Population expansion as a main driver for the shift of agricultural strategies through the Yangshao culture (6.8-4.7 ka BP) in the west Central Plain of China

In this study, charred plant seeds from the Yangshao culture (6.8 − 4.7 ka BP) in the Western Central Plain of China were collected for nitrogen isotopic measurements to probe the drivers for the shift of agricultural strategies in the prehistoric societies. The nitrogen isotope values (1.1–6.2 ‰) reveal the widespread use of manuring, but their intensity depends on settlement size, with higher manuring intensity at sites ranging from 5 to 40 hm², suggesting that cropland management strategies were shaped by both population size and resource availability. This is further indicated by positive correlations between quick increases in manuring intensity and regional demographic data from the summed probability distribution of radiocarbon dates and settlement patterns during the early phase. Intensified agricultural strategies led to population growth quickly and development of larger settlements at the middle phase. While larger settlements demonstrated lower manuring intensities, this likely indicates cropland expansion. Although climatic deterioration induced a decline in population growth, elevated nitrogen isotope values during the late phase still indicate ongoing cultivation practices. This study highlights population growth as one of the most important drivers promoting the development of early agriculture, offering new insights into the role of agriculture in shaping early social structures.