The Racial Heredity of the Negro.--It is generally agreed by anthropologists and biologists that mankind constitutes but a single species, developed from a single pre-human anthropoid stock. The various races of mankind have had, therefore, a common origin, but having developed in different geographical areas they each present certain peculiar racial traits adapting each to the environment in which it was developed. Now, the negro race is that part of mankind which was developed in the tropics. In all the negro's physical and mental make-up he shows complete adaptation to a tropical environment. The dark color of his skin, for example, was developed by natural selection to exclude the injurious actinic rays of the sun. The various ways in which the negro's tropical environment influenced the development of his mind, particularly of his instincts, cannot be here entered into in detail. Suffice to say that the African environment of the ancestors of the present negroes in the United States deeply stamped itself upon the mental traits and tendencies of the race. For example, the tropical environment is generally unfavorable to severe bodily labor. Persons who work hard in the tropics are, in other words, apt to be eliminated by natural selection. On the other hand, nature furnishes a bountiful supply of food without much labor. Hence, the tropical environment of the negro failed to develop in him any instinct to work, but favored the survival of those naturally shiftless and lazy. Again, the extremely high death rate in Africa necessitated a correspondingly high birth rate in order that any race living there might survive; hence, nature fixed in the negro strong sexual propensities in order to secure such a high birth rate. It is not claimed that the shiftlessness and sensuality of the masses of the American negroes to-day can be wholly attributed to hereditary influences, but it would be a great mistake to suppose that the African environment did not have something to do with these two dominant characteristics of the present American negro. So we might go through the whole list of the conspicuous traits and tendencies of the American negro, and in practically every case we would find good reason for believing that these racial traits and tendencies are at least in part instinctive, that is, due to the influence of racial heredity.