We must first discuss the word race in its physiological sense.

A good many observers, who judge by first impressions and so take extreme views, assert that there are such radical and essential differences between human families that one must refuse them any identity of origin.^[48] The writers who adhere to such a notion assume many other genealogies by the side of that from Adam. To them there is no original unity in the species, or rather there is no single species; there are three or four, or even more, which produce perfectly distinct types, and these again have united to form hybrids.

The supporters of this theory easily win belief by citing the clear and striking differences between certain human groups. When we see before us a man with a yellowish skin, scanty hair and beard, a large face, a pyramidal skull, small stature, thick-set limbs, and slanting eyes with the skin of the eyelids turned so much outwards that the eye will hardly open^[49]—we recognize a very well-marked type, the main features of which it is easy to bear in mind.

From him we turn to another—a negro from the West Coast of Africa, tall, strong-looking, with thick-set limbs and a tendency to fat. His colour is no longer yellowish, but entirely black; his hair no longer thin and wiry, but thick, coarse, woolly, and luxuriant; his lower jaw juts out, the shape of the skull is what is known as prognathous. “The long bones stand out, the front of the tibia and the fibula are more convex than in a European, the calves are very high and reach above the knee; the feet are quite flat, and the heel-bone, instead of being arched, is almost in a straight line with the other bones of the foot, which is very large. The hand is similarly formed.”

When we look for a moment at an individual of this type, we are involuntarily reminded of the structure of the monkey, and are inclined to admit that the negro races of West Africa come from a stock that has nothing in common, except the human form, with the Mongolian.

We come next to tribes whose appearance is still less flattering to the self-love of mankind than that of the Congo negro. Oceania has the special privilege of providing the most ugly, degraded, and repulsive specimens of the race, which seem to have been created with the express purpose of forming a link between man and the brute pure and simple. By the side of many Australian tribes, the African negro himself assumes a value and dignity, and seems to derive from a nobler source. In many of the wretched inhabitants of this New World, the size of the head, the extreme thinness of the limbs, the famished look of the body, are absolutely hideous. The hair is flat or wavy, and generally woolly, the flesh is black on a foundation of grey.

When, after examining these types, taken from all the quarters of the globe, we finally come back to the inhabitants of Europe, and of South and West Asia, we find them so superior in beauty, in just proportion of limb and regularity of feature, that we are at once tempted to accept the conclusions of those who assert the multiplicity of races. Not only are these peoples more beautiful than the rest of mankind, which is, I confess, a pestilent congregation of ugliness;^[50] not only have they had the glory of giving the world such admirable types as a Venus, an Apollo, a Farnese Hercules; but also there is a visible hierarchy of beauty established from ancient times even among themselves, and in this natural aristocracy the Europeans are the most eminent, by their grace of outline and strength of muscular developement. The most reasonable view appears to be that the families into which man is divided are as distinct as are animals of different species. Such was the conclusion drawn from simple observation, and so long as only general facts were in question, it seemed irrefutable.

Camper was one of the first to reduce these observations to some kind of system. He was no longer satisfied with merely superficial evidence, but wished to give his proofs a mathematical foundation; he tried to define anatomically the differences between races. He succeeded in establishing a strict method that left no room for doubt, and his views gained the numerical accuracy without which there can be no science. His method was to take the front part of the skull and measure the inclination of the profile by means of two lines which he called the facial lines. Their intersection formed an angle, the size of which gave the degree of elevation attained by the race to which the skull belonged. One of these lines connected the base of the nose with the orifice of the ear; the other was tangential to the most prominent part of the forehead and the jut of the upper jaw. On the basis of the angle thus formed, he constructed a scale including not only man but all kinds of animals. At the top stood the European; and the more acute the angle, the further was the distance from the type which, according to Camper, was the most perfect. Thus birds and fishes showed smaller angles than the various mammals. A certain kind of ape reached 42°, and even 50°. Then came the heads of the African negro and the Kalmuck, which touched 70°. The European stood at 80°, and, to quote the inventor’s own words, which are very flattering to our own type, “On this difference of 10° the superior beauty of the European, what one might call his ‘comparative beauty,’ depends; the ‘absolute beauty’ that is so striking in some of the works of ancient sculpture, as in the head of Apollo and the Medusa of Sosicles, is the result of a still greater angle, amounting in this instance to 100°.”^[51]

This method was attractive by its simplicity. Unhappily, the facts are against it, as against so many systems. By a series of accurate observations, Owen showed that, in the case of monkeys, Camper had studied the skulls only of the young animals; but since, in the adults, the growth of the teeth and jaws, and the development of the zygomatic arch, were not accompanied by a corresponding enlargement of the brain, the numerical difference between these and human skulls was much greater than Camper had supposed, since the facial angle of the black orang-outang or the highest type of chimpanzee was at most 30° or 35°. From this to the 70° of the negro and the Kalmuck the gap was too great for Camper’s scale to have any significance.

Camper’s theory made considerable use of phrenology. He attempted to discover a corresponding development of instinct as he mounted his scale from the animals to man. But here too the facts were against him. The elephant, for example, whose intelligence is certainly greater than the orang-outang’s, has a far more acute facial angle; and even the most docile and intelligent monkeys do not belong to the species which are the “highest” in Camper’s series.

Beside these two great defects, the method is very open to attack in that it does not apply to all the varieties of the human race. It leaves out of account the tribes with pyramidally shaped heads, who form, however, a striking division by themselves.

Blumenbach, who held the field against his predecessor, elaborated a system in his turn; this was to study a man’s head from the top. He called his discovery norma verticalis, the “vertical method.” He was confident that the comparison of heads according to their width brought out the chief differences in the general configuration of the skull. According to him, the study of this part of the body is so pregnant with results, especially in its bearing on national character, that it is impossible to measure all the differences merely by lines and angles; to reach a satisfying basis of classification, we must consider the heads from the point of view in which we can take in at one glance the greatest number of varieties. His idea was, in outline, as follows: “Arrange the skulls that you wish to compare in such a way that the jaw-bones are on the same horizontal line; in other words, let each rest on its lower jaw. Then stand behind the skulls and fix the eye on the vertex of each. In this way you will best see the varieties of shape that have most to do with national character; these consist either (1) in the direction of the jaw-bone and maxillary, or (2) in the breadth or narrowness of the oval outline presented by the top half of the skull, or (3) in the flattened or vaulted form of the frontal bone.”^[52]

Blumenbach’s system resulted in the division of mankind into five main categories, which were in their turn subdivided into a certain number of types and classes.

This classification was of very doubtful value. Like that of Camper, it overlooked many important characteristics. It was partly to escape such objections that Owen proposed to examine skulls, not from the top, but from the bottom. One of the chief results of this new method was to show such a strong and definite line of difference between a man and an orang-outang that it became for ever impossible to find the link that Camper imagined to exist between the two species. In fact, one glance at the two skulls, from Owen’s point of view, is enough to bring out their radical difference. The diameter from front to back is longer in the orang-outang than in man; the zygomatic arch, instead of being wholly in the front part of the base, is in the middle, and occupies just a third of its diameter. Finally the position of the occipital orifice, which has such a marked influence on general structure and habits, is quite different. In the skull of a man, it is almost at the centre of the base; in that of an orang-outang, it is a sixth of the way from the hinder end.^[53]

Owen’s observations have, no doubt, considerable value; I would prefer, however, the most recent of the craniological systems, which is at the same time, in many ways, the most ingenious, I mean that of the American scholar Morton, adopted by Carus.^[54] In outline this is as follows:

To show the difference of races, Morton and Carus started from the idea, that the greater the size of the skull, the higher the type to which the individual belonged, and they set out to investigate whether the development of the skull is equal in all the human races.

To solve this question, Morton took a certain number of heads belonging to whites, Mongols, negroes, and Redskins of North America. He stopped all the openings with cotton, except the foramen magnum, and completely filled the inside with carefully dried grains of pepper. He then compared the number of grains in each. This gave him the following table:

The results set down in the first two columns are certainly very curious. On the other hand, I attach little importance to those in the last two; for if the extraordinary variations from the average in the second column are to have any real significance, Morton should have taken a far greater number of skulls, and further, have given details as to the social position of those to whom the skulls belonged. He was probably able to procure, in the case of the whites and the Redskins, heads which had belonged to men at any rate above the lowest level of society, while it is not likely that he had access to the skulls of negro chiefs, or of Chinese mandarins. This explains how he has been able to assign the number 100 to an American Indian, while the most intelligent Mongol whom he has examined does not rise above 93, and is thus inferior even to the negro, who reaches 94. Such results are a mere matter of chance. They are quite incomplete and unscientific; in such questions, however, one cannot be too careful to avoid judgments founded merely on individual cases. I am inclined therefore to reject altogether the second half of Morton’s calculations.

I must also question one detail in the other half. In the second column, there is a clear gradation from the number 87, indicating the capacity of the white man’s skull, to the numbers 83 and 78 for the yellow and black man respectively. But the figures 83, 81, 82, for the Mongols, Malays, and Redskins, give average results which evidently shade into one another; all the more so, because Carus does not hesitate to count the Mongols and Malays as the same race, and consequently to put the numbers 83 and 81 together. But, in that case, why allow the number 82 to mark a distinct race, and thus create arbitrarily a fourth great division of mankind?

This anomaly, however, actually buttresses the weak point in Carus’ system. He likes to think that, just as we see our planet pass through the four stages of day and night, evening and morning twilight, so there must be in the human species four subdivisions corresponding to these. He sees here a symbol, which is always a temptation for a subtle mind. Carus yields to it, as many of his learned fellow-countrymen would have done in his place. The white races are the nations of the day; the black those of the night; the yellow those of the Eastern, and the red those of the Western twilight. We may easily guess the ingenious comparisons suggested by such a picture. Thus, the European nations, owing to the brilliance of their scientific knowledge and the clear outlines of their civilization, are obviously in the full glare of day, while the negroes sleep in the darkness of ignorance, and the Chinese live in a half-light that gives them an incomplete, though powerful, social development. As for the Redskins, who are gradually disappearing from the earth, where can we find a more beautiful image of their fate than the setting sun?

Unhappily, comparison is not proof, and by yielding too easily to this poetic impulse, Carus has a little damaged his fine theory. The same charge also may be levelled at this as at the other ethnological doctrines; Carus does not manage to include in a systematic whole the various physiological differences between one race and another.^[55]

The supporters of the theory of racial unity have not failed to seize on this weak point, and to claim that, where we cannot arrange the observations on the shape of the skull in such a way as to constitute a proof of the original separation of types, we must no longer consider the variations as pointing to any radical difference, but merely regard them as the result of secondary and isolated causes, with no specific relevance.

The cry of victory may be raised a little too soon. It may be hard to find the correct method, without being necessarily impossible. The “unitarians,” however, do not admit this reservation. They support their view by observing that certain tribes that belong to the same race show a very different physical type. They cite, for instance, the various branches of the hybrid Malayo-Polynesian family, without taking account of the proportion in which the elements are mingled in each case. If groups (they say) with a common origin can show quite a different conformation of features and skull, the unity of the human race cannot be disproved along these lines at all. However foreign the negro or Mongol type may appear to European eyes, this is no evidence of their different origin; the reasons why the human families have diverged will be found nearer to hand, and we may regard these physiological deviations merely as the result of certain local causes acting for a definite period of time.^[56]

In face of so many objections, good and bad, the champions of multiplicity tried to extend the sphere of their arguments. Relying no longer on the mere study of skulls, they passed to that of the individual man as a whole. In order to prove (as is quite true) that the differences do not merely lie in the facial appearance and the bony conformation of the head, they brought forward other important differences with regard to the shape of the pelvis, the proportions of the limbs, the colour of the skin, and the nature of the capillary system.

Camper and other anthropologists had already recognized that the pelvis of the negro showed certain peculiarities. Dr. Vrolik pushed these inquiries further, and observed that the difference between the male and female pelvis was far less marked in the European, while in the negro race he saw in the pelvis of both sexes a considerable approximation to the brute. Assuming that the configuration of the pelvis necessarily affected that of the embryo, he inferred a difference of origin.^[57]

Weber attacked this theory, with little result. He had to recognize that some formations of the pelvis were found in one race more frequently than in another; and all he could do was to show that there were some exceptions to Vrolik’s rule, and that certain American, African, and Mongolian specimens showed formations that were usually confined to Europeans. This does not prove very much, especially as, in speaking of these exceptions, Weber does not seem to have inquired whether the peculiar configuration in question might not result from a mixture of blood.

With regard to the size of the limbs, the opponents of a common origin assert that the European is better proportioned. The answer—which is a good one—is that we have no reason to be surprised at the thinness of the extremities in peoples who live mainly on vegetables or have not generally enough to eat. But as against the argument from the extraordinary development of the bust among the Quichuas, the critics who refuse to recognize this as a specific difference are on less firm ground. Their contention that the development among the mountaineers of Peru is explained by the height of the Andes, is hardly serious. There are many mountain-peoples in the world who are quite differently constituted from the Quichuas.^[58]

The next point is the colour of the skin. The unitarians deny this any specific influence, first because the colour depends on facts of climate, and is not permanent—a very bold assertion; secondly because the colour is capable of infinite gradation, passing insensibly from white to yellow, from yellow to black, without showing a really definite line of cleavage. This proves nothing but the existence of a vast number of hybrids, a fact which the unitarians are continually neglecting, to the great prejudice of their theory.

As to the specific character of the hair, Flourens is of opinion that this is no argument against an original unity of race.

After this rapid review of the divergent theories I come to the great scientific stronghold of the unitarians, an argument of great weight, which I have kept to the end—I mean the ease with which the different branches of the human family create hybrids, and the fertility of these hybrids.

The observations of naturalists seem to prove that, in the animal or vegetable world, hybrids can be produced only from allied species, and that, even so, they are condemned to barrenness. It has also been observed that between related species intercourse, although possibly fertile, is repugnant, and usually has to be effected by trickery or force. This would tend to show that in the free state the number of hybrids is even more limited than when controlled by man. We may conclude that the power of producing fertile offspring is among the marks of a distinct species.

As nothing leads us to believe that the human race is outside this rule, there is no answer to this argument, which more than any other has served to hold in check the forces opposed to unity. We hear, it is true, that in certain parts of Oceania the native women who have become mothers by Europeans are no longer fitted for impregnation by their own kind. Assuming this to be true, we might make it the basis of a more profound inquiry; but, so far as the present discussion goes, we could not use it to weaken the general principle of the fertility of human hybrids and the infertility of all others; it has no bearing on any conclusions that may be drawn from this principle.