Estudos isotópicos da dieta Guarani e a cadeia trófica associada à bacia do rio Taquari, Rio Grande do Sul

In this study we present the results of isotopic analysis (δ13C, δ15N y δ18O) of human and faunal bones recovered in Guarani archaeological sites located in the rainforest of the center of the state of Rio Grande do Sul (Brazil). The isotopic values obtained in prey reflect a predominantly C3 or monoisotopic C3 pattern, both among herbivores and terrestrial omnivores, while a mixed pattern is observed for fish. The values of the spacing of the carbon sources and the values of δ15N reflect differences between each respective guild, which are within expected values. Humans have a diet based mostly based on C3 proteins and minor contribution of C4 proteins, with a significant intake of C4 carbohydrates, which, given the archaeological context, must correspond to the consumption of maize. The isotopic values of the diet of humans are equivalent to those observed in other individuals recovered at sites of this archaeological unit, located in other regions of Brazil as well as in Argentina and Paraguay. The results obtained in oxygen-18 are those expected for the region east of the Uruguay River, whose surface water comes from the precipitation of the Intertropical Convergence Zone and the South Atlantic Convergence Zone