Carroll Quigley - The Evolution of Civilizations

But the domestication of animals and, later, the use of metals were not excluded. In the period before 3000 B.C., both of these diffused from the Highland Zone to the flat-lands of Arabia and of the trans-Caspian steppes. Thus, at the dawn of history the peoples of those areas had made the shift from Stone Age hunting peoples to Bronze Age pastoral peoples, while retaining and even intensifying their warlike, patriarchal social system. And, naturally, their linguistic and physical characteristics remained as before.

In order to explain these linguistic and physical characteristics of the three-zoned sandwich of western Asia, we must go much more deeply into the prehistory of the peoples involved. This will require some speculations about the origins of these peoples before they arrived in their respective areas of western Asia. In order to handle these problems, we must have a chronological system that will permit us to organize the population movements that brought these peoples to the places they occupied at the dawn of history. Such a chronology can be established in terms of climate changes.

Once again we must begin with the better-known present and work backward into the less-known past. On the oversimplified picture of the Northwest Quadrant as a three-zoned geographic pattern, we should like to superimpose an equally simplified climate picture of a six-zoned pattern. This pattern is most clear on the western, oceanic border of the Northwest Quadrant, and is modified considerably farther east by the influence of high altitudes and continental land masses. From north to south the six zones are:

1. arctic

2. cyclonic rainfall

3. Mediterranean

4. desert

5. subequatorial

6. equatorial (or tropical)

The nature of these six zones is well known, but the influences that they have exercised throughout history on the matrix of civilizations is not generally recognized. The arctic, or polar, climate is one of almost permanent frost. South of it the zone of cyclonic storms has adequate rainfall, coming from the west and equally distributed throughout the year. The third zone with Mediterranean climate and the fifth zone with subequatorial climate are both transition zones and have rain in half of the year and drought in the other half. They have the significant difference that the Mediterranean zone gets rainfall in the winter with drought in the summer, while the subequatorial has the opposite experience with rain during the summer and drought in the winter. The fourth zone between these two is a region of permanent desert, while the sixth, or southernmost, zone of tropical climate has excessive rainfall throughout the year.

The zone of equatorial rainfall is the area of low atmospheric pressure directly below the vertical rays of the sun. Because of the seasonal tipping of the earth on its axis, this area of vertical rays and of rainfall moves northward as far as the Tropic of Cancer in June and southward as far as the Tropic of Capricorn in December. It is this northward extension of the tropical area that creates the subequatorial zone of summer rains in latitudes otherwise desert. The northern belt of adequate rainfall, associated with the eastward moving cyclonic storms, also moves northward and southward with the sun, forcing the arctic zone northward in the summer and forcing the desert zone southward in the winter. This desert zone, holding a position between the cyclonic-rainfall zone of the north and the equatorial-rainfall zone of the south, is the area that is never reached by either of these rainy belts, while its northern and southern edges are reached by one or the other, in opposite seasons of the year, to create the two transition zones (Mediterranean and subequatorial) that we have mentioned.

Since the rainfall of the Northwest Quadrant comes generally from the Atlantic in the west, the eastern portions of the quadrant have much less moisture even in the cyclonic and equatorial zones, and it is frequently quite inadequate in the two transition zones between these. This really means that the desert zone in the middle widens considerably as it stretches eastward and that the eastern portions of both the Southern Flatlands (Arabia) and the Northern Flatlands (Kirghiz Steppe) are generally desert.

The seasonal changes with which we are familiar are caused by the annual tipping of the earth on its axis. As a result of this, the arctic and cyclonic-rainfall zones move southward and then return northward, giving us winter followed by summer conditions in the Northern Hemisphere. For reasons we do not yet understand, this movement southward of the first two zones was greatly exaggerated and long maintained on four separate occasions during the last 900,000 years. By "greatly exaggerated" we mean that arctic conditions extended southward as far as the Highland Zone, while the cyclonic storms followed tracks across the Southern Flatlands over what is today the Sahara Desert. By "long maintained" we mean that these exaggerated winter conditions continued for tens of thousands of years, probably for as long as 75,000 years at a time. These periods of extreme cold are known as the glacial ages.

There have been four of these glacial ages of Europe in the vicinity of the Alps, although probably fewer in some other areas. In southern Germany, where they have been most studied, the four glaciers have been given Alpine names: Gunz, Mindel, Riss, and Wurm. These names are sometimes applied to the glacial periods in other areas, although it will be just as convenient to speak of them by numbers from one to four. The periods between the glaciers, when there were temperate or even semitropical conditions in Europe, are called interglacial periods and are also numbered. The period in which we live, following the fourth glacier, is known as the postglacial period, or, more technically, as the Holocene. If we were to assume that a fifth glacial period might occur in the future, it would probably be more accurate to call the Holocene, in which we live, the fourth interglacial period.

Each glacial period lasted for about 75,000 years. The interglacial periods were not of uniform length, the first and third lasting for about 150,000 years, while the second, or "Great Interglacial," lasted almost twice as long. If we add together the lengths of the four glacials, the three interglacials, and the postglacial, we obtain a total of about 920,000 years. This period of something less than a million years happens also to be the period in which man in a biological form somewhat like our own has been on this earth. The whole million-year epoch is called the Quaternary Age, while the major portion of it, during which the glaciers were advancing and retreating, is known as the Pleistocene.

During the glacial periods when Europe was under arctic conditions and the Sahara was under pluvial conditions, the former was an undesirable place for human residence, while the latter was well adapted to man. In the interglacial periods when the pluvial zone had moved northward and the Sahara had become desert, Europe was a desirable place for human habitation, while the African flatlands became almost uninhabitable. For this reason, the pluvial and interpluvial periods of African history are even more significant than the contemporary glacial and interglacial periods of European history. In effect, man followed the pluvial zone north into Europe and south into Africa four times during the Pleistocene era. Of course, the movement of people was considerably less than this implies. In reality, relatively few persons followed the rain belt north and south, and these moved so slowly that they were probably unaware that they were moving. As Africa became drier with the approach of an interglacial period, the grass became scantier and grasseating game animals fewer. The human population, which had increased substantially there in the preceding, more lush, pluvial period, dwindled in numbers and moved both northward and southward in search of more adequate hunting grounds. The majority, unsuccessful in this search, perished, either from lack of food or in combat with other tribesmen for control of the diminishing hunting grounds. Those who moved south mostly died in an effort to deal with the inhospitable tropical jungles. Those who moved northward had a similar fate along the southern shores of the Mediterranean seas, except for the comparatively small number who could find a way northward across Sinai and the Levant to the Highland Zone and the Northern Flatlands beyond. It has been suggested that the glacial age tied up so much water in the form of ice on the northern land sur faces that the level of the ocean fell sufficiently to create land bridges between Europe and Africa at Gibraltar and Sicily.