Degenerative variance on age-related traits from pelvic bone articulations and its implication for age estimation

Age at death estimation methods, when applied to skeletal remains of adults, have provided inaccurate results. These aging methods often depend on observations of the degenerative changes occurring at specific articulations, however, the effects of the aging process on the human skeleton are only partially known. Therefore a need exists to increase our understanding about the age related metamorphosis process to improve aging methods. The aim of this study is to determine which age-related traits observable on the pelvic bone articulations are correlated and to quantify their shared degenerative variance. Thus it is intended to quantify the degenerative relationship among features within each pelvic joint. Fifteen age related traits were analyzed for the pubic symphysis, eight traits for the auricular surface of the ilium, and six traits for the acetabulum. Age-related traits from the pelvic joints were recorded on adult skeletons from two reference collections the William Bass Donated Skeletal Collection and the Coimbra Collection. A Principal Components Analysis, partial correlation controlling for age, and a Kendall's W coefficient of concordance were calculated to determine the level of dependence among traits. A similar pattern of correlation amongst traits was obtained for both collections. Some of the traits shared a high to moderate correlation. However, some features, such as dense bone at the auricular surface, possessed a high independence from other traits. Results suggest that age estimation methods should take into consideration how age-related traits correlate and their level of dependence, which may possibly assist in the establishment of more effective scoring systems in new and revised age at death estimation methods.