Below the taxonomic level of the subspecies, zoologists find a sometimes bewildering array of local racial variations of a minor nature, which exist because subspecies as well as species can be polytypic. This is as true of men as it is of mice, for man is the most mobile of mammals. He walks the land, flies the skies, and rides the oceans.
Part of the racial complexity of Homo sapiens disappears if we disregard for the moment the distribution of modern peoples like white and Negroid Americans, Latin Americans, South Africans, and white Australians and New Zealanders, whose ancestors reached their homes by ocean-going ships in recent times. Before then each of the five subspecies recognized in this book was firmly and uniquely installed in its geographical center. Between the nuclei of these five centers lie intermediate regions of two kinds.
One of them is the mosaic, which contains relict populations living as enclaves in refuge areas. For example, in India at least two forms of Australoids, classified as "tribal peoples," dwell in the hills, surrounded by Caucasoids whose home is the plains. Such a mosaic pattern is the product of earlier, but not geologically ancient, migrations that have not had time to fuse. As will be shown in the next chapter, it is typical of the tropics of the Old World. The other is a region of racial transition, a frontier-in-depth within which a subspecies grades into another through intermediate forms. It may be called a clinal zone because in it the population of the species intergrades in one or more measurable characters. In each heritable feature, the gradient is called a cline.1 For example, the living Europeans grade from a high frequency of blue eyes in the northwest, particularly in Ireland and Scandinavia, to a high frequency of brown eyes in the southeastern part of the continent. This eye-color gradient is a cline.
Whole complexes of related clines are found in clinal zones. For example, in central Asia north of the Himalayas Caucasoids merge into Mongoloids through the persons of several Turkic-speaking peoples like the Kirghiz, Uzbeks, and Turkomans. This clinal zone is a broad one. On the southern face of the Himalayan wall a similar but narrow clinal zone stretches through a steep intermediate altitude zone, in northern India, Nepal, Sikkim, Bhutan, and NEFA (Northeast Frontier Agency). As can be seen by these examples, the sharper the environmental barrier the narrower the clinal zone between subspecies.
Not only in relict enclaves and clinal zones, but also within the nuclear territories of subspecies, regional populations of minor rank may be found which differ from each other in perceptible ways short of the requirements of subspecies. These are known as local races. As they rise and disappear rapidly, they receive little attention from zoologists and usually none from paleontologists. In man they are considered important by people without a biological background, usually because such groups may be identified to a certain extent with social, political, or religious units.
How many local races could be identified and counted among living men is difficult to say, and different anthropologists might each find a different number. Such details are of no importance in this book, but it is important for us to know that local races exist and are formed by the same biological mechanisms that have fostered larger taxonomic units in the past.
Races like the Nordic, Alpine, Mediterranean, East Baltic, and Dinaric, which loom large in the Europe-centered literature of anthropology, are neither subspecies nor, in a strict sense, local races, although some local races may be defined in these terms. These words have also been used in the sense of types, which can be picked out of local populations. One may find a Spaniard who is typically Nordic in the midst of a population of Mediterraneans, including his own brothers. In a sense the situation is genetically comparable to finding a man of blood group B whose father's group was A. Types selected in this fashion are interesting to observe, and we notice them every day. Whether or not they reflect the origins of a population in one way or another, we must remember that from the taxonomic point of view such types are not races but simply the visible expressions of the genetic variability of the intermarrying groups to which they belong.
However, if we return to the first test of subspecies, geographical integrity, we are at first sight on shakier ground. Whites, Negroes, and American Indians occupy the United States sympatrically. Hindus, Fijians, and Europeans similarly occupy the Fiji Islands, and many other examples might be cited. As we study each instance, we find that this situation is a recent one, as time is measured biologically, and it is always associated with the expansion of peoples who have left the food-gathering stage of subsistence far behind.
Let us omit, for the moment, the agricultural peoples of the world and the colonists, and consider only the peoples who still are, or until recently were, food gatherers. These hunters and collectors are drawn from all five geographical races listed on page 3. Each race is confined to a single territory without overlap except in two regions: India, and southeast Asia plus Indonesia. Owing to a lack of skeletal material, we do not know when the ancestors of the various food gatherers moved into India, nor indeed which race was earliest there. In southeast Asia and Indonesia we know, as will be explained in Chapter 10, that Mongoloids began replacing Australoids about 10,000 years ago, after the invention of the bow and the domestication of the dog had made some hunters more efficient than others.
This southward movement was a trickle compared to what happened in many other places 4,000 years later. By or after 6,000 s.c. a number of local populations began to advance from the ecological niche of hunters and gatherers to that of food producers, and territorial expansions followed. These movements started no more than four hundred generations ago, counting twenty-five years to a generation. The colonial movements that brought Europeans to America, South Africa, Australia, and New Zealand took place less than twenty-five generations ago; only about twelve generations separate most descendants of passengers on the Mayflower from their celebrated forebears.
These various movements have greatly restricted the territories of aboriginal food gatherers, but gatherers are still present in reduced numbers. Many more have been absorbed into the new food-producing populations or have borrowed the techniques of food production from newcomers to their territories. Since the beginning of agriculture no new subspecies have arisen; the principal changes that have taken place have been vast increases in the numbers of some populations and decreases to the threshold of ex tinction in others. All this points to one conclusion: the living subspecies of man are ancient. The origins of races of subspecific rank go back into geological antiquity, and at least one of them is as old, by definition, as our species.