MONOGENISTS, the term applied to those anthropologists who claim that all mankind is descended from one original stock (μόνος single, and γένος, race), and generally from a single pair; while polygenists (πολύς, many) contend that man has had many original ancestors. Of the older school of scientific monogenists J. F. Blumenbach and J. C. Prichard are eminent representatives, as is A. de Quatrefages of the more modern. The great problem of the monogenist theory is to explain by what course of variation races of man so different have sprung from a single stock. In ancient times little difficulty was felt in this, authorities such as Aristotle and Vitruvius seeing in climate and circumstance the natural cause of racial differences, the Ethiopian having been blackened by the tropical sun, &c. Later and closer observations, however, have shown such influences to be, at any rate, far slighter in amount and slower in operation than was supposed. M. de Quatrefages brings forward (Unité de l’espèce humaine, Paris, 1861, ch. 13) his strongest arguments for the variability of races under change of climate, &c. (action du milieu), instancing the asserted alteration in complexion, constitution, and character of negroes in America, and Englishmen in America and Australia. But although the reality of some such modification is not disputed, especially as to stature and constitution, its amount is not enough to countervail the remarkable permanence of type displayed by races ages after they have been transported to climates extremely different from that of their former homes. Moreover, physically different races, such as the Bushmen and the pure negroid types in Africa, show no signs of approximation under the influence of the same climate: on the other hand, the coast tribes of Tierra del Fuego and forest tribes of tropical Brazil continue to resemble each other, in spite of extreme differences of climate and food. Darwin, than whom no naturalist could be more competent to appraise the variation of a species, is moderate in his estimation of the changes produced on races of man by climate and mode of life within the range of history (Descent of Man, pt. i. chs. 4 and 7). The slightness and slowness of variation in human races having been acknowledged, a great difficulty of the monogenist theory was seen to lie in the shortness of the chronology with which it was formerly associated. Inasmuch as several well-marked races of mankind, such as the Egyptian, Phoenician and Ethiopian, were much the same three or four thousand years ago as now, their variation from a single stock in the course of any like period could hardly be accounted for except by a miracle. This difficulty was escaped by the polygenist theory (see Georges Pouchet, Plurality of the Human Race, 1858, 2nd ed., 1864, Introd.). Two modern views have, however, intervened which have tended to restore, though under a new aspect, the doctrine of a single human stock. One has been the recognition of the fact that man has existed during a vast period of time, which has made it easier to assume the continuance of very slow natural variation of races. The other view is that of the evolution or development of species. It does not follow necessarily from a theory of evolution of species that mankind must have descended from a single stock, for the hypothesis of development admits of the argument that several simian species may have culminated in several races of man (Vogt, Lectures on Man, London, 1864, p. 463). The general tendency of the development theory, however, is against constituting separate species where the differences are moderate enough to be accounted for as due to variation from a single type. Darwin’s summing up of the evidence as to unity of type throughout the races of mankind is as distinctly a monogenist argument as those of Blumenbach, Prichard or Quartefages:—
“Although the existing races of man differ in many respects, as in colour, hair, shape of skull, proportions of the body, &c., yet if their whole organization be taken into consideration they are found to resemble each other closely in a multitude of points. Many of these are so unimportant, or of so singular a nature, that it is extremely improbable that they should have been independently acquired by aboriginally distinct species or races. The same remark holds good with equal or greater force with respect to the numerous points of mental similarity between the most distinct races of man. . . . Now when naturalists observe a close agreement in numerous small details of habits, tastes and dispositions, between two or more domestic races, or between nearly allied natural forms, they use this fact as an argument that all are descended from a common progenitor who was thus endowed, and, consequently, that all should be classed under the same species. The same argument may be applied with much force to the races of man.” (Descent of Man, pt. i. ch. 7.)
A suggestion by A. R. Wallace has great importance in the application of the development theory to the origin of the various races of man; it is aimed to meet the main difficulty of the monogenist school, how races which have remained comparatively fixed in type during the long period of history, such as the white man and the negro, should have, in even a far longer period, passed by variation from a common original. Wallace’s view is substantially that the remotely ancient representatives of the human race, being as yet animals too low in mind to have developed those arts of maintenance and social ordinances by which man holds his own against influences from climate and circumstance, were in their then wild state much more plastic than now to external nature; so that “natural selection” and other causes met with but feeble resistance in forming the permanent varieties or races of man, whose complexion and structure still remain fixed in their descendants (Contributions to the Theory of Natural Selection, p. 319).