High-resolution enamel strontium isotope analysis and early spatial management of pigs at the Mopanshan site

Domestic pigs (Sus scrofa domesticus) are among the key livestock independently domesticated in China and played an important role in prehistoric subsistence systems and the development of early complex societies. In many Neolithic communities, pigs constituted a major source of animal protein and were closely integrated with agricultural production and settlement life. Despite extensive zooarchaeological research, however, the early process of pig domestication in the lower Yangtze region remains poorly understood. Compared with northern China, where multiple lines of evidence indicate relatively early and clear patterns of pig management, the lower Yangtze presents a more complex picture of human-pig interactions. Traditional zooarchaeological indicators, including skeletal morphology, mortality profiles, and population structure, often yield ambiguous results, making it difficult to determine whether pigs recovered from archaeological contexts represent hunted wild boar or animals already under sustained human management. This problem is further complicated by the ecological setting of southern China, where dense C3 vegetation and abundant wild boar populations obscure dietary distinctions between wild and managed animals. Consequently, the mechanisms through which humans gradually exerted control over pig populations in this region remain insufficiently understood. In this study, we apply high-resolution strontium isotope (87Sr/86Sr) analysis to investigate early pig management in the lower Yangtze region from the perspective of animal mobility and human spatial control. Strontium isotope ratios preserved in tooth enamel reflect the geological signatures of landscapes where animals forage during tooth formation and therefore provide a powerful proxy for reconstructing geographic origin and movement patterns. Tooth enamel from pigs associated with the Majiabang (ca. 7000–6300 BP) and Songze (ca. 6300–5300 BP) cultural phases at the Mopanshan site in Langxi County, Anhui Province, was analyzed using sequential micro-sampling along the enamel growth axis. This procedure generated high-resolution 87Sr/86Sr sequences that allow reconstruction of individual pigs’ activity ranges during tooth development and enable comparison with local environmental baselines and other contemporary animals. The results reveal clear diachronic differences between the two cultural periods. Pigs from the Majiabang phase exhibit 87Sr/86Sr values that are very similar to those of contemporaneous wild sika deer and significantly higher than the environmental baseline surrounding the site. These isotopic signatures suggest that the animals likely originated from the broader Jiangnan Hills region rather than the immediate vicinity of the settlement. Their wide-ranging mobility patterns are consistent with pigs obtained through hunting rather than animals confined within human-managed spaces. In contrast, pigs from the subsequent Songze phase display a marked reduction in 87Sr/86Sr variability, with values closely approximating those measured from contemporaneous humans. This pattern, together with the occurrence of linear enamel hypoplasia and other physiological stress indicators, suggests that pigs’ activity ranges had become restricted to the vicinity of the settlement and that their movements were increasingly constrained by human control. Taken together, these results indicate that pig domestication in the lower Yangtze region was not a rapid or uniform transformation but instead involved a gradual transition from hunting wild animals to the emergence of low-intensity, spatially controlled husbandry practices. Rather than representing an abrupt shift from wild to domestic status, the Mopanshan evidence suggests a progressive intensification of human spatial management over time. The study highlights the value of strontium isotope analysis for identifying changes in animal mobility and, by extension, the degree of human management. By providing direct isotopic evidence for incremental spatial restriction of pigs within a complex environmental landscape, this research contributes to a deeper understanding of the diversity and regional variability of domestication processes in East Asia.