1Département d'anthropologie, Université de Montréal, 2Department of Anthropology, University of Northern British Columbia, 3Department of Anthropology, Boise State University
March 27, 2015 , Archview Ballroom
Bone remodeling has been proposed as a mechanism to repair microdamage and, as a consequence, it is expected to be higher in bones that incur larger or more loading events. Handedness in humans, in which one upper limb is favored relative to the other, is a natural experiment of different loading environment while controlling for all other factors that can influence remodeling (age, diet, sex, etc.). In this study, we test for correlations between the asymmetry of bone cross-sectional geometry and bone remodeling in the human second metacarpal (MC2). We use right and left cross sections from two archaeological samples (Eurocanadians = 59, Inuit = 23, total=82) and measured total and cortical areas, second moment areas (Imin, Imax, Iml, Iap) and polar moment of inertia (J). Osteon population density (OPD) was measured on the medial, anterior, lateral and posterior quadrants. We expected that larger cross sections would be characterized by greater remodeling. However, we found that right-left % differences of all macroscopic variables were negatively correlated with OPD. Closer inspection of the sample revealed that the correlation was observed only on the medial quadrant and only for the Inuit subset of our sample. The Inuit MC2s are characterized by relatively thin cortex, particularly on the medial side. We conclude that remodeling does not directly reflect external loading history, but may, instead, be differentially needed only in areas that are relatively weaker or in areas that are highly strained due to the proximity of muscle insertions.
This study was funded in part by NSERC and UNBC Seed grant (to RAL) and by FQRSC and CFI (to MSMD).