Low trabecular bone density in recent sedentary modern humans

ObjectivesResearch on a limited number of samples suggests that trabecular bone density (i.e., bone volume fraction, BVF) within specific articulations is lower among more sedentary Holocene agricultural populations compared with Holocene foragers, implying that activity levels have a significant effect on trabecular BVF. However, it is unclear to what extent BVF differs among groups with varying activity levels and how general this phenomenon is across multiple limb articulations. Here, we test two hypotheses that: (i) sedentary populations have lower BVF compared with active populations across limb articulations; and (ii) these declines are more uniform in the lower limb (because of its more direct relationship to mobility), and more variable in the upper limb. Materials and MethodsWe estimated BVF in seven lower and upper limb articulations of five Holocene population samples with subsistence strategies spanning from foraging through horticultural to industrial using pQCT (peripheral Quantitative Computed Tomography). ResultsBoth hypotheses are largely supported. First, the most active groups have significantly greater BVF in most limb elements compared with more sedentary groups. Second, all sedentary groups have relatively similar (and lower) BVF in the lower limb but show more variation in upper limb articulations. ConclusionsThese results suggest that a decline in activity levels associated with the adoption of agriculture and industrialization significantly contributed to the reduction in BVF in recent modern humans, but specific behavioral changes, particularly in the upper limb, also affected these patterns.