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Nasty, Brutish, but Not Necessarily Short: A Reconsideration of the Statistical Methods Used to Calculate Age at Death from Adult Human Skeletal and Dental Age Indicators

Published online by Cambridge University Press:  20 January 2017

Robert G. Aykroyd ,
David Lucy ,
A. Mark Pollard  and
Charlotte A. Roberts
Robert G. Aykroyd
Affiliation:
Department of Statistics, School of Mathematics, University of Leeds, Leeds LS2 9JT, England
David Lucy
Affiliation:
Department of Archaeological Sciences, University of Bradford, Bradford BD7 1DP, England
A. Mark Pollard
Affiliation:
Department of Archaeological Sciences, University of Bradford, Bradford BD7 1DP, England
Charlotte A. Roberts
Affiliation:
Department of Archaeological Sciences, University of Bradford, Bradford BD7 1DP, England
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Abstract

It is generally assumed that life expectancy in antiquity was considerably shorter than it is now. In the limited number of cases where skeletal or dental age-at-death estimates have been made on adults for whom there are other reliable indications of age, there appears to be a clear systematic trend towards overestimating the age of young adults, and underestimating that of older individuals. We show that this might be a result of the use of regression-based techniques of analysis for converting age indicators into estimated ages. Whilst acknowledging the limitations of most age-at-death indicators in the higher age categories, we show that a Bayesian approach to converting age indicators into estimated age can reduce this trend of underestimation at the older end. We also show that such a Bayesian approach can always do better than regression-based methods in terms of giving a smaller average difference between predicted age and known age, and a smaller average 95-percent confidence interval width of the estimate. Given these observations, we suggest that Bayesian approaches to converting age indicators into age estimates deserve further investigation. In view of the generality and flexibility of the approach, we also suggest that similar algorithms may have a much wider application.

Résumé

Résumé

Está generalmente aceptado el postulado de que la expectativa de vida en la Antigüedad fue considerablemente más corta que la de ahora. En algunos casos, cuando era posible comprobar la edad estimada de adultos al momento de su muerte según el esqueleto y la dentadura era posible comprobarla con otros indicadores fiables de su edad, se nota una clara tendencia metodológica hacia la sobreestimación de la edad de adultos jóvenes y hacia la subestimación de edad en personas mayores. Demostramos que aquello puede ser resultado de la aplicación de técnicas de análisis que se utilizan para convertir indicadores de edad en edades estimadas. Reconociendo las limitaciones de la mayoría de los indicadores para determinar la edad en el momento de la muerte para las personas pertenecientes a las categorías de edades avanzadas, demostramos que el método Bayes utilizado para convertir indicadores de edad en la edad estimada, puede reducir tales tendencias de subestimación a edades avanzadas. Demostramos también que un método como el de Bayes siempre es mejor que cualquier método basado en la regresión, asegurando un menor promedio de diferencia entre la edad pronosticada y la edad conocida, así como el menor promedio de un confianza de 95% intervalo de amplitud de estimatión. Tomando en consideratión esas observaciones, proponemos que los métodos Bayes para recalcular los indicadores de edad en la edad estimada merezcan una investigatión adicional. Teniendo en cuenta la universalidad y la flexibilidad del método, pronosticamos también que los algoritmos similares puedan tener una aplicación mucho más amplia.

Type
Reports
Information
American Antiquity , Volume 64 , Issue 1 , January 1999 , pp. 55 - 70
Copyright
Copyright © The Society for American Archaeology 1999

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