MIGRATION. Migrations, or the shiftings of peoples, have been universal on the earth in space and time, but there have also been migrations or transmissions of cultural objects and ideas which frequently have little relation with the former and these may be termed cultural drifts.
Most primary migrations of mankind may be traced to need of food. The practice of tilling the soil, in order to obtain a more or less reliable supply of food, by its nature tends to anchor a people to the land, and all permanence of work with a re liable food supply forms an essential condition for continuous residence in one spot ; when these fluctuate, unrest arises and in dividuals or communities are set in motion.
For the greater part of the very long time that man has been in existence he has been merely a collector of food or a hunter. Where game was plentiful or wild vegetable food abundant he could live in moderate sized communities, but normally any country would be very sparsely inhabited, therefore there would be a necessity for migration when the population grew too numer ous for the food supply. Usually the game migrate seasonally to seek fresh feeding-grounds, or for other reasons, but this movement may be merely a backward and forward shifting within a particular range and naturally the hunters would ac company them ; during the winter months the Eskimos live on the sea coast so as to be able to catch seals on which they mainly depend for food, but in the summer they shift to inland areas, where they can hunt reindeer, or, in the more northerly regions, the musk ox, and also they can then procure more varied diet. Collectors of vegetable food within their various countries have similarly to move where a particular root, seed or fruit crop is ripe. Movements of these kinds though dictated by necessity are to some extent voluntary.
Movements are compulsory when changes of climate or of geographical conditions cause a complete shifting of the flora, and fauna, as, for example, during the major and minor fluctua tions of temperature in the glacial periods of northern latitudes, northerly or southerly shiftings of the rain belts further south, desiccation, elevation or depression of land, changes in the coast line, and so forth. Man was forced to move as his food decreased or the climate became too rigorous, and the directions in which he moved were similarly conditioned, but in addition were de termined to a large extent by open land or by barriers of vari ous kinds. Human movements resulting from these causes may well have been slow, and archaeological evidence shows that even in very early times they extended over the greater part of the earth's surface. A warning may here be given that a similarity in stone implements, for example, does not necessarily imply a strict" synchronism for these artifacts in Europe, South Africa, India or Australia. The fluctuating character of many of these phenomena acted frequently as a force-pump or as a suction pump, at one time expelling a people from a given area at another attracting them towards it. It is obvious that in very early times we can have no historical record of such happenings, but archae ology gives sufficient indications that they occurred.
As examples of historical events of this nature the following may be cited, though what occurred in earlier times can only be inferred, but it is not unreasonable to suppose that they were analogous.
It is obvious that during the advent of a glacial period the increasing fields of snow and ice would drive the people who then lived in north-west Europe (and we have evidence that there were men in England in preglacial times) further south where livelihood was possible, and similarly there would be a southerly shifting of peoples who were accustomed to a genial climate. The formation of a northern ice-cap would result in a southerly shifting of the temperate rain- and storm-belts in pro portion to the advance of the ice. Thus the wide belt of northern Africa which is now the desert of Sahara would then be a well watered, habitable country of grass-land and savanna. The same applies to the arid areas of western Asia. There was, therefore, a continuous stretch of pleasant lands from Central Asia, through Persia, Arabia and north Africa to the Atlantic. When the ice retreated the storm-belt shifted further north and these areas once more became dry and thirsty lands. A recurrent phenome non of this kind must have occurred with each major glaciation. If we assume that a people long habituated to live on the fringe of the ice-cap and to hunt reindeer and other arctic animals would prefer to continue its mode of existence then it would fol low the retreating ice, and it seems as if this had been the case for the Eskimo. Magdalenian man in western Europe lived under arctic conditions and certainly the characters of the Chancelade skull of western France are very similar to those of the Eskimo of arctic North America, but it does not follow that the Eskimo ever lived in Europe. The savanna belt of north Africa and western Asia, just referred to, would afford an easy migration corridor between Asia and Africa, and when that area became uncomfortably dry a movement of population could take place to the north or south. If the people then living there were origi
nally inhabitants of a temperate region they would be more likely to drift northwards than southwards. (See the article CLIMATIC HISTORY.) According to Pettersson a period of maxima of tide-generating force attained its latest phase in A.D. 1434 and has a periodicity of about 1,800 years. In the 14th century the devastating storm floods of the North sea and the Baltic coasts resulted in cold periods and inundations in the northern countries with their consequences, famine and migrations of the population. About I ,800 years earlier similar storm-floods impoverished the people of the late Bronze age of Scandinavia, and land-elevation and de terioration of climate occurred throughout the north Atlantic. About 700 B.C. the amber trade route shifted from the Elbe and Weser to the Vistula, which indicates that the supply of amber was thenceforth chiefly derived from the Baltic instead of from the North sea, which was then in a tempestuous condition. There are statements in literature which connect the invasion of the Teutons and Cimbri into Gallia and later into Italy with a big inundation of the sea which destroyed their homesteads in Jut land. These catastrophes probably began as early as the 6th century B.C. There were also traditions amongst the Druids that their ancestors had been expelled from the islands on the other side of the Rhine by hostile tribes and by a great invasion of the ocean. Pettersson regards this as the primary cause of the great migrations in the first millennium B.C. which began with the de cline of the Bronze-age civilization through catastrophes in nature which forced the inhabitants of the North sea countries to emi grate, and he finds that a maximum of oceanic disturbances must have occurred about the 3rd and 4th century B.C., as also hap pened about A.D. 1300-1400. He adds, "Apparently a warm, ice less period, which favoured agriculture and shipping and allowed the Scandinavian races to expand in the powerful manner which characterizes the Viking age, must have occurred between the interval of the two maxima of 400 B.C. and A.D. 1400. This pros perous epoch then corresponds to the former post-glacial heat period or the Kjokken-modding—and the earliest stage of the Bronze age. The remembrance of the bygone civilization 2,000 years earlier lived in the myths of the German race and found its expression in the Edda. According to Victor Rydberg the myths of the Edda centre in a great catastrophe in nature, the Fimbul-winter, or "Gotterdammerung," when frost and snow ruled the world for generations. (0. Pettersson, Ur Svenska Hydrografisk-Biol. Kom. Skrifter, V., and cf . C. E. P. Brooks, The Evolution of Climate, p. 147, 1922; Climate through the Ages [1926] ; cf. G. C. Simpson, Q.J.R. Meteorol. Soc. liii., p. 213, 1927.) 0. Pettersson (Ur Svenska Hydrografisk-Biol. Kom. Skrifter, V.) states that in the loth and 11th centuries a strong emigration took place from Norway to Iceland and Greenland, one Viking fleet taking 75o to L000 persons to Greenland ; at this time the climate of Iceland and Greenland was comparatively mild, as there was no ice-blockage of the north coast of Iceland or round southern Greenland. At the end of the 13th century the first signs of an ice blockade appeared and at the close of the 14th century there was a great accumulation of drift ice off the east coast of Greenland. At the close of the 13th and beginning of the 14th century there began an invasion of Eskimo from the north which eventually wiped out the colonies of Norsemen. This invasion must not be regarded as a common raid, it was the migration of a people, and like other big movements of this kind was impelled by altered conditions of nature, in this case the alterations of climate caused by the advance of the ice. The Eskimo then lived further north in Greenland and North America, but when the climate deteriorated and the sea which gave them their living was closed by ice the Eskimo had to find a more suit able neighbourhood. It should, however, be noted that F. Nansen (In Northern Mists, p. 95, 1911) strongly combats the view that the Eskimo gradually overpowered and exterminated the Norsemen. The settlements were almost entirely cut off from Norway, imports of corn and flour finally ceased, stock could not be renewed, and unaccustomed dietary conditions, disease and probable decreased birth-rate in his view sufficiently account for the decline of the settlements and he asserts that this was not due to "the peaceful and unwarlike Eskimo." In any case this illustrates the difficulty of maintaining an artificial migra tion in a country where conditions are such that Europeans, who are dependent upon fresh supplies from the home country, can barely live. The climatically induced migration of the Eskimo at least reasserted the superior viability of a people long accus tomed to special local conditions.