Rumania and northern Italy; (2) North America east of the Rockies from southern Canada to the thirty-eighth parallel; (3) the Pacific Coast; (4) Japan and (5) New Zealand and the adjacent corner of Australia.29 It is most interesting to note that these are the seats of the most progressive civilizations of today.

No matter what modifications further study may necessitate it would seem that at last we are reaching the point where definite measurements may be made of man's reactions to the physical world, and we may hope for much greater knowledge in the near future.

The question of survival in the tropics has been mentioned. That change of residence from the temperate zones to the tropics may have pronounced effects is undoubted. "Practically every northerner who goes to the Torrid Zone says at first that he works as well as at home, and that he finds the climate delightful. He may even be stimulated to unusual exertion. Little by little, however, he slows down. He does not work so hard as before, nor does the spirit of ambition prick him so keenly. On the low, damp seacoast, and still more in the lowland forests, the process of deterioration is relatively rapid, although its duration may vary enormously in different individuals. In the dry interior the process is slower, and on the high plateaus it may take many years. Both in books and in conversation with inhabitants of tropical regions one finds practical unanimity as to this tropical inertia, and it applies to both body and mind." 30

5. Psychical Effects.- Man is often strangely reluctant to admit that earth exercises any control over his ideas. Yet a moment of reflection will show that there

29 HUNTINGTON, E. o. c., p. 250 ff.

30 Ibid., pp. 41-42.

are such influences. All our knowledge is mediated by the senses and finds its source in the world about us. Even our imaginations are bounded by details which we gain by personal contact or in some indirect way. We never dream of anything really new. All we can do is to put together in some new combination the elements with which everyday life has made us familiar. On the Isle of Man in days gone by the stealing of a pig or chicken was punished by death, while the stealing of a horse was only a minor offense. This grew out of the fact that the horse could not be taken off the island without detection nor could it be long concealed. The people accustomed to the awful heat of the desert pictured the place of punishment of the next world, Hell, in terms of heat; while the Eskimo, accustomed to great cold, thought a place of constant heat would be most desirable and to him it became Heaven. Our languages will show our main interests. The Samoyedes of northern Russia have a dozen terms to distinguish the shades of brown and gray of their reindeer, while the Malay vocabulary is rich in nautical terms. Our language reflects also the relative development of our The qualities of colors, the vibrations of tones are carefully worked out and we have a great series of descriptive adjectives. On the other hand, so defective is our sense of smell that accurate definitions of odors are practically impossible. "In all the forms of its creeds and cults, humanity does not seem to be able to get away from its earthly patterns. The Elysian fields, the Valhalla, the life that now is reflected upon the life beyond, are all shaped after models familiar upon the earth."

senses.

In the earlier stages of his career man was in utter ignorance of the nature of the earth. It is not too much

to say that these unknown elements can hardly be considered as being in his environment. Hence it follows that man's discoveries are constantly changing in a real sense the world in which he lives. It is one world when he knows a few of the properties of wood and stone. It is another when he discovers the metals, learns to use copper, tin, zinc, gold, silver, iron, and yesterday platinum and aluminum, today radium.

There can be no greater mistake than to think of the physical environment as fixed and unchanging, though that mistake is far from rare. Geology was once taught as if the earth were completed ages ago. As a matter of fact, it is changing as rapidly today as ever, so far as we can tell. The formation of rocks and their gradual disintegration under the influence of snow, rain and wind is still going on. Change, eternal change, is the one great

fact in nature.

Our evidence shows that the physical contour of the earth has been greatly altered in the course of time. We know that the Appalachian Mountains are but the stumps left of a great range. We know that there were four (possibly five) glacial epochs when the ice sheet covered North America as far south as Pennsylvania and Missouri. Sometime during this period the Great Lakes came into existence. The cause of these epochs, their duration, their disappearance and their effect upon organic life are some of the most fascinating puzzles of history. Oceans now exist where once were dry land and mountain ranges, whose slopes were once ocean beaches.

It is evident too that the climate of any given area of the earth has often undergone tremendous changes. Iceland was once a subtropical country with a flora resembling that of Florida, rather than its own. All the country recently

labeled as the Great American Desert was once a moist, fertile land, densely populated by animals. Now these great herds are gone and the Great Salt Lake is but a puddle in comparison to its ancient self when it had an outlet to the Pacific. It appears that west Central Asia has been drying up throughout all recorded time. Huntington says: "If it be proved that the climate of any region has changed during historic times, it follows that the nature of the geographic provinces concerned must have been altered more or less. For example, among the human inhabitants of Central Asia widespread poverty, want and depression have been substituted for comparative competence, prosperity and contentment. Disorder, wars and migrations have arisen. Race has been caused to mix with race under new physical conditions, which have given rise to new habits and character. The impulse toward change and migration received in the vast arid regions of Central Asia has spread outward and involved all Europe in the confusion of the Dark Ages. And more than this, the changes of climate which affected Central Asia were not confined to that region apparently, but extended over a large part of the inhabited earth.” 32 In 1911 and 1912 Huntington had opportunity to examine some 450 big trees of California which varied in age from 230 to 3200 years. Eighty were over 2000 years old. Judging from the width of the rings the sequoia grew on the average of 30 per cent faster at the time of Christ than it did A.D. 1500.33 In our own arid southwest there are many evidences of an earlier civilization when large areas were cultivated both with and without irrigation. The Pimas call these people the Hohokam or "perished

32 HUNTINGTON, E. The Pulse of Asia, pp. 15, 16.

33 HUNTINGTON, E. American Historical Review, January, 1913.

ones." Mr. Huntington has recently made some most interesting studies in this country. Of the Santa Cruz Valley in New Mexico he writes: "The part of the valley which is now capable of cultivation contains ruins which indicate that all the available land was utilized in the past. Below the point where irrigation is now possible there are three large groups of ruins, and the three together must have had as many people as the higher regions where there is still water. In other words, it seems as if the Santa Cruz Valley once had at least twice as many people as it could at present support, and half of these lived where the white man could not now get a living from agriculture." 34

The question over which scientists are now puzzling is whether these and other changes come in cycles. There are many who believe that there is a periodicity in the sun spots and, correspondingly, periods of greater evaporation and rainfall on earth. The decision must be left to the future.

Certain other changes are also clear. The rivers of the world are building great alluvial deltas out of the material taken from the hills. Thus through the ages the Mississippi has made its delta from Cairo, Illinois, to its present mouth. It annually carries to the sea 225,000 acre feet of fertile soil and builds new land for future men. That this process may involve serious loss to existing society is also evident.

Now all these changes, whether the yearly cycle of temperature, or the greater pulsations as they have been called, involve constant readjustments of life. Sudden changes are always most dangerous. Even change in food and drink may produce serious results. There are many

34 HUNTINGTON, E. Report of Smithsonian Institute, 1912, p. 393.