Reconstructing Human Paleodiet with Stable Isotopes at Ille Cave and Rockshelter, Dewil Valley, El Nido, Palawan, Philippines

John Krigbaum1, Michelle S. Eusebio2*, Myra C. Lara3, Jack Gilbert L. Medrana4, Victor J. Paz2†, and Helen Lewis5

The Palawan Island Pre-/Palaeohistory Research Project (PIPRP), focused on northern Palawan, Philippines, was established to better understand dynamics of Holocene human-environment interactions and human adaptation, including patterns of foraging in island Southeast Asia. Nine samples of human remains of eight individuals from the Ille Cave and Rockshelter site were analysed for stable isotope ratios to assess patterns of foraging in light of known faunal and floral evidence recovered from the site. In addition to the assayed bone samples, tooth enamel from two individuals were sampled for radiogenic isotopes including strontium and lead isotope ratios. For the light isotopes, bone collagen yields were surprisingly good (C:N ranged from 3.2 to 3.4) with stable carbon ratios averaged -19.2 (±0.26) per mil and nitrogen ratios averaged +10.6 (±0.61) per mil. These data strongly support a C3 terrestrial diet with a strong marine component. To complement the bone collagen results, bone apatite or ‘bioapatite’ was assayed from these same samples and stable carbon ratios averaged at -13.8 (±1.21) per mil. Carbon apatite-collagen spacing for these samples averaged at +5.4 (±1.55), which suggests differences in carbohydrate source between individuals. Isotopic data presented are situated against contextual evidence from the site regarding broad spectrum foraging and are presented in comparison to data from other prehistoric Holocene contexts in the region.