Early intensive millet-pig agriculture in the high-elevation Tibetan Plateau

Abstract

Over 5500 years ago, a sustainable and intensive millet-pig system emerged in northern China. This system, which included common millet (Panicum miliaceum), foxtail millet (Setaria italica), and domestic pig (Sus scrofa domesticus), played a crucial role in supporting the development of complex societies. Around 5000 years ago, the spread of these two millets to the Tibetan Plateau facilitated agriculturalization in the high-elevation river valley areas of the plateau (>2500 m above sea level). Previous studies tended to suggest that there were no domesticated pigs at the early settlements in high-elevation river valleys of the Tibetan Plateau, where subsistence strategies primarily relied on hunting wild animals and millet cultivation. Here, we report the earliest known domestic pigs identified through ancient DNA (aDNA) analysis of pig bones excavated from these high-elevation sites, dating back to approximately 4800–4100 years ago. Additionally, we conducted stable isotope analysis on pig and wild herbivore bone remains, as well as crop remains from the La Phob site. The δ¹³C and δ¹⁵N values provide clear evidence of intensive millet-pig agriculture, with pigs primarily consuming both common and foxtail millets, and their manure used for field fertilization. Our study demonstrates that by 4800 years ago, not only domestic pig and the two millets but also an intensive millet-pig system had spread to the high-elevation Tibetan Plateau, contributing to the early sedentary lifestyle of humans in these regions.