Bone resorption of the pubis and preauricular area in humans and nonhuman mammals

Some innominates of adult human females show areas of bone resorption on the dorsal aspect of the pubic corpus and preauricular area of the ilium. For both sites, many studies have shown a positive association between degree of resorption and parity. The present study tested hypotheses concerning resorption of the pubis and preauricular area. Samples of innominates from three prehistoric Amerindian populations were used. Within each population, only a minority of females, in general, showed resorption more severe than that which characterized males. The severity of resorption of the pubis was not significantly associated with that of the preauricular area. Pitting of the pubis, but not of the preauricular area, was significantly correlated with age-at-death in each sample of Amerindian females. Also, sacral angulation was not significantly associated with resorption of the preauricular area. Observations on resorption of the pubis and preauricular area in samples of Pan troglodytes and Gorilla gorilla are reported. In previous studies on resorption of the pubis and preauricular area in the human innominate, the proposed etiologies involve ligamentous hyperplasia and joint trauma. However, a number of studies on resorption of the pubis in the nonhuman mammalian innominate have been overlooked by anthropologists. These latter studies demonstrate that estrogen alone can induce resorption of the mammalian pubis by stimulating the synthesis of osteoclastic enzymes. Partial resorption of the pubis may be obstetrically advantageous in some mammals, as resorption would delay or inhibit synostosis of the interpubic joint. The relationship between estrogen and the preauricular area is an issue that requires further research.