Darwin and Modern Science (1909)
Edited by A.C. Seward
VIII. CHARLES DARWIN AS AN ANTHROPOLOGIST.
By By ERNST HAECKEL.
Professor of Zoology in the University of Jena.
he great advance that anthropology has made in the second half of the
nineteenth century is due in the first place, to Darwin's discovery of the
origin of man. No other problem in the whole field of research is so
momentous as that of "Man's place in nature," which was justly described by
Huxley (1863) as the most fundamental of all questions. Yet the scientific
solution of this problem was impossible until the theory of descent had
been established.
It is now a hundred years since the great French biologist Jean Lamarck
published his "Philosophie Zoologique". By a remarkable coincidence the
year in which that work was issued, 1809, was the year of the birth of his
most distinguished successor, Charles Darwin. Lamarck had already
recognised that the descent of man from a series of other Vertebrates—that
is, from a series of Ape-like Primates—was essentially involved in the
general theory of transformation which he had erected on a broad inductive
basis; and he had sufficient penetration to detect the agencies that had
been at work in the evolution of the erect bimanous man from the arboreal
and quadrumanous ape. He had, however, few empirical arguments to advance
in support of his hypothesis, and it could not be established until the
further development of the biological sciences—the founding of comparative
embryology by Baer (1828) and of the cell-theory by Schleiden and Schwann
(1838), the advance of physiology under Johannes Muller (1833), and the
enormous progress of palaeontology and comparative anatomy between 1820 and
1860—provided this necessary foundation. Darwin was the first to
coordinate the ample results of these lines of research. With no less
comprehensiveness than discrimination he consolidated them as a basis of a
modified theory of descent, and associated with them his own theory of
natural selection, which we take to be distinctive of "Darwinism" in the
stricter sense. The illuminating truth of these cumulative arguments was
so great in every branch of biology that, in spite of the most vehement
opposition, the battle was won within a single decade, and Darwin secured
the general admiration and recognition that had been denied to his
forerunner, Lamarck, up to the hour of his death (1829).
Before, however, we consider the momentous influence that Darwinism has had
in anthropology, we shall find it useful to glance at its history in the
course of the last half century, and notice the various theories that have
contributed to its advance. The first attempt to give extensive expression
to the reform of biology by Darwin's work will be found in my "Generelle
Morphologie" (1866) ("Generelle Morphologie der Organismen", 2 vols.,
Berlin, 1866.) which was followed by a more popular treatment of the
subject in my "Naturliche Schopfungsgeschichte (1868) (English translation;
"The History of Creation", London, 1876.), a compilation from the earlier
work. In the first volume of the "Generelle Morphologie" I endeavoured to
show the great importance of evolution in settling the fundamental
questions of biological philosophy, especially in regard to comparative
anatomy. In the second volume I dealt broadly with the principle of
evolution, distinguishing ontogeny and phylogeny as its two coordinate main
branches, and associating the two in the Biogenetic Law. The Law may be
formulated thus: "Ontogeny (embryology or the development of the
individual) is a concise and compressed recapitulation of phylogeny (the
palaeontological or genealogical series) conditioned by laws of heredity
and adaptation." The "Systematic introduction to general evolution," with
which the second volume of the "Generelle Morphologie" opens, was the first
attempt to draw up a natural system of organisms (in harmony with the
principles of Lamarck and Darwin) in the form of a hypothetical pedigree,
and was provisionally set forth in eight genealogical tables.
In the nineteenth chapter of the "Generelle Morphologie"—a part of which
has been republished, without any alteration, after a lapse of forty years—I
made a critical study of Lamarck's theory of descent and of Darwin's
theory of selection, and endeavoured to bring the complex phenomena of
heredity and adaptation under definite laws for the first time. Heredity I
divided into conservative and progressive: adaptation into indirect (or
potential) and direct (or actual). I then found it possible to give some
explanation of the correlation of the two physiological functions in the
struggle for life (selection), and to indicate the important laws of
divergence (or differentiation) and complexity (or division of labour),
which are the direct and inevitable outcome of selection. Finally, I
marked off dysteleology as the science of the aimless (vestigial, abortive,
atrophied, and useless) organs and parts of the body. In all this I worked
from a strictly monistic standpoint, and sought to explain all biological
phenomena on the mechanical and naturalistic lines that had long been
recognised in the study of inorganic nature. Then (1866), as now, being
convinced of the unity of nature, the fundamental identity of the agencies
at work in the inorganic and the organic worlds, I discarded vitalism,
teleology, and all hypotheses of a mystic character.
It was clear from the first that it was essential, in the monistic
conception of evolution, to distinguish between the laws of conservative
and progressive heredity. Conservative heredity maintains from generation
to generation the enduring characters of the species. Each organism
transmits to its descendants a part of the morphological and physiological
qualities that it has received from its parents and ancestors. On the
other hand, progressive heredity brings new characters to the
species—characters that were not found in preceding generations.
Each organism may transmit to its offspring a part of the morphological and
physiological features that it has itself acquired, by adaptation, in the
course of its individual career, through the use or disuse of particular organs,
the influence of environment, climate, nutrition, etc. At that time I gave the
name of "progressive heredity" to this inheritance of acquired characters,
as a short and convenient expression, but have since changed the term to
"transformative heredity" (as distinguished from conservative). This term
is preferable, as inherited regressive modifications (degeneration,
retrograde metamorphisis, etc.) come under the same head.
Transformative heredity—or the transmission of acquired characters—is one
of the most important principles in evolutionary science. Unless we admit
it most of the facts of comparative anatomy and physiology are
inexplicable. That was the conviction of Darwin no less than of Lamarck,
of Spencer as well as Virchow, of Huxley as well as Gegenbaur, indeed of
the great majority of speculative biologists. This fundamental principle
was for the first time called in question and assailed in 1885 by August
Weismann of Freiburg, the eminent zoologist to whom the theory of evolution
owes a great deal of valuable support, and who has attained distinction by
his extension of the theory of selection. In explanation of the phenomena
of heredity he introduced a new theory, the "theory of the continuity of
the germ-plasm." According to him the living substance in all organisms
consists of two quite distinct kinds of plasm, somatic and germinal. The
permanent germ-plasm, or the active substance of the two germ-cells (egg-
cell and sperm-cell), passes unchanged through a series of generations, and
is not affected by environmental influences. The environment modifies only
the soma-plasm, the organs and tissues of the body. The modifications that
these parts undergo through the influence of the environment or their own
activity (use and habit), do not affect the germ-plasm, and cannot
therefore be transmitted.
This theory of the continuity of the germ-plasm has been expounded by
Weismann during the last twenty-four years in a number of able volumes, and
is regarded by many biologists, such as Mr Francis Galton, Sir E. Ray
Lankester, and Professor J. Arthur Thomson (who has recently made a
thoroughgoing defence of it in his important work "Heredity" (London,
1908.)), as the most striking advance in evolutionary science. On the
other hand, the theory has been rejected by Herbert Spencer, Sir W. Turner,
Gegenbaur, Kolliker, Hertwig, and many others. For my part I have, with
all respect for the distinguished Darwinian, contested the theory from the
first, because its whole foundation seems to me erroneous, and its
deductions do not seem to be in accord with the main facts of comparative
morphology and physiology. Weismann's theory in its entirety is a finely
conceived molecular hypothesis, but it is devoid of empirical basis. The
notion of the absolute and permanent independence of the germ-plasm, as
distinguished from the soma-plasm, is purely speculative; as is also the
theory of germinal selection. The determinants, ids, and idants, are
purely hypothetical elements. The experiments that have been devised to
demonstrate their existence really prove nothing.
It seems to me quite improper to describe this hypothetical structure as
"Neodarwinism." Darwin was just as convinced as Lamarck of the
transmission of acquired characters and its great importance in the scheme
of evolution. I had the good fortune to visit Darwin at Down three times
and discuss with him the main principles of his system, and on each
occasion we were fully agreed as to the incalculable importance of what I
call transformative inheritance. It is only proper to point out that
Weismann's theory of the germ-plasm is in express contradiction to the
fundamental principles of Darwin and Lamarck. Nor is it more acceptable in
what one may call its "ultradarwinism"—the idea that the theory of
selection explains everything in the evolution of the organic world. This
belief in the "omnipotence of natural selection" was not shared by Darwin
himself. Assuredly, I regard it as of the utmost value, as the process of
natural selection through the struggle for life affords an explanation of
the mechanical origin of the adapted organisation. It solves the great
problem: how could the finely adapted structure of the animal or plant
body be formed unless it was built on a preconceived plan? It thus enables
us to dispense with the teleology of the metaphysician and the dualist, and
to set aside the old mythological and poetic legends of creation. The idea
had occurred in vague form to the great Empedocles 2000 years before the
time of Darwin, but it was reserved for modern research to give it ample
expression. Nevertheless, natural selection does not of itself give the
solution of all our evolutionary problems. It has to be taken in
conjunction with the transformism of Lamarck, with which it is in complete
harmony.
The monumental greatness of Charles Darwin, who surpasses every other
student of science in the nineteenth century by the loftiness of his
monistic conception of nature and the progressive influence of his ideas,
is perhaps best seen in the fact that not one of his many successors has
succeeded in modifying his theory of descent in any essential point or in
discovering an entirely new standpoint in the interpretation of the organic
world. Neither Nageli nor Weismann, neither De Vries nor Roux, has done
this. Nageli, in his "Mechanisch-Physiologische Theorie der
Abstammungslehre" (Munich, 1884.), which is to a great extent in agreement
with Weismann, constructed a theory of the idioplasm, that represents it
(like the germ-plasm) as developing continuously in a definite direction
from internal causes. But his internal "principle of progress" is at the
bottom just as teleological as the vital force of the Vitalists, and the
micellar structure of the idioplasm is just as hypothetical as the
"dominant" structure of the germ-plasm. In 1889 Moritz Wagner sought to
explain the origin of species by migration and isolation, and on that basis
constructed a special "migration-theory." This, however, is not out of
harmony with the theory of selection. It merely elevates one single factor
in the theory to a predominant position. Isolation is only a special case
of selection, as I had pointed out in the fifteenth chapter of my "Natural
history of creation". The "mutation-theory" of De Vries ("Die
Mutationstheorie", Leipzig, 1903.), that would explain the origin of
species by sudden and saltatory variations rather than by gradual
modification, is regarded by many botanists as a great step in advance, but
it is generally rejected by zoologists. It affords no explanation of the
facts of adaptation, and has no causal value.
Much more important than these theories is that of Wilhelm Roux ("Der Kampf
der Theile im Organismus", Leipzig, 1881.) of "the struggle of parts within
the organism, a supplementation of the theory of mechanical adaptation."
He explains the functional autoformation of the purposive structure by a
combination of Darwin's principle of selection with Lamarck's idea of
transformative heredity, and applies the two in conjunction to the facts of
histology. He lays stress on the significance of functional adaptation,
which I had described in 1866, under the head of cumulative adaptation, as
the most important factor in evolution. Pointing out its influence in the
cell-life of the tissues, he puts "cellular selection" above "personal
selection," and shows how the finest conceivable adaptations in the
structure of the tissue may be brought about quite mechanically, without
preconceived plan. This "mechanical teleology" is a valuable extension of
Darwin's monistic principle of selection to the whole field of cellular
physiology and histology, and is wholly destructive of dualistic vitalism.
The most important advance that evolution has made since Darwin and the
most valuable amplification of his theory of selection is, in my opinion,
the work of Richard Semon: "Die Mneme als erhaltendes Prinzip im Wechsel
des organischen Geschehens" (Leipzig, 1904.). He offers a psychological
explanation of the facts of heredity by reducing them to a process of
(unconscious) memory. The physiologist Ewald Hering had shown in 1870 that
memory must be regarded as a general function of organic matter, and that
we are quite unable to explain the chief vital phenomena, especially those
of reproduction and inheritance, unless we admit this unconscious memory.
In my essay "Die Perigenesis der Plastidule" (Berlin, 1876.) I elaborated
this far-reaching idea, and applied the physical principle of transmitted
motion to the plastidules, or active molecules of plasm. I concluded that
"heredity is the memory of the plastidules, and variability their power of
comprehension." This "provisional attempt to give a mechanical explanation
of the elementary processes of evolution" I afterwards extended by showing
that sensitiveness is (as Carl Nageli, Ernst Mach, and Albrecht Rau express
it) a general quality of matter. This form of panpsychism finds its
simplest expression in the "trinity of substance."
To the two fundamental attributes that Spinoza ascribed to substance—Extension
(matter as occupying space) and Cogitation (energy, force)—we
now add the third fundamental quality of Psychoma (sensitiveness, soul). I
further elaborated this trinitarian conception of substance in the
nineteenth chapter of my "Die Lebenswunder" (1904) ("Wonders of Life",
London, 1904.), and it seems to me well calculated to afford a monistic
solution of many of the antitheses of philosophy.
This important Mneme-theory of Semon and the luminous physiological
experiments and observations associated with it not only throw considerable
light on transformative inheritance, but provide a sound physiological
foundation for the biogenetic law. I had endeavoured to show in 1874, in
the first chapter of my "Anthropogenie" (English translation; "The
Evolution of Man", 2 volumes, London, 1879 and 1905.), that this
fundamental law of organic evolution holds good generally, and that there
is everywhere a direct causal connection between ontogeny and phylogeny.
"Phylogenesis is the mechanical cause of ontogenesis"; in other words, "The
evolution of the stem or race is—in accordance with the laws of heredity
and adaptation—the real cause of all the changes that appear, in a
condensed form, in the development of the individual organism from the
ovum, in either the embryo or the larva."
It is now fifty years since Charles Darwin pointed out, in the thirteenth
chapter of his epoch-making "Origin of Species", the fundamental importance
of embryology in connection with his theory of descent:
"The leading facts in embryology, which are second to none in importance,
are explained on the principle of variations in the many descendants from
some one ancient progenitor, having appeared at a not very early period of
life, and having been inherited at a corresponding period." ("Origin of
Species" (6th edition), page 396.)
He then shows that the striking resemblance of the embryos and larvae of
closely related animals, which in the mature stage belong to widely
different species and genera, can only be explained by their descent from a
common progenitor. Fritz Muller made a closer study of these important
phenomena in the instructive instance of the Crustacean larva, as given in
his able work "Fur Darwin" (1864). (English translation; "Facts and
Arguments for Darwin", London, 1869.) I then, in 1872, extended the range
so as to include all animals (with the exception of the unicellular
Protozoa) and showed, by means of the theory of the Gastraea, that all
multicellular, tissue-forming animals—all the Metazoa—develop in
essentially the same way from the primary germ-layers. I conceived the
embryonic form, in which the whole structure consists of only two layers of
cells, and is known as the gastrula, to be the ontogenetic recapitulation,
maintained by tenacious heredity, of a primitive common progenitor of all
the Metazoa, the Gastraea. At a later date (1895) Monticelli discovered
that this conjectural ancestral form is still preserved in certain
primitive Coelenterata—Pemmatodiscus, Kunstleria, and the nearly-related
Orthonectida.
The general application of the biogenetic law to all classes of animals and
plants has been proved in my "Systematische Phylogenie". (3 volumes,
Berlin, 1894-96.) It has, however, been frequently challenged, both by
botanists and zoologists, chiefly owing to the fact that many have failed
to distinguish its two essential elements, palingenesis and cenogenesis.
As early as 1874 I had emphasised, in the first chapter of my "Evolution of
Man", the importance of discriminating carefully between these two sets of
phenomena:
"In the evolutionary appreciation of the facts of embryology we must take
particular care to distinguish sharply and clearly between the primary,
palingenetic evolutionary processes and the secondary, cenogenetic
processes. The palingenetic phenomena, or embryonic recapitulations, are
due to heredity, to the transmission of characters from one generation to
another. They enable us to draw direct inferences in regard to
corresponding structures in the development of the species (e.g. the chorda
or the branchial arches in all vertebrate embryos). The cenogenetic
phenomena, on the other hand, or the embryonic variations, cannot be traced
to inheritance from a mature ancestor, but are due to the adaptation of the
embryo or the larva to certain conditions of its individual development
(e.g. the amnion, the allantois, and the vitelline arteries in the embryos
of the higher vertebrates). These cenogenetic phenomena are later
additions; we must not infer from them that there were corresponding
processes in the ancestral history, and hence they are apt to mislead."
The fundamental importance of these facts of comparative anatomy, atavism,
and the rudimentary organs, was pointed out by Darwin in the first part of
his classic work, "The Descent of Man and Selection in Relation to Sex"
(1871). ("Descent of Man" (Popular Edition), page 927.) In the "General
summary and conclusion" (chapter XXI.) he was able to say, with perfect
justice: "He who is not content to look, like a savage, at the phenomena
of nature as disconnected, cannot any longer believe that man is the work
of a separate act of creation. He will be forced to admit that the close
resemblance of the embryo of man to that, for instance, of a dog—the
construction of his skull, limbs, and whole frame on the same plan with
that of other mammals, independently of the uses to which the parts may be
put—the occasional reappearance of various structures, for instance of
several muscles, which man does not normally possess, but which are common
to the Quadrumana—and a crowd of analogous facts—all point in the
plainest manner to the conclusion that man is the co-descendant with other
mammals of a common progenitor."
These few lines of Darwin's have a greater scientific value than hundreds
of those so-called "anthropological treatises," which give detailed
descriptions of single organs, or mathematical tables with series of
numbers and what are claimed to be "exact analyses," but are devoid of
synoptic conclusions and a philosophical spirit.
Charles Darwin is not generally recognised as a great anthropologist, nor
does the school of modern anthropologists regard him as a leading
authority. In Germany, especially, the great majority of the members of
the anthropological societies took up an attitude of hostility to him from
the very beginning of the controversy in 1860. "The Descent of Man" was
not merely rejected, but even the discussion of it was forbidden on the
ground that it was "unscientific."
The centre of this inveterate hostility for thirty years—especially after
1877—was Rudolph Virchow of Berlin, the leading investigator in
pathological anatomy, who did so much for the reform of medicine by his
establishment of cellular pathology in 1858. As a prominent representative
of "exact" or "descriptive" anthropology, and lacking a broad equipment in
comparative anatomy and ontogeny, he was unable to accept the theory of
descent. In earlier years, and especially during his splendid period of
activity at Wurzburg (1848-1856), he had been a consistent free-thinker,
and had in a number of able articles (collected in his "Gesammelte
Abhandlungen") ("Gesammelte Abhandlungen zur wissenschaftlichen Medizin",
Berlin, 1856.) upheld the unity of human nature, the inseparability of body
and spirit. In later years at Berlin, where he was more occupied with
political work and sociology (especially after 1866), he abandoned the
positive monistic position for one of agnosticism and scepticism, and made
concessions to the dualistic dogma of a spiritual world apart from the
material frame.
In the course of a Scientific Congress at Munich in 1877 the conflict of
these antithetic views of nature came into sharp relief. At this memorable
Congress I had undertaken to deliver the first address (September 18th) on
the subject of "Modern evolution in relation to the whole of science." I
maintained that Darwin's theory not only solved the great problem of the
origin of species, but that its implications, especially in regard to the
nature of man, threw considerable light on the whole of science, and on
anthropology in particular. The discovery of the real origin of man by
evolution from a long series of mammal ancestors threw light on his place
in nature in every aspect, as Huxley had already shown in his excellent
lectures of 1863. Just as all the organs and tissues of the human body had
originated from those of the nearest related mammals, certain ape-like
forms, so we were bound to conclude that his mental qualities also had been
derived from those of his extinct primate ancestor.
This monistic view of the origin and nature of man, which is now admitted
by nearly all who have the requisite acquaintance with biology, and
approach the subject without prejudice, encountered a sharp opposition at
that time. The opposition found its strongest expression in an address
that Virchow delivered at Munich four days afterwards (September 22nd), on
"The freedom of science in the modern State." He spoke of the theory of
evolution as an unproved hypothesis, and declared that it ought not to be
taught in the schools, because it was dangerous to the State. "We must
not," he said, "teach that man has descended from the ape or any other
animal." When Darwin, usually so lenient in his judgment, read the English
translation of Virchow's speech, he expressed his disapproval in strong
terms. But the great authority that Virchow had—an authority well founded
in pathology and sociology—and his prestige as President of the German
Anthropological Society, had the effect of preventing any member of the
Society from raising serious opposition to him for thirty years. Numbers
of journals and treatises repeated his dogmatic statement: "It is quite
certain that man has descended neither from the ape nor from any other
animal." In this he persisted till his death in 1902. Since that time the
whole position of German anthropology has changed. The question is no
longer whether man was created by a distinct supernatural act or evolved
from other mammals, but to which line of the animal hierarchy we must look
for the actual series of ancestors. The interested reader will find an
account of this "battle of Munich" (1877) in my three Berlin lectures
(April, 1905) ("Der Kampf um die Entwickelungs-Gedanken". (English
translation; "Last Words on Evolution", London, 1906.)
The main points in our genealogical tree were clearly recognised by Darwin
in the sixth chapter of the "Descent of Man". Lowly organised fishes, like
the lancelet (Amphioxus), are descended from lower invertebrates resembling
the larvae of an existing Tunicate (Appendicularia). From these primitive
fishes were evolved higher fishes of the ganoid type and others of the type
of Lepidosiren (Dipneusta). It is a very small step from these to the
Amphibia:
"In the class of mammals the steps are not difficult to conceive which led
from the ancient Monotremata to the ancient Marsupials; and from these to
the early progenitors of the placental mammals. We may thus ascend to the
Lemuridae; and the interval is not very wide from these to the Simiadae.
The Simiadae then branched off into two great stems, the New World and Old
World monkeys; and from the latter, at a remote period, Man, the wonder and
glory of the Universe, proceeded." ("Descent of Man" (Popular Edition),
page 255.)
In these few lines Darwin clearly indicated the way in which we were to
conceive our ancestral series within the vertebrates. It is fully
confirmed by all the arguments of comparative anatomy and embryology, of
palaeontology and physiology; and all the research of the subsequent forty
years has gone to establish it. The deep interest in geology which Darwin
maintained throughout his life and his complete knowledge of palaeontology
enabled him to grasp the fundamental importance of the palaeontological
record more clearly than anthropologists and zoologists usually do.
There has been much debate in subsequent decades whether Darwin himself
maintained that man was descended from the ape, and many writers have
sought to deny it. But the lines I have quoted verbatim from the
conclusion of the sixth chapter of the "Descent of Man" (1871) leave no
doubt that he was as firmly convinced of it as was his great precursor Jean
Lamarck in 1809. Moreover, Darwin adds, with particular explicitness, in
the "general summary and conclusion" (chapter XXI.) of that standard work
("Descent of Man", page 930.):
"By considering the embryological structure of man—the homologies which he
presents with the lower animals,—the rudiments which he retains,—and the
reversions to which he is liable, we can partly recall in imagination the
former condition of our early progenitors; and can approximately place them
in their proper place in the zoological series. We thus learn that man is
descended from a hairy, tailed quadruped, probably arboreal in its habits,
and an inhabitant of the Old World. This creature, if its whole structure
had been examined by a naturalist, would have been classed amongst the
Quadrumana, as surely as the still more ancient progenitor of the Old and
New World monkeys."
These clear and definite lines leave no doubt that Darwin—so critical and
cautious in regard to important conclusions—was quite as firmly convinced
of the descent of man from the apes (the Catarrhinae, in particular) as
Lamarck was in 1809 and Huxley in 1863.
It is to be noted particularly that, in these and other observations on the
subject, Darwin decidedly assumes the monophyletic origin of the mammals,
including man. It is my own conviction that this is of the greatest
importance. A number of difficult questions in regard to the development
of man, in respect of anatomy, physiology, psychology, and embryology, are
easily settled if we do not merely extend our progonotaxis to our nearest
relatives, the anthropoid apes and the tailed monkeys from which these have
descended, but go further back and find an ancestor in the group of the
Lemuridae, and still further back to the Marsupials and Monotremata. The
essential identity of all the Mammals in point of anatomical structure and
embryonic development—in spite of their astonishing differences in
external appearance and habits of life—is so palpably significant that
modern zoologists are agreed in the hypothesis that they have all sprung
from a common root, and that this root may be sought in the earlier
Palaeozoic Amphibia.
The fundamental importance of this comparative morphology of the Mammals,
as a sound basis of scientific anthropology, was recognised just before the
beginning of the nineteenth century, when Lamarck first emphasised (1794)
the division of the animal kingdom into Vertebrates and Invertebrates.
Even thirteen years earlier (1781), when Goethe made a close study of the
mammal skeleton in the Anatomical Institute at Jena, he was intensely
interested to find that the composition of the skull was the same in man as
in the other mammals. His discovery of the os intermaxillare in man
(1784), which was contradicted by most of the anatomists of the time, and
his ingenious "vertebral theory of the skull," were the splendid fruit of
his morphological studies. They remind us how Germany's greatest
philosopher and poet was for many years ardently absorbed in the
comparative anatomy of man and the mammals, and how he divined that their
wonderful identity in structure was no mere superficial resemblance, but
pointed to a deep internal connection. In my "Generelle Morphologie"
(1866), in which I published the first attempts to construct phylogenetic
trees, I have given a number of remarkable theses of Goethe, which may be
called "phyletic prophecies." They justify us in regarding him as a
precursor of Darwin.
In the ensuing forty years I have made many conscientious efforts to
penetrate further along that line of anthropological research that was
opened up by Goethe, Lamarck, and Darwin. I have brought together the many
valuable results that have constantly been reached in comparative anatomy,
physiology, ontogeny, and palaeontology, and maintained the effort to
reform the classification of animals and plants in an evolutionary sense.
The first rough drafts of pedigrees that were published in the "Generelle
Morphologie" have been improved time after time in the ten editions of my
"Naturaliche Schopfungsgeschichte" (1868-1902). (English translation; "The
History of Creation", London, 1876.) A sounder basis for my phyletic
hypotheses, derived from a discriminating combination of the three great
records—morphology, ontogeny, and palaeontology—was provided in the three
volumes of my "Systematische Phylogenie (Berlin, 1894-96.) (1894 Protists
and Plants, 1895 Vertebrates, 1896 Invertebrates). In my "Anthropogenie"
(Leipzig, 1874, 5th edition 1905. English translation; "The Evolution of
Man", London, 1905.) I endeavoured to employ all the known facts of
comparative ontogeny (embryology) for the purpose of completing my scheme
of human phylogeny (evolution). I attempted to sketch the historical
development of each organ of the body, beginning with the most elementary
structures in the germ-layers of the Gastraea. At the same time I drew up
a corrected statement of the most important steps in the line of our
ancestral series.
At the fourth International Congress of Zoology at Cambridge (August 26th,
1898) I delivered an address on "Our present knowledge of the Descent of
Man." It was translated into English, enriched with many valuable notes
and additions, by my friend and pupil in earlier days Dr Hans Gadow
(Cambridge), and published under the title: "The Last Link; our present
knowledge of the Descent of Man". (London, 1898.) The determination of
the chief animal forms that occur in the line of our ancestry is there
restricted to thirty types, and these are distributed in six main groups.
The first half of this "Progonotaxis hominis," which has no support from
fossil evidence, comprises three groups: (i) Protista (unicellular
organisms, 1-5: (ii) Invertebrate Metazoa (Coelenteria 6-8, Vermalia 9-
11): (iii) Monorrhine Vertebrates (Acrania 12-13, Cyclostoma 14-15). The
second half, which is based on fossil records, also comprises three groups:
(iv) Palaeozoic cold-blooded Craniota (Fishes 16-18, Amphibia 19, Reptiles
20: (v) Mesozoic Mammals (Monotrema 21, Marsupialia 22, Mallotheria 23):
(vi) Cenozoic Primates (Lemuridae 24-25, Tailed Apes 26-27, Anthropomorpha
28-30). An improved and enlarged edition of this hypothetic "Progonotaxis
hominis" was published in 1908, in my essay "Unsere Ahnenreihe".
("Festschrift zur 350-jahrigen Jubelfeier der Thuringer Universitat Jena".
Jena, 1908.)
If I have succeeded in furthering, in some degree, by these anthropological
works, the solution of the great problem of Man's place in nature, and
particularly in helping to trace the definite stages in our ancestral
series, I owe the success, not merely to the vast progress that biology has
made in the last half century, but largely to the luminous example of the
great investigators who have applied themselves to the problem, with so
much assiduity and genius, for a century and a quarter—I mean Goethe and
Lamarck, Gegenbaur and Huxley, but, above all, Charles Darwin. It was the
great genius of Darwin that first brought together the scattered material
of biology and shaped it into that symmetrical temple of scientific
knowledge, the theory of descent. It was Darwin who put the crown on the
edifice by his theory of natural selection. Not until this broad inductive
law was firmly established was it possible to vindicate the special
conclusion, the descent of man from a series of other Vertebrates. By his
illuminating discovery Darwin did more for anthropology than thousands of
those writers, who are more specifically titled anthropologists, have done
by their technical treatises. We may, indeed, say that it is not merely as
an exact observer and ingenious experimenter, but as a distinguished
anthropologist and far-seeing thinker, that Darwin takes his place among
the greatest men of science of the nineteenth century.
To appreciate fully the immortal merit of Darwin in connection with
anthropology, we must remember that not only did his chief work, "The
Origin of Species", which opened up a new era in natural history in 1859,
sustain the most virulent and widespread opposition for a lengthy period,
but even thirty years later, when its principles were generally recognised
and adopted, the application of them to man was energetically contested by
many high scientific authorities. Even Alfred Russel Wallace, who
discovered the principle of natural selection independently in 1858, did
not concede that it was applicable to the higher mental and moral qualities
of man. Dr Wallace still holds a spiritualist and dualist view of the
nature of man, contending that he is composed of a material frame
(descended from the apes) and an immortal immaterial soul (infused by a
higher power). This dual conception, moreover, is still predominant in the
wide circles of modern theology and metaphysics, and has the general and
influential adherence of the more conservative classes of society.
In strict contradiction to this mystical dualism, which is generally
connected with teleology and vitalism, Darwin always maintained the
complete unity of human nature, and showed convincingly that the
psychological side of man was developed, in the same way as the body, from
the less advanced soul of the anthropoid ape, and, at a still more remote
period, from the cerebral functions of the older vertebrates. The eighth
chapter of the "Origin of Species", which is devoted to instinct, contains
weighty evidence that the instincts of animals are subject, like all other
vital processes, to the general laws of historic development. The special
instincts of particular species were formed by adaptation, and the
modifications thus acquired were handed on to posterity by heredity; in
their formation and preservation natural selection plays the same part as
in the transformation of every other physiological function. The higher
moral qualities of civilised man have been derived from the lower mental
functions of the uncultivated barbarians and savages, and these in turn
from the social instincts of the mammals. This natural and monistic
psychology of Darwin's was afterwards more fully developed by his friend
George Romanes in his excellent works "Mental Evolution in Animals" and
"Mental Evolution in Man". (London, 1885; 1888.)
Many valuable and most interesting contributions to this monistic
psychology of man were made by Darwin in his fine work on "The Descent of
Man and Selection in Relation to Sex", and again in his supplementary work,
"The Expression of the Emotions in Man and Animals". To understand the
historical development of Darwin's anthropology one must read his life and
the introduction to "The Descent of Man". From the moment that he was
convinced of the truth of the principle of descent—that is to say, from
his thirtieth year, in 1838—he recognised clearly that man could not be
excluded from its range. He recognised as a logical necessity the
important conclusion that "man is the co-descendant with other species of
some ancient, lower, and extinct form." For many years he gathered notes
and arguments in support of this thesis, and for the purpose of showing the
probable line of man's ancestry. But in the first edition of "The Origin
of Species" (1859) he restricted himself to the single line, that by this
work "light would be thrown on the origin of man and his history." In the
fifty years that have elapsed since that time the science of the origin and
nature of man has made astonishing progress, and we are now fairly agreed
in a monistic conception of nature that regards the whole universe,
including man, as a wonderful unity, governed by unalterable and eternal
laws. In my philosophical book "Die Weltratsel" (1899) ("The Riddle of the
Universe", London, 1900.) and in the supplementary volume "Die
Lebenswunder" (1904) "The Wonders of Life", London, 1904.), I have
endeavoured to show that this pure monism is securely established, and that
the admission of the all-powerful rule of the same principle of evolution
throughout the universe compels us to formulate a single supreme law—the
all-embracing "Law of Substance," or the united laws of the constancy of
matter and the conservation of energy. We should never have reached this
supreme general conception if Charles Darwin—a "monistic philosopher" in
the true sense of the word—had not prepared the way by his theory of
descent by natural selection, and crowned the great work of his life by the
association of this theory with a naturalistic anthropology.
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