THE ARCHAIC HORIZON 47 
sacred maize. It is known that maize is at its best in a 
semi-arid tropical environment. It cannot be brought 
to withstand frost although the growing season can be 
cut down to meet the requirements of a short summer. 
Geographically its use extended from the St. Lawrence 
to the Rio de la Plata and from sea level to an elevation 
of fifteen thousand feet in tropical regions. The Mexi- 
ean highlands occupy the central position in the area 
of its distribution and archeological evidence strongly 
points to this region as being the cradle of agriculture 
and the attendant arts. Besides maize, the most 
widely distributed food plants of the New World are 
beans and squashes. Certain other plants were culti- 
vated in more restricted areas and may have had dif- 
ferent places of origin. For instance, manioc was 
doubtless brought under cultivation in a humid lowland 
region, probably the Amazon Valley, and the same may 
be said of sweet potatoes. The common potato was 
found under domestication in Peru and there is no very 
good evidence that its use extended into Central America. 
Irrigation would have been necessary before agricul- 
ture could have been developed to any great extent on 
the highlands of Mexico. Although irrigation is often 
looked upon as a remarkable sequel of the introduction 
of agriculture into an arid country, yet from the best 
historical evidence at our command we should rather 
regard it as a conception which accounts for the very 
origin of agriculture itself. The earliest records of 
cultivated plants are from Mesopotamia, Egypt, 
Mexico, and Peru where irrigation was practised and 
where in these regions are also seen the earliest develop- 
ments of the characteristic arts of sedentary peoples, 
namely, pottery and weaving and the elaborate social 
and religious structures that result from a sure food 
supply and a reasonable amount of leisure. 
