A study suggests that rice domestication may have begun at least 9,400 years ago. Researchers have previously reported that microscopic bodies of silica, called phytoliths, from rice (Oryza saliva L.) found at the Shangshan site in the Lower Yangtze of China might represent the earliest example of rice cultivation. However, the age of the rice fossils was derived through radiocarbon dating of organic matter in pottery shards, which can be contaminated with older carbon sources. To constrain the age of the phytoliths, Houyuan Lu and colleagues isolated rice phytoliths from carbon sources, such as clays and carbonate, and dated the phytoliths directly using radiocarbon dating. The authors validated the technique for directly dating phytoliths with radiocarbon ages of seeds and charcoal samples from the same stratigraphic layer at a nearby site called Huxi. The authors estimate that phytoliths retrieved from the early stages of the Shangshan and neighboring Hehuashan sites are approximately 9,400 and 9,000 years old, respectively. The morphology of specialized cells on the rice phytoliths indicate that the Shangshan rice specimens are more closely related to modern domesticated rice species than to wild rice species. According to the authors, rice domestication may have begun at Shangshan in the Lower Yangtze during the beginning of the Holocene. - Read at PNAS
Article #17-04304: “Dating rice remains through phytolith carbon-14 study reveals domestication at the beginning of the Holocene,” by Xinxin Zuo et al.