The high rate of crown caries (8.6%; 119/1,377 teeth) and other oral pathologies in 101 central Japan Middle to Late Jomon Period (ca. 1000 B.C.) crania indicate a level of carbohydrate consumption consistent with an agriculture hypothesis. Because Jomon dental crown and root morphology shows strong resemblances with past and present Southeast Asians, but not with ancient Chinese or modern Japanese, Jomon agriculture could be of great antiquity in the isolated Japanese islands. These dental data and other assembled facts suggest that ancestral Jomonese might have carried to Japan a cariogenic cultigen such as taro before the end of the Pleistocene from tropical Sundaland by way of the now-submerged east Asian continental shelf.