Feasting on fish. Specialized function of pre-colonial pottery of the Cerritos mound builders of southern Brazil

Abstract

Some of the oldest coastal pottery in South America is found in the Pampas region of southern Brazil, Uruguay and Argentina. In the region's extensive estuarine systems pre-colonial indigenous groups built earthen mounds, known as Cerritos, from ca. 4700 BP. The Cerritos have multifunctional purposes, and while pottery was widely used, its role in the economic or ritual life of the mound builders remains uncertain. Intriguingly, molecular and isotopic characterization of food residues from Cerritos ceramics shows that vessels were used for either cooking estuarine fish, or plant products. Microbial-derived lipids were predominantly associated with the latter, suggesting that plants were fermented, presumably to make alcoholic beverages. We suggest that dispersed communities were drawn to the mounds seasonally to exploit and celebrate the return of migrating fish. This finding is supported by the diversity of stable isotope values of human remains recovered from Cerritos and sheds new light on the lifeways of these pre-colonial groups.

Fig 1. Map of South America, with the location of Cerritos sites in Patos Lagoon (yellow), study site highlighted in red.

Map generated using ArcGIS 10.8 and Inkscape 1.1.2. We used publicly available data (CC BY 4.0) data from World Bank’s Data Catalog (https://datacatalog.worldbank.org/search/dataset/0038272/World-Bank-Official-Boundaries), Flanders Marine Institute (www.marineregions.org), and NASA/JPL-Caltech (adapted from https://www.jpl.nasa.gov/images/pia03388-south-america-shaded-relief-and-colored-height).

Fig 2. Carbon isotope values of palmitic (C_16:0) and stearic (C_18:0) acid of Cerritos ceramics from Pontal da Barra.

Red = PSG-02; yellow = PSG-07, against 68% confidence ellipses based on modern reference materials (see S2 Table) and as a density plot illustrating the two use categories of Cerritos pottery. Star shapes refer to samples containing aquatic biomarkers in the form of APAAs with a C_20/18 ratio of >0.06 [27], symbol size reflects lipid concentrations.

Fig 3. Overview of lipid residue biomarker and isotope results.

Individual samples from PSG-02 and PSG-07 shown in columns, rows reflect interpretation of the samples as aquatic, maize and/or C₃ plants; the potential of mixing in samples based on the offset of the isotopic values of C_16:0 and C_18:0 fatty acids [45]; lipid concentration (> 100 μg ^-1); presence of heating markers: APAAs, ketones, and retene [28]; hopanes [35]; plant biomarkers (sterols, terpenes, APAA E/H ratio [27], and high % C_12:0 reflecting the potential presence of palm products [30]; P/S ratios over 4 from fatty acids and reconstituted P/S ratios from ketones [37]; the presence of n-dotriacontanol [40]; abietic acid and derivatives [34]; high and low δ¹³C values of fatty acids and ketones (the latter only in sample 771); and the presence of aquatic biomarkers (APAAs C_20/18 ratio > 0.06, and SRR isomer >75.5% [31]).