Not so many years ago, Indian corn, or maize, was carelessly considered the first plant cultivated in the Americas—probably because it was the most spectacular—and was supposed to have originated in the highlands of Mexico or Guatemala. Now we know that pumpkins preceded corn, and so, in all probability, did most of the commoner food plants. Beans and melons, with their free-running vines and prominent flowers and seed pods, would seem most likely to have first attracted man—or, perhaps, woman—and led him to assist the processes of nature. When corn was king, semiarid farm lands were supposed to be the place of its origin. Spinden saw “irrigation as an invention which accounts for the very origin of agriculture itself.”[5] Semiarid land, however, is notoriously hard to clear; though its plants are few, they have deep, tenacious roots. River flood plains of the Sonoran desert in Mexico—ideal by Spinden’s standard—yield no evidence of long or extensive occupation, according to Carl Sauer. Where irrigation was used in our Southwest, dates are not early. The evidence of the plants themselves, he writes, “overwhelmingly points not to desert or steppe but to several humid climates for their origin.”[6] There has never been much enthusiasm for the humid tropic lowlands as the seedbed of agriculture. Of late years the students of botany have turned to the temperate forest area and particularly to the mountain valley as the seat of agriculture. This has been championed by N. I. Vavilov and a group of Russian scientists, sent to the Americas in the 1920’s, who made a most elaborate study of our native cultivated plants. Much of their evidence is too technical for presentation here, but their conclusions have seemed convincing to many students.[7] A mountain valley provides a wider range of temperature and rainfall and a greater variety of native plants. Its forest trees, before they are cleared by girdling and burning, store up a rich humus under their shade. Costa Rica and El Salvador—full of isolated mountain valleys—contain, according to Henry J. Bruman, as many species of plants as the United States, in spite of the fact that the United States is a hundred times the size of the two countries together.[8] The Russians believe that agriculture took early shape in certain mountain valley areas, including southern Mexico, Central America, Colombia, highland Peru, western Bolivia, and southern Chile. Though they do not commit themselves as to whether agriculture originated in one place and spread later to others, “their evidence,” Sauer thinks, “may be interpreted in favor of multiple independent beginnings.”[9] But Bruman, writing of their work, points out that the “enormous spread of maize and beans, of cotton and tobacco, for example, shows that there is ‘something of the undivided whole’ in the great cultures of the New World, as Vavilov well expresses it.”[10] Richard S. MacNeish, an archaeologist who spent at least a dozen years