THE STRUGGLE OVER OUR GENEALOGICAL TREE

OUR APE-RELATIVES AND THE VERTEBRATE-STEM

EXPLANATION OF PLATE II

SKELETONS OF FIVE ANTHROPOID APES

Plate II.

SKELETONS OF FIVE ANTHROPOID APES.

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CHAPTER II

THE STRUGGLE OVER OUR GENEALOGICAL TREE

OUR APE-RELATIVES AND THE VERTEBRATE-STEM

In the previous chapter I tried to give you a general idea of the present state of the controversy in regard to evolution. Comparing the various branches of thought we found that the older mythological ideas of the creation of the world were driven long ago out of the province of inorganic science, but that they did not yield to the rational conception of natural development until a much later date in the field of organic nature. Here the idea of evolution did not prove completely victorious until the beginning of the twentieth century, when its most zealous and dangerous opponent, the Church, was forced to admit it. Hence the open acknowledgment of the Jesuit, Father Wasmann, deserves careful attention, and we may look forward to a further development. If his force of conviction and his moral courage are strong enough, he will go on to draw the normal conclusions from his high scientific attainments and leave the Catholic Church, as the prominent Jesuits, Count Hoensbroech and the able geologist, Professor Renard of Ghent, one of the workers on the deep-sea deposits in the Challenger expedition, have lately done. But even if this does not happen, his recognition of Darwinism, in the name of Christian belief, will remain a landmark in the history of evolution. His ingenious and very Jesuitical attempt to bring together the opposite poles will have no very mischievous effect; it will rather tend to hasten the victory of the scientific conception of evolution over the mystic beliefs of the Churches.

You will see this more clearly if we go on to consider the important special problem of the "descent of man from the ape," and its irreconcilability with the conventional belief that God made man according to His own image. That this ape or pithecoid theory is an irresistible deduction from the general principle of evolution was clearly recognised forty-five years ago, when Darwin's work appeared, by the shrewd and vigilant theologians; it was precisely in this fact that they found their strongest motive for vigorous resistance. It is quite clear. Either man was brought into existence, like the other animals, by a special creative act, as Moses and LinnÉ taught (an "embodied idea of the Creator," as the famous Agassiz put it so late as 1858); or he has been developed naturally from a series of mammal ancestors, as is claimed by the systems of Lamarck and Darwin.

In view of the very great importance of this pithecoid theory, we will first cast a brief glance at its founders and then summarise the proofs in support of it. The famous French biologist, Jean Lamarck, was the first scientist definitely to affirm the descent of man from the ape and seek to give scientific proof of it. In his splendid work, fifty years in advance of his time, the Philosophie Zoologique (1809), he clearly traced the modifications and advances that must have taken place in the transformation of the man-like apes (the primate forms similar to the orang and the chimpanzee); the adaptation to walking upright, the consequent modification of the hands and feet, and later, the formation of speech and the attainment of a higher degree of intelligence. Lamarck's remarkable theory, and this important consequence of it, soon fell into oblivion. When Darwin brought evolution to the front again fifty years afterwards, he paid no attention to the special conclusion. He was content to make the following brief prophetic observation in his work: "Light will be thrown on the origin and the history of man." Even this innocent remark seemed so momentous to the first German translator of the work, Bronn, that he suppressed it. When Darwin was asked by Wallace whether he would not go more fully into it, he replied: "I think of avoiding the whole subject, as it is so much involved in prejudice; though I quite admit that it is the highest and most interesting problem for the thinker."

The first thorough works of importance on the subject appeared in 1863. Thomas Huxley in England, and Carl Vogt in Germany, endeavoured to show that the descent of man from the ape was a necessary consequence of Darwinism, and to provide an empirical base for the theory by every available argument. Huxley's work on Man's Place in Nature was particularly valuable. He first gave convincingly, in three lectures, the empirical evidence on the subject—the natural history of the anthropoid apes, the anatomical and embryological relations of man to the next lowest animals, and the recently discovered fossil human remains. I then (1866) made the first attempt to establish the theory of evolution comprehensively by research in anatomy and embryology, and to determine the chief stages in the natural classification of the vertebrates that must have been passed through by our earlier vertebrate ancestors. Anthropology thus becomes a part of zoology. In my History of Creation I further developed these early evolutionary sketches, and improvements were made in the successive editions.

In the meantime, the great master, Darwin, had decided to deal with this chief evolutionary problem in a special work. The two volumes of his Descent of Man appeared in 1871. They contained an able discussion of sexual selection, or the selective influence of sexual love and high psychic activities connected therewith, and their significance in regard to the origin of man. As this part of Darwin's work was afterwards attacked with particular virulence, I will say that, in my opinion, it is of the greatest importance, not only for the general theory of evolution, but also for psychology, anthropology, and Æsthetics.

My own feeble early efforts (1866), not only to establish the descent of man from the nearest related apes, but also to determine more precisely the long series of our earlier and lower vertebrate ancestors, had not at all satisfied me. In particular, I had had to leave unanswered in my General Morphology the very interesting question: from which invertebrate animals the vertebrate stem originally came. A clear and unexpected light was thrown on it some time afterwards by the astounding discoveries of Kowalevsky, which revealed an essential agreement in embryonic development between the lowest vertebrate (Amphioxus) and a lowly tunicate (Ascidia). In the succeeding years, the numerous discoveries in connection with the formation of the germinal layers in different animals so much enlarged our embryological outlook that I was able to prove the complete homology of the two-layered gastrula (a cup-shaped embryonic form) in all the tissue-forming animals (metazoa) in my Monograph on the Sponges. From this I inferred, in virtue of the biogenetic law, the common descent of all the metazoa from one and the same gastrula-shaped stem-form, the gastrÆa. This hypothetical stem-form, to which man's earliest multicellular ancestors also belong, was afterwards proved by Monticelli's observations to be still in existence. The evolution of these very simple tissue-forming animals from still simpler unicellular forms (protozoa) is shown by the corresponding processes that we witness in what is called the segmentation of the ovum or gastrulation, in the development of the two-layered germ from the single cell of the ovum.

Encouraged by these great advances of modern phylogeny, and with the support of many new discoveries in comparative anatomy and embryology, in which a number of distinguished observers were at work, I was able in 1874 to venture on the first attempt to trace continuously the whole story of man's evolution. In doing so, I took my stand on the firm ground of the biogenetic law, seeking to give a phylogenetic cause for each fact of embryology. My Evolution of Man, which made the first attempt to accomplish this difficult task, was materially improved and enlarged as new and important discoveries were made. The latest edition (1903 [1904 in English]) contains thirty chapters distributed in two volumes, the first of which deals with embryology (or ontogeny), and the second with the development of species (or phylogeny).

Though I was quite conscious that there were bound to be gaps and weak points in these first attempts to frame a natural anthropogeny, I had hoped they would have some influence on modern anthropology, and especially that the first sketches of a genealogical tree of the animal world would prove a stimulus to fresh research and improvement. In this I was much mistaken. The dominant school of anthropology, especially in Germany, declined to suffer the introduction of the theory of evolution, declaring it to be an unfounded hypothesis, and described our carefully prepared ancestral trees as mere figments. This was due, in the first place, to the great authority of the founder and president (for many years) of the German Anthropological Society, Rudolf Virchow, as I briefly pointed out in the previous chapter. In view of the great regard that is felt for this distinguished scientist, and the extent to which his powerful opposition prevented the spread of the theory, it is necessary to deal more fully with his position on the subject. I am still further constrained to do this because of the erroneous views of it that are circulating, and my own fifty years' acquaintance with my eminent teacher enables me to put them right.

Not one of Virchow's numerous pupils and friends can appreciate more than I do his real services to medical science. His Cellular Pathology (1858), his thorough application of the cell-theory to the science of disease, is, in my opinion, one of the greatest advances made by modern medicine. I had the good fortune to begin my medical studies at WÜrzburg in 1852, and to spend six valuable terms under the personal guidance of four biologists of the first rank—Albert KÖlliker, Rudolf Virchow, Franz Leydig and Carl Gegenbaur. The great stimulus that I received from these distinguished masters in every branch of comparative and microscopic biology was the starting-point of my whole training in that science, and enabled me subsequently to follow with ease the higher intellectual flight of Johannes MÜller. From Virchow especially I learned, not only the analytic art of careful observation and judicious appreciation of the detailed facts of anatomy, but also the synthetic conception of the whole human frame, the profound conviction of the unity of our nature, the inseparable connection of body and mind, to which Virchow gave a fine expression in his classic essay on "The Efforts to bring about Unity in Scientific Medicine" (1849). The leading articles which he wrote at that time for the Journal of Pathological Anatomy and Physiology, which he had founded, contain much new insight into the wonders of life, and a number of excellent general reflections on their significance—pregnant ideas that we can make direct use of for Monistic purposes. In the controversy that broke out between empirical rationalism and materialism and the older vitalism and mysticism, he took the side of the former, and fought together with Jacob Moleschott, Carl Vogt, and Ludwig BÜchner. I owe the firm conviction of the unity of organic and inorganic nature, of the mechanical character of all vital and psychic activity, which I have always held to be the foundation of my Monistic system, in a great measure to Virchow's teaching and the exhaustive conversations I had with him when I was his assistant. The profound views of the nature of the cell and the independent individuality of these elementary organisms, which he advanced in his great work Cellular Pathology, remained guiding principles for me in the prolonged studies that I made thirty years afterwards of the organisation of the radiolaria and other unicellular protists; and also in regard to the theory of the cell-soul, which followed naturally from the psychological study of it.

His life at WÜrtzburg was the most brilliant period of Virchow's indefatigable scientific labours. A change took place when he removed to Berlin in 1856. He then occupied himself chiefly with political and social and civic interests. In the last respect he has done so much for Berlin and the welfare of the German people that I need not enlarge on it. Nor will I go into his self-sacrificing and often thankless political work as leader of the progressive party; there are differences of opinion as to its value. But we must carefully examine his peculiar attitude towards evolution, and especially its chief application, the ape-theory. He was at first favourable to it, then sceptical, and finally decidedly hostile.

When the Lamarckian theory was brought to light again by Darwin in 1859, many thought that it was Virchow's vocation to take the lead in defending it. He had made a thorough study of the problem of heredity; he had realised the power of adaptation through his study of pathological changes; and he had been directed to the great question of the origin of man by his anthropological studies. He was at that time regarded as a determined opponent of all dogmas; he combated transcendentalism either in the form of ecclesiastical creeds or anthropomorphism. After 1862 he declared that "the possibility of a transition from species to species was a necessity of science." When I opened the first public discussion of Darwinism at the Stettin scientific congress in 1863, Virchow and Alexander Braun were among the few scientists who would admit the subject to be important and deserving of the most careful study. When I sent to him in 1865 two lectures that I had delivered at Jena on the origin and genealogical tree of the human race, he willingly received them amongst his Collection of Popular Scientific Lectures. In the course of many long conversations I had with him on the matter, he agreed with me in the main, though with the prudent reserve and cool scepticism that characterised him. He adopts the same moderate attitude in the lecture that he delivered to the Artisans' Union at Berlin in 1869 on "Human and Ape Skulls."

His position definitely changed in regard to Darwinism from 1877 onward. At the Scientific Congress that was then held at Munich I had, at the pressing request of my Munich friends, undertaken the first address (on 18th September) on "Modern Evolution in Relation to the whole of Science." In this address I had substantially advanced the same general views that I afterwards enlarged in my Monism, Riddle of the Universe, and Wonders of Life. In the ultramontane capital of Bavaria, in sight of a great university which emphatically describes itself as Catholic, it was somewhat bold to make such a confession of faith. The deep impression that it had made was indicated by the lively manifestations of assent on the one hand, and displeasure on the other, that were at once made in the Congress itself and in the Press. On the following day I departed for Italy (according to an arrangement made long before). Virchow did not come to Munich until two days afterwards, when he delivered (on 22nd September, in response to entreaties from people of position and influence) his famous antagonistic speech on "The Freedom of Science in the Modern State." The gist of the speech was that this freedom ought to be restricted; that evolution is an unproved hypothesis, and ought not to be taught in the school because it is dangerous to the State: "We must not teach," he said, "that man descends from the ape or any other animal." In 1849, the young Monist, Virchow, had emphatically declared this conviction, "that he would never be induced to deny the thesis of the unity of human nature and its consequences"; now, twenty-eight years afterwards, the prudent Dualistic politician entirely denied it. He had formerly taught that all the bodily and mental processes in the human organism depend on the mechanism of the cell-life; now he declared the soul to be a special immaterial entity. But the crowning feature of this reactionary speech was his compromise with the Church, which he had fought so vigorously twenty years before.

The character of Virchow's speech at Munich is best seen in the delight with which it was at once received by the reactionary and clerical papers, and the profound concern of all Liberal journals, either in the political or the religious sense. When Darwin read the English translation of the speech he—generally so gentle in his judgments—wrote: "Virchow's conduct is shameful, and I hope he will some day feel the shame." In 1878, I made a full reply to it in my Free Science and Free Teaching, in which I collected the most important press opinions on the matter.[6]

From this very decided turn at Munich until his death, twenty-five years afterwards, Virchow was an indefatigable and very influential opponent of evolution. In his annual appearances at congresses he has always contested it, and has obstinately clung to his statement that "it is quite certain that man does not descend from the ape or any other animal." To the question: "Whence does he come, then?" he had no answer, and retired to the resigned position of the Agnostic, which was common before Darwin's time: "We do not know how life arose, and how the various species came into the world." His son-in-law, Professor Rabl, has tried to draw attention once more to his earlier conception, and has declared that even in later years Virchow often recognised the truth of evolution in private conversation. This only makes it the more regrettable that he always said the contrary in public. The fact remains that ever since the opponents of evolution, especially the reactionaries and clericals, have appealed to the authority of Virchow.

The wholly reactionary system that this led to has been well described by Robert Drill (1902) in his Virchow as a Reactionary. How little qualified the great pathologist was to appreciate the scientific bases of the pithecoid theory is clear from the absurd statement he made, in the opening speech of the Vienna Congress of Anthropologists, in 1894, that man might just as well be claimed to descend from a sheep or an elephant as from an ape. Any competent zoologist can see from this the little knowledge Virchow had of systematic zoology and comparative anatomy. However, he retained his authority as president of the German Anthropological Society, which remained impervious to Darwinian ideas. Even such vigorous controversialists as Carl Vogt, and such scientific partisans of the ape-man of Neanderthal as Schaafhausen, could make no impression. Virchow's authority was equally great for twenty years in the Berlin Press, both Liberal and Conservative. The Kreutzzeitung and the Evangelische Kirchenzeitung were delighted that "the learned progressist was conservative in the best sense of the word as regards evolution." The ultramontane Germania rejoiced that the powerful representative of pure science had, "with a few strokes of his cudgel, reduced to impotence" the absurd ape-theory and its chief protagonist, Ernst Haeckel. The National-Zeitung could not sufficiently thank the free-thinking, popular leader for having lifted from us for ever the oppressive mountain of the theory of simian descent. The editor of the Volks-Zeitung, Bernstein, who has done so much for the spread of knowledge in his excellent popular manuals of science, obstinately refused to admit articles that ventured to support the erroneous ape-theory "refuted" by Virchow.

It would take up too much space to attempt to give even a general survey of the remarkable and enormous literature of the subject that has accumulated in the last three decades in the shape of thousands of learned treatises and popular articles. The greater part of these works have been written under the influence of conventional religious prejudice, and without the necessary acquaintance with the subject, that can only be obtained by a thorough training in biology. The most curious feature of them is that most of the authors restrict their genealogical interests to the most manlike apes, and do not deal with their origin, or with the deeper roots of our common ancestral tree. They do not see the wood for the trees. Yet it is far easier and safer to penetrate the great mysteries of our animal origin, if we look at the subject from the higher standpoint of vertebrate phylogeny and go deeper into the earlier records of the evolutionary history of the vertebrates.

Since the great Lamarck established the idea of the vertebrate at the beginning of the nineteenth century (1801), and his Parisian colleague, Cuvier, shortly afterwards recognised the vertebrates as one of his four chief animal groups, the natural unity of this advanced section of the animal world has not been contested. In all the vertebrates, from the lowest fishes and amphibians up to the apes and man, we have the same type of structure, the same characteristic disposition and relations of the chief organs; and they differ materially from the corresponding features in all other animals. The mysterious affinities of the vertebrates induced Goethe, 140 years ago, long before Cuvier, to make prolonged and laborious studies in their comparative anatomy at Jena and Weimar. Just as he had, in his Metamorphosis of Plants, established the unity of organisation by means of the leaf as the common primitive organ, he, in the metamorphosis of the vertebrates, found this common element in the vertebral theory of the skull. And when Cuvier established comparative anatomy as an independent science, this branch of biology was developed to such an extent by the classic research of Johannes MÜller, Carl Gegenbaur, Richard Owen, Thomas Huxley, and many other morphologists, that Darwinism found its most powerful weapons in this arsenal. The striking differences of external form and internal structure that we find in the fishes, amphibians, reptiles, birds, and mammals, are due to adaptation to the various uses of their organs and their environments. On the other hand, the astonishing agreement in their typical character, that persists in spite of their differences, is due to inheritance from common ancestors.

The evidence thus afforded by comparative anatomy is so cogent that anyone who goes impartially and attentively through a collection of skeletons can convince himself at once of the morphological unity of the vertebrate stem. The evolutionary evidence of comparative ontogeny, or embryology, is less easy to grasp and less accessible, but not less important. It came to light at a much later date, and its extreme value was only made clear, by means of the biogenetic law, some forty years ago. It shows that every vertebrate, like every other animal, develops from a single cell, but that the course of its embryonic development is peculiar, and characterised by embryonic forms that are not found in the invertebrates. We find in them especially the chordula, or chorda-larva, a very simple worm-shaped embryonic form, without limbs, head, or higher sense-organs; the body consists merely of six very simple primitive organs. From these are developed steadily the hundreds of different bones, muscles, and other organs that we afterwards distinguish in the mature vertebrate. The remarkable and very complex course of this embryonic development is essentially the same in man and the ape, and in the amphibians and fishes. We see in it, in accordance with the biogenetic law, a new and important witness to the common descent of all vertebrates from a single primitive form, the chordÆa.

But, important as these arguments of comparative embryology are, one needs many years' study in the unfamiliar and difficult province of embryology before one can realise their evolutionary force. There are, in fact, not a few embryologists (especially of the modern school of experimental embryology) who do not succeed in doing so. It is otherwise with the palpable proofs that we take from a remote science, paleontology. The remarkable fossil remains and impressions of extinct animals and plants give us directly the historical evidence we need to understand the successive appearance and disappearance of the various species and groups. Geology has firmly established the chronological order of the sedimentary rocks, which have been successively formed of mud at the floor of the ocean, and has deduced their age from the thickness of the strata, and determined the relative date of their formation. The vast period during which organic life has been developing on the earth runs to many million years. The number is variously estimated at less than a hundred or at several hundred million years.[7] If we take the smaller number of 200 million years, we find them distributed amongst the five chief periods of the earth's organic development in such a way that the earlier or archeozoic period absorbs nearly one half. As the sedimentary rocks of this period, chiefly gneisses and crystalline schists, are in a metamorphosed condition, the fossil remains in them are unrecognisable. In the next succeeding strata of the paleozoic period we find the earliest remains of fossilised vertebrates, Silurian primitive fishes (selachii) and ganoids. These are followed, in the Devonian system, by the first dipneust fishes (a transitional form from the fishes to the amphibia). In the next, the Carboniferous system, we find the first terrestrial or four-footed vertebrates—amphibians of the order of the stegocephala. A little later, in the Permian rocks, the earliest amniotes, lowly, lizard-like reptiles (tocosauria), make their appearance; the warm-blooded birds and mammals are still wanting. We have the first traces of the mammals in the Triassic, the earliest sedimentary rocks of the mesozoic age; these are of the monotreme sub-class (pantotheria and allotheria). They are succeeded by the first marsupials (prodidelphia) in the Jurassic, the ancestral forms of the placentals (mallotheria), in the Cretaceous. See p. 115.

But the richest development of the mammal class takes place in the next or Tertiary age. In the course of its four periods—the eocene, oligocene, miocene, and pliocene—the mammal species increase steadily in number, variety, and complexity, down to the present time. From the lowest common ancestral group of the placentals proceed four divergent branches, the legions of the carnassia, rodents, ungulates, and primates. The primate legion surpasses all the rest. In this LinnÉ long ago included the lemurs, apes, and man. The historical order in which the various stages of vertebrate development make their successive appearance corresponds entirely to the morphological order of their advance in organisation, as we have learned it from the study of comparative anatomy and embryology.

These paleontological facts are among the most important proofs of the descent of man from a long series of higher and lower vertebrates. There is no other explanation possible except evolution for the chronological succession of these classes, which is in perfect harmony with the morphological and systematic distribution. The anti-evolutionists have not even attempted to give any other explanation. The fishes, dipneusts, amphibians, reptiles, monotremes, marsupials, placentals, lemurs, apes, anthropoid apes, and ape-men (pithecanthropi), are inseparable links of a long ancestral chain, of which the last and most perfect link is man. (Cf. the tables pp. 116-118.)

One of the paleontological facts I have quoted, namely, the late appearance of the mammal class in geology—is particularly important. This most advanced group of the vertebrates comes on the stage in the Triassic period, in the second and shorter half of the organic history of the earth. It is represented only by low and small forms in the whole of the mesozoic age, during the domination of the reptiles. Throughout this long period, which is estimated by some geologists at 8-11, by others at 20 or more, million years, the dominant reptile class developed its many remarkable and curious forms; there were swimming marine reptiles (halisauria), flying reptiles (pterosauria), and colossal land reptiles (dinosauria). It was much later, in the Tertiary period, that the mammal class attained the wealth of large and advanced placental forms that secured its predominance over this more recent period.

The many and thorough investigations made during the last few decades into the ancestral history of the mammals have convinced all zoologists who were engaged in them that they may be traced to a common root. All the mammals, from the lowest monotremes and marsupials to the ape and man, have a large number of striking characteristics in common, and these distinguish them from all other vertebrates: the hair and glands of the skin, the feeding of the young with the mother's milk, the peculiar formation of the lower jaw and the ear-bones connected therewith, and other features in the structure of the skull; also, the possession of a knee-cap (patella), and the loss of the nucleus in the red blood-cells. Further, the complete diaphragm, which entirely separates the pectoral cavity from the abdominal, is only found in the mammals; in all the other vertebrates there is still an open communication between the two cavities. The monophyletic (or single) origin of the whole mammalian class is therefore now regarded by all competent experts as an established fact.

In the face of this important fact, what is called the "ape-question" loses a good deal of the importance that was formerly ascribed to it. All the momentous consequences that follow from it in regard to our human nature, our past and future, and our bodily and psychic life, remain undisturbed whether we derive man directly from one of the primates, an ape or lemur, or from some other branch, some unknown lower form, of the mammalian stem. It is important to point this out, because certain dangerous attempts have been made lately by Jesuitical zoologists and zoological Jesuits to cause fresh confusion on the matter.

In a richly illustrated and widely read work that Hans Kraemer published a few years ago, under the title, The Universe and Man, an able and learned anthropologist, Professor Klaatsch of Heidelberg, deals with "the origin and development of the human race," and admirably describes the primitive history of man and his civilisation. However, he denounces the idea of man's descent from the ape as "irrational, narrow-minded, and false"; he grounds this severe censure on the fact that none of the living apes can be the ancestor of humanity. But no competent scientist had ever said anything so foolish. If we look closer into this fight with windmills, we find that Klaatsch holds substantially the same view of the pithecoid theory as I have done since 1866. He says expressly: "The three anthropoid apes, the gorilla, chimpanzee, and orang, seem to diverge from a common root, which was near to that of the gibbon and man." I had long ago given the name of archiprimas to this single hypothetical root-form of the primates, which he calls the "primatoid." It lived in the earliest part of the Tertiary period, and had probably been developed in the Cretaceous from older mammals. The very forced and unnatural hypothesis by means of which Klaatsch goes on to make the primates depart very widely from the other mammals, seems to me to be quite untenable, like the similar hypothesis that Alsberg, Wilser, and other anthropologists who deny our pithecoid descent, have lately advanced.

All these attempts have a common object—to save man's privileged position in Nature, to widen as much as possible the gulf between him and the rest of the mammals, and to conceal his real origin. It is the familiar tendency of the parvenu, which we so often notice in the aristocratic sons of energetic men who have won a high position by their own exertions. This sort of vanity is acceptable enough to the ruling powers and the Churches, because it tends to support their own fossilised pretensions to a "Divine image" in man and a special "Divine grace" in princes. The zoologist or anthropologist who studies our genealogy in a strictly scientific spirit takes no more notice of these tendencies than of the Almanach de Gotha. He seeks to discover the naked truth, as it is yielded by the great results of modern science, in which there is no longer any doubt that man is really a descendant of the ape—that is to say, of a long extinct anthropoid ape. As has been pointed out over and over again by distinguished supporters of this opinion, the proofs of it are exceptionally clear and simple—much clearer and simpler than they are in regard to many other mammals. Thus, for instance, the origin of the elephants, the armadilloes, the sirena, or the whales, is a much more difficult problem than the origin of man.

When Huxley published his powerful essay on "Man's Place in Nature" in 1863, he gave it a frontispiece showing the skeletons of man and the four living anthropoid apes, the Asiatic orang and gibbon, and the African chimpanzee and gorilla. Plate II. in the present work differs from this in giving two young specimens of the orang and the chimpanzee, and raising their size to correspond with the other three skeletons. Candid comparison of these five skeletons shows that they are not only very like each other generally, but are identical in the structure, arrangement, and connection of all the parts. The same 200 bones compose the skeleton in man and in the four tailless anthropoid apes, our nearest relatives. The same 300 muscles serve to move the various parts of the skeleton. The same hair covers the skin; the same mammary glands provide food for the young. The same four-chambered heart acts as central pump of the circulation; the same 32 teeth are found in our jaws; the same reproductive organs maintain the species; the same groups of neurona or ganglionic cells compose the wondrous structure of the brain, and accomplish that highest function of the plasm which we call the soul, and many still believe to be an immortal entity. Huxley has thoroughly established this profound truth, and by further comparison with the lower apes and lemurs he came to formulate his important pithecometra principle: "Whatever organ we take, the differences between man and the anthropoid apes are slighter than the corresponding differences between the latter and the lower apes." If we make a superficial comparison of our skeletons of the anthropomorpha, we certainly notice a few salient differences in the size of the various parts; but these are purely quantitative, and are due to differences in growth, which in turn are caused by adaptation to different environments. There are, as is well known, similar differences between human beings; their arms are sometimes long, sometimes short; the forehead may be high or low, the hair thick or thin, and so on.

These anatomic proofs of the pithecoid theory are most happily supplemented and confirmed by certain recent brilliant discoveries in physiology. Chief amongst these are the famous experiments of Dr. Hans Friedenthal at Berlin. He showed that the human blood acts poisonously on and decomposes the blood of the lower apes and other mammals, but has not that effect on the blood of the anthropoid apes.[8]

From previous transfusion experiments it had been learned that the affinity of mammals is connected to a certain extent with their chemical blood-relationship. If the living blood of two nearly related animals of the same family, such as the dog and the fox, or the rabbit and the hare, is mixed together, the living blood-cells of each species remain uninfluenced. But if we mix the blood of the dog and the rabbit, or the fox and the hare, a struggle for life immediately takes place between the two kinds of blood-cells. The watery fluid or serum destroys the blood-cells of the rodent, and vice versÂ. It is the same with specimens of the blood of the various primates. The blood of the lower apes and lemurs, which are close to the common root of the primate stem, has a destructive effect on the blood of the anthropoid apes and man, and vice versÂ. On the other hand, the human blood has no injurious effect when it is mixed with that of the anthropoid apes.

In recent years these interesting experiments have been continued by other physiologists and physicians, such as Professor Uhlenhuth at Greifswald and Nuttall at London, and they have proved directly the blood-relationship of various mammals. Nuttall studied them carefully in 900 different kinds of blood, which he tested by 16,000 reactions. He traced the gradation of affinity to the lowest apes of the New World; and Uhlenhuth continued as far as the lemurs. By these results the affinity of man and the anthropoid apes, long established by anatomy, has now been proved physiologically to be in real "blood-relationship."[9]

Not less important are the embryological discoveries of the deceased zoologist, Emil Selenka. He made two long journeys to the East Indies, in order to study on the spot the embryology of the Asiatic anthropoid apes, the orang and gibbon. By means of a number of embryos that he collected he showed that certain remarkable peculiarities in the formation of the placenta, that had up to that time been considered as exclusively human, and regarded as a special distinction of our species, were found in just the same way in the closely related anthropoid apes, though not in the rest of the apes. On the ground of these and other facts, I maintain that the descent of man from extinct Tertiary anthropoid apes is proved just as plainly as the descent of birds from reptiles, or the descent of reptiles from amphibians, which no zoologist hesitates to admit to-day. The relationship is as close as was claimed by my former fellow-student, the Berlin anatomist, Robert Hartmann (with whom I sat at the feet of Johannes MÜller fifty years ago), in his admirable work on the anthropoid apes (1883). He proposed to divide the order of primates into two families, the primarii (man and the anthropoid apes), and simianÆ (the real apes, the catarrhine or eastern, and the platyrrhine or western apes).

Since the Dutch physician, Eugen Dubois, discovered the famous remains of the fossil ape-man (pithecanthropus erectus) eleven years ago in Java, and thus brought to light "the missing link," a large number of works have been published on this very interesting group of the primates. In this connection we may particularly note the demonstration by the Strassburg anatomist, Gustav Schwalbe, that the previously discovered Neanderthal skull belongs to an extinct species of man, which was midway between the pithecanthropus and the true human being—the homo primigenus. After a very careful examination, Schwalbe at the same time refuted all the biassed objections that Virchow had made to these and other fossil discoveries, trying to represent them as pathological abnormalities. In all the important relics of fossil men that prove our descent from anthropoid apes Virchow saw pathological modifications, due to unsound habits, gout, rickets, or other diseases of the dwellers in the diluvial caves. He tried in every way to impair the force of the arguments for our primate affinity. So in the controversy over the pithecanthropus he raised the most improbable conjectures, merely for the purpose of destroying its significance as a real link between the anthropoid apes and man.

Even now, in the controversy over this important ape-question, amateurs and biassed anthropologists often repeat the false statement that the gap between man and the anthropoid ape is not yet filled up and the "missing link" not yet discovered. This is a most perverse statement, and can only arise either from ignorance of the anatomical, embryological, and paleontological facts, or incompetence to interpret them aright. As a fact, the morphological chain that stretches from the lemurs to the earlier western apes, from these to the eastern tailed apes, and to the tailless anthropoid apes, and from these direct to man, is now uninterrupted and clear. It would be more plausible to speak of missing links between the earliest lemurs and their marsupial ancestors, or between the latter and their monotreme ancestors. But even these gaps are unimportant, because comparative anatomy and embryology, with the support of paleontology, have dissipated all doubt as to the unity of the mammalian stem. It is ridiculous to expect paleontology to furnish an unbroken series of positive data, when we remember how scanty and imperfect its material is.

I cannot go further here into the interesting recent research in regard to special aspects of our simian descent; nor would it greatly advance our object, because all the general conclusions as to man's primate descent remain intact, whichever way we construct hypothetically the special lines of simian evolution. On the other hand, it is interesting for us to see how the most recent form of Darwinism, so happily described by Escherich as "ecclesiastical evolution," stands in regard to these great questions. What does its astutest representative, Father Erich Wasmann, say about them? The tenth chapter of his work, in which he deals at length with "the application of the theory of evolution to man," is a masterpiece of Jesuitical science, calculated to throw the clearest truths into such confusion and so to misrepresent all discoveries as to prevent any reader from forming a clear idea of them. When we compare this tenth chapter with the ninth, in which Wasmann represents the theory of evolution as an irresistible truth on the strength of his own able studies, we can hardly believe that they both came from the same pen—or, rather, we can only understand when we recollect the rule of the Jesuit Congregation: "The end justifies the means." Untruth is permitted and meritorious in the service of God and his Church.

The Jesuitical sophistry that Wasmann employs in order to save man's unique position in Nature, and to prove that he was immediately created by God, culminates in the antithesis of his two natures. The "purely zoological conception of man," which has been established beyond question by the anatomical and embryological comparison with the ape, is said to fail because it does not take into account the chief feature, his "mental life." It is "psychology that is best fitted to deal with the nature and origin of man." All the facts of anatomy and embryology that I have gathered together in my Evolution of Man in proof of the series of his ancestors are either ignored or misconstrued and made ridiculous by Wasmann. The same is done with the instructive facts of anthropology, especially the rudimentary organs, which Robert Wiedersheim has quoted in his Man's Structure as a Witness to his Past. It is clear that the Jesuit writer lacks competence in this department; that he has only a superficial and inadequate acquaintance with comparative anatomy and embryology. If Wasmann had studied the morphology and physiology of the mammals as thoroughly as those of the ants, he would have concluded, if he were impartial, that it is just as necessary to admit a monophyletic (or single) origin for the former as for the latter. If, in Wasmann's opinion, the 4,000 species of ants form a single "natural system"—that is to say, descend from one original species—it is just as necessary to admit the same hypothesis for the 6,000 (2,400 living and 3,600 fossil) species of mammals, including the human species.

The severe strictures that I have passed on the sophisms and trickery of this "ecclesiastical evolution" are not directed against the person and the character of Father Wasmann, but the Jesuitical system which he represents. I do not doubt that this able naturalist (who is personally unknown to me) has written his book in good faith, and has an honourable ambition to reconcile the irreconcilable contradictions between natural evolution and the story of supernatural creation. But this reconciliation of reason and superstition is only possible at the price of a sacrifice of the reason itself. We find this in the case of all the other Jesuits—Fathers Cathrein, Braun, Besmer, Cornet, Linsmeier, and Muckermann—whose ambiguous "Jesuitical science" is aptly dealt with in the article of R. H. FrancÉ that I mentioned before (No. 22 of the Freie Wort, 16th February, 1904, Frankfort).

This interesting attempt of Father Wasmann's does not stand alone. Signs are multiplying that the Church militant is about to enter on a systematic campaign. I heard from Vienna on the 17th of February, that on the previous day (which happened to be my birthday), a Jesuit, Father Giese, had, in a well-received address, admitted not only evolution in general, but even its application to man, and declared it to be reconcilable with Catholic dogmas—and this at a crowded meeting of "catechists"! It is important to note that in a new Catholic cyclopÆdia, Benziger's Library of Science, the first three volumes (issued at Einsiedeln and Cologne, 1904) deal very fully and ably with the chief problems of evolution: the first with the formation of the earth, the second with spontaneous generation, the third with the theory of descent. The author of them, Father M. Gander, makes most remarkable concessions to our theory, and endeavours to show that they are not inconsistent with the Bible or the dogmatic treatises of the chief fathers and schoolmen. But, though there is a profuse expenditure of sophistical logic in these Jesuitical efforts, Gander will hardly succeed in misleading thoughtful people. One of his characteristic positions is that spontaneous generation (as the development of organised living things by purely material processes) is inconceivable, but that it might be made possible "by a special Divine arrangement." In regard to the descent of man from other animals (which he grants), he makes the reserve that the soul must in any case have been produced by a special creative act.

It would be useless to go through the innumerable fallacies and untruths of these modern Jesuits in detail, and point out the rational and scientific reply. The vast power of this most dangerous religious congregation consists precisely in its device of accepting one part of science in order to destroy the other part more effectively with it. Their masterly act of sophistry, their equivocal "probabilism," their mendacious "reservatio mentalis," the principle that the higher aim sanctifies the worst means, the pernicious casuistry of Liguori and Gury, the cynicism with which they turn the holiest principles to the gratification of their ambition, have impressed on the Jesuits that black character that Carl Hoensbroech has so well exposed recently.

The great dangers that menace real science, owing to this smuggling into it of the Jesuitical spirit, must not be undervalued. They have been well pointed out by FrancÉ, Escherich, and others. They are all the greater in Germany at the present time, as the Government and the Reichstag are working together to prepare the way for the Jesuits, and to yield a most pernicious influence on the school to these deadly enemies of the free spirit of the country. However, we will hope that this clerical reaction represents only a passing episode in modern history. We trust that one permanent result of it will be the recognition, in principle, even by the Jesuits, of the great idea of evolution. We may then rest assured that its most important consequence, the descent of man from other primate forms, will press on victoriously, and soon be recognised as a beneficent and helpful truth.