Stone Age people began cultivating rice in what is now China more than 7,700 years ago by burning trees in coastal marshes and building dams to hold back seawater, converting the marshes to rice paddies that would support growth of the high-yield cereal grain, researchers reported today.
New analysis of sediments from the site of Kuahuqiao at the mouth of the Yangtze River near present-day Hangzhou provides the earliest evidence in China of such large-scale environmental manipulation, experts said.
"It shows people were changing the environment, actively manipulating the system, and well on their way to having an agricultural way of life," said anthropologist Gary Crawford of the University of Toronto at Mississauga, who was not involved in the research.
Using data from the site, it is possible to extrapolate a timeline back to the first attempts at domesticating rice, which would have occurred about 10,000 years ago, said archeologist Li Liu of La Trobe University in Victoria, Australia, who was also not involved. That is contemporary with the development of agriculture in the Middle East.
The finding also sheds new light on an ongoing controversy in archeology: How long did it take for crops to become fully domesticated?
The evidence from China, and new finds elsewhere, indicates that the process took much longer than previously thought, said archeobotanist Dolores Piperno of the Smithsonian Tropical Research Institute in Panama.
Nonetheless, she said, there is now "little doubt that by 7,700 years ago, these people were dedicated rice farmers. . . . I think people were getting all the benefits of agriculture before plants were fully domesticated."
When agriculture developed is a key question in archeology because the production of abundant food, thereby freeing time for other pursuits, is one of the chief requirements for development of a civilization.
Kuahuqiao was discovered in the early 1970s after it was exposed by the construction of a brick factory. The site is buried under 9 to 12 feet of sediment, which led to remarkable preservation of organic materials.
Chinese archeologists have found remnants of wooden houses built on stilts over the water, fine pottery that initially made researchers think the site was more recent, bamboo and wooden tools and even a dugout canoe, complete with paddles.
