Reconstructing northern Chinese Neolithic subsistence practices by isotopic analysis

Stable isotope signatures of both human and non-human animal bone samples indicate that Neolithic farmers of the Yellow and Wei River basins in China potentially cultivated millet for two reasons: as a staple for human consumption and as fodder for domesticated animals, specifically pigs, dogs, and perhaps chicken. Bone samples were analyzed from four Neolithic sites: Jiangzhai, Shijia, Xipo, and Kangjia, spanning the time period from 7000 to 4000 years ago. A combination of very high carbon isotope ratios (δ13C = −7.7 ± 0.4‰) and low nitrogen isotope ratios (δ15N = 7.5 ± 0.5‰) in samples of Xipo pig and dog bone suggests that these monogastric animals consumed substantial quantities of C4 plants, almost certainly millets. In fact, the proportion of C4 plants in animal diets appears to have been even greater than that in human diet. Stable isotope values (δ13C = −10.0 ± 0.8‰; δ15N = 8.3 ± 0.5‰) of human bone collagen recovered at Jiangzhai and Shijia indicate a staple role for millets, as well as the consumption of both wild and other non-C4 domesticated plant foods. As millet agriculture and animal husbandry apparently depended on one another, a strong mutualism between them was likely established in northern China during the Neolithic. We propose that variable redistribution of agricultural products between humans and animals, depending on the availability of wild resources and annual fluctuations in agricultural output, helped ensure the stability of Neolithic human subsistence in the Yellow and Wei River basins.