“It is notorious that man is constructed on the same general type or model with other mammals. All the bones in his skeleton can be compared with corresponding bones in a monkey, bat, or seal. So it is with his muscles, nerves, blood-vessels, and viscera. The brain, the most important of all the organs, follows the same law, as shown by Huxley and other anatomists.”24 Man’s nearest animal relations are the tailless anthropoid or man-like apes—namely, the gorilla, the chimpanzee, the orang, and the gibbon. “Now that all the details of the human organisation have been studied, and the anatomical structures of man and large monkeys without tails have been compared, bone with bone, and muscle with muscle, a truly astonishing analogy between these organisms is made manifest—an analogy apparent in every detail.”25 The following are some of the points more particularly calling for notice:—

Dentition.—In the natural history of mammals the teeth play an important part as a means of determining differences and relationships. “Everyone knows the milk teeth and the permanent teeth of man. The anthropoid apes bear in this respect an astonishing likeness to man. The number (thirty-two in the adult), the form and general arrangement of the crown, are identical in man and anthropoid apes. The differences are to be found only in minor details.”26 “But the fact must not be lost sight of that all these differences are less pronounced than those which exist between the dentition of anthropoid apes and that of all other monkeys.”27

The Foot.—Anti-evolutionists have laid great stress on the difference between the foot of a man and that of an anthropoid ape. But it is clearly shown by Huxley that in all essential respects the hinder limb of the gorilla terminates in as true a foot as that of man,28 and “that, be the differences between the hand and foot of man and those of the gorilla what they may, the differences between those of the gorilla and those of the lower apes are much greater.”29

The Sacrum.—“In monkeys, as a whole, the sacrum is composed of three, or rarely four, vertebræ, while in anthropoid apes it contains five—that is to say, just as many as in man.”30

The Skull.—Here the differences are more marked; but again we must remind ourselves that, as regards the osteology, Professor Huxley tells us that “for the skull, no less than for the skeleton in general, the proposition holds good that the differences between man and the gorilla are of smaller value than those between the gorilla and some other apes.”31

The Brain.—Several distinguished zoologists at one time insisted on the absence in all monkeys of certain parts of the brain peculiarly characteristic of man, but now it is unanimously accepted that the parts of the brain in question are “precisely those structures which are the most marked cerebral characters common to man with the apes. They are among the most distinctly simian peculiarities which the human organism exhibits.”32

The difference between the brain of the orang and that of man is a mere difference of degree, and not of kind; and most students of comparative psychology now admit that the intellectual faculties of animals differ from those in man in degree only, not in their essence. Replying to his opponents, Professor Huxley compares the brain of man and that of ape with two watches, one of which will, and the other will not, keep accurate time. He exclaims: “A hair in the balance-wheel, a little rust on a pinion, a bend in a tooth of the escapement, a something so slight that only the practised eye of the watchmaker can discover it, may be the source of all the difference.”33

The late Sir Charles Lyell mentions in his Antiquity of Man how Dr. Sumner, the late Archbishop of Canterbury, brought out in strong relief fifty years ago, in his Records of Creation, one essential character separating man from the brute. As the same argument is still being “brought out,” and is, on the face of it, exceedingly plausible, and as the answer to it has to do with the brain, it cannot be passed over. Dr. Sumner said: “It has been sometimes alleged, and may be founded on fact, that there is less difference between the highest brute animal and the lowest savage than between the savage and the most improved man. But, in order to warrant the pretended analogy, it ought to be also true that this lowest savage is no more capable of improvement than the chimpanzee or orang-outang.” This objection is met by some such consideration as the following:—When you examine the enormous difference in the formation of the skull in man and ape (look, for instance, at plate xvii., vol. ii. of Haeckel’s Evolution of Man), and when you remember that this sets hard at an early date, you surely have a good reason for limited improvability. Further, the brain of even the lowest savage represents a development of some half a million years above the ape along the line of intelligence. How, then, can we dream of making this up in one or a few generations by artificial training of the ape? Lastly, we have the enormous leverage of language, the inherited wealth of thousands of speaking generations, and an incalculable aid to thought. How much is the intelligence of the Microcephalæ, the clucking “small heads” lately on show at the Hippodrome, capable of rapid improvement? Our experiments do not show that the ape is not improvable, but only that we cannot, in a single generation, lift it over a gulf representing 500,000 years of human development. How can we expect it?

The Blood.—In the last few years an astonishing confirmation of our relationship to the anthropoid ape has been discovered. We are blood relations. Elie Metchnikoff, Professor at the Pasteur Institute, shows this clearly in his book, The Nature of Man.34 Until quite recently it was not known how to distinguish human blood from that of other mammals. A method giving conclusive results has now been discovered, and is used in forensic medicine. The same method has been employed in comparing the blood of man and the anthropoid apes, resulting in the discovery35 that, in their case, there is practically no blood difference whatever!

The opponents of Evolution used to appeal to the special features of human embryology, which were supposed to distinguish man from all the other mammals; but in 1890 Emil Selenka proved that the same features are found in anthropoid apes, especially in the orang, while the lower apes are without them.

“When Huxley wrote, the embryological history of anthropoid apes was practically unknown. Darwin, Vogt, and Haeckel, in their attempts to support the theory of the animal origin of man, had not sufficient knowledge of the embryology of monkeys. It is only recently that important work on this subject has been published.... The placenta often gives information of great importance in the classification of mammals. It is sufficient to glance at the zonary placenta of dogs and seals to be convinced of the relationship of these two species which at first sight seem so different. Now, the placentas of all the anthropoid apes examined up to the present are of the same discoid type as that of man. The arrangement of the umbilical cord of man, which was formerly considered as quite peculiar to him, is found in anthropoid apes, as has been established by Deniker and Selenka. It is striking that the anthropoids resemble man rather than the lower monkeys in the relation of the fœtus to the fœtal membranes. With regard to the embryos themselves, the similarity between those of monkeys and man is very great.... The youngest stages of human development that have been obtained can hardly be distinguished from those of the lower monkeys either in position or shape. More advanced stages exhibit greater differentiation, and the later embryos of man resemble those of anthropoids much more closely than those of the lower monkeys. The resemblance between the nearly mature fœtus of anthropoids and human embryos of about the sixth month is evident enough.”36

We are thus bound, in all honesty, to own up to our ape-like progenitors. But this is only a small portion of the wonderful tale told by Embryology. “Man is developed from an ovule about 125th of an inch in diameter, which differs in no respect from the ovules of other animals,”37 and, marvellous to relate, from that stage upwards the embryo is one continuous epitome of the history of man’s evolution from lower forms of life.38 Up to a certain point the germs, not only of all mammals, but of all vertebrate animals, fishes, reptiles, and birds, are scarcely distinguishable. A sceptic may convince himself by studying the plates given in Haeckel’s The Evolution of Man, and especially plates ix. to xiv., where the embryos of various animals are compared. At the more advanced stage, where the embryo has already passed the reptilian form, we find that for a considerable time the line of development remains the same as that of other mammalia. The resemblance, for example, after the first four weeks’ growth, between the embryo of a man and that of a dog is such that it is scarcely possible to distinguish the one from the other. Even at the age of eight weeks the embryo man is an animal with a tail, hardly to be distinguished from an embryo puppy.39 After this period the embryo emerges from the general mammalian type into the special order of primates to which man belongs. Thus does the growth of the egg from which man springs compress into a few weeks the results of millions of years, and set before us the history of his development from fish-like and reptilian forms (which, as we have seen, p. 211, Mr. Gladstone deemed so contemptible and “fallen from greatness”), and of his more immediate descent from a hairy, tailed quadruped, the extinct common ancestor of man and monkey. As evolution proceeds the embryo rises up to man, and the differences specialising the human infant at its birth, such as the largeness and more complex convolutions of the brain, become more and more accentuated as its growth proceeds.

Regarding the question of “gaps,” we have to bear in mind that it is part of the evolutionary theory that the active processes of evolution have very largely ceased, that existing forms are but a surviving remnant with enormous gaps, and that the survivors are so fitted at present to their surroundings that evolutionary forces are causative of equilibrium rather than change. We have already seen, too, that in the struggle for existence it is among the closely-allied species that the contest is more strenuous, and that the weakest, or least fitted to survive, has to go to the wall—to be wiped out. Thus it is that there is a tendency for species to become extinct, and for the gaps to be widened. The extraordinary thing is not that we have so little direct evidence of descent, but that we have so much. That there are not more links missing is due principally to the discovery of fossil remains. When an animal dies, the probabilities are, of course, enormously against geological preservation of its bones, yet the gaps are continually being filled up by geological finds, and, though the remaining gaps may be great, they are not unaccountable.

I must now pass on to the remaining set of proofs of our origin.

Perhaps nothing furnishes a more conclusive proof of our animal origin than the study of rudimentary structures—muscles, sense-organs, hair, bones, reproductive organs, etc. There are some which are “either absolutely useless, such as the mammæ of the male quadrupeds or the incisor teeth of ruminants which never cut through the gums; or they are of such slight service to their present possessors that we cannot suppose that they were developed under the conditions which now exist.”40 Of useless rudimentary organs, or parts of organs, there are not less than one hundred and seven in man.41 To this category belong the coccyx—the vestige of a tail—the muscles of the ear, the vermiform appendage, etc.

“The os coccyx in man, though functionless as a tail, plainly represents this part in other vertebrate animals. At an early embryonic period it is free, and, as we have seen, projects beyond the lower extremities.”42 It sometimes happens that we find external relics of a tail. Professor Haeckel, in Fig. 195, vol. i. of The Evolution of Man (library edition), shows the tail of a six months’ old boy, which Granville Harrison removed by operation. The anthropoid ape, like man, has only the rudiment of a tail.

The ear muscles are rudimentary in man. “It is well known how readily domestic animals—horses, cows, dogs, hares, etc.—point their ears and move them in different directions. Most of the apes do the same, and our earlier ape ancestors were also able to do it. But our later simian ancestors, which we have in common with the anthropoid apes, abandoned the use of these muscles, and they gradually became rudimentary and useless. However, we possess them still. In fact, some men can still move their ears a little backward and forward by means of the drawing and withdrawing muscles; and with practice this faculty can be much improved. But no man can now lift up his ears by the raising muscle, or change the shape of them by the small inner muscles. These muscles were very useful to our ancestors, but are of no consequence to us. This applies to most of the anthropoid apes as well.”43

The vermiform appendage of the cœcum is not only practically useless, but the source of that extremely dangerous complaint, appendicitis. It is remarkable that this organ is practically identical with the vermiform appendage of anthropoid apes, yet none of the other monkeys present any such resemblance with men. Professor Haeckel, speaking of the vermiform appendage, says: “The only significance of it in man is that not infrequently a cherry-stone or some other hard and indigestible matter penetrates into its narrow cavity, and by setting up inflammation and suppuration causes the death of otherwise sound men. Teleology has great difficulty in giving a rational explanation of, and attributing to a beneficent Providence, this dreaded appendicitis. In our plant-eating ancestors this rudimentary organ was much larger, and had a useful function.”44

“In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously indicated.”45

Whatever the precise explanation may be, can we bring ourselves to suppose that God created us with a number of useless organs, or that He placed them there as a snare to entrap our judgment? Again, “rudimentary organs, for the most part, display a congenital lack of the power of resistance, and, as Darwin suggested, for this reason they are frequently the seats of disease.”46 Can anyone imagine his Maker arranging all this on purpose? I can not. We are assured by pious apologists that God has instituted pain in order to save us from injuring ourselves; how can He, then, have specially provided us with organs whose only function is to be a source of danger?

Many other examples might be given bearing on this line of argument; but enough has been said, I hope, to convince the reader that in these rudimentary organs there is overpowering evidence against separate acts of creation, and in favour of an animal origin of the human race. Besides this, we have also the evidence derived from the study of our bodily structure and embryonic development. The bearing of these three great classes of fact is, as Charles Darwin remarks, unmistakeable. “It is only our natural prejudice, and that arrogance which made our own forefathers declare that they were descended from demi-gods, which lead us to demur to this conclusion.”47