19I3-] HIGHEST NATIVE AMERICAN CIVILIZATION 487 



Farther south in the torrid zone, however, the effect would appear 

 to be the exact opposite. That is, if the belt of cyclonic storms is 

 pushed equatorward in winter it would seem to mean that the belt 

 of sub-tropical high pressure and drought whence the trade winds 

 take their rise is also pushed equatorward. Thus during the winter 

 the dry conditions of the semi-arid or desert belt which encircles 

 the earth at about latitude 25° to 30° would be pushed farther toward 

 the equator. The result of this would seem to be to force the trade 

 winds so far south during winter that they would not have their 

 present effect in causing rainfall throughout practically the whole 

 winter in Peten. On the contrary, there would be a dry season of 

 several months duration such as now prevails in Yucatan and in the 

 Guatemalan Highlands. This would prevent the growth of forests 

 and cause them to be replaced by jungle or bush. Here again, then, 

 a third line of evidence appears to point to a pulsatory climatic 

 change which would produce results in accordance with our first 

 assumption. 



Here we must let the matter rest. The theory of changes of 

 climate involves so many historic and economic consequences that 

 it demands most careful consideration. Perhaps it is possible to 

 explain the peculiar location of the ancient Maya civilization on 

 some other hypothesis, but thus far no other seems to be supported 

 by so much independent evidence. The acceptance of the climatic 

 theory does not oblige us to change our ideas as to the remarkable 

 character of the Mayas, or as to the causes of the development of 

 civilization. It merely provides conditions under which it becomes 

 probable rather than merely possible that a race might have devel- 

 oped. In other words it removes the great difficulties of agricul- 

 ture. It provides a habitat which to a certain extent would be 

 more free than at present from the debilitating influences of heat 

 and moisture ; and it does away with the conditions that now cause 

 such terrible fevers. In all these ways, then, while it does not con- 

 flict with accepted ideas as to the historic development of civiliza- 

 tion, it removes some of the difficulties in the way of accepting 

 those ideas. 



Yale University, 

 New Haven. 



