The impact of terrain on lower limb bone structure

Area of Science:

• Paleoanthropology and biomechanics.
• Skeletal biology and functional morphology.

Background:

• Lower limb diaphyseal geometry is traditionally used to infer mobility in past populations.
• High shape indices, often linked to mobility, may also be influenced by terrain.
• Investigating terrain's role is crucial for accurate interpretations of skeletal adaptations.

Purpose of the Study:

• To investigate the effects of different terrain types on lower limb diaphyseal cross-sectional geometric dimensions.
• To differentiate the influence of terrain from mobility and subsistence strategies on bone structure.

Main Methods:

• Analysis of femoral and tibial diaphyseal shape and strength dimensions from a large skeletal sample (N=3,195) across diverse geographic locations and time periods.
• Quantification of local terrain (flat, hilly, mountainous) using GIS and elevation data.
• Statistical analysis (ANOVA) to compare geometric properties across terrain categories, controlling for subsistence and latitude.

Main Results:

• Significant differences in femoral and tibial shape ratios and relative strength were found across terrain categories (p < .05).
• Hilly and mountainous terrains were associated with more anteroposteriorly oriented diaphyseal shapes and greater relative strength.
• Terrain effects were more pronounced in hunter-gatherer and agriculturalist groups than in recent populations.

Conclusions:

• Traveling over rough terrain is a significant mechanical factor shaping lower limb bone diaphyseal structure.
• Interactions between mobility, terrain, and body shape are complex and influence skeletal adaptations.
• This study refines our understanding of how environmental factors, not just mobility, affect bone morphology.