Fourier analysis of acetabular shape in native American Arikara populations before and after acquisition of horses.

This research relates to the potential physical changes in the pelvic bone, specifically the acetabulum, as a result of horseback riding in Native American Arikara populations. The study reveals differences in acetabular shape between horse-riding and non-riding populations, demonstrating the potential osteological marker for horseback riding.

Research Methodology

• The research compared the acetabular shapes in adult males from the Larson and Leavenworth Arikara populations. Significantly, these two populations had different exposure and usage levels of horses, with the Larson population primarily being non-riders, and the Leavenworth population, riders.
• The researchers managed to digitize and analyze the outlines of acetabular rims. The study used a 12-point Fourier analysis which proved to be a useful method in accurately looking at acetabular shape.

Findings

• The team found significant differences in two Fourier coefficients between the horse-riding and non-riding populations, with a P-value less than 0.10. A smaller P-value indicates a stronger evidence of a difference.
• Particularly, they noticed that members of the horse-riding Arikara population had smaller B(4) coefficients and more positive B(2) coefficients. This implies that the acetabula in these individuals are expanded towards the anterior-superior borders, compared to those of the non-riding population.

Implications

• This study demonstrates that habitual activities, in this case, horseback riding, can leave osteological markers. These changes in the acetabular shape offer the potential to trace back certain habitual practices in historical and anthropological studies.
• The difference in acetabular shape can also be linked to different levels of comfort and health issues when engaging in horse-riding, providing possible insights into osteological health care for populations engaging in similar activities.