When Linnaeus in pre-Darwinian days distinguished four varieties of man, the white European, the red American, the yellow Asiatic, and the black African, he did not dream of providing the basis of anything more than an artificial classification.  He probably would have agreed with Buffon in saying that in every case it was one and the same kind of man, only dyed differently by the different climates.  But the Darwinian is searching for a natural classification.  He wants to distinguish men according to their actual descent.  Now race and descent mean for him the same thing.  Hence a race-mark, if one is to be found, must stand for, by co-existing with, the whole mass of properties that form the inheritance.  Can colour serve for a race-mark in this profound sense?  That is the only question here.

First of all, what is the use of being coloured one way or the other?  Does it make any difference?  Is it something, like the heart-line of the hand, that may go along with useful qualities, but in itself seems to be a meaningless accident?  Well, as some unfortunate people will be able to tell you, colour is still a formidable handicap in the struggle for existence.  Not to consider the colour-prejudice in other aspects, there is no gainsaying the part it plays in sexual selection at this hour.  The lower animals appear to be guided in the choice of a mate by externals of a striking and obvious sort.  And men and women to this day marry more with their eyes than with their heads.

The coloration of man, however, though it may have come to subserve the purposes of mating, does not seem in its origin to have been like the bright coloration of the male bird.  It was not something wholly useless save as a means of sexual attraction, though in such a capacity useful because a mark of vital vigour.  Colour almost certainly developed in strict relation to climate.  Right away in the back ages we must place what Bagehot has called the race-making epoch, when the chief bodily differences, including differences of colour, arose amongst men.  In those days, we may suppose, natural selection acted largely on the body, because mind had not yet become the prime condition of survival.  The rest is a question of pre-historic geography.  Within the tropics, the habitat of the man-like apes, and presumably of the earliest men, a black skin protects against sunlight.  A white skin, on the other hand—­though this is more doubtful—­perhaps economizes sun-heat in colder latitudes.  Brown, yellow and the so-called red are intermediate tints suitable to intermediate regions.  It is not hard to plot out in the pre-historic map of the world geographical provinces, or “areas of characterization,” where races of different shades corresponding to differences in the climate might develop, in an isolation more or less complete, such as must tend to reinforce the process of differentiation.