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DOMESTICATION
From a wild Asian grass to a refined crop that is the staple diet of half the world's population, the domestication of Oryza sativa spans centuries, but the grain's ancestry is hotly contested.
Asian civilization was built on rice - on Oryza sativa, to be exact. The crop, which today is the primary food source for half of the worlds population, transformed nomadic hunter-gatherers into stay-at-home farmers, spawned the first urban centres and built empires and dynasties. "Probably more so than any crop, it drove societies and econo- mies to become densely populated, potentially more urbanized, and it also transformed land- scapes," says Dorian Fuller, an archaeobotanist at University College London.
Despite - or possibly because of - rice's primacy, the history of the grain remains con- troversial, with little agreement on where, when and how many times humans tamed O. sativa in Asia to create the world's most important crop. (The only other domesticated rice species, Oryza glaberrima, has its roots in Africa. See 'The sec- ond story'.) "Almost every part of Asia had been pinpointed as the area where rice originated," says Michael Purugganan, an evolutionary geneticist at New York University who studies rice domestication. Unravelling the history of rice in Asia would illuminate a turning point in human civilization and give scientists fresh insight that could help improve the crop for the future. Thanks to advances in genetics and to new archaeological finds, that history is becom- ing clearer - and it is a lot more complicated and convoluted than anyone thought.
COMPETING CLAIMS
Oryza rufipogon, the Asian wild grass that is most closely related to O. sativa, is a sinewy, weedy plant. Its red grains are edible, but some modern rice growers consider it a pest. As humans started intentionally planting rice around 8,000 to 9,000 years ago, they sought out plants with the most desirable traits. Over time, the cultivated grass became stouter and straighter, producing heftier grains in greater quantities and that clung to the plant instead of tumbling to the soil - or 'shattering' - to facilitate spread. Claiming the title of the birthplace of rice would be a matter of great pride for a nation. This, along with the wide geographical range of O. rufipogon,...