Is sexual dimorphism in the femur a "population specific phenomenon"?

The patterns of sexual dimorphism as well as the differences in amount between the populations were studied on a sample of 162 male and 159 female left femora, which were classified as Zulu, Sotho, Xosa and South Africans of European extraction. Multivariate analyses revealed that even adjacent African tribes exhibit a different pattern of sexual dimorphism, but there were similarities between Zulu and European femora. Furthermore, relative size differences, i.e. shape, discriminated more clearly between the sexes than did absolute size. Bicondylar width yielded a statistically significant higher degree of sexual dimorphism in Europeans when compared to African populations. This finding was interpreted in terms of the biomechanical demands on the femur under different living conditions. On the other hand, sexual dimorphism of femoral length did not differ among the populations. This was unexpected since femoral length correlates highly with stature, which was reported to show a lesser degree of sexual dimorphism in Africans than in Europeans. Detailed analyses of the results of the present study led to suggest that different living conditions may affect bones in complex ways of which linear growth is only one aspect.