Taphonomic analysis of ‘scratches’ on medieval human crania from the Zaimokuza site, Kamakura, Japan

Abstract

Three excavations in the 1950s of the Zaimokuza site in Kamakura, Japan, uncovered human skeletal remains, mainly crania, of a large number of individuals buried in mass graves. Materials from the first and second excavations were previously reported as being victims of Nitta Yoshisada’s siege of Kamakura (1333) in part due to the high incidence of weapon-related trauma. Recent archaeological excavations in the area near the site have shown that it lies within a large contemporary medieval graveyard and despite consistencies in burial conditions, evidence for violent trauma, while present, was found in much lower frequencies in surrounding sites. Many of the traumas reported in the original study on the Zaimokuza skeletal remains were ‘scratches,’ described as extremely short and shallow cut marks on the crania, and it had been suggested that taphonomically induced bone surface modifications may have been mistakenly recognized as human-induced traumas. This study uses scanning electron microscopy to re-examine the Zaimokuza materials for ‘scratches’ and investigates their causes. A total of 235 examples of marks matching the description of ‘scratches’ were found on 38.2% of individuals examined that varied in their morphologies and were likely caused by different agents for different reasons. The results indicate that most were groups of ‘weak and shallow’ marks that display microscopically identifiable features commonly found on marks caused by sedimentary abrasion described in recent taphonomic studies, and so were likely caused by natural processes before burial. In addition, we found marks similar to ‘scratches’ inflicted post-excavation on clay used to restore a specimen. When taking the results into consideration, some of the interments at the Zaimokuza site may represent burial customs of the medieval period such as ‘corpse abandonment,’ rather than casualties of warfare and violence.