Professor of Zoology in the University of Jena.
The 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.