High lamb natural mortality versus specialized culling at Bangga on the southern Tibetan Plateau 3000 BP

Pastoralism has a long history on the high-elevation Tibetan Plateau. However, the specific risks faced by early flocks on the plateau and ways that herders managed their animals have not been well explored. Dated to the third millennium BP, the archeological settlement of Bangga represents an early agro-pastoral community at 3800 m above sea level (m a.s.l.) and a rare opportunity to examine these issues. Mortality profiles have been a powerful tool for reconstructing livestock herding strategies from archeological sites globally. Here, we used dental eruption and wear to reconstruct sheep mortality profiles from Bangga. To contextualize regional archeological data, we also simulated sheep natural mortality levels using flock culling profiles and die off data for recent Tibetan flocks. Mortality profiles from Bangga revealed that 64.28% (N = 42) of the sheep died within the first year of their life. This profile was consistent with Payne's Anatolian models for specialized management for milk. Simulations revealed that the same profile might be the product of low culling levels and high natural lamb death rates. In this high elevation, high-risk pastoral setting, specialization was a less probable interpretation than environmentally driven lamb mortality. Evidence for corralling at Bangga pointed to specific ancient disease and nutritional risks associated with periodic confinement and lack of access to pasture. Our findings indicate that high juvenile mortality presented a threat for ancient sheep herders who suffered serious environmental pressures on the Tibetan Plateau. Ethnographically grounded mortality simulations have utility for consideration of equifinality between culling and die off profiles constituting a global challenge in zooarcheological research.