Late Holocene dietary and cultural variability on the Xingu River, Amazon Basin: A stable isotopic approach

Abstract

Although once considered a 'counterfeit paradise', the Amazon Basin is now a region of increasing interest in discussions of pre-colonial tropical land-use and social complexity. Archaeobotany, archaeozoology, remote sensing and palaeoecology have revealed that, by the Late Holocene, populations in different parts of the Amazon Basin were using various domesticated plants, modifying soils, building earthworks, and even forming 'Garden Cities' along the Amazon River and its tributaries. However, there remains a relatively limited understanding as to how diets, environmental management, and social structures varied across this vast area. Here, we apply stable isotope analysis to human remains (n = 4 for collagen, n = 17 for tooth enamel), and associated fauna (n = 61 for collagen, n = 28 for tooth enamel), to directly determine the diets of populations living in the Volta Grande do Rio Xingu, an important region of pre-Columbian cultural interactions, between 390 cal. years BC and 1,675 cal. years AD. Our results highlight an ongoing dietary focus on C3 plants and wild terrestrial fauna and aquatic resources across sites and time periods, with varying integration of C4 plants (i.e. maize). We argue that, when compared to other datasets now available from elsewhere in the Amazon Basin, our study highlights the development of regional adaptations to local watercourses and forest types.

Fig 1. Map showing the location of the Amazon rainforest (darkest part), and archaeological sites of study in the Volta Grande do Rio Xingu (red points).

The map was created for this study by Renato Gonzalez (Geoprocessing Analyst for the Scientia Consultoria Científica, Brazil) using QGIS 3.2.4 https://qgis.org/pt_BR/site/ and the Natural Earth Database from https://visibleearth.nasa.gov/images/147190/explorer-base-map (Landsat images courtesy of NASA Goddard Space Flight Center and US Geological Survey).

Fig 2. Dates from archaeological sites from VGRX.

Most were occupied in the last millennium. Calibrations performed online using OxCal 4.4.4.

Fig 3. Fauna bulk bone collagen δ¹³C and δ¹⁵N results for VGRX.

Fig 4. Fauna and human bulk bone collagen δ¹³C and δ¹⁵N results grouped by diet for VGRX.

Fig 5. Faunal bulk tooth enamel δ¹³C and δ¹⁸O for VGRX.

Fig 6. Faunal and human bulk tooth enamel δ¹³C and δ¹⁸O grouped by diet for VGRX.

Fig 7. δ¹³C_co and δ¹⁵N values of archaeological human bones from VGRX, Marajó, Maracá, São Luis and Ucayali.