Multicropping Pattern Reveals Human Adaptation at the Wanbei Site (ca. 5.7–4.4 ka cal. BP) in the Middle and Lower Huai River Valley, China

The middle and lower Huai River Valley, located between the Yangtze and Yellow Rivers, was a key transitional zone for the northward spread of rice and southward migration of millet agriculture in central-eastern China during the Holocene. Knowing when millets spread here, how they were combined with rice in mixed farming, the reasons for their spread, and the temporal variation of cropping patterns is of crucial significance to the development of our understanding of ancient adaptation strategies adopted by human societies in response to climatic and cultural changes. Focusing on crops, phytolith analyses of the soil samples, in tandem with radiocarbon dating from the Wanbei site, reveal evidence of a multicropping pattern of combining rice (Oryza sative), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica) during the Dawenkou culture period between 5720 and 4426 cal. BP in the middle and lower Huai River Valley, China. The data show that rice was always the principal crop of the pattern, and that domesticated rice was developed during the early and middle Dawenkou culture periods. However, its domestication rate became lower during the late Dawenkou culture period. Broomcorn millet and foxtail millet with domesticated traits appeared only in lower proportions of the total produced throughout the period. The proportions of rice and foxtail millet increased slightly, while the proportions of broomcorn millet decreased over time. Finally, the formation of the multicropping pattern at Wanbei may have been primarily influenced by both the warm and wet climatic environment and the cultural exchange and communication between the Haidai region and the middle and lower Huai River Valley during the Dawenkou culture period. The findings in this paper may not only contribute to mapping the spatiotemporal route for the northward expansion of rice agriculture and southward spread of millet agriculture, but also assist in understanding the human adaptation strategies employed in eastern China during the Holocene.