Sexual Dimorphism and Allometric Variation in the Human Coxal Bone from Two Coeval Italian Skeletal Samples

Sexual dimorphism of the human pelvis is well documented, but the extent to which different factors contribute to pelvic variation remains debated. This study assessed whether allometric scaling contributes to pelvic morphology and whether these patterns differ between sexes and populations. 19 metric measurements from 132 coxal bones from the two coeval Documented Human Osteological Collections of Bologna and Sassari (Italy) were used as dimorphic variables. Maximum femoral length and femoral head diameter were collected and their geometric mean was calculated as a proxy for body size. Standardized Major Axis analysis was performed to assess static allometry. Longitudinal measurements follow allometric scaling, indicating that individuals with larger body size tend to have proportionally larger hip dimensions. Some measurements related to coxal bone depth scale with body size only in males, suggesting that factors beyond allometric scaling (e.g., obstetric demands) may contribute to female pelvic morphology. Other variables display divergent trends between populations or sexes. Differences in allometric patterns between Bologna and Sassari may reflect population-specific environmental (peninsula vs. island), lifestyle and genetic factors. Our findings highlight the role of allometry in pelvic sexual dimorphism, with variable degrees of size dependence across traits, suggesting a potentially modular organization of pelvic morphology.