Department of Anthropology, University of Massachusetts Amherst
March 27, 2015 , Archview Ballroom
Femoral and tibial diaphyseal geometry has been used extensively to evaluate physical activity patterns in past populations, in particular mobility. The high antero-posterior (A-P) to medio-lateral (M-L) bending strength ratio (eg. Ix/Iy) typical of many hunter-gatherer femora, for instance, may reflect mechanical loads associated with long distance travel. The possible confounding effects of physical terrain on lower limb bone shape is rarely evaluated. This study investigates the possible effect of terrain on lower limb bone diaphyseal shape in adult skeletons from Europe, North America, Africa, and Asia, covering a time span from around 40,000 BP to the present. Midshaft femoral and tibial cross-sectional geometric properties for nearly 3000 individuals were gathered from databases kindly provided by researchers. Geographic coordinates were found for each archaeological site. Local terrain for each site was quantified with ArcGIS mapping software using USGS elevation data, and characterized as flat, hilly, or mountainous. Analysis of variance shows significant differences (p<0.032 to p<0.0005) in shape ratio (Ix/Iy) of both femoral and tibial midshaft among the three terrain categories, with higher A-P bending strength in hilly and mountainous groups (Tukey HSD test).
This suggests that local topography needs to be considered when interpreting the cross-sectional properties of lower limb bones. Walking or climbing sloped surfaces is associated with greater A-P bending loads about the knee joint, so relatively greater A-P bending strength in the femur and tibia should be expected with more rugged local terrain.