The stable isotope ecology of early (3100 B.P.) hunter-gatherers/farmers from Tula, Tamaulipas, Mexico. Isotopic evidence in bone and teeth

The objective of the present work is to reconstruct the subsistence strategies of an early transitional hunting-gathering/farming population living in dry caves in the southwestern region of Tamaulipas, northeastern Mexico. Specifically, a sample of 12 human individuals from the mortuary cave, Sepultura Cave (TCS) dating to 3100 B.P., is analyzed for stable isotope ratios of carbon, nitrogen, and oxygen. To obtain a nuanced understanding of the lifeways of this population, bone and dentine samples from each individual are analyzed to reconstruct how dietary practices changed over throughout life. Overall, the stable carbon isotope results suggest a high amount of C4 or CAM plant consumption, the stable nitrogen isotope results are consistent with terrestrial omnivory within an arid environment, and the stable oxygen isotope suggest the presence of two non-local individuals. Our results indicate small differences of diet between the individuals, probably reflecting variable stages of mixed economies of hunting-gathering and low intensive agriculture even though consumption of maize is difficult to differentiate from consumption of collected or managed CAM plants.