CHAPTER XVI 1 1. 



CLIMATIC CHANGES AND MAYA HISTORY. 



As a last step in our investigation of climatic changes in Central America let us briefly 

 consider Maya history and see how the future elucidation of this most perplexing subject 

 will either disprove certain parts of our hypothesis, or else greatly strengthen them. Let 

 us first state what expectations the hypothesis would lead to and then compare them with 

 the conclusions of the best authorities on Maya history. For the thousand years previous 

 to the time of Christ, to judge from figure 50, on page 172, the general climatic conditions 

 were such that in subtropical regions, like central California or Palestine, the driest times 

 were as moist as the wettest times are at present. This seems to mean a pronounced dis- 

 placement of the zone of westerly storms toward the south, especially in winter. Therefore 

 in winter the whole Maya country probably had a long dry season comparable to that which 

 now prevails only in the relatively progressive region of northern Yucatan. Under such cir- 

 cumstances jungle rather than forest would be the prevalent growth over the whole area, and 

 the contrast between summer and winter would be greater than it is now in any part of the 

 country. Thus the two chief drawbacks to civilization, namely, the feverish, irreclaimable 

 forests and the deadening climatic monotony, would be in part removed. A thousand years 

 of such conditions would give opportunity for the growth of civihzation, which we should 

 expect to find making rapid strides from the sixth to the fourth century b. c, falling off then 

 somewhat for 200 years, rising again during the second century, and continuing at a high level 

 for 200 to 300 years. Then from 200 a. d. to 650 a. d., as appears in figure 72 on page 209, 

 which is merely a part of figure 50 with an enlarged vertical scale, the general tendency would 

 be downward, with an interruption perhaps in the sixth century, but reaching a very low 

 ebb in the seventh. The long decUne of the California curve of figure 50 from soon after 

 the time of Christ to 650 a. d., it must be remembered, is probably more important than 

 the apparently sharper and greater declines of earlier times, for those are exaggerated 

 because of the small number of trees available more than 2,000 years ago. During the 

 decline after the time of Christ the southern parts of Maya land would suffer first and 

 might so far revert to true forest as to become uninhabitable by any one except wandering 

 savages, while the northern parts would still possess comparatively favorable conditions. 

 In the seventh, eighth, and ninth centuries we should expect that conditions would be 

 no better than at present. Forests would naturally prevail wherever they are now found, 

 the area where civihzation is possible would be restricted to northern Yucatan, and the 

 people would be steadily weakened by fevers and a warm, monotonous climate. Before 

 their energy was wholly sapped, however, and before the ancient culture had completely 

 disappeared, improved conditions, beginning about 880 a. d. and lasting two centuries,would 

 cause a revival; the forest belt would be pushed back somewhat, but not so far by any 

 means as at the time of Christ, and for a time the greater contrast of the seasons would 

 help to stimulate the people. Then would follow a decline culminating about 1300 a. d. 

 At the beginning of the foiu-teenth century another revival of culture might be expected, 

 but it would be of slight importance for two reasons: In the first place, the adverse con- 

 ditions of the twelfth and thirteenth centuries would probably have reduced the jungle- 

 covered area to small extent and would have brought the vigor of the people to a condition 

 even lower than was reached in the preceding adverse period. In the second place, the 

 favorable period is limited to about a hundred years, chiefly during the fourteenth century, 

 too short a time to produce very pronounced effects. Then would come a third relapse, 

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