108. Bronze
A striking case of independent development is offered by the history of bronze. Bronze is copper alloyed with five to twenty per cent of tin. The metals form a compound with properties different from those of the two constituents. Tin is a soft metal, yet bronze is harder than copper, and therefore superior for tools. Also, it melts at a lower temperature and expands in solidifying from the molten condition, and thus is better material for castings.
In the eastern hemisphere bronze was discovered early and used widely. For nearly two thousand years it was the metal par excellence of the more advanced nations. A Bronze Age, beginning about 4,000 B.C., more or less simultaneously with the first phonetic writing, is recognized as one of the great divisions of cultural time (§ [66], [225]).
In the western hemisphere bronze was apparently invented later than in the eastern and spread less extensively. It was discovered in or near the Bolivian highland, which is rich in tin (§ [196]). From there its use diffused to the Peruvian highland, then to the coast, then north to about Ecuador, and finally, perhaps by maritime contacts, to Mexico, where local deposits of tin were probably made use of after their value was realized.
Theoretically, it might be queried whether knowledge of bronze had possibly been carried to the Andes from the eastern hemisphere by some now forgotten migration or culture transmission. Against such a supposition there stands out first of all the isolated and restricted distribution of the South American bronze art. It is ten thousand miles by land from the metal-working nations of Asia to the middle Andes. A people or culture wave that had traveled so far could not but have left traces of its course by the way. The utilitarian superiority of bronze over stone tools is so great that no people that had once learned the art would be likely to give it up. Even if here and there a group of tribes had retrograded, it cannot be imagined that all the nations between China and Peru could have slipped back so decisively. Certainly peoples like the Mayas and Chibchas, expert metallurgists, would never have abandoned bronze-making.
The theory of a Chinese junk swept out of its course and washed on a South American shore might be invoked. But the original South American bronze culture occupies an inland mountain area. Further, while Asiatic ships have repeatedly been wrecked on the Pacific coast of North America and probably at times also on that of South America, there is everything to indicate that the civilizational effects of such accidents were practically nil. The highest cultures of Mexico and South America were evolved in interior mountain valleys or plateaus. Not one of the great accomplishments of the American race—architecture, sculpture, mathematics, metallurgy—shows any specific localization on the shore of the Pacific.
Further, it is hard to understand how the arrival of a handful of helpless strangers could initiate an enduring culture growth. It is easy enough for us, looking backward through the vista of history, to fancy the lonely Indians standing on the shore to welcome the strangers from the west, and then going with docility to school to learn their superior accomplishments. Actually, however, people normally do not feel or act in this way. Nations are instinctively imbued with a feeling of superiority. They look down upon the foreigner. Even where they admit his skill in this matter or that, they envy rather than admire him. Thus, there is historic record of Oriental and European vessels being wrecked on the Pacific coast of North America, during the last century and a half, among tribes that were still almost wholly aboriginal. In no case did the natives make any attempt to absorb the higher culture of the strangers. Generally these were enslaved or killed, their property rifled; sometimes the wreck was set on fire. The greed for immediate gain of the treasures in sight proved stronger than any dim impulses toward self-improvement by learning.
As one conservative author has put it, occasional visits of Asiatics or Pacific islanders to the shores of America would be, from the point of view of the growth of the vast mass of culture in that continent, “mere incidents.” From the review given below, in Chapter [XIII], it is clear that the main determinants of American culture accumulation, after the first primitive start, were internal; and the case seems as clear for metal working as for any phase.