AND ITS INHABITANTS 189 



great impression on the world. In the plateaus of Peru, 

 Yemen, and Rhodesia, civilization took a few steps and then 

 halted. This corresponds closely with their climate. In mean 

 temperature and humidity they are admirable. Therefore to 

 that extent they are stimulating. A competent race migrating 

 to any one of them would be invigorated and would be led to 

 make important advances. There is no evidence, however, 

 that any of them ever enjoyed any great degree of climatic 

 variability due to strong seasonal changes and frequent storms. 

 Therefore they lacked the stimulus needed to keep them 

 steadily progressing. 



The only tropical center of civilization which developed 

 any really remarkable ideas was Central America, where the 

 Mayas evolved a decidedly high type of architecture, a re- 

 markably accurate calendar based on extensive astronomical 

 knowledge, and a system of writing more advanced than that 

 which the Chinese have even yet attained. It is perhaps sig- 

 nificant that the center of Maya culture in Yucatan and Guate- 

 mala lies in the longitude where storm tracks today swing 

 farthest south and where they apparently swung much farther 

 south in the past. To this day the Yucatecan descendants of 

 the Mayas say that they work fastest when the temperature is 

 lowered by the "northers" which follow in the wake of storms 

 whose centers pass farther north. In the past such northers 

 were apparently much more frequent than now. Hence it 

 looks as if the relatively active Maya civilization were asso- 

 ciated with variability just as are the high civilizations of 

 today. 7 



As to the cultural center in southeastern Asia, we cannot 

 speak with much certainty. It never showed anything like the 

 originality of the Central American center, for most of its 

 ideas were borrowed from places farther north. It did not 



7 This subject is fully discussed in the author's volume, "The Climatic 

 Factor." Pub. No. 192, Carnegie Institution of Washington. 



