New Tools for Ancient Populations - Estimating Age-at-Death Distributions from Skeletal Remains

Jutta Gampe, Max Planck Institute for Demographic Research
George Milner, Pennsylvania State University
Jesper L. Boldsen, Syddansk Universitet
Svenja Weise, Max Planck Institute for Demographic Research

Paleodemography aims at identifying the demographic parameters of past populations. Information about individuals is mostly derived from archaeological finds and estimates of ages-at-death are obtained from the assessment of skeletal remains. In this paper we present new methodology, Calibrated Expert Inference, to estimate age-at-death distributions in paleodemography. We propose a novel age-indicator that avoids many problems of previously proposed indicators, such as poor preservation of some body parts or the need for multivariate calibration. This indicator is calibrated with a new method using generalized additive models for location, scale and shape (gamlss). The target age-at-death distribution is then estimated by a weighted maximum-likelihood approach. We present the accuracy and repeatability of the new age-indicator within and between observers, show the calibration results and demonstrate the validity of the method by using skeletons from two know-age collections.