Pre-Hispanic Maize Consumption in the South-Central Andes: Evidence from Organic Residues in Archaeological Pottery from Tinogasta (Catamarca, Argentina).

LANTOS, IRENE JOHANNA; SPANGENBERG, JORGE E.; MAIER, MARTA SILVIA; RATTO, NORMA

Tenerife

Congreso; 26th International Meeting on Organic Geochemistry (IMOG); 2013

European Association of organic Geochemists (EAOG)

Pre-Hispanic Andean societies depended economically to a large degree on the extensive horticultural production of maize (Zea mays), the main staple food crop in the region. Carbonized maize and maize-based food residues can be identified in archaeological ceramics by a combination of chemical and stable carbon isotope analyses of preserved lipids by using gas chromatographic and mass-spectrometric techniques [1, 2]. The fatty acids profile and the relatively high δ13C values characteristic of C4 plants can unambiguously pinpoint the presence of residual maize oil in archaeological artifacts. Archaeological finds at the West Tinogasta area in the Catamarca Province, NW Argentina record a long and discontinuous history of pre-Columbian human occupation from early hunter-gatherers to the Inka State in the south-central Andes. Here we report the results of the first chemical and isotopic analyses of organic residues in ceramic potsherds recovered from different sites at Tinogasta covering two distinct periods, the Formative Period (450-1020 cal. AD) and the Inka State Period (1400-1550 cal. AD) which overlaps with the first Hispanic contact. The results were compared with test samples derived from i) typical Andean food products including local maize landraces, beans (Phaseolus vulgaris), peppers (Capsicum annuum), and animal fat (native Lama glama and introduced Bos taurus), and ii) three replicate test pots used each for cooking traditional Andean maize-based recipes, such as locro, mazamorra and pochoclo. The extracted lipids were analyzed by TLC, GC-FID, GC-MS and GC-C-IRMS. The test food products showed a high concentration of triacylglycerols (TAG), low concentrations of diacylglycerols (DAG), monoacylglycerols (MAG) and free fatty acids (FFA), and significant amount of sterols. Relatively high amount of lipids were recovered from the test pots (18 to 0.25 mg/g) and the Tinogasta potsherds (0.5 to 0.05 mg/g). The test pots had higher concentration of DAG, MAG and FFA than the food products, due to degradation during cooking. The archaeological had mainly FFA and sterols, with low amounts of partially hydrolysed acylglycerols, most probably due to degradation at the burial site. The fatty acid concentration ranges and concentration ratios are given in Table 1. Andean maize landraces have similar profiles to commercial maize species, with high levels of oleic and linoleic acids. Archaeological samples compare favourably to test pots (Figure 1). The FA profiles are typical of degraded mixtures of vegetable oils (linoleic acid) and animal fats (myristic and stearic acids). Polyunsaturated acids tend to disappear in more degraded samples. Variability in the fatty acid profiles within the archaeological samples set suggest differences in the type of food products stored/cooked and use of the pots. The first results of the ongoing compound specific isotopic analyses showed high δ13C values for the main fatty acids in the archaeological samples, indicating that Pre-Columbian societies in the south-central Andes had maize and maize-based food as an important part of the daily diet.