Abstract: Paleoanthropologists have been paying more attention to human femoral cross- sectional surface areas, shapes and bilateral asymmetry because of the application of this informations to human evolution, population differences, and survival movements. Traditional analyses of femoral cross-sections usually adopt methods of destructive cutting, or labor- intensive model making. In this study, using 3D laser scanning, we nondestructively and conveniently get the outer contour of 20 paired femoral 3-D data from a modern Chinese population. With the software of CAD and method of geometric morphometrics, we examine bilateral asymmetry between the left and right femoral cross-sectional area and shape. The results indicate that bilateral asymmetry in femoral size and shape exists. Cross-sectional areas of paired femora have no significant differences in absolute values, but have significant differences in relative ones. Paired femora show flutuating asymmetry, rather than directional asymmetry. Moreover, significant differences on paired femoral cross-sectional shapes show fluctuating asymmetry. Directional asymmetry exists on paired femoral cross-sectional shapes, but it is not statistically significant. Average cross-sectional shapes and areas seem to indicate that human femora have a slight left-lateral dominance. Although the samples in this study are limited, and the conclusion need more specimens for further verification, our results show that using 3D laser scanning techniques, we can get data of femoral cross-sectional outer contour, and the methods of morphometric analysis does reveal some important information that traditional methods can not determine. This paper establishes a new method to examine bone asymmetry, and can be used for additional studies in human evolution.

Key words: Modern human, Femoral cross-section, Bilateral asymmetry, 3D laser scanning, Geometric morphometrics