Asymmetry in the human skeleton. A study on prehistoric Polynesians and Thais.

Atlantal, long bone, and craniofacial measurements of prehistoric Polynesian and Thai skeletons were analysed to ascertain the extent and direction of bilateral asymmetry. The atlantal articular mass was constantly and significantly higher on the right side than on the left. In Thais, the midlongitudinal axis of the atlanto-occipital facet on the right side had a steeper inclination than that on the left. In both groups the dental occlusion was less mesial on the right side and the mandible was shorter, significantly so in the Thais. The long bones were more asymmetric in the Polynesians than in the Thais. Height asymmetry of atlas lateral tuberculum correlated inversely with mandibular ramal width asymmetry. Atlanto-occipital facet length asymmetry correlated with asymmetry of the gonial angle and facet angulation asymmetry correlated inversely with radial length asymmetry. Our results suggest a pervading asymmetry of skeletal structures which we ascribe as local adaptations to functional demands rather than as due to a uniform asymmetric growth pattern.