Asynchronous transformation of human livelihoods in key regions of the trans-Eurasia exchange in China during 4000-2200 BP

Abstract

The emergence and intensification of the trans-Eurasian exchange during the Late Neolithic and Bronze Ages profoundly influenced human lifestyles, notably in the arc and the Central Plains. Though the exchange was critical to socioeconomic development, humans adopting livelihood strategies in varying ways depending on geography and social pressures remains unclear. Stable C and N isotopic analysis is the primary approach to study paleodiet—an important insight into ancient human livelihoods. Unfortunately, isotopic data are largely absent in China's Yunnan Province—a component of the arc—especially in the periods prior to 3000 BP. Here, we report the earliest and direct evidence of human diets in Yunnan during the Holocene, as shown by stable C and N isotopes and radiocarbon dates from human and animal bones unearthed from the Baiyangcun site. Integrating our data with archaeobotanical and zooarchaeological data from the Late Neolithic and Bronze Ages throughout the arc and Central Plains, we found that humans heavily relied on C3 foods in Yunnan during 4800–4600 BP and ∼3800–3300 BP and millet remains (C4) found in both periods were probably used for feeding other livestock and/or ritual practices rather than as staple food for humans. We also detected asynchronous transformation of human livelihoods across different regions during 4000–2200 BP, when wheat, barley, and herbivorous livestock were generally utilized in China. These exotic crops and livestock were adopted as necessary subsistence during 4000–3000 BP and became the dominant livelihood during 3000–2200 BP in the Gansu-Qinghai region. However, these practices were auxiliary strategies in Yunnan and the Central Plains during 4000–3000 BP and displayed a significant degree of spatial variation during 3000–2200 BP. We propose that the difference in livelihood transformation in these regions is largely a result of the physical features of crops and livestock, local natural environment, terrain, human survival pressures associated with climate change and population fluctuation.