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

The goal of this study was to identify changes in acetabular morphology ass ociated with the use of horses by Native Americans. Previous studies report ed "elongate" acetabula in horseback-riding members of the Omaha and Ponca populations. Such a difference in acetabular shape is a potentially useful osteological marker of habitual horseback riding. This report compares acet abula of adult males from two Native American Arikara populations known to have differed substantially in their use of horses. Population samples were from separate sites in South Dakota: Larson (nonriding) and Leavenworth (r iding). Outlines of acetabular rims were digitized and analyzed, using a si mplified 12-point Fourier analysis. A Fourier series with six terms accurat ely described acetabular shape. Significant differences (P < 0.10) between riding and nonriding populations were observed in two Fourier coefficients. Acetabula of riding Arikara were found to have smaller B-4 coefficients (P = 0.061) and more positive B-2 coefficients (P = 0.080), indicating expand ed anterior-superior borders relative to acetabula of nonriding Arikara. (C ) 2000 Wiley-Liss, Inc.