If from Egypt we turn to the most probable source of alien culture elements found there, viz., to the region of Mesopotamia, possibly the oldest seat of higher civilization in Asia, we find again that the culture of Babylonia under the famous lawgiver Hammurabi (about 2,000 B. C.) is not the product of purely indigenous growth but represents the resultant of at least two components, that of the Sumerian civilization of southern Babylonia and the Accadian culture of the North. It is certain that the Accadians adopted the art of writing from the Sumerians and were also stimulated by this contact in their artistic development. The evolution of Sumerian civilization is lost in obscurity but on the basis of well-established historical cases we should hesitate to assign to them an exclusively creative, and to other populations an exclusively receptive, rôle. We may quite safely assume that the early splendor of Sumerian civilization was also in large part due to stimuli received through foreign relations. That cultural elements of value may be borrowed from an inferior as well as from a higher level, has already been exemplified by the case of maize. It is also, among other things, illustrated by the history of the Chinese.
The Chinese have generally been represented as developing in complete isolation from other peoples. This traditional conception, however, breaks down with more intimate knowledge. Dr. Laufer has demonstrated that Chinese civilization, too, is a complex structure due to the conflux of distinct cultural streams. As an originally inland people inhabiting the middle and lower course of the Yellow River, they gradually reached the coast and acquired the art of navigation through contact with Indo-Chinese seafarers. Acquaintance with the northern nomads of Turkish and Tungus stock led to the use of the horse, donkey and camel, as well as the practice of felt and rug weaving, possibly even to the adoption of furniture and the iron technique.[8-iv] Most important of all, it appears that essentials of agriculture, cattle-raising, metallurgy and pottery, as well as less tangible features of civilization are common to ancient China and Babylonia, which forces us to the conclusion that both the Chinese and Babylonian cultures are ramifications from a common Asiatic sub-stratum. It would be idle to speculate as to the relative contributions of each center to this ancient cultural stock. The essential point is that the most ancient Asiatic civilizations of which we have any evidence already indicate close contact of peoples and the dispersal of cultural elements.
Contact of peoples is thus an extraordinary promoter of cultural development. By the free exchange of arts and ideas among a group of formerly independent peoples, a superiority and complexity is rendered possible which without such diffusion would never have occurred. The part played in this process by the cruder populations must not be underestimated. They may contribute both actively and passively; actively, by transmitting knowledge independently acquired, as in the case of the felt technique the Chinese learned from the northern nomads; passively, by forming a lower caste on which the economic labors devolve and thus liberating their conquerors for an enlarged activity in the less utilitarian spheres of culture.
Nevertheless, before peoples can communicate their cultures to others with whom they come into contact, they must first evolve these cultures. The question thus remains, What determines this evolution? In order to gain a proper perspective in this matter, we must for a moment consider the progress of human civilization as a whole. Archæological research shows that the modern era of steel and iron tools was preceded by an age of bronze and copper implements, which in turn was preceded by a stone age subdivided into a more recent period of polished, and an earlier of merely chipped, stone tools. Now the chronological relations of these epochs are extremely suggestive. The very lowest estimate by any competent observer of the age of Palæolithic man in Europe sets it at 50,000 years;[9-iv] since this is avowedly the utmost minimum value that can be assigned on geological grounds, we may reasonably assume twice that figure for the age of human culture generally. Using the rough estimate permissible in discussions of this sort, we may regard the end of the Palæolithic era as dating back about 15,000 years ago. In short, for more than eight-tenths of its existence, the human species remained at a cultural level at best comparable with that of the Australian. We may assume that it was during this immense space of time that dispersal over the face of the globe took place and that isolation fixed the broader diversities of language and culture, over and above what may have been the persisting cultural sub-stratum common to the earliest undivided human group. The following Neolithic period of different parts of the globe terminated at different times and had not been passed at all by most of the American aborigines and the Oceanians at the time of their discovery. However, from the broader point of view here assumed, it was not relieved by the age of metallurgy until an exceedingly recent past. The earliest estimate I have seen does not put the event back farther than 6000 B. C. even in Mesopotamia. During nine-tenths of his existence, then, man was ignorant of the art of smelting copper from the ore. Finally, the iron technique does not date back 4,000 years; it took humanity ninety-six hundredths of its existence to develop this art.
We may liken the progress of mankind to that of a man a hundred years old, who dawdles through kindergarten for eighty-five years of his life, takes ten years to go through the primary grades, then rushes with lightning rapidity through grammar school, high school and college. Culture, it seems, is a matter of exceedingly slow growth until a certain ‘threshold’ is passed, when it darts forward, gathering momentum at an unexpected rate. For this peculiarity of culture as a whole, many miniature parallels exist in special subdivisions of culture history. Natural science lay dormant until Kepler, Galileo and Newton stirred it into unexampled activity, and the same holds for applied science until about a century ago.
This discontinuity of development receives strong additional illustration from a survey of special subdivisions of ancient culture. Though the Palæolithic era certainly preceded the later Stone Age, archæologists have hitherto failed to show the steps by which the later could develop out of the earlier. This gap may, of course, be due merely to our lack of knowledge. Yet when we take subdivisions of the Palæolithic period, the same fact once more confronts us. There is no orderly progression from Solutrean to Magdalenian times. The highly developed flint technique of the former dwindles away in the latter and its place is taken by what seems a spontaneous generation of bone and ivory work, with a high development of realistic art.
In view of the evidence, it seems perfect nonsense to say that early European civilization, by some law inherent in the very nature of culture, developed in the way indicated by archæological finds. Southern Scandinavia could not possibly have had a bronze age without alien influence. In this case, discontinuity was the result of cultural contact. It may be that the lack of definite direction observed throughout the Stone Age may in part be due to similar causes, the migrations and contact of different peoples, as Professor Sollas suggests. But it is important to note that discontinuity is a necessary feature of cultural progress. It does not matter whether we can determine the particular point in the series at which the significant trait was introduced. It does not matter whether, as I have suggested in the discussion of racial features, the underlying causes of the phenomena proceed with perfect continuity. Somewhere in the observed cultural effects there is the momentous innovation that leads to a definite break with the past. From a broad point of view, for example, it is immaterial whether the doctrine of evolution clings to the name of the younger or the elder Darwin, to Lamarck or St. Hilaire; the essential thing is that somehow the idea originated, and that when it had taken root it produced incalculable results in modern thought.
If culture, even when uninfluenced by foreign contact, progresses by leaps and bounds, we should naturally like to ascertain the determinants of such ‘mutations.’ In this respect, the discontinuity of indigenous evolution differs somewhat from that connected with cultural development due to diffusion. It was absolutely impossible that Scandinavia should produce bronze in the absence of tin. But a priori it is conceivable that an undisturbed culture might necessarily develop by what biologists call ‘orthogenetic evolution’, i.e., in a definite direction through definite stages. This is, indeed, what is commonly known as the classical scheme of cultural evolution, of which men like Morgan are the protagonists. Now, how do the observed facts square with this theoretical possibility?
As Professor Boas and American ethnologists generally have maintained,[10-iv] many facts are quite inconsistent with the theory of unilinear evolution. That theory can be tested very simply by comparing the sequence of events in two or more areas in which independent development has taken place. For example, has technology in Africa followed the lines ascertained for ancient Europe? We know today that it has not. Though unlike southern Scandinavia, the Dark Continent is not lacking in copper deposits, the African Stone Age was not superseded by a Copper Age, but directly by a period of Iron. Similarly, I have already pointed out that the possession of the same domesticated animals does not produce the same economic utilization of them while the Tungus rides his reindeer, other Siberians harness their animals to a sledge; the Chinaman will not milk his cattle, while the Zulu’s diet consists largely of milk. That a particular innovation occurred at a given time and place is, of course, no less the result of definite causes than any other phenomenon of the universe. But often it seems to have been caused by an accidental complex of conditions rather than in accordance with some fixed principle.
For example, the invention of the wheel revolutionized methods of transportation. Now, why did this idea develop in the Old World and never take root among the American Indians? We are here face to face with one of those ultimate data that must simply be accepted like the physicist’s fact that water expands in freezing while other substances contract. So far as we can see, the invention might have been made in America as well as not; and for all we know it would never have been made there until the end of time. This introduces a very important consideration. A given culture is, in a measure, at least, a unique phenomenon. In so far as this is true it must defy generalized treatment, and the explanation of a cultural phenomenon will consist in referring it back to the particular circumstances that preceded it. In other words, the explanation will consist in a recital of its past history; or, to put it negatively, it cannot involve the assumption of an organic law of cultural evolution that would necessarily produce the observed effect.