Archaic grinding stone tools in the basin of Mexico. A study through use-wear analysis and micro-residues

Abstract

This study reevaluates one of the most poorly understood periods in the archaeology of the Basin of Mexico through microscopic functional analysis and residue identification on grinding tools from the San Gregorio, Atlapulco site. To achieve this, experimental work was conducted using various plant species, fruits, and tubers identified via starch analysis, creating a reference catalog for comparison with our archaeological assemblage.

This approach identified artifacts used for plant processing, revealing starch grains from Ipomoea batatas, Phaseolus vulgaris, Zea mays, Physalis sp., Capsicum sp., and Dioscorea sp. through residue analysis. Use-wear traces, including pits, micro-striations, and micro-polishes, suggest brief but intense grinding activities on the surface of these materials. These findings indicate that the diet of these societies was based on the collection of plants and lakeshore plain resources, supplemented by the consumption of domesticated plants like maize during a period of climatic improvement preceding the emergence of the earliest ceramics in central Mexico, specifically during the Atlapulco Phase (ca. 4200–3800).