Improved Skeletal Age-at-Death Estimation and its Impact on Archaeological Analyses
Open Access
- Author:
- Getz, Sara Marie
- Graduate Program:
- Anthropology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 25, 2016
- Committee Members:
- George R. Milner, Dissertation Advisor/Co-Advisor
George R. Milner, Committee Chair/Co-Chair
James W. Wood, Committee Member
Joan T. Richtsmeier, Committee Member
Neil A. Sharkey, Outside Member
Jesper L. Boldsen, Special Member - Keywords:
- Transition Analysis
age-at-death estimation
skeletal aging
biological profile
paleodemography
forensic anthropology
adult skeleton - Abstract:
- Skeletons are the most direct way to study long-term trends in longevity, mortality patterns, and disease experience for much of human existence. Adequate age estimates can be produced for children and young adults, but such estimates for most of adulthood remain elusive. This four-phase dissertation is a large-scale proof-of-concept that accurate and precise age estimates can be produced for all of adulthood without the two most widely used skeletal indicators—the pubic symphysis and auricular surface. This work builds on over two decades of research by an international research team and an existing age-estimation method called Transition Analysis (TA). In Phase 1, more than 200 trait variants were investigated to identify and refine a set of age-informative features throughout the skeleton, and primary reference data were collected from four collections of modern, known-age North American skeletons (N=1010). In Phase 2, a simplified procedure based on existing TA was developed to produce age estimates from Phase 1 reference data. In Phase 3, standard age-estimation methods and new TA were applied to additional known-age samples—one modern and one historical. In both samples, the estimates produced by new TA have similar accuracy to traditional methods, but the ranges are, on average, half as wide and show essentially no systematic point estimate bias. In Phase 4, traditional methods and new TA were applied to two Danish archaeological samples. Comparing the Phase 3 and 4 samples reveals that each traditional method produces a characteristic pattern of adult mortality that is practically independent of the age distribution of the sample. Thus, all mortality profiles generated for past populations using traditional techniques should be viewed with critical skepticism. In contrast, new TA produces mortality distributions that more closely approximate reality, including details that could not be detected using traditional techniques. This dissertation, in conjunction with a larger NIJ-funded research project using the same approach for geographically diverse modern populations, provides every indication that the new TA procedure may become the new gold standard for adult age estimation.