MOLECULAR ISOTOPIC ANALYSIS REVEALS DETAILS OF CLIMATE CHANGES AND ITS IMPACT ON THE EARLY DEVELOPMENT OF RICE DOMESTICATION IN EASTERN CHINA DURING THE NEOLITHIC PERIOD

High resolution isotopic analysis of molecular carbon (δ¹³C) and hydrogen (δD) of n-alkanes from a 360 cm sedimentary sequence spanning ~7,000 years of the Tianluoshan archaeological site in China’s eastern coastal region revealed environmental changes that coincided with the early development of rice domestication during Neolithic times. The isotopic values for n-alkanes compounds C₂₇, C₂₉, and C₃₁ are highly synchronized for both C and H isotopes. Based upon a revised age model, the sequence can be divided into four major segments; (I) 7044 - 6382 cal. age BP (295 - 255 cm), in which δ¹³C and δD co-vary and become more negative; (II) 6382 - 6258 cal. age BP (255 - 180 cm), a major positive shift up to 5‰ for δ¹³C and 60‰ for δD; (III) 6258 - 4478 cal. age BP (180 - 80 cm), a period of isotopic fluctuations where δ¹³C and δD are anti-phased; (IV) 4478 - 1942 cal. age BP (180 - 60 cm), a period where rice cultivation in the region ceased, and δ¹³C and δD co-vary. Segment II represents a major warm/dry event, corresponding to a period of significant transgression along with increased evapotranspiration that can be correlated with similar events in other parts of the world. This event interrupted rice domestication and separated two periods of relatively wet periods represented by more-negative hydrogen isotope records, segments I and III. The flourish of rice agriculture in the lower Yangtze River Valley during the time of segment III coincided with a cooler/wetter climate pattern, compared with segment II, as indicated by the opposite trend of C and H isotopic curves. Our study represents the most complete molecular δ¹³C and δD isotope record during this critical time of early development of rice domestication in this region. While collaborated with biological and stratigraphic data, the new isotope data not only confirms the previously revealed impact of environmental changes on cultural development, but also provides more detailed evidence for climatic change history during the Neolithic period in eastern China.