The Identification of Arable Rice Systems in Prehistory

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We will determine the nature of early rice agricultural systems in East and South Asia, whether they were based on wetland paddy cultivation or dryland cultivation, and how the ecology of early rice fields developed out of that of wild rice. In order to do this we will develop a clear and easily applied method for detecting rice ecosystems, whether or wild type, wetland paddy type or dry, rainfed type using both archaeological seed assemablages and phytolith (plant silica) analyses. This will involve study of modern populations of wild rice and associated wild plants (weeds) and the weeds associated with different agricultural practices in modern but traditional contexts in Eastern India, Thailand, Cambodia and China. We will apply these methods to archaeological sites from the Lower Yangzte region of China dating from 5000 BC to 2000 BC and in Central China from ca. 4000 BC to 1500 BC, and in northern and eastern India dating from 2000 BC to 200 BC. We will then be able to see how the ecology of rice plants changes when people domesticated this species and in relation to later agricultural developements. Because wet rice fields produce quantities of methane, a better understanding of h0ow much wet rice cultivation in the past can contribute to a better understanding of the role of human activities in modifying the global environment in prehistory. Since Methane is a greenhouse gas, it has been proposed that rice cultivation from 3000 BC began to elevate methane levels and cause global warming. Our new methods will allow us to test this hypothesis from the archaeobotanical evidence from sites of prehistoric rice cultivators.