Taphonomic observation of Jomon human skeletal remains from a collective burial of the Gongenbara shell-mound, Chiba Prefecture, Japan

Abstract

To evaluate burial customs in the Jomon period of Japan, we observed the taphonomic signatures of human bones from a secondary collective burial and compared them with those from individual burials. We compared the compositions of identified bone parts, degree of weathering, and damage of the bone surfaces based on two neighboring shell-mound sites, Gongenbara and Horinouchi in Chiba Prefecture; a famous secondary collective burial had previously been discovered at the Gongenbara shell-mound. The degree of weathering differed between the collective and individual burials, and also differed depending on the horizontal and vertical location within the collective burial. These differences imply that a variable degree of weathering plausibly occurred at or after the secondary burial, but not at the primary burial. Regarding bone surface damage, specific types of damage were more frequently observed on the limb bones in the collective burial than in the individual burials, although different types of damage were observed in the skull assemblage. These findings suggest that different burial processes could cause the secondarily reburied bones to be exposed to the air for a longer duration of time or more easily be accessed by insects or other small animals, which might have produced variable taphonomic signatures.