Take a load off: skeletal implications of sedentism in the feet of modern body donors

Abstract

Background and Objectives: Modern biocultural environments continue to place selective pressures on our skeletons. In the past century, a major cultural pressure has been the rise in sedentism. However, studies considering the effects of sedentism on the foot have largely considered pathological changes to the gross foot without particular regard for the pedal skeleton. To address this gap in the literature, temporal trends in the development of osteoarthritis and entheseal changes on the tarsals and metatarsals were analyzed in the context of biodemographic data for recent modern humans. Methodology: The sample utilized for this project is comprised of 71 individuals from the William M. Bass Donated Skeletal Collection, with birth years ranging from 1909 to 1993. Temporal trends in osteoarthritis and entheseal changes were determined via ANCOVA, using year of birth as the explanatory variable and biodemographic variables (age, sex, stature, body mass index and tibial robusticity) as covariates. Results: Results indicate that entheseal changes and osteoarthritis have decreased over time, and these trends are statistically significant. Temporal trends in pedal entheseal changes and osteoarthritis vary by sex. Conclusions and Implications: The increase in sedentary behavior over time has usually been framed as a net negative for human health and well-being. However, considered in isolation, the decrease in entheseal changes and osteoarthritis presented here might be considered a positive development as they suggest overall less stress on the modern human foot. This study also has the potential to inform the health sciences and general public about biocultural contributors to modern foot health. Lay summary In the past 100 years, people in the USA have become increasingly physically inactive. This study shows that this trend has led to decreased foot osteoarthritis, as well as potentially decreased muscle mass and muscle usage in the foot and calf. These changes may be both positive and negative.