*Ordinarily it is stated that this practice was due to the
exhaustion of the soil. That, however, is open to question, for five
or ten years' desultory cultivation on the part of the Indian would
scarcely exhaust the soil so much that people would go to the great
labor of making new clearings and moving their villages. Moreover, in
the Southern States it is well known today that the soil is exhausted
much more rapidly than farther north because it contains less humus.
Nevertheless the southern tribes cultivated the land about their
villages for long periods. Tribes like the Creeks, the Cherokees, and
the Natchez appear to have been decidedly less prone to move than the
Iroquois, in spite of the relatively high development of these northern
nations.
What hindered agriculture most in the northern part of the deciduous forest was the grass. Any one who has cultivated a garden knows how rapidly the weeds grow. He also knows that there is no weed so hard to exterminate as grass. When once it gets a foothold mere hoeing seems only to make it grow the faster. The only way to get rid of grass when once it has become well established is to plow the field and start over again, but this the Indians could not do. When first a clearing was made in the midst of the forest, there was no grass to be contended with. Little by little, however, it was sure to come in, until at length what had been a garden was in a fair way to become a meadow. Then the Indians would decide that it was necessary to seek new fields.
One might suppose that under such circumstances the Indians would merely clear another patch of forest not far from the village and so continue to live in the old place. This, however, they did not do because the labor of making a clearing with stone axes and by the slow process of girdling and burning the trees was so great that it was possible only in certain favored spots where by accident the growth was less dense than usual. When once a clearing became grassy, the only thing to do was to hunt for a new site, prepare a clearing, and then move the village. This was apparently the reason why the Iroquois, although successful in other ways, failed to establish permanent towns like those of the Pueblos and the Haidas. Their advancement not only in architecture but in many of the most important elements of civilization was for this reason greatly delayed. There was little to stimulate them to improve the land to which they were attached, for they knew that soon they would have to move.
Farther south the character of the grassy vegetation changes, and the condition of agriculture alters with it. The grass ceases to have that thick, close, turfy quality which we admire so much in the fields of the north, and it begins to grow in bunches. Often a southern hillside may appear from a distance to be as densely covered with grass as a New England hayfield. On closer examination, however, the growth is seen to consist of individual bunches which can easily be pulled up, so that among the southern tribes the fields did not become filled with grass as they did in the north, for the women had relatively little difficulty in keeping out this kind of weed as well as others.
In this survey of aboriginal America we have been impressed by the contrast between two diverse aspects of the control of human activities by physical environment. We saw, in the first place, that in our own day the distribution of culture in America is more closely related to climatic energy than to any other factor, because man is now so advanced in the arts and crafts that agricultural difficulties do not impede him, except in the far north and in tropical forests. Secondly, we have found that, although all the geographical factors acted upon the Indian as they do today, the absence of metals and beasts of burden compelled man to be nomadic, and hence to remain in a low stage of civilization in many places where he now can thrive. In the days long before Columbus the distribution of civilization in the Red Man's Continent offered still a third aspect, strikingly different both from that of today and from that of the age of discovery. In that earlier period the great centers of civilization were south of their present situation. In the southern part of North America from Arizona to Florida there are abundant evidences that the Indians whom the white man found were less advanced than their predecessors. The abundant ruins of Arizona and New Mexico, their widespread distribution, and the highly artistic character of the pottery and other products of handicraft found in them seem to indicate that the ancient population was both denser and more highly cultured than that which the Europeans finally ousted. In the Gulf States there is perhaps not much evidence that there was a denser population at an earlier period, but the excellence of the pre-Columbian handicrafts and the existence of a decadent sun worship illustrate the way in which the civilization of the past was higher than that of later days. The Aztecs, who figure so largely in the history of the exploration and conquest of Mexico, were merely a warlike tribe which had been fortunate in the inheritance of a relatively high civilization from the past. So, too, the civilization found by the Spaniards at places such as Mitla, in the extreme south of Mexico, could not compare with that of which evidence is found in the ruins. Most remarkable of all is the condition of Yucatan and Guatemala. In northern Yucatan the Spaniards found a race of mild, decadent Mayas living among the relics of former grandeur. Although they used the old temples as shrines, they knew little of those who had built these temples and showed still less capacity to imitate the ancient architects. Farther south in the forested region of southern Yucatan and northern Guatemala the conditions are still more surprising, for today these regions are almost uninhabitable and are occupied by only a few sickly, degraded natives who live largely by the chase. Yet in the past this region was the scene of by far the highest culture that ever developed in America. There alone in this great continent did men develop an architecture which, not only in massiveness but in wealth of architectural detail and sculptural adornment, vies with that of early Egypt or Chaldea. There alone did the art of writing develop. Yet today in those regions the density of the forest, the prevalence of deadly fevers, the extremely enervating temperature, and the steady humidity are as hostile to civilization as are the cold of the far north and the dryness of the desert.
The only explanation of this anomaly seems to be that in the past the climatic zones of the world have at certain periods been shifted farther toward the equator than they are at present. Practically all the geographers of America now believe that within the past two or three thousand years climatic pulsations have taken place whereby places like the dry Southwest have alternately experienced centuries of greater moisture than at present and centuries as dry as today or even drier. During the moist centuries greater storminess prevailed, so that the climate was apparently better not only for agriculture but for human energy. At such times the standard of living was higher than now not only in the Southwest but in the Gulf States and in Mexico. In periods when the deserts of the southwestern United States were wet, the Maya region of Yucatan and Guatemala appears to have been relatively dry. Then the dry belt which now extends from northern Mexico to the northern tip of Yucatan apparently shifted southward. Such conditions would cause the forests of Yucatan and Guatemala to become much less dense than at present. This comparative deforestation would make agriculture easily possible where today it is out of the question. At the same time the relatively dry climate and the clearing away of the vegetation would to a large degree eliminate the malarial fevers and other diseases which are now such a terrible scourge in wet tropical countries. Then, too, the storms which at the present time give such variability to the climate of the United States would follow more southerly courses. In its stimulating qualities the climate of the home of the Mayas in the days of their prime was much more nearly like that which now prevails where civilization rises highest.
From first to last the civilization of America has been bound up with its physical environment. It matters little whether we are dealing with the red race, the black, or the white. Nor does it matter whether we deal with one part of the continent or another. Wherever we turn we can trace the influence of mountains and plains, of rocks and metals from which tools are made, of water and its finny inhabitants, of the beasts of the chase from the hare to the buffalo, of domestic animals, of the native forests, grass-lands, and deserts, and, last but not least, of temperature, moisture, and wind in their direct effects upon the human body. At one stage of human development the possibilities of agriculture may be the dominant factor in man's life in early America. At another, domestic animals may be more important, and at still another, iron or waterways or some other factor may be predominant. It is the part of the later history of the American Continent to trace the effect of these various factors and to chronicle the influence that they have had upon man's progress.
BIBLIOGRAPHICAL NOTE
Although many books deal with the physical features of the Western Hemisphere and many others with the Indians, few deal with the two in relation to one another. One book, however, stands out preeminent in this respect, namely, Edward John Payne's "History of the New World Called America," 2 vols. (1892-99). This book, which has never been finished, attempts to explain the conditions of life among the American aborigines as the result of geographical conditions, especially of the food supply. Where the author carries this attempt into the field of special customs and religious rites, he goes too far. Nevertheless his work is uncommonly stimulating and deserves the careful attention of the reader who would gain a broad grasp of the relation of geography to the history of the New World.