Hydrological changes facilitated early rice farming in the lower Yangtze River Valley in China: A molecular isotope analysis

摘要

The prosperity of Neolithic rice agriculture along the Yangtze River Valley (China) under the humid East Asian Monsoon has been well documented. However, the way in which major hydrological changes influenced the expansion of rice farming remains elusive, mainly because detailed climate records associated with critical periods of the development of early rice farming are still lacking. Here we present high-resolution n-alkane carbon (delta C-13) and hydrogen (delta D) isotope data sampled every 5 cm from a 360 cm sedimentary sequence spanning an similar to 5 k.y. period at the Tianluoshan archaeological site in China's eastern coastal region. Combined with micropale-ontological records, our dual isotope data reveal a detailed climate change profile between 7.0 and 4.6 ka, showing major hydrological changes that coincided with the early development of rice farming in the lower Yangtze region. Two major evapotranspiration events, indicated by synchronized positive delta C-13 and delta D shifts of as much as 5% (delta C-13) and 60% (delta D), are evident ca. 7.0 ka and 6.4 ka, and coincided with regional sea-level changes. Our new isotope data suggest that these short drought climate conditions superimposed upon local sea-level regressions opened suitable new habitats for expanding rice agriculture in the lower Yangtze Delta when subsequent humid climate regimes returned.