But what are these limits? Here we are on the verge of the arbitrary, for there exists no fixed rule determining the point to which individual unlikeness may go in order to be considered as characteristic of a species. A difference which entitles one zoologist to create a species hardly suffices, according to another, to constitute a “variety,” a “sub-species,” or a “race.” As to the second criterion of species drawn from the transmission and the descent of characters, it is theoretic rather than practical. Without dwelling on the numerous examples of “varieties” as fertile among themselves as “species,”[4] let us ask ourselves how many zoologists or botanists have verified experimentally the fertility of the species which they have created. In the large majority of cases, the species of plants and animals have been established solely from morphological characters, very often from the examination of dead specimens, and without any guarantee that the beings in question proceeded from common parents and that when crossed they would be fertile or not.
In the case of man, as in that of the majority of plants and animals, fertility or non-fertility among the different groups has not been experimentally proved, to enable us to decide if they should be called “races” or “species.” To a dozen facts in favour of one of the solutions, and to general theories in regard to half-breeds, can be opposed an equal number of facts, and the idea, not less general, of reversion to the primitive type.[5] And again, almost all the facts in question are borrowed from cross-breeding between the Whites and other races. No one has ever tried cross-breeding between the Australians and the Lapps, or between the Bushmen and the Patagonians, for example. If certain races are indefinitely fertile among themselves (which has not yet been clearly shown), it may be there are others which are not so.[6] A criterion of descent being unobtainable, the question of the rank to be assigned to the genus Homo is confined to a morphological criterion, to the differences in physical type.
According to some, these differences are sufficiently pronounced for each group to form a “species”; according to others they are of such a nature as only to form racial distinctions. Thus it is left to the personal taste of each investigator what name be given to these.
We cannot do better than cite upon this point the opinion of a writer of admitted authority. “It is almost a matter of indifference,” says Darwin, “whether the so-called races of man are thus designated, or ranked as ‘species’ or ‘sub-species,’ but the latter term appears the most appropriate.”[7] The word “race” having been almost universally adopted nowadays to designate the different physical types of mankind, I shall retain it in preference to that of “sub-species,” while reiterating that there is no essential difference between these two words and the word “species.”
From what has just been said, the question whether humanity forms a single species divided into varieties or races, or whether it forms several species, loses much of its importance.
The whole of this ancient controversy between monogenists and polygenists seems to be somewhat scholastic, and completely sterile and futile; the same few and badly established facts are always reappearing, interpreted in such and such a fashion by each disputant according to the necessities of his thesis, sometimes led by considerations which are extra-scientific. Perhaps in the more or less near future, when we shall have a better knowledge of present and extinct races of man, as well as of living and of fossil animal species most nearly related to man, we shall be able to discuss the question of origin. At the present time we are confined to hypothesis without a single positive fact for the solution of the problem. We have merely to note how widely the opinions of the learned differ in regard to the origin of race of certain domestic animals, such as the dog, the ox, or the horse, to get at once an idea of the difficulty of the problem. And yet, in these cases, we are dealing with questions much less complicated and much more carefully studied.
Moreover, whether we admit variety, unity or plurality of species in the genus Homo we shall always be obliged to recognise the positive fact of the existence in mankind of several somatological units having each a character of its own, the combinations and the intermingling of which constitute the different ethnic groups. Thus the monogenists, even the most intractable, as soon as they have established hypothetically a single species of man, or of his “precursor,” quickly cause the species to evolve, under the influence of environment, into three or four or a greater number of primitive “stocks,” or “types,” or “races,”—in a word, into somatological units which, intermingling, form “peoples,” and so forth.
We can sum up what has just been said in a few propositions. On examining attentively the different “ethnic groups” commonly called “peoples,” “nations,” “tribes,” etc., we ascertain that they are distinguished from each other especially by their language, their mode of life, and their manners; and we ascertain besides that the same traits of physical type are met with in two, three, or several groups, sometimes considerably removed the one from the other in point of habitat. On the other hand, we almost always see in these groups some variations of type so striking that we are led to admit the hypothesis of the formation of such groups by the blending of several distinct somatological units.
It is to these units that we give the name “races,” using the word in a very broad sense, different from that given to it in zoology and zootechnics. It is a sum-total of somatological characteristics once met with in a real union of individuals, now scattered in fragments of varying proportions among several “ethnic groups,” from which it can no longer be differentiated except by a process of delicate analysis.