’s, after illustrating during many years of
personal research the orthodox Darwinian standpoint, finally developed
into an outspoken opponent not only of the theory of selection but of the
doctrine of descent. So also Friedmann.(6) Driesch started from the
mechanical theory of life and advanced through the connected series of his
own biological essays to vitalism. Romanes, a prominent disciple of
Darwin, ended in Christian theism, and Wallace, the discoverer of “the
struggle for existence,” landed in spiritualism.
Nothing like an exhaustive view of the present state of Darwinism and its
many champions can here be attempted. But it will be necessary to get to
know what we may call its possibilities by a study of typical and leading
examples. In the course of our study many of the problems to which the
theory gives rise will reveal themselves, and their orientation will be
possible.
This task falls naturally into two subdivisions: (1) the present state of
the theory of Evolution and Descent, and how far the religious conception
of the world is or is not affected by it; (2) the truth as to the
originative and directive factors of Evolution, especially as to “natural
selection in the struggle for existence,” whether they are tenable and
sufficient, and what attitude religion must take towards them. These two
problems must be kept distinct throughout, and must be discussed in order.
For the validity of what is characteristically _Darwinism_ is in no way
decided by proving descent and evolution, although it appears so in most
popular expositions.(7)
The Theory of Descent.
Again and again we hear and read, even in scientific circles and journals,
that Darwinism breaks down at many points, that it is insufficient, and
even that it has quite collapsed. Even the assurances of its most
convinced champions are rather forced, and are somewhat suggestive of
bills payable in the future.(8) But here again it is obvious that we must
distinguish clearly between the Theory of Descent and Darwinism. Of the
Theory of Descent it is by no means true that it has “broken down.” With a
slight exaggeration, but on the whole with justice, Weismann has asserted
that the Theory of Descent is to-day a “generally accepted truth.” Even
Weismann’s most pronounced opponents, such as Eimer, Wolff, Reinke, and
others, are at one with him in this, that there has been evolution in some
form; that there has been a progressive transformation of species; that
there is real (not merely ideal) relationship or affiliation connecting
our modern forms of life, up to and including man, with the lower and
lowest forms of bygone æons.
The evidences are the same as those adduced by Darwin and before his time,
but they have been multiplied and more sharply defined:—namely, that the
forms of life can be arranged in an ascending scale of evolution, both in
their morphological and their physiological aspects, both as regards the
general type and the differentiation of individual organs and particular
characters, bodily and mental. All the rubrics used by Darwin in this
connection, from comparative anatomy, from the palæontological record
itself, and so on, have been filled out with ever-increasing detail.
Palæontology, in particular, is continually furnishing new illustrations
of descent and new evidence of its probability, more telling perhaps in
respect of general features and particular groups than in regard to the
historical process in detail. For certain species and genera palæontology
discloses the primitive forms, discovers “synthetic types” which were the
starting-point for diverging branches of evolution, bridges over or
narrows the yawning gulfs in evolution by the discovery of “intermediate
forms”; and, in the case of certain species, furnishes complete
genealogical trees. The same holds true of the facts of comparative
anatomy, embryology, and so on. In all detailed investigations into an
animal type, in the study of the structure, functions, or the instincts of
an ant, or of a whale or of a tape-worm, the standpoint of the theory of
descent is assumed, and it proves a useful clue for further investigation.
In regard to man—so we are assured—the theory finds confirmation through
the discovery of the Neanderthal, Spy, Schipka, La Naulette skulls and
bones—the remains of a prehistoric human race, with “pithecoid” (ape-like)
characters. And the theory reaches its climax in Dubois’ discovery of the
remains of “Pithecanthropus,” the upright ape-man, in Java, 1891-92, the
long sought-for Missing Link between animals and man;(9) and in the still
more recent proofs of “affinity of blood” between man and ape, furnished
by experiments in transfusion. Friedenthal has revived the older
experiments of transfusing the blood of one animal into another, the blood
of an animal of one species into that of another, of related species into
related species, more remote into more remote, and finally even from
animals into man. The further apart the two species are, the more
different are the physiological characters of the blood, and the more
difficult does a mingling of the two become. Blood of a too distantly
related form does not unite with that of the animal into which it is
transfused, but the red corpuscles of the former are destroyed by the
serum of the latter, break up and are eliminated. In nearly related
species or races, however, the two kinds of blood unite, as in the case of
horse and ass, or of hare and rabbit. Human blood serum behaves in a
hostile fashion to the blood of eel, pigeon, horse, dog, cat, and even to
that of Lemuroids, or that of the more remotely related “non-anthropoid”
monkey; human blood transfused from a negro into a white unites readily,
as does also that of orang-utan transfused into a gibbon. But human blood
also unites without any breaking-up or disturbance with the blood of a
chimpanzee; from which the inference is that man is not to be placed in a
separate sub-order beside the other sub-orders of the Primates, the
platyrrhine and catarrhine monkeys, not even in a distinct sub order
beside the catarrhines; but is to be included with them in one zoological
sub-order. This classification was previously suggested by Selenka on
other grounds, namely, because of the points in common in the embryonic
development of the catarrhine monkeys and of man, and their common
distinctiveness as contrasted with the platyrrhines.(10)
Haeckel’s Evolutionist Position.
The average type of the Theory of Descent of the older or orthodox school,
which still lingers in the background with its Darwinism unshaken, is that
set forth by Haeckel, scientifically in his “Generelle Morphologie der
Organismen” (1866), and “Systematische Phylogenie” (1896), and popularly
in his “Natural History of Creation” and “Riddles of the Universe,” with
their many editions. We may assume that it is well known, and need only
briefly recall its chief characteristics. The “inestimable value,” the
“incomparable significance,” the “immeasurable importance” of the Theory
of Descent lies, according to Haeckel, in the fact that by means of it we
can explain the origin of the forms of life “in a mechanical manner.” The
theory, especially in regard to the descent of man from the apes, is to
him not a working hypothesis or tentative mode of representation; it is a
result comparable to Newton’s law of gravitation or the Kant-Laplace
cosmogony. It is “a certain historical fact.” The proofs of it are those
already mentioned.
What is especially Haeckelian is the “fundamental biogenetic law,”
“ontogeny resembles phylogeny,” that is to say, in development, especially
in embryonic development, the individual recapitulates the history of the
race. Through “palingenesis,” man, for instance, recapitulates his
ancestral stages (protist, gastræad, vermine, piscine, and simian). This
recapitulation is condensed, disarranged, or obscured in detail by
“cenogenesis” or “cænogenesis.” The groups and types of organisms exhibit
the closest genetic solidarity. The genealogical tree of man in particular
runs directly through a whole series. From the realm of the protists it
leads to that of the gastræadæ (nowadays represented by the Cœlentera),
thence into the domain of the worms, touches the hypothetical “primitive
chordates” (for the necessary existence of which “certain proofs” can be
given), the class of tunicates, ascends through the fishes, amphibians and
reptiles to forms parallel to the modern monotremes, then directly through
the marsupials to the placentals, through lemuroids and baboons to the
anthropoid apes, from them to the “famous Pithecanthropus” discovered in
Java, out of which _homo sapiens_ arose. (The easy transition from one
group of forms to another is to be noted. For it is against this point
that most of the opposition has been directed, whether from “grumbling”
critics, or thoroughgoing opponents of the Theory of Descent.)
Haeckel’s facile method of constructing genealogical trees, which ignores
difficulties and discrepant facts, has met with much criticism and
ridicule even among Darwinians. The “orator of Berlin,” Du Bois-Reymond,
declared that if he must read romances he would prefer to read them in
some other form than that of genealogical trees. But they have at least
the merit that they give a vivid impression of what is most plausible and
attractive in the idea of descent, and moreover they have helped towards
orientation in the discussion. Nor can we ignore the very marked taxonomic
and architectonic talent which their construction displays.
Weismann’s Evolutionist Position.
The most characteristic representative, however, of the modern school of
unified and purified Darwinism is not Haeckel, but the Freiburg zoologist,
Weismann. Through a long series of writings he has carried on the conflict
against heterodox, and especially Lamarckian theories of evolution, and
has developed his theories of heredity and the causes of variation, of the
non-transmissibility of acquired characters, and the all-sufficiency of
natural selection. In his latest great work, in two volumes, “Lectures on
the Theory of Descent,”(11) he has definitely summed up and systematised
his views. These will interest us when we come to inquire into the problem
of the factors operative in evolution. For the moment we are only
concerned with his attitude to the Theory of Descent as such. It is
precisely the same as Haeckel’s, although he is opposed to Haeckel in
regard to the strictly Darwinian standpoint. The Theory of Descent has
conquered, and it may be said with assurance, for ever. That is the firm
conviction on which the whole work is based, and it is really rather
treated as a self-evident axiom than as a statement to be proved. Weismann
takes little trouble to prove it. All the well-known, usually very clear
proofs from palæontology, comparative anatomy, &c., which we are
accustomed to meet with in evolutionist books are wanting here, the
genealogical trees of the Equidæ, with the gradually diminishing number of
toes and the varying teeth, of _Planorbis multiformis_, of the ammonites,
the graduated series of stages exhibited by individual organs, for
instance, from the ganglion merely sensitive to light up to the intricate
eye, or from the rayed skeleton of the paired fins in fishes up to the
five-fingered hands and feet of the higher vertebrates, &c. These are only
briefly touched upon in the terse “Introduction,” and the whole of the
comprehensive work is then directed to showing what factors can have been
operative, and to proving that they must have been “Darwinian” (selection
in the struggle for existence), and not Lamarckian or any other. This is
shown in regard to the coloration of animals, the phenomena of mimicry,
the protective arrangements of plants, the development of instinct in
animals, and the origin of flowers.
In reality Weismann only adduces _one_ strict proof, and even that is only
laying special stress on what is well known in comparative embryology;
namely, the possibility of “predicting” on the basis of the theory of
descent, as Leverrier “predicted” Neptune. For instance, in the lower
vertebrates from amphibians upwards there is an _os centrale_ in the
skeleton of wrist, but there is none in man. Now if man be descended from
lower vertebrates, and if the fundamental biogenetic law be true (that
every form of life recapitulates in its own development, especially in its
embryonic development, the evolution of its race, though with
abbreviations and condensations), it may be predicted that the _os
centrale_ is to be found in the early embryonic stages of man. And
Rosenberg found it. In the same way the “gill-clefts” of the fish-like
ancestors have long since been discovered in the embryo of the higher
vertebrates and of man. Weismann himself “predicted” that the markings of
the youngest stage of the caterpillars of the Sphingidæ (hawk-moths) would
be found to be not oblique but longitudinal stripes, and ten years later a
fortunate observation verified the prediction. Because of the abundance of
evidential facts Weismann does not go into any detailed proof of
evolution. “One can hardly take up any work, large or small, on the finer
or more general structural relations, or on the development of any animal,
without finding in it proofs for the evolution theory.”
But assured as the doctrine of descent appears,(12) and certain as it is
that it has not only maintained its hold since Darwin’s day, but has
strengthened it and has gained adherents, this foundation of Darwinism is
nevertheless not the unanimous and inevitable conclusion of all scientific
men in the sense and to the extent that the utterances of Weismann and
others would lead us to suppose. Apart from all apologetic attempts either
in religious, ethical, or æsthetic interests, apart, too, from the
superior standpoint of the philosophers, who have not, so to speak, taken
the theory very seriously, but regard it as a provisional theory, as a
more or less necessary and useful method of grouping our ideas in regard
to the organic world, there are even among the biologists themselves some
who, indifferent towards religious or philosophical or naturalistic dogma,
hold strictly to fact, and renounce with nonchalance any pretensions at
completeness of knowledge if the data do not admit of it, and on these
grounds hold themselves aloof from evolutionist generalisation. From among
these come the counsels of “caution,” admissions that the theory is a
scientific hypothesis and a guide to research, but not knowledge, and
confessions that the Theory of Descent as a whole is verifiable rather as
a general impression than in detail.
Virchow’s Position.
Warnings of this kind have come occasionally from Du Bois-Reymond, but the
true type of this group, and its mode of thought, is Virchow. It will
repay us and suffice us to make acquaintance with it through him. His
opposition to Darwinism and the theory of descent was directed at its most
salient point: the descent of man from the apes. In lectures and
treatises, at zoological and anthropological congresses, especially at the
meetings of his own Anthropological-Ethnological Society in Berlin, from
his “Vorträge über Menschen-und Affen-Schädel” (Lectures on the Skulls of
Man and Apes, 1869), to the disputes over Dubois’ _Pithecanthropus
erectus_ in the middle of the nineties, he threw the whole weight of his
immense learning—ethnological and anthropological, osteological, and above
all “craniological”—into the scale against the Theory of Descent and its
supporters. Virchow has therefore been reckoned often enough among the
anti-Darwinians, and has been quoted by apologists and others as against
Darwinism, and he has given reason for this, since he has often taken the
field against “the Darwinists” or has scoffed at their “longing for a
pro-anthropos.”(13) Sometimes even it has been suggested that he was
actuated by religious motives, as when he occasionally championed not only
freedom for science, but, incidentally, the right of existence for “the
churches,” leaving, for instance, in his theory of psychical life, gaps in
knowledge which faith might occupy in moderation and modesty. But this
last proves nothing. With Virchow’s altogether unemotional nature it is
unlikely that religious or spiritual motives had any rôle in the
establishment of his convictions, and in Haeckel’s naïve blustering at
religion, there is, so to speak, more religion than in the cold-blooded
connivance with which Virchow leaves a few openings in otherwise frozen
ponds for the ducks of faith to swim in! And he has nothing of the pathos
of Du Bois-Reymond’s “ignorabimus.” He is the neutral, prosaic scientist,
who will let nothing “tempt him to a transcendental consideration,”(14)
either theological or naturalistic, who holds tenaciously to matters of
fact, who, without absolutely rejecting a general theory, will not concern
himself about it, except to point out every difficulty in the way of it;
in short, he is the representative of a mood that is the ideal of every
investigator and the despair of every theoriser.
His lecture of 1869 already indicates his subsequent attitude. “Considered
logically and speculatively” the Theory of Descent seems to him
“excellent,”(15) indeed a logical moral(!) hypothesis, but unproved in
itself, and erroneous in many of its particular propositions. As far back
as 1858, before the publication of Darwin’s great work, he stated at the
Naturalists’ Congress in Carlsruhe, that the origin of one species out of
another appeared to him a necessary scientific inference, but——And
throughout the whole lecture he alternates between favourable recognition
of the theory in general, and emphasis of the difficulties which confront
it in detail. The skull, which, according to Goethe’s theory, has evolved
from three modified vertebræ, is fundamentally different in man and
monkeys, both in regard to its externals, crests, ridges and shape, and
especially in regard to the nature of the cavity which it forms for the
brain. Specifically distinctive differences in the development and
structure of the rest of the body must also be taken into account. The
so-called ape-like structures in the skull and the rest of the body, which
occasionally occur in man (idiots, microcephaloids, &c.) cannot be
regarded as atavisms and therefore as proofs of the Theory of Descent;
they are of a pathological nature, entirely facts _sui generis_, and “not
to be placed in a series with the normal results of evolution.” A man
modified by disease “is still thoroughly a man, not a monkey.”
Virchow continued to maintain this attitude and persisted in this kind of
argument. He energetically rejected all attempts to find “pithecoid”
characters in the prehistoric remains of man. He declared the narrow and
less arched forehead, the elliptical form, and the unusually large frontal
cavities of the “Neanderthal skull” found in the Wupperthal in 1856, to be
simply pathological features, which occur as such in certain examples of
_homo sapiens_.(16) He explained the abnormal appearance of the jaw from
the Moravian cave of Schipka as a result of the retention of teeth,(17)
accompanied by directly “antipithecoid” characters.
The proceedings at the meetings of the Ethnological Society in 1895, at
which Dubois was present, had an almost dramatic character.(18) In the
diverse opinions of Dubois, Virchow, Nehring, Kollmann, Krause and others,
we have almost an epitome of the present state of the Darwinian question.
Virchow doubted whether the parts put together by Dubois (the head of a
femur, two molar teeth, and the top of a skull) belonged to the same
individual at all, disputed the calculations as to the large capacity of
the skull, placed against Dubois’ very striking and clever drawing of the
curves of the skull-outline, which illustrated, with the help of the
Pithecanthropus, the gradual transition from the skull of a monkey to that
of man, his own drawing, according to which the Pithecanthropus curve
simply coincides with that of a gibbon (_Hylobates_), and asserted that
the remains discovered were those of a species of gibbon, refusing even to
admit that they represented a new genus of monkeys. He held fast to his
_ceterum censeo_: “As yet no diluvial discovery has been made which can be
referred to a man of a pithecoid type.” Indeed, his polemic or “caution”
in regard to the Theory of Descent went even further. He not only refused
to admit the proof of the descent of man from monkey, he would not even
allow that the descent of one race from another has been demonstrated.(19)
In spite of all the plausible hypotheses it remains “so far only a _pium
desiderium_.” The race obstinately maintains its specific distinctness,
and resists variation, or gradual transformation into another. The negro
remains a negro in America, and the European colonist of Australia remains
a European.
Yet all Virchow’s opposition may be summed up in the characteristic words,
which might almost be called his motto, “I warn you of the need for
caution,” and it is not a seriously-meant rejection of the Theory of
Descent. In reality he holds the evolution-idea as an axiom, and in the
last-named treatise he shows distinctly how he conceives of the process.
He starts with variation (presumably “kaleidoscopic”), which comes about
as a “pathological” phenomenon, that is to say, not spontaneously, but as
the result of environmental stimulus, as the organism’s reaction to
climatic and other conditions of life. The result is an alteration of
previous characteristics, and a new stable race is established by an
“acquired anomaly.”(20)
Other Instances of Dissatisfaction with the Theory of Descent.
What was with Virchow only a suggestion of the need for caution, or
controversial matter to be subsequently allowed for or contradicted, had
more serious consequences to others, and led to still greater hesitancy as
regards evolutionist generalisations and speculations, and sometimes to
sharp antagonism to them.
One of the best known of the earlier examples of this mood is Kerner von
Marilaun’s large and beautiful work on “Plant Life.”(21) He does, indeed,
admit that our species are variations of antecedent forms, but only in a
very limited sense. Within the stocks or grades of organisation which have
always existed, variations have come about, through “hybridisation,”
through the crossing of similar, but relatively different forms; these
variations alter the configuration and appearance in detail, but neither
affect the general character nor cause any transition from “lower” to
“higher.”
Kerner disposes of the chief argument in favour of the theory of descent,
the homology of individual organs, by explaining that the homology is due
to the similarity of function in the different organisms. A similar
argument is used in regard to “ontogeny recapitulating phylogeny.”
Palæontology does not disclose in the plant-world any “synthetic types,”
which might have been the common primitive stock from which many now
divergent branches have sprung, nor does it disclose any “transition
links” really intermediate, for instance, between cryptogams and
gymnosperms, or between gymnosperms and angiosperms. That the higher races
are apparently absent from the earlier strata is not a proof that they
have never existed. The peat-bog flora must have involved the existence of
a large companion-flora, without which the peat could not have been
formed, but all trace of this is absent in the still persistent vestiges
of these times.(22) Life, with energy and matter, has existed as a
phenomenon of the universe from all eternity, and thus its chief forms and
manifestations have not “arisen,” but have always been. If facts such as
these contradict the Kant-Laplace theory of the universe, then the latter
must be corrected in the light of them, not conversely. The extreme
isolation of Kerner and his theory is probably due especially to this
corollary of his views.
Among the most recent examples of antagonism to the Evolution-Theory, the
most interesting is a book by Fleischmann, professor of zoology in
Erlangen, published in 1901, and entitled, “The Theory of Descent.” It
consists of “popular lectures on the rise and decline of a scientific
hypothesis” (namely, the Theory of Descent), and it is a complete
recantation by a quondam Darwinian of the doctrine of his school, even of
its fundamental proposition, the concept of evolution itself. For
Fleischmann is not guilty, like Weismann, of the inaccuracy of using
“Theory of Descent” as equivalent to Darwinism; he is absolutely
indifferent to the theory of natural selection. His book keeps strictly to
matters of fact, and rejects as speculation everything in the least beyond
these; it does not express even an opinion on the question of the origin
of species, but merely criticises and analyses.
It does not bring forward any new and overwhelming arguments in refutation
of the Theory of Descent, but strongly emphasises difficulties that have
always beset it, and discusses these in detail. The old dispute which
interested Goethe, Geoffroy St. Hilaire, and Cuvier, as to the unity or
the fundamental heterogeneity of the “architectural plan” in nature is
revived. Modern zoology recognises not merely the four types of Cuvier,
but seventeen different styles, “phyla,” or groups of forms, to derive one
of which from another is hopeless. And what is true of the whole is true
also of the subdivisions within each phylum; _e.g._, within the vertebrate
phylum with its fishes, amphibians, reptiles, birds and mammals. No bridge
leads from one to the other. This is proved particularly by the very
instance which is the favourite illustration in support of the Theory of
Descent—the fin of fishes and its relation to the five-fingered hand of
vertebrates. The so-called transition forms (Archæopteryx, monotremes,
&c.) are discredited. So with the “stalking-horse” of evolutionists—the
genealogical tree of the Equidæ, which is said to be traceable
palæontologically right back, without a break, from the one-toed horses of
the present day to the normal five-toed ancestry; and so with another
favourite instance of evolution, the history of the pond-snails
(_Planorbis multiformis_), the numerous varieties of which occur with
transitions between them in actual contiguity in the Steinheim beds, and
thus seem to afford an obvious example of the transformation of species.
Against these cases, and against using the palæontological archives as a
basis for the construction of genealogical trees in general, the weighty
and apparently decisive objection is urged, that nowhere are the soft
parts of the earlier forms of life preserved, and that it is impossible to
establish relationships with any certainty on the basis of hard parts
only, such as bones, teeth and shells. Even Haeckel admits that snails of
very different bodily structure may form very similar and even hardly
distinguishable shells.
Fleischmann further asserts that Haeckel’s “fundamental biogenetic law”
has utterly collapsed. “Recapitulation” does not occur. Selenka’s figures
of ovum-segmentation show that there are specific differences in the
individual groups. The origin and development of the blastoderm or
germinal disc has nothing to do with recapitulation of the phylogeny. It
is not the case that the embryos of higher vertebrates are
indistinguishable from one another. Even the egg-cell has a specific
character, and is totally different from any unicellular organism at the
Protistan level. The much-cited “gill-clefts” of higher vertebrates in the
embryonic stage are not persistent reminiscences of earlier lower stages;
they are rudiments or primordia shared by all vertebrates, and developing
differently at the different levels; (thus in fishes they become breathing
organs, and in the higher vertebrates they become in part associated with
the organs of hearing, or in part disappear again).
Though Fleischmann’s vigorous protest against over-hastiness in
construction and over-confidence on the part of the adherents of the
doctrine of descent is very interesting, and may often be justified in
detail, it is difficult to resist the impression that the wheat has been
rejected with the chaff.(23)
Even a layman may raise the following objections: Admitting that the great
groups of forms cannot be traced back to one another, the palæontological
record still proves, though it may be only in general outline, that within
each phylum there has been a gradual succession and ascent of forms. How
is the origin of what is new to be accounted for? Without doing violence
to our thinking, without a sort of intellectual autonomy, we cannot rest
content with the mere fact that new elements occur. So, in spite of all
“difficulties,” the assumption of _an actual descent_ quietly forces
itself upon us as the only satisfactory clue. And the fact, which
Fleischmann does not discuss, that even at present we may observe the
establishment of what are at least new breeds, impels us to accept an
analogous origin of new species. Even if the biogenetic law really “finds
its chief confirmation in its exceptions,” even if we cannot speak of a
strict recapitulation of earlier stages of evolution, there are
indisputable facts which are most readily interpreted as reminiscences, as
due to affiliation (ideal or hereditary), with ancestral forms. (Note, for
instance, Weismann’s “prediction,” &c.(24)) Even if Archæopteryx and other
intermediate forms cannot be regarded as connecting links in the strict
sense, _i.e._, as being stages in the actual pedigree, yet the occurrence
of reptilian and avian peculiarities side by side in one organism, goes
far to prove the close relationship of the two classes.
Fleischmann’s book strengthens the impression gained elsewhere, that a
general survey of the domain of life as a whole gives force and
convincingness to the Theory of Descent, while a study of details often
results in breaking the threads and bringing the difficulties into
prominence. But the same holds true of many other theoretical
constructions, and yet we do not seriously doubt their validity. (Take,
for instance, the Kant-Laplace theory, and theories of ethnology, of the
history of religion, of the history of language, and so on.) And it is
quite commonly to be observed that those who have an expert and specialist
knowledge, who are aware of the refractoriness of detailed facts, often
take up a sceptical attitude towards every comprehensive theory, though
the ultimate use of detailed investigation is to make the construction of
general theories possible. Fleischmann does exactly what, say, an
anthropologist would do if, under the impression of the constancy and
distinctiveness of the human races, which would become stronger the more
deeply he penetrated, he should resignedly renounce all possibility of
affiliating them, and should rest content with the facts as he found them.
Similarly, those who are most intimately acquainted with the races of
domesticated animals often resist most strenuously all attempts, although
these seem to others a matter of course, to derive our “tame” forms from
“wild” species living in freedom.
But to return. Even where the Theory of Descent is recognised, whether
fully or only half-heartedly, the recognition does not always mean the
same thing. Even the adherents of the general, but in itself quite vague
view that a transformation from lower forms to higher, and from similar to
different forms, has taken place, may present so many points of
disagreement, and may even stand in such antagonism to one another, that
onlookers are apt to receive the impression that they occupy quite
different standpoints, and are no longer at one even in the fundamentals
of their hypotheses.
The most diverse questions and answers crop up; whether evolution has been
brought about “monophyletically” or “polyphyletically,” _i.e._, through
one or many genealogical trees; whether it has taken place in a continuous
easy transition from one type to another, or by leaps and bounds; whether
through a gradual transformation of all organs, each varying individually,
or through correlated “kaleidoscopic” variations of many kinds throughout
the whole system; whether it is essentially asymptotic, or whether
organisms pass from “labile” phases of vital equilibrium by various
halting-places to stable states, which are definitive, and are, so to
speak, the blind alleys and terminal points of evolutionary possibilities,
_e.g._, the extinct gigantic saurians, and perhaps also man. And to these
problems must be added the various answers to the question, What precedes,
or may have preceded, the earliest stages of life of which we know? Whence
came the first cell? Whence the first living protoplasm? and How did the
living arise from the inorganic? These deeper questions will occupy us in
our chapter on the theory of life. Some of the former, in certain of their
aspects, will be considered in the sixth chapter, which deals with factors
in evolution.
The Theory of Descent itself and the differences that obtain even among
its adherents can best be studied by considering for a little the works of
Reinke and of Hamann.
Reinke, Professor of Botany in Kiel, has set forth his views in his book,
“Die Welt als Tat,”(25) and more recently in his “Einleitung in die
theoretische Biologie” (1901). Both books are addressed to a wide circle
of readers. Reinke and Hamann both revive some of the arguments and
opinions set forth in the early days of Darwinism by Wigand,(26) an author
whose works are gradually gaining increased appreciation.
It is Reinke’s “unalterable conviction” that organisms have evolved, and
that they have done so after the manner of fan-shaped genealogical trees.
The Theory of Descent is to him an axiom of modern biology, though as a
matter of fact the circumstantial evidence in favour of it is extremely
fragmentary. The main arguments in favour of it appear to him to be the
general ones; the homologies and analogies revealed by comparative
morphology and physiology, the ascending series in the palæontological
record, vestigial organs, parasitic degeneration, the origin of those
vital associations which we call consortism and symbiosis. These he
illustrates mainly by examples from his own special domain and personal
observation.
The simplest unicellular forms of life are to be thought of as at the
beginning of evolution; and, since mechanical causes cannot explain their
ascent, it must be assumed that they have an inherent “phylogenetic
potential of development,” which, working epigenetically, results in
ascending evolution. He leaves us to choose between monophyletic and
polyphyletic evolution, but himself inclines towards the latter,
associating with it a rehabilitation of Wigand’s theory of the primitive
cells. If, in the beginning, primitive forms of life arose (probably as
unicellulars) from the not-living, it is not obvious why we need think of
only one so arising, and, if many did so, why they should not have
inherent differences which would at once result in typically different
evolutionary series and groups of forms. But evolution does not go on _ad
libitum_ or _ad infinitum_, for the capacity for differentiation and
transformation gradually diminishes. The organisation passes from a labile
state of equilibrium to an increasingly stable state, and at many points
it may reach a terminus where it comes to a standstill. Man, the dog, the
horse, the cereals, and fruit trees appear to Reinke to have reached their
goal. The preliminary stages he calls “Phylembryos,” because they bear to
the possible outcome of their evolution the same relation that the embryo
does to the perfect individual. Thus, _Phenacodus_ may be regarded as the
Phylembryo of the modern horse. It is quite conceivable that each of our
modern species may have had an independent series of Phylembryos reaching
back to the primitive cells. But the palæontological record, and
especially its synthetic types, lead Reinke rather to assume that instead
of innumerable series, there have been branching genealogical trees, not
one, however, but several.
These views, together or separately, which are characterised chiefly by
the catch-words “polyphyletic descent,” “labile and stable equilibrium,”
and so on, crop up together or separately in the writings of various
evolutionists belonging to the opposition wing. They are usually
associated with a denial of the theory of natural selection, and with
theories of “Orthogenesis,” “Heterogenesis,” and “Epigenesis.”
We shall discuss them later when we are considering the factors in
evolution. But we must first take notice of a work in which the theories
opposed to Darwinian orthodoxy have been most decisively and aggressively
set forth. As far back as 1892 O. Hamann, then a lecturer on zoology in
Göttingen, gathered these together and brought them into the field,
against Haeckel in particular, in his book “Entwicklungslehre und
Darwinismus.”(27)
Hamann’s main theme is that Darwinism overlooks the fact that “there
cannot have been an origin of higher types from types already finished.”
For this “unfortunate and unsupported assumption” there are no proofs in
embryology, palæontology, or anatomy. He adopts and expands the arguments
and anti-Haeckelian deliverances of His in embryology, of Snell and Heer
in palæontology, of Kölliker and von Baer in their special interpretation
of evolution, of Snell particularly as regards the descent of man. It is
impossible to derive Metazoa from Protozoa in their present finished state
of evolution; even the Amoeba is so exactly adapted in organisation and
functional activity to the conditions of its existence that it is a
“finished” type. It is only by a stretch of fancy that fishes can be
derived from worms, or higher vertebrates from fishes. One of his
favourite arguments—and it is a weighty one, though neglected by the
orthodox Darwinians—is that living substance is capable, under similar
stimuli, of developing spontaneously and afresh, at quite different points
and in different groups, similar organs, such as spots sensitive to light,
accumulations of pigment, eye-spots, lenses, complete eyes, and similarly
with the notochord, the excretory organs, and the like. Therefore homology
of organs is no proof of their hereditary affiliation.(28) They rather
illustrate “iterative evolution.”
Another favourite argument is the fact of “Pædogenesis.” Certain animals,
such as _Amphioxus lanceolatus_, _Peripatus_, and certain Medusæ, are very
frequently brought forward as examples of persistent primitive stages and
“transitional connecting links.” But considered from the point of view of
Pædogenesis, they all assume quite a different aspect, and seem rather to
represent very highly evolved species, and to be, not primitive forms, but
conservative and regressive forms. Pædogenesis is the phenomenon exhibited
by a number of species, which may stop short at one of the stages of their
embryonic or larval development, become sexually mature, and produce
offspring without having attained their own fully developed form.
Another argument is the old, suggestive, and really important one urged by
Kölliker, that “inorganic nature shows a natural system among minerals
(crystals) just as much as animals and plants do, yet in the former there
can be no question of any genetic connection in the production of forms.”
Yet another argument is found in the occurrence of “inversions” and
anomalies in the palæontological succession of forms, which to some extent
upsets the Darwinian-Haeckelian genealogical trees. (Thus there are forms
in the Cambrian whose alleged ancestors do not appear till the Silurian.
Foraminifera and other Protozoa do not appear till the Silurian.)
From embryology in particular, as elsewhere in general, we read the
“fundamental biogenetic law,” that evolution is from the general to the
special, from the imperfect to the more perfect, from what is still
indefinite and exuberant to the well-defined and precise, but never from
the special to the special. According to Hamann’s hypothesis we must think
of evolution as going on, so to speak, not about the top but about the
bottom. The phyla or groups of forms are great trunks bearing many
branches and twigs, but not giving rise to one another. Still less do the
little side branches of one trunk bear the whole great trunk of another
animal or plant phylum. But they all grow from the same roots among the
primitive forms of life. Unicellulars these must have been, but not like
our “Protists.” They should be thought of as primitive forms having within
themselves the potentialities of the most diverse and widely separate
evolution-series to which they gave rise, as it were, along diverging
fan-like rays.
It would be instructive to follow some naturalist into his own particular
domain, for instance a palæontologist into the detailed facts of
palæontology, or an embryologist into those of embryology, in order to
learn whether these corroborate the assumptions of the Theory of Descent
or not. It is just in relation to these detailed facts that criticisms or
even denials of the theory have been most frequent. Koken, otherwise a
convinced supporter of the theory, inquires in his “Vorwelt,” _apropos_ of
the tortoises, what has become of the genealogical trees that were
scattered abroad in the world as proved facts in the early days of
Darwinism. He asserts, in regard to _Archæopteryx_, the instance which is
always put forward as the intermediate link in the evolution of birds,
that it does not show in any of its characters a fundamental difference
from any of the birds of to-day, and further, that, through convergent
development under similar influences, similar organs and structural
relations result, iterative arrangements which come about quite
independently of descent. He maintains, too, that the principle of the
struggle for existence is rather disproved than corroborated by the
palæontological record.
In embryology, so competent an authority as O. Hertwig—himself a former
pupil of Haeckel’s—has reacted from the “fundamental biogenetic law.” His
theory of the matter is very much that of Hamann which we have already
discussed; development is not so much a recapitulation of finished
ancestral types as the laying down of foundations after the pattern of
generalised simple forms, not yet specialised; and from these foundations
the special organs rise to different levels and grades of differentiation
according to the type.(29) But we must not lose ourselves in details.
Looking back over the whole field once more, we feel that we are justified
in maintaining with some confidence that the different pronouncements in
regard to the detailed application and particular features of the Theory
of Descent, and the different standpoints that are occupied even by
evolutionists, are at least sufficient to make it obvious that, even if
evolution and descent have actually taken place, they have not run so
simple and smooth a course as the over-confident would have us believe;
that the Theory of Descent rather emphasises than clears away the riddles
and difficulties of the case, and that with the mere corroboration of the
theory we shall have gained only something relatively external, a clue to
creation, which does not so much solve its problems as restate them. The
whole criticism of the “right wing,” from captious objections to actual
denials, proves this indisputably. And it seems likely that in the course
of time a sharpening of the critical insight and temper will give rise to
further reactions from the academic theory as we have come to know it.(30)
On the other hand, it may be assumed with even greater certainty that the
general evolutionist point of view and the great arguments for descent in
some form or other will ultimately be victorious if they are not so
already, and that, sooner or later, we shall take the Theory of Descent in
its most general form as a matter of course, just as we now do the
Kant-Laplace theory.