190 EVOLUTION OF THE EARTH 



last so long as the other. It is worth noting, however, that its 

 relation to the continent of Asia is almost the same as the 

 relation of the Maya civilization to the continent of America. 

 There is some reason to think that when the southern storm 

 belt was intensified even this region, like its American counter- 

 part, may have had a more variable climate than at present. 



Effect of climate upon Roman history. The history of 

 Rome furnishes a good example of the way in which climatic 

 changes appear to influence the march of history.^ The golden 

 age of Rome occurred 400 or 500 years B. c. In the fourth 

 century B. c, as appears in Figure 38, storms and rainfall 

 seem to have been abundant in subtropical lands like Cali- 

 fornia and Italy. In Rome five acres of land was then con- 

 sidered enough to support an average family, although this 

 presumably does not include the land used for pasturage. Cul- 

 tivation, as we know from numerous classical accounts, was 

 highly intensive, so that the most advanced methods of agri- 

 culture were developed. The crops rarely failed and there 

 was widespread prosperity. The farmers were independent 

 and sturdy, and the difference between rich and poor was slight 

 The towns were small and the conditions were all higj 

 favorable to a strong democratic form of government. 



Turning back to Figure 38 we see that during the thi 

 century B. c. there was a marked diminution of rainfall. In 

 Rome this was accompanied by two occurrences of sinister 

 omen. One was a serious decline in agriculture. The small 

 tracts of land which had hitherto been the rule were no longer 

 large enough to furnish a living for the farmer and his family. 

 Crops that had previously been profitable ceased to be worth 

 while. Hence there arose much discontent and the agrarian 

 troubles with which the names of the Gracci are closely asso- 



8 See Simkhovitch, V. G., "Rome's Fall Reconsidered," Pol. Sci. Quart, Ju 

 1916; and Huntington, Ellsworth, "Climatic Change and Agricultural Exha 

 tlon as Elements in the Fall of Rome," Quart. Jour. Econ., vol. 31, 1917, pp. 1 

 208. 



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