The Femoral Midshaft Index as Evidence of a Transition in Mobility Patterns in the Chalcolithic and Bronze Age Populations of Anatolia

Abstract

Several studies have demonstrated mechanical loading to be associated with activity patterns such as human subsistence strategies and to generate an adaptive response in bone. The femoral midshaft index (FMI), also known as the pilasteric index, is used to infer functional loading effects on the femur to indicative of bone strength as a product of physiological loading. FMI is calculated by dividing the femoral midshaft anteroposterior (AP) diameter by its mediolateral (ML) diameter; measurements are taken from the periosteal surface. This research examines FMI in Chalcolithic and Bronze Age populations across Anatolian regions to observe changes in midshaft geometry and test correlations with spatiotemporal and sociocultural transformations. The FMI data were sourced from published literature containing post-cranial measurements of anatomically modern humans from the populations of interest. Overall, FMI in the Anatolian region declined over time, with the exception of Central Anatolian sites where FMI increased through the Chalcolithic to Early Bronze Ages before decreasing during the Middle Bronze Age. Fluctuations in FMI during the transition from the Chalcolithic and Bronze Ages correlate to the gradual lifestyle changes in the region, with sociocultural transformations being linked to the development of new activities. The observed overall decline in FMI correlates to the archaeological evidence, which depicts a local decline in pastoral communities and development of complex export-driven villages