Auditory Exostoses among Ancient Human Populations in the Circum-Pacific Area--Regional Variations in the Occurrence and Its Implications
Auditory exostoses were investigated macroscopically in a total of 1209 crania. This sample represents 24 ancient human populations covering the circum-Pacific area of Remote Oceania through Southeast and East Asia. Regional variations in its frequency were considered. It was found that there were several foci in the area, where the character frequently occurred in the past; specifically, New Zealand, Easter Island, the Marquesas, Tonga and Japan. This finding suggested that prehistoric Polynesian and Japanese populations were engaged in the heavy exploitation of marine resources through diving, taking into account the so-called 'thermal aquatic hypothesis' on the causative relationship between diving for marine resources and the exostosis development. It is difficult, however, to discuss the extent of aquatic activities for the populations in Southeast Asia, because possibly due to the hot climate there through the year, the development of exostoses is not as pronounced. Though largely speculative, the present results may also provide a kind of evidence of a biological relationship in the rehistoric time between Polynesians and some East Asians, represented in the present paper by the Jomon and Yayoi Japanese.