The archaeological excavation of the Xiaogao site in Zibo, Shandong Province has achieved major results after entering the laboratory research stage: the remains of carbonized adzuki beans (red beans) dating back 9,000 years ago were discovered, which is about 4,000 years earlier than previous similar discoveries in China.

What is the concept of adzuki beans 9,000 years ago? It was born 4,000 years earlier than the legend of Yellow Emperor and Yan Emperor, and nearly 7,000 years earlier than Qin Shihuang unified the six kingdoms. In this way, it silently witnessed a period of time that was longer than the "entire history of civilization" as we know it, until it was discovered by today's archaeologists.

This discovery advances the history of adzuki bean utilization in China by 4,000 years, confirming that a dry farming system with "millet + beans" as the core was formed in the lower reaches of the Yellow River 9,000 years ago, providing disruptive evidence for the study of the origin of agriculture in East Asia.

The Xiaogao site is a typical Houli cultural site. Joint excavations revealed rich remains such as house sites, ash pits, pottery, and stone millstones, dating from 9,000 to 7,500 years ago. Through systematic analysis of 891 flotation samples, archaeologists identified crops such as millet, millet, rice, soybeans and adzuki beans from 32,000 carbonized plants. Among them, 45 carbonized adzuki beans are particularly precious. They are not only the earliest evidence of adzuki beans in the Yellow River Basin, but also make the history of adzuki bean utilization in China parallel to the early evidence of Jomon in Japan.

The greatest significance of this discovery is that it reveals that a "millet + legume" compound crop system was established in the lower reaches of the Yellow River 9,000 years ago. The unearthed presence of adzuki beans, broomcorn millet, millet, and soybeans shows that our ancestors had mastered the ecological wisdom of crop combinations and used the nitrogen-fixing properties of beans to improve soil fertility and achieve the sustainability of the agricultural system. This system is more complex than the traditional agricultural model of “millet and millet dominated”, highlighting the Zibo region’s pioneering status in the process of East Asian agricultural civilization.

Lang Jianfeng, a professor at the School of Archeology of Shandong University, said that the domestication of adzuki beans in East Asia was a long-term, multi-center, complex process. The research team compared adzuki bean remains from more than 140 sites in East Asia and found that the evolutionary trajectories of adzuki beans in the Yellow River Basin, Japan, and the Korean Peninsula were very different. The volume of adzuki beans from the Xiaogao site is only 5.8 cubic millimeters, which is much smaller than modern wild species, showing the "original form" of the early stages of domestication. The significant increase in the size of adzuki beans in China occurred 4,000 years ago, and the domestication process was slower than in Japan and South Korea - the latter had large-sized adzuki beans 6,000 years ago. This may be closely related to local society's selection pressure on crops and dietary preferences.

Editing|Duan Lian Yi Qijiang

Proofreading|Zhang Yiming

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