Age and Sex Composition of Zooarchaeological Measurements via Bayesian Mixture Models

Summary

Zooarchaeologists reconstruct age- and sex-specific animal mortality profiles in order to examine past human strategies of animal exploitation. Traditionally, animal age structures and sex ratios were derived from complementary but distinct data (e.g., age via epiphyseal fusion data, sex via bone morphology or metrics), though recent research has highlighted the value of integrating these data. This paper describes how zooarchaeologists can further that integration by fitting standard zooarchaeological measurements to mixture models via Bayesian inference. Bayesian inference emphasizes the probabilistic nature of sex identifications (inherent in all zooarchaeological analyses), which can be used to estimate sex proportions of different subsets of the assemblage via Monte Carlo integration. It also provides a flexible framework for incorporating prior knowledge about mortality patterns and comparing competing hypotheses about exploitation patterns. This paper demonstrates the utility of Bayesian mixture models using sheep (Ovis aries) remains from the Neolithic site of Catalhoyuk (Turkey; ca. 7200-6500 cal BCE). The model provides age and sex proportions for both the hunted and the herded sheep populations. Bayesian mixture models can thus explore synchronic and diachronic changes in the composition of herds in a straightforward manner that relies on commonly recorded zooarchaeological evidence.

This Resource is Part of the Following Collections

• Society for American Archaeology 81st Annual Meeting, Orlando, FL (2016)   •
• New Methods in Zooarchaeology

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