Stable isotope analyses and early maize intensification at La Playa archaeological site (SON:F:10:3) Sonora, Mexico

This thesis presents analysis of Early Agricultural period diet from La Playa, Sonora, Mexico. The plants and animals consumed by a person can be explored through the analysis of stable carbon isotopes found in bone collagen and stable nitrogen isotopes found in bone apatite. Bone collagen provides an assessment of protein intake, while bone apatite reflects whole diet, including carbohydrates, fats, and proteins. Stable isotope data was obtained for fourteen individuals from La Playa. Each individual was previously radiocarbon dated and the sample represents two phases of the Early Agricultural Period, San Pedro phase and the Cienega phase, and the early Ceramic period. The resulting data from Isotope Ratio Mass Spectrometry (IRMS) analyses of bone collagen and apatite showed elevated δ 13 C and δ15 N values. This research explores potential causes for these elevated values, including an assessment of dietary reliance on important C4 and CAM plants. This includes the changing role of maize, a C4 plant. Elevated δ15 N values are considered through two possibilities: the incorporation of aquatic resources into diets, or local ecological conditions. Dietary variation between the San Pedro and Cienega phase is explored to address questions on changes in production and diet throughout the Early Agricultural period.