Archaeology and paleobotany provide us with a provisional picture of the origin of American agriculture, the basis for any subsequent cultural evolution. According to this picture, the first experiments took place in the seventh millennium B.C.E. in the heart of preceramic migratory communities in Mexico and in the central-southern Andean region. They.started with the seasonal cultivation of certain wild fruits. In the fifth millennium, the domestication of maize began in the Tehuacan Valley. However, for a long time the ratio of cultivated vegetables to foraged and hunted foods in the diet in the central Mexican region did not exce~d 10 percent'!