The New Coimbra Method for Recording Entheseal Changes and the Effect of Age-at-Death

Abstract

Entheseal changes have been widely used in anthropology to study activity patterns, but there is an increasing awareness that ageing is associated with these changes. The aim of this study was to test each feature of the new Coimbra method for its variability, side asymmetry and its relationship with age. In addition to this, an overall relationship with age was tested for a larger sample. Males 16 and over from the Coimbra skeletal collection of historically identified individuals were recorded using the new method (N = 260). To reduce the impact of occupation, side variability in asymmetry and age were only tested in the labourers (N = 51). All occupation groups were included to test the overall relationship with age using a random forest test. The results show that scores lack variability for many of the features and entheses. Where there is side asymmetry this is typically in favour of higher scores in the right side, excepting the biceps brachii insertion. Most of the features scored show a relationship with ageing, but this is not uniform for all features or entheses. Some features are associated with an increase in age (bone formation and erosions), while others generally occur in younger individuals (fine porosity and textural change). Logistic regression showed that ageing explains at most 44% of the variability. This alongside the side asymmetry may indicate that biomechanics has an explanatory role.