Ageing the 40+ category: testing the ageing method for the sternal end of the clavicle

Estimating the age of individuals becomes increasingly more difficult with advancing age due to the effects of life history, random individual variation and the genetic framework. This makes it also increasingly more complicated to relate chronological and biological age, and thus to estimate age-at-death above approximately 45 years. In 2015 however, Dr. C.G. Falys and Dr. D. Prangle published a newly developed method to estimate age of older adults specifically, based on the sternal end of the clavicle. The method evaluates the degeneration of three distinct features: surface topography, porosity and osteophyte formation. These features are scored individually, after which these scores are added up to form a composite score, which is used to ascribe an age stage to an individual. This thesis has aimed to test this method on a post-medieval Dutch skeletal collection with individuals of known ages-at-death from the 18th-19th century. The collection originates from a cemetery in...Show moreEstimating the age of individuals becomes increasingly more difficult with advancing age due to the effects of life history, random individual variation and the genetic framework. This makes it also increasingly more complicated to relate chronological and biological age, and thus to estimate age-at-death above approximately 45 years. In 2015 however, Dr. C.G. Falys and Dr. D. Prangle published a newly developed method to estimate age of older adults specifically, based on the sternal end of the clavicle. The method evaluates the degeneration of three distinct features: surface topography, porosity and osteophyte formation. These features are scored individually, after which these scores are added up to form a composite score, which is used to ascribe an age stage to an individual. This thesis has aimed to test this method on a post-medieval Dutch skeletal collection with individuals of known ages-at-death from the 18th-19th century. The collection originates from a cemetery in Middenbeemster, Noord-Holland, and is well-documented due to the availability of a cemetery ledger and military document describing names, ages, sexes, marriages, etc. of many individuals. Out of the 118 individuals listed in these archival records, 57 individuals were suitable for this analysis (98 clavicles). The overall levels of agreement between the three different observers were calculated using Cohen’s kappa (k), which revealed a relatively low agreement, varying from slight to moderate (k = 0.100 to 0.534). Fortunately, these results did not influence the accuracy of the method greatly, which varied between 87% and 94%, depending on the side chosen to estimate age. Unfortunately the age ranges that are used in the method are too large for the method to be deemed precise. Previously existing methods are however not at all capable of subdividing the 45+ category into smaller stages. Although the age stages are large, the method is thus capable of recognizing the older members within a society and place them into a more specific age class than other methods currently can. The method does need more testing and revising, but can currently be concluded to accurately estimate olders adults’ ages-at-death in Dutch post-medieval collections.Show less

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Ageing the 40+ category: testing the ageing method for the sternal end of the clavicle