Preadult diets in the prehistoric Lima-city: Stable isotopes from Huaca 20 (620–780 CE), Maranga Complex, Peru

Using stable isotope and Bayesian Mixing Models, this study aims to understand the preadult dietary patterns of human individuals from Huaca 20 (H20, 620–780 CE), a residential sector of the main urban center in the lower Rimac Valley of the Peruvian Central Coast. Due to preservation issues, a practical approach was employed to understand the diet of this population, using data for δ¹³C and δ¹⁵N obtained from the dentine of anatomic tooth segments of 20 adult individuals, which were analyzed by sex and broad life-stages (i.e., infant, child, adolescent). We then conducted individual paleodietary reconstructions using a Bayesian Mixing Model to obtain the quantitative contribution of four food groups. The results indicate that this population relied on a mixed diet mainly composed of C₄ (maize) and C₃ resources complemented with marine protein in variable proportions, and minimal contributions of terrestrial protein. Maize and C₃ resources were the main foods during infancy and childhood of these adults, whereas the diet during adolescence shows more marine protein, possibly more similar to the adult diet of this community. This isotopic evidence from Huaca 20 suggests the use of specific infant feeding strategies.