subsistence is reflected in the sparse population. Indeed, the fact of its scarcity has been responsible for certain characters in the culture of the Eskimo which are revolting to us and seem quite inconceivable, largely because the mitigated rigors of our environment have accustomed us to milder usages. For example, while it is customary with us to respect and look after the aged members of our family, among the Eskimo it is required of children to kill their parents after they have become too old to help the family or serve the community. It is considered a breach of filial duty not to kill the aged parent. The custom is founded upon the ethical law of the Eskimo and rests upon the whole mass of traditional lore and custom.19 When members of the community cannot work and contribute to the food supply they have to be made away with because there are young mouths to feed and there is otherwise not sufficient food for all.

Races are very sensitive to climatic environment. Although man is more adaptable to climatic changes than many animals, environment in its climatic influences does act nevertheless as a selective agency. For example, the Eskimo sickens and dies in the temperate and semi-torrid zone. The European cannot endure the long winters and the severe cold of the Arctic Circle. The negro perhaps would die out in northern United States were he not replenished from the South. And the Scandinavian does not seem to prosper in the dry, sunny portions of the United States where he is subject to diseases of the skin and nerves which appear seriously to deplete his numbers in a few generations. But in the 19 Boas, F.-"The Mind of Primitive Man," Jour. Amer. Folk-Lore, v. 14,

p. 10.

rainy Northwest, which resembles his native habitat, he thrives both in body and estate.20

Besides the climatic gradations in temperature which are found in different latitudes, there is climatic variation in temperature correlated with altitude. There are zones of latitude and zones of altitude.21

Miss Semple tells us that the southern slope of the Monte Rosa Alps, from glacier cap at 4,500 meters to the banks of the Po River, yields within certain limits a zonal epitome of European life from Lapland to the Mediterranean.22 Climate changes with altitude in much the same way as with latitude. Generally speaking, heat and absolute humidity diminish as height increases, while rainfall becomes greater up to a certain level. “The effect of ascending and descending currents of air is to diminish the range of temperature on mountain slopes and produce rather an oceanic type of climate." 23 Uniform climate is usually found in a land of monotonous relief, while a region rich in vertical articulations is rich also in local varieties of climate. Plant and animal life conform to the climatic levels at different altitudes.

"Central Asia has a threefold cultural stratification of its population, each attended by the appropriate density, according to location in steppe, piedmont and mountain. The steppes have their scattered pastoral nomads; the piedmonts, with their irrigation streams, support sedentary agricultural peoples, concentrated at focal points in commercial and industrial towns; the higher reaches of the mountains are occupied by sparse groups 20 Huntington, H.-"Changes of Climate and History," Amer. Hist. Review, vol. 18, no. 2, Jan. 1913, p. 231.

21 See figure 52.

22 Semple, op. cit., p. 557.

23 Ibid., p. 558.

of peasants and shepherds, wringing from upland pasture and scant field a miserable subsistence." 24

Thus far we have discussed climatic differences as though they occurred in certain fixed bands circling the earth. But climate in any given locality is, as we all know from our own experience, a relatively variable quantity. Aside from seasonal change there is much latitude of variation. This climatic cycle when considered in its wider aspect, that is, leaving out the temporary fluctuations of the year, and concentrating our attention upon changes that occur or recur over the period of many years or even centuries, is an important cause of movements of population. Recognition of the part played in history by climatic changes has led to the formulation of the theory of pulsatory climatic changes by Ellsworth Huntington.25 "It seems to be true, as a principle, that, in regions occupied by the ancient empires of Eurasia and northern Africa, unfavorable changes of climate have been the cause of depopulation, war, migration, the overthrow of dynasties, and the decay of civilization; while favorable changes have made it possible for nations to expand, grow strong, and develop the arts and sciences." 26 However, this by no means implies that all invasions and all prosperity are supposed to be due to climatic causes, but merely that climate has been one of the important factors in producing such results.27

"In relatively dry regions increasing aridity is a dire calamity, giving rise to famine and distress. These, in turn, are fruitful causes of wars and migrations, which 24 Ibid., p. 558.

25 The Pulse of Asia, 1907.

26 Huntington, E.-Palestine and Its Transformation, 1910, p. 251. 27 Huntington, "Changes of Climate and History," p. 215.