The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

New estimates for ages in historic Italian populations derived from Bayesian analysis: pubic symphyses


1School of Natural Sciences, School of Social Sciences, Humanities, and Arts, University of California, Merced, 2Department of Anthropology, University of Tennessee, Knoxville, 3Departmento of Anthropology, California State University, Sacramento

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Age estimation is experiencing intensified interest as anthropologists recognize the advantage provided by statistical modeling of skeletal indicators. Thus, visual examination and phase assessment have been improved upon by implementation of Bayesian analysis. In our prior work, we presented both a forensic and Rostockian approach to Bayesian age estimation from pubic symphyses. The purely methodological focus of our Rostockian analysis prevented us from presenting lookup tables with revised age estimates for historic Italian populations. The age estimates reported here are derived from the Rostockian analysis, with demonstrated accuracy at 50%, 75%, 90%, and 95% confidence levels.

The test sample in our Rostockian analysis is comprised of turn of the 20th Century blue-collar workers excavated from a cemetery in Sardinia, Italy. Individuals from the Terry Collection were the best fit for transition analysis. Another historic Italian sample (Torino), which is contemporary to both Terry and Sardinia, functioned as the prior. Transition analysis parameters from the Terry Collection were obtained from published sources and a Gompertz hazard model best described the Torino prior. The hazard and transition analysis parameters were input into Bayes’ Theorem to calculate probability density functions (PDF), and subsequently, highest posterior density regions (HPDR). In our previous research, we tested the accuracy of the HPDRs from Terry and Torino on the target sample (Sardinia), finding 50%, 75%, 90%, and 95% accuracy, depending on the desired coverage. Here, the HPDR values are tabulated to provide an easy reference for estimating age from pubic symphysis phase in modern historic Italian populations.

The data collection was facilitated by a grant for Samantha M. Hens from the Office of Research and Sponsored Projects, California State University, Sacramento.

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