To the investigator who believes in the unity of the human species, whether he be a proper ethnologist, or a zoologist in the more current signification of the term, the phænomena exhibited by the numerous families of mankind supply ninetenths of the data for that part of natural history which deals with varieties as subordinate to, and as different from, species. The history of domestic animals in comprehensiveness and complexity yields to the history of the domesticator. Compare upon this point such a work as G. Cuvier's on the Races of Dogs, with Dr. Prichard's Natural History of Man. The mere difference in bulk of volume is a rough measure of the difference in the magnitude of the subjects. Even if the dog were as ubiquitous as man, and consequently as much exposed to the influence of latitude, and altitude, there would still be wanting to the evolution of canine varieties the manifold and multiform influences of civilization. The name of these is legion; whilst the extent to which they rival the more material agencies of climate and nutrition is getting, day by day, more generally admitted by the best and most competent inquirers. Forms as extreme as any that can be found within the pale of the same species are to be found within that of the species Homo. Transitions as gradual as those between any varieties elsewhere are also to be found. In summing up the value of the data supplied by man towards the natural history of varieties, it may be said that they are those of a species which has its geographical distribution everywhere and a moral as well as a physical series of characteristics. Surely, if the question under notice be a question that must be studied inductively, Man gives us the field for our induction.
Before I come to the special point of the present notice and to the explanation of its somewhat enigmatical heading, I must further define the sort of doctrine embodied in what I have called the belief of the unity of our species. I do not call the upholder of the developmental doctrine a believer of this kind. His views—whether right or wrong—are at variance with the current ideas attached to the word species. Neither do I identify with the recognition of single species the hypothesis of a multiplicity of protoplasts, so long as they are distributed over several geographical centres. The essential element to the idea of a single species is a single geographical centre. For this, the simplest form of the protoplast community is a single pair.
All this is mere definition and illustration. The doctrine itself may be either right or wrong. I pass no opinion upon it. I assume it for the present; since I wish to criticize certain terms and doctrines which have grown up under the belief in it, and to show, that, from one point of view, they are faulty, from another, legitimate.
It will simplify the question if we lay out of our account altogether the islands of the earth's surface, limiting ourselves to the populations of the continent. Here the area is continuous, and we cannot but suppose the stream of population by which its several portions were occupied to have been continuous also. In this case a population spreads from a centre like circles on a still piece of water. Now, if so, all changes must have been gradual, and all extreme forms must have passed into each other by means of a series of transitional ones.
It is clear that such forms, when submitted to arrangement and classification, will not come out in any definite and wellmarked groups, like the groups that constitute what is currently called species. On the contrary, they will run into each other, with equivocal points of contact, and indistinct lines of demarcation; so that discrimination will be difficult, if not impracticable. If practicable, however, it will be effected by having recourse to certain typical forms, around which such as approximate most closely can most accurately and conveniently be grouped. When this is done, the more distant outliers will be distributed over the debateable ground of an equivocal frontier. To recapitulate: varieties as opposed to species imply transitional forms, whilst transitional forms preclude definite lines of demarcation.
Yet what is the actual classification of the varieties of mankind, and what is the current nomenclature? To say the least, it is very like that of the species of a genus. Blumenbach's Mongolians, Blumenbach's Caucasians, Blumenbach's Æthiopians,—where do we find the patent evidence that these are the names of varieties rather than species? Nowhere. The practical proof of a clear consciousness on the part of a writer that he is classifying varieties rather than species, is the care he takes to guard his reader against mistaking the one for the other, and the attention he bestows on the transition from one type to another. Who has ever spent much ethnology on this? So far from learned men having done so, they have introduced a new and lax term—race. This means something which is neither a variety nor yet a species—a tertium quid. In what way it differs from the other denomination has yet to be shown.
Now if it be believed (and this belief is assumed) that the varieties of mankind are varieties of a species only, and if it cannot be denied that the nomenclature and classification of ethnologists is the nomenclature and classification of men investigating the species of a genus, what is to be done? Are species to be admitted, or is the nomenclature to be abandoned? The present remarks are made with the view of showing that the adoption of either alternative would be inconsiderate, and that the existing nomenclature, even when founded upon the assumption of broad and trenchant lines of demarcation between varieties which (ex vi termini) ought to graduate into each other, is far from being indefensible.
Man conquers man, and occupant displaces occupant on the earth's surface. By this means forms and varieties which once existed become extinct. The more this extinction takes place, the greater is the obliteration of those transitional and intermediate forms which connect extreme types; and the greater this obliteration, the stronger the lines of demarcation between geographically contiguous families. Hence a variational modification of a group of individuals simulates a difference of species; forms which were once wide apart being brought into juxtaposition by means of the annihilation of the intervening transitions. Hence what we of the nineteenth century,—ethnologists, politicians, naturalists, and the like—behold in the way of groups, classes, tribes, families, or what not, is beholden to a great extent under the guise of species; although it may not be so in reality, and although it might not have been so had we been witnesses to that earlier condition of things when one variety graduated into another and the integrity of the chain of likeness was intact. This explains the term subjectivity. A group is sharply defined simply because we know it in its state of definitude; a state of definitude which has been brought about by the displacement and obliteration of transitional forms.
The geographical distribution of the different ethnological divisions supplies a full and sufficient confirmation of this view. I say "full and sufficient," because it cannot be said that all our groups are subjective, all brought about by displacement and obliteration. Some are due to simple isolation; and this is the reason why the question was simplified by the omission of all the insular populations. As a general rule, however, the more definite the class, the greater the displacement; displacement which we sometimes know to have taken place on historical evidence, and displacement which we sometimes have to infer. In thus inferring it, the language is the chief test. The greater the area over which it is spoken with but little or no variation of dialect, the more recent the extension of the population that speaks it. Such, at least, is the primâ facie view.
A brief sketch of the chief details that thus verify the position of the text is all that can now be given.