JINAN -- China has been confirmed as one of the centers of origin of the adzuki bean (Vigna angularis), according to a study published recently in the Proceedings of the National Academy of Sciences (PNAS) of the United States of America by an international research team led by Chinese scholars.The team discovered carbonized adzuki bean remains dating back about 9,000 years at the Xiaogao site of the Houli culture in the city of Zibo, East China's Shandong province. Using archaeobotanical analysis and radiocarbon dating, researchers identified 45 carbonized adzuki beans among more than 32,000 plant remains collected from the site."This finding predates previously known adzuki beans in China by some 4,000 years," said Chen Xuexiang, a professor at the School of Archaeology, Shandong University, and the paper's first author. The beans were unearthed alongside foxtail millet, broomcorn millet and soybeans, providing direct evidence that an early mixed cropping system of "grains and ...