| In human females the bony pelvis must find a balance between being small (narrow) to accommodate the mechanical requirements of efficient bipedal locomotion, and being large to accommodate a relatively large newborn. It has been demonstrated that taller/larger-bodied women have larger pelvic canals. This study investigates whether in a population where small body size is the norm, pelvic geometry (size and shape) is adapted to protect the obstetric canal.; Osteometric data (25 measurements) were collected from the pelves (articulated and non-articulated elements), femora and clavicles (body size indicators, along with bi-iliac breadth) of adult skeletons of small-bodied Later Stone Age (LSA) foragers from southern Africa (n = 28 females, mean estimated body mass = 44 kg, stature =152 cm; n = 31 males, estimated body mass = 46 kg, stature = 158 cm), larger-bodied Portuguese from the Coimbra Identified Skeletal Collection (CISC) (n = 40 females, mean estimated body mass = 55 kg, stature =153 cm; n = 40 males, estimated body mass = 63 kg, stature =167 cm) and large-bodied European-Americans from the Hamann-Todd Osteological Collection (H-T) (n = 40 females, mean estimated body mass = 59 kg, stature =157 cm; n = 40 males, estimated body mass = 67 kg, stature = 168 cm).; Patterns of sexual dimorphism are similar in the samples, with the highest indices of dimorphism in the canal dimensions. The LSA sample displays the highest dimorphism in the canal dimensions and the lowest dimorphism in body size. Correlation and regression analyses indicate that differences exist among the samples in the relationships between pelvic dimensions and body size; canal variables tend to show low or non-significant correlations with body size. Univariate and multivariate analyses of raw and Mosimann shape-variables indicate that compared to the CISC and H-T females, the LSA females have relatively large midplane and outlet canal planes (particularly posterior and A-P lengths). The LSA males also follow this pattern. The CISC females, who also have equally small stature, but larger body mass, do not show the same type of pelvic canal size and shape accommodation. |
