Lastly, in regard to the American nations, it is sufficient to remark, that the appel lation " red men," is by no means charac teristic of them as a whole ; for not only are tribes elsewhere found at least equally deserving of it, but it is not applicable to a large proportion of the population of the New Continent. For although some of the North-American Indians are copper-coloured, some are as fair as many Europeans ; others are of a brown or yellow complexion ; and others nearly, if not quite, as black as African Negroes. Similar diversities exist among the aborigines of South America. Here, also, therefore, we should be forced into the sup position of a large number of primitive stocks in near vicinity to each other, were so much authority to be attributed to colour, as to allow it to rank as a sufficiently distinctive character for the specific discrimination of any of the races of mankind.
We have now to examine if the peculiari ties of colour seen among different races can be attributed with any considerable degree of probability to external agencies ; and the evi dence bearing on this question may he con sidered under two heads, namely (1.) the constancy of the relation between the habitual operation of particular climatic influences and particular shades of complexion ; and (2.) the historical evidence of an actual change of complexion, in races or tribes that are known to have migrated from one locality to an other of a different character, or to have changed their mode of life.
Now, the general relation between climate and complexion is apparent on the most cur sory survey of the facts. It is only in the intertropical regions, and in the countries bordering on them, that we meet with the greatest depth of colour in the skin ; and all the nations inhabiting the level parts of those regions exhibit a tendency towards a very dark hue. On the other hand, the colder temperate regions are the residence of the fair races. And the intermediate coun tries exhibit the transition from one com plexion to the other, as we see on passing from Central Africa, through Northern Africa and Southern Europe, to Northern Eu rope. Now this, if we had no evidence to the contrary, might fairly be held to indicate that each race had been created with especial reference to a particular cli mate; the principal difficulty in the way of such a supposition, being the great number of different races whose separate origins it would be necessary to assume, if it he held that each has uniformly exhibited the complexion which it now possesses. But it is most re markable that elevation above the sea-level is found to have the same uniform relation to the human complexion, that it has to vege tation. For as we find the plants of temperate
or even arctic regions on the sides of inter tropical mountains, so do we notice that high mountains and table-lands of great elevation are almost uniformly inhabited by people of lighter hue than those of the surrounding country, however close may be their affinity; whilst low and level countries, especially those which border on the sea, are as com monly tenanted by people of an unusually dark colour. Thus the deepest hue among the African races is to be found among the negroes of the swampy plains of the Guinea coast ; yet there are several instances, in which nations residing at no great distance from these, but at a higher level, are compa ratively light, although their ancestry is un doubtedly the same. In Northern India, again, the lightness of complexion among the inhabitants of the mountains and table-lands is almost exactly in accordance with the elevation at which the tribe has been accus tomed to dwell ; and some of these present complexions of almost European fairness. On the other hand, among the tribes that wander along the shores of the Icy Sea, their proximity to the ocean, together with their habitual exposure, seem to compensate in some degree for their distance from the equator ; so that their hue is much swarthier than that of the more civilised inhabitants of Northern Europe. The influence of seclu sion from exposure, in lightening the hue of the skin among the higher castes of various tropical races, has been already remarked upon ; and another indication of the import ance of this influence is derived from the concurrent though independent observations of M. D'Orbigny and Sir R. Schomburgh upon the people of the New World, both having remarked that those tribes which live under the damp shade of dense and lofty forests, are much fairer than those which are freely exposed to solar light and heat in dry and open spaces. The influence of continued exposure to the solar rays is often strongly marked in individuals of the lighter races ; those who are naturally of a "brunette" complexion becoming swarthy, whilst in those who are naturally fair or " blonde," there is a tendency either to a general reddening or "tanning" of the skin, or to the development of " freckles," which are nothing else than local collections of pigmentary matter, usually of a reddish-yellow colour. In such cases, the parts of the body which are habitually kept covered retain their original fairness.