INFLUENCES OF ENVIRONMENT 141 



engender the fall of djiiasties and empires, the rise of 

 new nations, and the growth of new civilizations. If, 

 on the contrary, a country becomes steadily less arid, and 

 the conditions of life improve, prosperity and content- 

 ment are the rule. There is less temptation to war, and 

 men's attention is left more free for the gentler arts 

 and sciences which make for higher civilization, "^s 

 *'. . . Among primitive men the nature of the province 

 which a tribe happens to inhabit determines its mode 

 of life, industries, and habits; and these in turn give 

 rise to various moral and mental traits, both good and 

 bad. Thus definite characteristics are acquired, and are 

 passed on by inheritance or training to future genera- 

 tions. 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 compara- 

 tive competence, prosperity and contentment. Dis- 

 orders, wars, 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."-" 



The pulsations of climate which have been important 

 factors in the movements of populations both in prehis- 

 toric and historic times are of several types. The first 

 type of climatic change is that of the Glacial period, dur- 

 ing which great fluctuations took place, probably sfmul- 



2s T/ie Pulse of Asia, p. 14. ^^ Ibid., pp. 15-lG. 



