Nitrogen and Carbon Stable Isotope Analysis of Holocene Pigs from Liang Bua (Flores, Indonesia)

Abstract

In this study, pigs from Liang Bua (Flores, Indonesia) are examined using nitrogen and carbon stable isotopes to explore possible changes to their diet over the past ~5,000 years. This temporal period is of particular interest because major changes occurred at Liang Bua during this time and these changes are thought to be related to the dispersal of Austronesian people and/or culture. Most importantly, this research attempts to address whether pig diet changed in relation to the onset of farming activities in the area surrounding Liang Bua ~3 ka and, if so, in what ways. Stable isotope values (δ 13C and δ 15N) were obtained for 57 (39 bone, 18 tooth) pig specimens from Liang Bua that spanned in age from ~4,300 until ~400 years ago, and one horse and seven human samples from the site were used to provide a comparative context. Results of this study show that the δ 13C values of pigs and humans changed at Liang Bua after the onset of farming ~3,000 years ago, as did the δ 15N values of pigs. Changes in δ 13C values suggest that beginning after ~3,000 years ago, one or more types of C4 plants were consumed by pigs and humans, leading to more enriched δ 13C values compared with earlier populations. Foxtail millet, a C4 plant long associated with the dispersal of Austronesian people throughout island Southeast Asia, is the most likely candidate for a C4 plant used as an agricultural crop around Liang Bua during that time. Changes in the δ 15N values of pigs suggest that after ~3,000 years ago, the diet of some of the Liang Bua pigs was restricted, resulting in lower δ 15N values than observed among any pigs from earlier time intervals. Furthermore, these ‘captive’ pigs did not have access to the newly available C4 resources. The custom of keeping domesticated pigs in small enclosures and provisioning them with mostly C3 plants, practiced by Indigenous Manggarai people living around Liang Bua today, is the most likely explanation of these results.