Newly discovered banjo-shuseki-bo (square-shaped bone-pile burial) human bones from the Final Jomon Period Hobi shell-mound site, Aichi Prefecture, Japan

抄録

Banjo-shuseki-bo, unique accumulations of human bones among Jomon collective secondary burials, have been found intensively in the Final Jomon Period Mikawa region of Aichi Prefecture. At the Hobi shell-mound site in Tahara City (c. 3000–2400 BP), two cases of banjo-shuseki-bo have been so far documented, referred to as Ichi-go-shuseki (Accumulation No. 1) and B-shuseki (Accumulation B). During the 2010–2013 excavations at the Hobi site, we discovered a new case of banjo-shuseki-bo (named Accumulation 2010) and retrieved all the bones (1331 samples). Here we report anthropological data from this unpublished sample and confirm the differences between the three accumulations (2010, No. 1, and B) and individual skeletons of primary burial origin from the same archaeological site. The Accumulation 2010 bones contained 13 individuals in total: eight adult males; one subadult (late adolescent) male; three adult females; and a 1.5-year-old child of undetermined sex, thus indicating a male-dominated group. It was also found that the body-part composition of Accumulation 2010 exhibited a site-specific bias, specifically skewed toward the lower limb bones such as the femur and tibia, almost equivalent to those of Accumulations No. 1 and B. In comparisons of the femur between the banjo-shuseki-bo human bones and individual skeletons, no systematic size differences were found in either sex; however, the male femora from the three (2010, No. 1, and B) accumulations showed a significantly/near-significantly greater pilasteric index than those of the individual skeletons. One possible explanation for why the femur pilasteric structure was so developed in the Hobi banjo-shuseki-bo males is that people who worked in physically demanding labor during their lives or a specific kinship group may have been chosen as the subjects of the banjo-shuseki-bo burials.