AsianScientist (Jun. 12, 2017) – By studying the levels of carbon-14, researchers led by Professor Lu Houyan at the Institute of Geology and Geophysics of the Chinese Academy of Sciences suggest that rice domestication began in China during the beginning of the Holocene. This research was published in the Proceedings of the National Academy of Sciences.
Rice (Oryza sativa L.) is one of the world’s most important staple foods, as it sustains more than half the global population. Rice farming has provided an important material and cultural basis for the development and prosperity of Chinese civilization. Research into when, where and against what environmental background rice was domesticated has led to considerable discussion over the past decade.
Rice remains (mainly from phytoliths), found at the Shangshan site in the Lower Yangtze, may represent the first instance of rice cultivation. However, organic material at the site is poorly preserved due to acidic soil conditions. Therefore, debate exists as to whether this rice was domesticated, wild or transitional. The chronology of the Shangshan site also remains unclear. Accordingly, further dating initiatives are required to determine the absolute calendar time of the rice remains.
Phytoliths can occlude some organic carbon during their deposition, which is captured through photosynthesis from atmospheric carbon dioxide during plant growth. Carbon occluded in phytoliths can thus directly reflect the age of organic sources exploited by humans. Lu’s team carried out phytolith carbon-14 studies on three archaeological sites associated with Shangshan culture. The results show that the phytolith dates are consistent with their paired charcoal or seed dates.
Two phytoliths dating from the early (upper layer of the eighth cultural stratum) and late stages (upper layer of the fifth cultural stratum) of the site range from 9,417-9,134 calibrated years before the present (cal yr BP) to 8,175-8,012 cal yr BP. This suggests that the initial occupation of Shangshan may have occurred around 9,400 cal yr BP, or perhaps somewhat earlier, i.e., around 10,000 cal yr BP, since the phytolith sample SH-8 is derived from between the seventh and eighth cultural strata of the site.
Such an age for the origin of rice cultivation and domestication would agree with the parallel roots of agriculture in other regions of the world, during a period of profound environmental change when the Pleistocene was transitioning into the Holocene.
In East Asia, a significant strengthening monsoon at about 9500 yr BP is consistent with the initial occupation of Shangshan. Climatic amelioration during these transitional periods may thus serve as a key factor in the early process of rice domestication.
The article can be found at: Zuo et al. (2017) Dating Rice Remains through Phytolith Carbon-14 Study Reveals Domestication at the Beginning of the Holocene.
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Source: Chinese Academy of Sciences; Photo: Lu Houyuan.
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