In a previous chapter ([VII]) it has been shown that culture cannot be adequately explained either by the innate peculiarities of racial stocks nor by the influences of geographic environment; that the factors to be primarily considered in the interpretation of civilization are cultural or social ones.
In a subsequent chapter ([VIII]) it was made clear that civilization is to a great extent the result of accretion. New elements are handed down in time or passed along in space by a process which psychologically is one of imitation and in its cultural manifestations is spoken of as tradition or diffusion. The chapters on the arch and the week, and the alphabet ([X], [XI]) serve as exemplifications that the principle holds with equal validity in the domains of mechanical, institutional, and intellectual activity. It must be accepted therefore purely as the consequence of an objective or behavioristic examination of human civilization, that while the element of invention or creative progress remains unexplained, the factor of diffusion or imitation is the one that is operative in the majority of cultural events. As contrasted with it, instances of the principle of independent origin or parallel development prove to be decidedly rare, and tend to be illusory on searching analysis or to dissolve into only partial similarities.
In the analysis of the growth of religion in native California (Chapter [XII]), the attempt was made to apply an assumption derived from the diffusion principle—the assumption that normally the more widely spread element would be the more ancient—to the unraveling of the growth of a civilization which on account of its poverty has left no chronological records; in short, to reconstruct the tentative history of a field lacking ordinary historical data, by converting elements of space into elements of time.
It may now be worth while to apply this method on a larger scale and endeavor to outline the pre-Columbian history of the western hemisphere, which, with some brief and late exceptions in Mexico and Peru, is equally dateless. The cultural connections of native America with the Old World are generally conceded to have been slight: its civilization represents the most important one that in the main developed independently of the Eur-Asiatic nexus.
170. Limitations on the Diffusion Principle
To essay, by the mere principle of converting spatial extent into temporal duration, an accomplishment of such magnitude and ultimately of such complexity as this, may seem simplistic; and it would be. The distribution principle may be the most useful of the weapons in the ethnologist’s armory. But it requires supplement and qualification.
Fig. 33. Schematic illustration of distributions of culture traits as indicative of their history. A, distribution corresponding to one by accident, and suggesting that each occurrence is independent of the others. B, distribution by contiguous occurrences, strongly suggesting a single invention and subsequent diffusion. C, distribution interpretable as due either to independent, parallel origins; or to a single origin, diffusion over the whole area, and subsequent loss of the trait in most parts, with survival only in marginal tracts. The loss in the central area might be due to the growth of a supplanting trait, whose later diffusion had not yet penetrated to the farthest ends. D, distribution suggesting a single origin old enough for its diffusion to have become extensive, but checked in certain directions by adverse conditions in nature, communications, or cultural preoccupation. The specific demonstration of such adverse factors would substantiate the interpretation.