Decontaminating Archaeological Dental Calculus: A Protocol for Reliable Extractions

Summary

This is an abstract from the "SAA 2019: General Sessions" session, at the 84th annual meeting of the Society for American Archaeology.

During dental calculus formation, mineralization preserves microbotanical remains. These provide paleoenvironmental and dietary information. However, modern contaminants on archaeological samples overlap with target species thus necessitating decontamination procedures. We present an efficient protocol to avoid the presence of contaminants: a) testing the efficacy of Sodium hydroxide, calcium hydroxide, sodium EDTA and alpha-amylase when degrading starch polymers; b) synthetizing artificial dental calculi, from co-precipitating ammonium phosphate and calcium chloride; c) decontaminating samples under controlled conditions; and d) decalcification with EDTA and hydrochloric acid. Precipitation of synthetic calcium phosphate entrapping potato starches simulated the mineralization process in the oral cavity. These matrices were contaminated with a corn-glycine solution (1ml: 1.11M-2.66 M) to simulate the effect of modern contaminants. The immersion of samples in sodium hydroxide (1ml: 0.5M) for 24h, and deionized water (15ml), eliminated the corn granules. Starches originally trapped in the matrices remained undamaged, showing higher resistance to enzymatic and chemical reactions. Calculi were then decalcified using EDTA (1ml: 0.5M) and hydrochloric acid (1.5ml: 0.5M). This protocol has been applied to decontaminate calculi from a late Holocene Congolese individual, with a known C4-dominated diet, demonstrating the elimination of modern contaminants allow stronger paleo reconstructions.

This Resource is Part of the Following Collections

• Society for American Archaeology 84th Annual Meeting, Albuquerque, NM (2019)

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Record Identifiers

Abstract Id(s): 25015