Frequency variations of discrete cranial traits in major human populations. III. Hyperostotic variations

Seven discrete cranial traits usually categorised as hyperostotic character s, the medial palatine canal, hypoglossal canal bridging, precondylar tuber cle, condylus tertius, jugular foramen bridging, auditory exostosis, and my lohyoid bridging were investigated in 81 major human population samples fro m around the world. Significant asymmetric occurrences of the bilateral tra its were detected in the medial palatine canal and jugular foramen bridging in several samples. Significant intertrait associations were found between some pairs of the traits, but not consistently across the large geographic al samples. The auditory exostosis showed a predominant occurrence in males . With the exception of the auditory exostosis and mylohyoid bridging in a few samples, significant sex differences were slight. The frequency distrib utions of the traits (except for the auditory exostosis) showed some interr egional clinality and intraregional discontinuity, suggesting that genetic drift could have contributed to the observed pattern of variation.