In a study published online on September 5, 2014 in the open-access journal PLOS ONE, Dr. Gary Crawford, a University of Toronto-Mississauga anthropology professor, and two Chinese colleagues propose that the domestic peaches enjoyed worldwide today can trace their ancestry back at least 7,500 years to the lower Yangtze River Valley in Southern China, not far from Shanghai. The study, headed by Dr. Yunfei Zheng from the Zhejiang Institute of Archeology in China’s Zhejiang Province, was done in collaboration with Dr. Crawford and Dr. Xugao Chen, another researcher at the Zhejang Institute. “Previously, no one knew where peaches were domesticated,” said Dr. Crawford. “None of the botanical literature suggested the Yangtze Valley, although many people thought that it happened somewhere in China.” Radiocarbon dating of ancient peach stones (pits) discovered in the Lower Yangtze River Valley indicates that the peach seems to have diverged from its wild ancestors as early as 7,500 years ago. Archeologists have a good understanding of domestication – conscious breeding for traits preferred by people– of annual plants such as grains (rice, wheat, etc.), but the role of trees in early farming and how trees were domesticated is not well documented. Unlike most trees, the peach tree matures very quickly, producing fruit within two to three years, so selection for desirable traits could become apparent relatively quickly. The problem that Dr. Crawford and his colleagues faced was how to recognize the selection process in the archeological record. Peach stones are well represented at archeological sites in the Yangtze valley, so the researchers compared the size and structure of the stones from six sites that spanned a period of roughly 5,000 years.
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