THE UNITY OF THE HUMAN SPECIES.
Definition of the above considerations demonstrate that man has a number of traits which mark him off as a wholly distinct species, the question arises, Must we go farther and erect him into a genus, including a number of species? In other words, Is there but one species of man or are there several ? Some years ago this question assumed a certain degree of political importance in the United States, and several ambitious treatises were published to prove that the white and the negro races belong, zoolog ically, to different species. The aim of these efforts was, however, rather to defend a theory than to arrive at the truth.
Owing to the general acceptance of the modern doctrines of the evo lution and retrogression of organic forms, the definition of species is by no means so rigid as it was formerly. Indeed, it is no easy task to state precisely what we mean by a species. We can at best say that it includes all members of an organic group who have an obvious similarity between themselves, and who have been, or may be supposed to have been, descended from the same ancestral pair.
Such general similarity exists to a remarkable degree among all races of men, especially when we reflect to what extremely different food, climate, and surroundings they are subjected, in these respects far transcending any other animal. They agree not only in all those marked traits which have been mentioned above as distinguishing them from other species, but in a vast number of small and unim portant characteristics, such as we cannot imagine would have been acquired in any other way than by inheritance from some common ancestor.
This is observable in both physical and mental peculiarities. It has been repeatedly noticed by close observers that the physical differences of races are very much less in infancy and youth than in later life. The hue of the new-born babe in the colored races is much lighter than that of the adult, and in the shape of the head and the features of the face the babes of all races are strikingly alike. The racial differences only grad ually assert themselves. From the same street in Pekin we could select a full-blooded Mongolian child who would pass in Brazil for the offspring of a native Indian, and another from the same place domiciled in an Irish shanty would be taken for a son of the soil of Erin.
Every intelligent European who has become intimate with the repre sentatives of other races, be they of any clime or color, has discovered in them the same sentiments and tastes, the same emotions and passions, as in his fellow-countrymen of the like grade of culture ; wherever he wan ders, the highest type of man is ever forced to recognize, in all tribes who claim the name, his fellow-beings—men like himself, heirs of the same mental powers, brethren of the same household.
Fertility of conclusion is confirmed by the well ascertained fertility in the marriages between different races and in their offspring. This was long set up as the test of the unity of species. It was maintained that crosses between different species are uniformly barren, or at least that the offspring of such crosses are always sterile.
This position has now been abandoned. Though it holds good as a general rule, it is far from being a law of nature. Several of our domes tic animals are undoubted products of the crossing of several wild species ; for instance, the dog, the hog, and the ox. So far, however, as the rule goes, it is in favor of the unity of the human species. All its varieties blend in fertile unions, and produce offspring who in their turn are as fer tile as were their parents, when living under equally favorable conditions. The examples which from time to time have been brought forward to support the contrary -view have, on investigation, turned out to be errors of observation.
Parallelism of theory of unity is also supported by another line of facts whose correct appreciation is of the highest importance, not only to ethnology, but to the history of civilization ; and this is, the parallelism which prevails in the industrial and ethical development of the human race in all ages and in all parts of the globe. Turn where we will in history or in geography, we find nations of the same grade of culture, no matter of what race, presenting the most extra ordinary coincidences, not merely in their arts, customs, laws, and social arrangements, but even in the toys of their children, their purely imag inary tales of their gods, their religions symbols, their folk-lore, and the stories they invent for mere amusement. There are yet some authors who strive to explain these coincidences by the hypothesis of historic trans mission. When they find, for instance, as is the case, the story of " The House that Jack Built" in Europe, India, Caffir-Land, and Brazil, told in an original version by the natives of each land, they maintain that it must have descended from some remote period when the ancestors of these widely-dispersed tribes were in geographical relations. But this and the hundreds of instances of a similar kind which have been collected by writers are to be attributed to that oneness of mental nature which more than anything else proves that man is of one blood, and in his psycholog ical processes is everywhere the same.