1Biological Sciences, Marshall University, 2Human Origins Program, Department of Anthropology, National Museum of Natural History, Smithsonian Institution, 3Center for Functional Anatomy and Evolution, Johns Hopkins University
April 15, 2016 , Atrium Ballroom A/B
Despite a complex relationship between mechanical loading and skeletal morphology, reductions in diaphyseal cross-sectional strength and epiphyseal trabecular bone density have been consistently observed among Holocene humans and attributed to a decline in physical activity. Recent work on a limited number of samples also suggests that trabecular bone density (i.e., bone volume fraction) of the femoral head is lower among more sedentary agricultural populations than among foragers. These findings imply that activity levels have a significant effect on trabecular bone morphology. However, the extent to which trabecular bone density differs among groups with varying activity levels (i.e., farmers, urban-industrial dwellers, foragers, and populations transitioning from foraging to farming) and the variation across multiple skeletal elements is still unclear. This study tests the hypothesis that sedentary populations will exhibit lower trabecular bone density than active populations across elements.
We measured trabecular bone density in lower and upper limb articulations of recent (Holocene) modern humans (five population samples, N=120) using peripheral Quantitative Computed Tomography. Our results show that the active groups have significantly greater trabecular bone density in most limb elements of the upper and lower limb than the sedentary groups from different geographic locations. This result indicates that a decline in activity levels associated with the adoption of agriculture and industrialization contributed significantly to the reduction in trabecular bone density in recent modern humans. In addition, joint size did not have a correlation with activity type across elements, suggesting that articular surfaces are not environmentally plastic.
Research was supported by the Peter Buck Postdoctoral Fellowship through the National Museum of Natural History, Smithsonian Institution.