According to Mr. Darwin, racial differences are due to the different standards of beauty, whereas, according to the theory here indicated, the different standards of beauty are due to racial differences. “Let us suppose,” says Mr. Darwin, “the members of a tribe, practising some form of marriage, to spread over an unoccupied continent, they would soon split up into distinct hordes, separated from each other by various barriers, and still more effectually by the incessant wars between all barbarous nations. The hordes would thus be exposed to slightly different conditions and habits of life, and would sooner or later come to differ in some small degree. As soon as this occurred, each isolated tribe would form for itself a slightly different standard of beauty; and then unconscious selection would come into action through the more powerful and leading men preferring certain women to others. Thus the differences between the tribes, at first very slight, would gradually and inevitably be more or less increased.”[1622] This theory—that racial differences are due to sexual selection—obviously presupposes either that the human organism is alike well fitted to any climate and natural conditions; or that no correlation exists between the visible parts of the body and its functions. Otherwise, of course, little effect could be produced through the preference given to certain individuals; for in a savage state, where celibacy is an exception, those men and women whose constitution was best suited to the conditions of life would, in any case, in the end, determine the racial type. It is also difficult to see how those slight variations from the original human type, which, according to Mr. Darwin, characterized the distinct hordes or tribes into which mankind was split up, could have developed into such enormous differences as we find in the colour of the skin of, for example, a negro and a European—only through the selection of the best representatives of these tribal peculiarities, these slight variations. Finally, it seems doubtful whether Mr. Darwin would have ascribed racial differences in colour to the influence of sexual selection, had he considered the important fact, already mentioned, that the larger apes have the same colour of the skin as the human races living in the same country.