Inter-population differences in acetabular senescence: relevance in age-at-death estimation

Since investigation of the timing of the skeletal traits among the acetabula of different populations is lacking, this study aims to evaluate the relevance of geographical origin in the acetabulum aging process and in the usability of the SanMillán-Rissech aging method. The acetabula of 826 European North Americans derived from the Bass Collection (USA) have been analyzed and compared with 611 Portuguese acetabula from the Luis Lopes Collection (Portugal) applying the most updated acetabular age estimation technique (2017). After evaluating and comparing the acetabular aging rates between both populations by Mann-Whitney U tests, the inaccuracy values (bias and absolute error) were analyzed and compared using population-specific reference samples and using references differing in geographical origin by Wilcoxon tests. In general terms, the North Americans age faster than the Portuguese, especially the females, reaching the consecutive acetabular stages at younger ages. Regarding the SanMillán-Rissech method accuracy, using population-specific reference samples produces, as a general rule, better outcomes. In addition, an exhaustive meta-analysis of inaccuracy values has demonstrated that this method provides better estimation values than pubic symphysis and auricular surfaces regardless of the geographic coherence of the reference sample. These inter-population skeletal differences are derived from different factors than age, highlighting the impact of both biological and social background on age estimation. A thorough analysis of the skeletal age-based timing becomes essential to understanding, deciphering and being able to minimize bias and potential inaccuracy or even counteract them when applying the age estimation methods to different populations.