Physical activity alters limb bone structure but not entheseal morphology

Area of Science:

• Paleoanthropology
• Biomechanics
• Skeletal Biology

Background:

• Ancient human skeletal remains are often analyzed to infer physical activity levels.
• Robust limb bones and rugose entheses are commonly assumed indicators of high physical activity.

Purpose of the Study:

• To experimentally test the assumption that entheseal morphology and limb bone structure reflect physical activity levels.
• To determine the reliability of these skeletal markers for inferring past human behavior.

Main Methods:

• Growing female turkeys were subjected to a 10-week treadmill running regimen or served as controls.
• Femoral bone structure (cortical and trabecular) was analyzed using micro-computed tomography (μCT).
• Entheseal morphology was quantified at the lateral epicondyle.

Main Results:

• Exercise significantly enhanced diaphyseal and trabecular bone architecture in the experimental group compared to controls.
• No significant differences in entheseal surface topography were detected between the exercise and control groups.
• This indicates physical activity affects bone structure but not entheseal morphology.

Conclusions:

• Limb bone structure, specifically diaphyseal and trabecular bone, are more reliable indicators of physical activity than entheseal morphology.
• The findings challenge long-held assumptions in paleoanthropology regarding the interpretation of skeletal markers.
• Future studies should consider bone structure over entheseal morphology when reconstructing activity patterns of ancient populations.