Isotopic investigation of skeletal remains at the Imdang tombs reveals high consumption of game birds and social stratification in ancient Korea

Understanding the development of early states on the Korean Peninsula is an important topic in Korean archaeology. However, it is not clear how social structure was organized by these early states and what natural resources were utilized from their surrounding environments. To investigate dietary adaptation and social status in ancient Korea, stable isotope ratios and radiocarbon dates were measured from humans and animals from the Imdang cemetery, Gyeongsan city, South Korea. The results indicate that the Imdang diet was mainly based on C(3) plants and terrestrial animals. Animal remains in the graves were directly consumed as daily food items as well as for ritual offerings. MixSIAR modeling results revealed that the dietary sources for the humans were: game birds > C(3) plants > terrestrial herbivores > marine fish > C(4) plants. The finding that the game birds represented the highest contribution to the whole diet, indicates that game birds must have been intensively hunted. Furthermore, elites consumed more game birds than their retainers and they also consumed seafood as a privileged dietary item in the Imdang society. This study demonstrates that the Apdok was a stratified society having high variations in the consumption of food items available to an individual and provides new insights about the subsistence and social status of the early ancient Apdok state on the Korean Peninsula.