This points to a further limiting consideration: that it is dangerous to argue from a fraction of culture history to the whole. Particularly dangerous is it to infer from the last four centuries to all that went before. In the present era distant communications have become infinitely more numerous and rapid. Space has in one sense been almost abolished. Diffusions that now encircle the planet in a hundred years would in previous ages often have required a thousand to cross a continent by halting steps from people to people.
Similarly, the results of the diffusion principle may be vitiated by an arbitrary bounding of the spatial field of investigation. A review of African distributions by themselves, for instance, would lead to many misleading conclusions, because it is obvious that African culture has evolved not integrally but as a part of the larger complex Europe-Asia-Africa. What from the angle of Africa thus appears central, like iron, may really be peripheral; what appears marginal, like Islam, is often actually central. By comparison America is so discrete from the Old World, both geographically and historically, that an analogous attempt is far more justifiable. Yet even here, as will appear, some influences from the Old World have operated, whose a priori elimination would lead to false conclusions.
As regards what is high and low, whole cultures as well as culture elements must be considered. Between two civilizations, it is fair to assume that the more advanced will normally radiate, the retarded one absorb. It is known that the drift of diffusion was from western Asia to Greece in 800 B.C., from Greece to western Asia in 300 B.C. In the case of a still unexplained trait common to the two areas and limited to them, the presumption of origin would thus lie in one or the other tract according to whether its appearance fell in the period of Asiatic or Greek culture domination. So in America, loom weaving is shared by Mexicans and Pueblos. If nothing else were known of them except that the former but not the latter had passed from oral tradition to visible records, there would be justification for belief in the probability of importation of the loom from Mexico into the adjacent Southwest. Since this one item of Mexican superiority is reinforced by the facts that the Mexicans cultivated a dozen plants to the Pueblos’ three; that they were expert in several metallurgical processes and the Pueblos at best, and rarely, hammered native copper; that the Mexicans alone carried on elaborate astronomical observations, computed with large figures, and had established an intercommunal dominion, the probability of their priority in loom weaving becomes so strong as to serve as a fairly reliable working basis. Still, it is important to remember that in the absence of the direct testimony of history or archæology such a probability does not become a certainty. The Greeks were without writing, metal working, successful astronomy, or empire while these already flourished in Egypt and Asia and were later carried to Greece. Yet in this general period the Greeks developed metrical poetry and vowel signs for the alphabet.
Another limitation to the regularity of the diffusion process is to be found in the inability or unreadiness of undeveloped culture to accept specialized products of more advanced civilizations; and of any culture to accept traits incompatible with its existing customs, except on severe or long continued pressure. A backward tribe might adopt a simple iron-working technique quite avidly, yet find the manufacture of sewing machines beyond its endeavors and wants. Among a people owning little property and no money and therefore not in the habit of counting, and indifferent to their ages or the lapse of time as expressed in numbers of years and days, a calendar system like that of the Babylonians or Mayas would certainly not become established merely because of contact. They might adopt and make use of the knowledge that there are some twelve moons in the round of the seasons, and that the solstices furnish convenient starting points for the count within each year. But generations and centuries of gradual preparation through acceptance of such elementary fragments of the elaborate calendrical scheme would ordinarily precede their ability to take the latter over in completeness. So with a religion like Christianity or Buddhism carried by a lone missionary, or shipwrecked sailors, to a people as simple in their life as the Indians of California. The religion would be too abstract, too remote, too dependent on unintelligible preconceptions, to be embraced. A particular Christian or Buddhist trait, say a symbol like the swastika or cross, might conceivably be taken over and perpetuated as a decorative motive or as a magical charm. True, if the missionary came in the company of troops and settlers, and introduced cattle, regular meals, comfortable clothing, intertribal peace, new occupations and diversions, the old simple culture would often crumble rapidly, and the higher religion be adopted as part of the larger change, as indeed happened in California when the Franciscans entered it. But one would not argue from the convertibility of the Indians under such circumstances to their equal readiness to accept Buddhism from sporadic East Asiatic castaways.
172. Cultural Abnormalities
Now and then a condition of cultural pathology must be discounted. About 1889 a messianic religious movement known as the Ghost-dance fired half the Indian tribes of the United States for a few years. In 1891 this had a wider diffusion than any ancient cult. It represented something struck from the contact of two culture systems: it was not of pure native evolution. A point had been reached where the old cultures felt themselves suffocated by the wave of Caucasian immigration and civilization. And in a last despairing delirium they flung forth the delusion of an impending cataclysm that would wipe out the white man with his labor, penalties, and restrictions, bring back the extinct buffalo, and restore the old untrammeled life. Such a cult could not of course have remained permanently active. If analogous excitements occurred in the prehistoric period, they died away without a trace and may therefore be disregarded in a view of long perspective. Or at most they served as ferments productive of other and more stable culture growths. Even if all knowledge of American religion were blotted out except its condition in 1891, the careful investigator would stand in no serious danger of inferring a high antiquity from the broad extent of the Ghost-dance cult, because of the conspicuous elements which it purloined from that very Christianity and Occidental civilization whose encroachments gave it birth.
173. Environmental Considerations
Two other qualifications on the distribution method must be observed, although they are sufficiently obvious to carry no great danger of oversight. The first concerns gaps or bounds due to physical environment. Metallurgy will not be practised on an isolated coral island. Snowshoes cannot be expected in equatorial lowlands. The spread of the cultivation of a tropical plant like manioc is necessarily restricted no matter how great the antiquity of its use. Limitations of diffusion, or breaks in the continuity of distribution, thus do not count as negative evidence if climate or soil suffice to explain them. This is in accord with what has been previously formulated (§ [83]) as to environment being a limiting condition rather than a cause of cultural phenomena.
Secondly, a marginal area need not be literally so. It may actually be nuclear. Thus in the Philippines, older elements of culture are best preserved in the interiors of the larger islands. The coasts show many more imported traits. Communication in the archipelago is by sea, internally as well as in foreign relations; resistance to travel, conquest, intercourse, or innovation is by land. The remote area as regards time may therefore be a mountain range fifty miles inland, while a coast a thousand miles away is near. So a rough hill tract in a level territory, a desert encircled by fertile lands, sometimes remain backward because they oppose the same obstacles to diffusion as great distances.
It is thus evident that valuable as the distribution principle is, perhaps most important of all non-excavating methods of prehistoric investigation, it can never be used mechanically. It must be applied with common sense, and with open-mindedness toward all other techniques of attack. With these provisos in mind, let us approach the problem of American culture.