The rice cultures
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Abstract
Common (Asian) rice was domesticated in the area between north India and the Pacific coast adjoining Vietnam and China. Rice cultivation began when the hunting, fishing, and food-gathering inhabitants near the rivers and along the foothills dropped seeds into low-lying fields. Land preparation, transplanting, and irrigation were largely developed in the Yellow-Han River basins, spreading later to Southeast Asia. As rice culture expanded from the naturally flooded areas into fringe areas where the water was deep or the soil was mesic, human and natural selection greatly accelerated the development of specialized types such as the floating and upland rices. Recognizable races of rice resulted from man's extension of its culture and persistent selection within a geographic region, but rapid changes in predominant varieties occurred within an area due to extensive contacts among the peoples. Such exchanges also resulted in population increases, changes in diet, and predominance of specific draft animals and associated farm tools. While rice cultivars lost their primitive characteristics and acquired wider adaptation, sterility barriers developed and some duplicate loci disappeared. A thrifty and productive plant-type evolved.