Ancient DNA analysis of brown bear skulls from a ritual rock shelter site of the Ainu culture at Bihue, central Hokkaido, Japan

摘要

Ancient DNA, sampled from ten brown bear ( Ursus arctos ) skulls excavated from a rock shelter site of the Ainu culture at Bihue, central Hokkaido, Japan, was analyzed. This ritual site ( iwaya or siratcise ), located in a mountainous area near the western coast of Lake Shikotsu, is considered to have been used for bear-sending ceremonies by the Ainu people at least until about 70 years ago. We identified four mitochondrial DNA (mtDNA) haplotypes at Bihue, all of which were shared by the modern brown bears of Hokkaido. A previous study showed that three mtDNA lineages (groups A, B, and C) of modern brown bears are allopatrically distributed: group A in north-central Hokkaido, group B in eastern Hokkaido, and group C in southern Hokkaido. The ritual site of Bihue is located in the group C area. While one haplotype of group C was recovered from four of the Bihue skulls, three haplotypes of group A were recovered from six skulls. No haplotype of group B was found. The distribution of the four identified haplotypes at Bihue overlaps extensively with the area of the Ainu community called Shumukuru . These results indicate that, at the Bihue ritual site, the Ainu people probably performed bear-sending ceremonies that included skulls of bears that lived far from the Bihue area. This suggests that, earlier in the Ainu culture period (after the 17th century), the Bihue ritual site could have been used by multiple villages within an Ainu community, such as the Shumukuru , and/or that bear-hunting areas may have expanded from Bihue. This might have led to the promotion of cultural communication and unity among local villages via bear-sending ceremonies.