Human skeletal asymmetry. A study of directional and fluctuating asymmetry in assessing health, environmental conditions, and social status in English populations from the 7th to the 19th centuries.

Abstract

Asymmetry is a useful tool for osteological analysis as it detects disruptions in the developmental stability of osseous structures attributed to environmental and biomechanical environments. The primary aim of this study is to establish a baseline for normal levels of asymmetry in English archaeological populations in order to distinguish between normal population variation and increased developmental instability or biomechanical stress. Directional and fluctuating asymmetry is assessed through a database of a comprehensive selection of osteological measurements throughout the skeletons of 1753 adults and subadults. The sample is from 11 archaeological sites spanning the Anglo-Saxon to the Victorian periods. The extent of developmental instability is also determined, for the first time, by employing the prevalence of population outliers. The normal range for directional asymmetry was found to be -5.79 to 6.62%, while fluctuating asymmetry was found to be 0 to 6.53%. The extent of asymmetry, however, was found to be trait specific. Deviations from normal population levels of asymmetry were found to be due to a complex mixture of biomechanical and environmental stresses influenced by age, sex, settlement type, socio-economic status, and period-specific origins of the sample populations. Possible causes of asymmetry could be discerned from comparisons of the levels of population asymmetry when placed in the context of physical activity, social networking, health, and environment developed from the historical, archaeological and osteological record.