Still more forcibly does nature herself bear witness to this antiquity of possession. Botanists declare that a very lengthy course of cultivation is required so to alter the form of a plant that it can no longer be identified with the wild species; and still more protracted must be the artificial propagation for it to lose its power of independent life, and to rely wholly on man to preserve it from extinction. Now this is precisely the condition of the maize, tobacco, cotton, quinoa, and mandioca plants, and of that species of palm called by botanists the _Gulielma speciosa_; all have been cultivated from immemorial time by the aborigines of America, and, except cotton, by no other race; all no longer are to be identified with any known wild species; several are sure to perish unless fostered by human care.[37-1] What numberless ages does this suggest? How many centuries elapsed ere man thought of cultivating Indian corn? How many more ere it had spread over nearly a hundred degrees of latitude, and lost all semblance to its original form? Who has the temerity to answer these questions? The judicious thinker will perceive in them satisfactory reasons for dropping once for all the vexed inquiry, "how America was peopled," and will smile at its imaginary solutions, whether they suggest Jews, Japanese, or, as the latest theory is, Egyptians.
While these and other considerations testify forcibly to that isolation I have already mentioned, they are almost equally positive for an extensive intercourse in very distant ages between the great families of the race, and for a prevalent unity of mental type, or perhaps they hint at a still visible oneness of descent. In their stage of culture, the maize, cotton, and tobacco could hardly have spread so widely by commerce alone. Then there are verbal similarities running through wide families of languages which, in the words of Professor Buschmann, are "calculated to fill us with bewildering amazement,"[38-1] some of which will hereafter be pointed out; and lastly, passing to the psychological constitution of the race, we may quote the words of a sharp-sighted naturalist, whose monograph on one of its tribes is unsurpassed for profound reflections: "Not only do all the primitive inhabitants of America stand on one scale of related culture, but that mental condition of all in which humanity chiefly mirrors itself, to wit, their religious and moral consciousness, this source of all other inner and outer conditions, is one with all, however diverse the natural influences under which they live."[38-2]