Department of Anthropology, University of Tennessee, Knoxville
Thursday 8:30-8:45, Ballroom B
Mechanical loading and metabolism concurrently shape human cortical bone morphology and strength at both macroscopic and microscopic levels. As few studies have focused on how these environmental factors interact in humans, researchers continue to investigate mechanical and metabolic influences on bone as if they act independently. Assessing their interaction not only has implications for our understanding of bone biology, but also may affect behavioral analyses in bioarchaeological samples.
This study is the first large scale study of this potential interaction, using an archaeological human juvenile sample (n = 72) recovered from a medieval Lithuanian cemetery (Alytus). Juvenile bone responds strongly to both mechanical and metabolic effects, a dynamic that favors its use over adult bone. Macroscopic and microscopic bone morphology were assessed in three skeletal elements under different levels of biomechanical loading (i.e., femora, humeri, ribs) and compared among individuals under varying amounts of metabolic stress (utilizing skeletal stress markers). Analyses evaluated whether, in the presence of bone loss due to metabolic stress, bone mass and strength were preferentially maintained in skeletal elements under the highest biomechanical demands.
Results indicate that such a preferential maintenance may occur in cortical bone. Ribs exhibit significant reductions in macroscopic and microscopic bone mass with metabolic stress, while femora demonstrate minimal reductions, and humeri are intermediate. However, alterations in femoral and humeral cross-sectional shape may, in fact, compensate for reductions in mass. Nonetheless, the results caution researchers against evoking solely mechanical or metabolic causes for variation in cortical bone morphology.