6. The races of man may have originated in the same manner with the breeds of our domesticated animals. There are many facts which render it probable that they did originate in this way. Take color, for instance. The fair varieties of man occur only in the northern temperate zone, and chiefly in the equable climates of that zone. In extreme climates, even when cold, dusky and yellow colors appear. The black and blackish-brown colors are confined to the inter-tropical regions, and appear in such portions of all the great races of mankind as have been long domiciled there. Diet and degree of exposure have also evidently very much to do with form, stature, and color. The deer-eating Chippewayan of certain districts of North America is a better developed man than his compatriots who subsist principally on rabbits and such meaner fare; and excess of carbonaceous food, and deficiency of perspiration or of combustion in the lungs, appear everywhere to darken the skin.[173] The Negro type in its extreme form is peculiar to low and humid river valleys of tropical Africa. In Australasia similar characters appear in men of a very different race in similar circumstances. The Mongolian type reappears in South Africa. The Esquimau is like the Fuegian. The American Indian, both of South and North America, resembles the Mongol; but in several of the middle regions of the American continent men appear who approximate to the Malay. Everywhere and in all races coarse features and deviations from the oval form of skull are observed in rude populations. Where men have sunk into a child-like simplicity, the elongated forms prevail. Where they have become carnivorous, aggressive, and actively barbarous, the brachy-kephalic forms abound. These and many other considerations tend to the conclusion that these varieties are inseparably connected with external conditions. It may still be asked--Were not the races created as they are, with especial reference to these conditions? I answer no--because the differences are of a character in every respect like those that appear in other true species as the results of influences from without.