Greater sciatic notch morphology: sex, age, and population differences.

The accuracy of a method for visually scoring sex differences in the greater sciatic notch was tested on 296 skeletons of known age and sex. The proportion of correct sex assignments is 80% when all specimens are classified, and 89% when os coxae assigned the score in which the sexes show the greatest overlap are excluded. Although many os coxae (35%) have this sexually intermediate morphology, excluding them has the advantage of substantially reducing sex biases in sexing errors. For both sexes, there is a strong relationship between age at death and sciatic notch score. People who die at a younger age tend to have wider, more feminine-appearing sciatic notches than people of greater longevity. There are also significant population differences. The 18th-19th century English sample from St. Bride's Church has a more feminine morphology than Americans of European or African ancestry. Environmental influences on skeletal development (vitamin D deficiency) appear to provide the most likely explanation for these population differences.