The human species

by A. de Quatrefages

Thus, without quitting morphological considerations, which correspond to the idea of resemblance contained in the definition of species, we are justified in concluding in favour of monogenism. To confirm this conclusion, however, we must turn our attention to other facts which correspond to the idea of filiation, and consider the teachings of physiology concerning the phenomena of generation.

CHAPTER VII.
CROSSING OF RACES AND SPECIES IN THE ANIMAL AND VEGETABLE KINGDOMS.—MONGRELS AND HYBRIDS.

I. Sexual unions in plants, as in animals, can take place between individuals of the same species and the same race; further, between different races of the same species, and, finally, between different species. In the two latter cases we have what is called a cross. This crossing itself is differently named according to whether it takes place between different races or different species. In the first case it produces a mongrel, in the second a hybrid. When the cross-unions are fertile the product of the union of mongrels is called a mongrel, the product of the union of hybrids a hybrid.

If the difference of the relations existing between the race and the species has been properly understood, we ought to be inclined to admit that mongrels and hybrids would not present the same phenomena; experience and observation confirm this presentiment.

We have, therefore, in this crossing a means of judging whether the human groups are only races of a single species, or rather distinct species. For this purpose it will be sufficient to study the phenomena which, in other organised and living beings, accompany the production of mongrels and hybrids, and then to compare with both the phenomena which characterise the crosses effected between human groups. If, in the latter case, the phenomena are those which characterise hybridism, we must conclude that the groups are specifically distinct, and admit the multiplicity of human species. If, however, crosses between human groups, morphologically different, are accompanied by phenomena peculiar to the production of mongrels, we shall only be justified in considering these groups as races of one species; we must take our stand upon the doctrine of the Specific Unity of all mankind.

The question before us becomes then entirely a physiological one, and depends simply upon observation and experiment. For its solution we must again turn our attention to plants as well as to animals. It is in the phenomena of reproduction that the two kingdoms show the greatest resemblance. This is not a case of mere analogy, but almost of identity, and it is not the superior which lowers itself but the inferior which is raised. We might say that, ennobled by the importance of the function, the plant, as far as its reproductive system is concerned, becomes, for the time, animal.

II. In these kingdoms the unions between races of the same species, that is to say, the production of mongrels, may be accomplished without any intervention on the part of man, or it may take place under his direction. It is consequently either natural or artificial.

Mongrels among plants could only be recognised after the discovery of the distinction of the sexes in 1744. The honour of this great discovery belongs to Linnæus. He at once comprehended the importance of the subject, and even exaggerated it, as we shall presently see. Linnæus admitted that cross-unions, which had been observed for centuries between animals, might be repeated between plants. And he thus explained the appearance of variegated tulips in the midst of borders originally formed of uniformly coloured flowers. Observation and experiment have confirmed the views of the founder of the natural sciences again and again. Moreover, it has been observed that the crossing may become apparent in all parts of the plant by a mixture of characters similar to that exhibited by the colouring of the tulips. M. Naudin, among others, who, during one year, watched the development of more than 1200 gourds, saw the seeds of a single fruit reproduce all the races contained in the garden in which his observations were made. Superfetation had taken place. It is a fact of great importance, as it demonstrates the equality of action enjoyed by the pollen of all these races, which, morphologically, differ so widely from each other. No better example could be given of the faculty of crossing between races.

The natural and spontaneous production of mongrels among animals presents the same characters. Facilitated by locomotion it is accomplished every day in our houses, our poultry-yards, and our farms. The difficulty does not consist in the accomplishment of the cross but in its prevention, and in the preservation of the purity of the race. The careful observations made by Isidore Geoffroy at the Paris Museum, have shown that with sheep, dogs, pigs, and fowls, mongrels between the most different races were invariably fertile. Here again the phenomena of superfetation was often proved. Bitches produced, by males of several races successively, young which showed three or four distinct sources. Here the case was the same as with the gourds of M. Naudin.