Bulk and amino acid isotope analyses of hair detail adult diets and infant feeding practices among pre- and post-maize populations of the northern Chilean coast of the Atacama Desert

This study investigates diet heterogeneity among Chinchorro and Inca adults and subadults living on the northern Chilean coast of the Atacama Desert before and after the introduction of maize cultivation. This is achieved by amino acid carbon isotope analysis and bulk carbon, nitrogen, and sulphur isotope analysis of 1-cm sequential segments of scalp hair from human remains deposited at the funerary sites of Morro 1 and 1–6 (Archaic Period) and Camarones 9 (Late Period). Results show that Chinchorro adults relied predominantly on marine resources and partially on wild plants. Inter-individual variability in diet was limited, indicating food redistribution between sexes. Childhood and adolescent diets were comparable to those of the adults. Partial breastfeeding was continued up to the age of 2–3 yrs. Subsequently, Inca adults relied on a combination of marine resources and maize. Intra- and inter-individual variability in diet was limited suggesting existence of a centralised system of food procurement and redistribution. Childhood and juvenile diets were comparable to those of the adults, except for two malnourished children being raised on maize. Amino acid δ13C analysis of hair keratin is proposed as a potential tool for reconstructing the nutritional status of an infant without population-specific maternal isotope baseline.