Skull Modification Practices of Ancient Japanese Ethnic Group Revealed

Human remains often don’t give much away. Imagine two skeletons, excavated from their resting places and scrubbed of dirt. Thousands of miles and hundreds of years separate the two sets of remains; one skeleton once belonged to a high-ranking member of the Collagua people, who tilled the high-altitude slopes of the Andes around the year 1300. The other remains are of a member of the Hirota people – shellfish traders who swung between the windswept shores of Tanegashima, part of Japan’s Ōsumi Islands, during the middle of the first millennium. You might not be able to see all of the details – skin and hair color, facial features – that separated these people while they were alive, but you will notice how they are linked in death – by the shape of their skulls.

New research reveals that the Hirota, like the Collagua, practiced cranial modification – a process where the skulls of infants and young children are bound, warping them out of shape. Cranial modification is remarkably widespread throughout human history, arising in multiple cultures on every inhabited continent independently. The practice, which continued into the 20^th century in both Congo and France, was used as an indicator of group affiliation or social status.

“Short head and flattened skull”

The Hirota lived on Tanegashima between the third and seventh centuries CE. The latest analysis looked at remains disinterred from a burial site that was excavated twice, from 1957 to 1959 and again from 2005 to 2006.

“From the initial excavation, we found remains with cranial deformations characterized by a short head and a flattened back of the skull, specifically the occipital bone and posterior parts of the parietal bones,” says Noriko Seguchi, a study coauthor and associate professor in the Faculty of Social and Cultural Studies at Kyushu University.

That initial work had been unable to establish whether the modifications were a deliberate cultural practice, or simply an unintended consequence of other practices.

In the new work, the team combined 2D and 3D imaging techniques to examine the skulls in detail. The Hirota skulls were compared to samples from other peoples, including the Kyushu Island Jomon people and Doigahama Yayoi people in Western Yamaguchi. The features of the skulls were analyzed to determine how similar the different cultures’ remains were.

Cranial modification was intentional

"Our results revealed distinct cranial morphology and significant statistical variability between the Hirota individuals with the Kyushu Island Jomon and Doigahama Yayoi samples," says Seguchi. "The presence of a flattened back of the skull characterized by changes in the occipital bone, along with depressions in parts of the skull that connects the bones together, specifically the sagittal and lambdoidal sutures, strongly suggested intentional cranial modification."

Lacking written documentation from this period, the research team can only speculate as to the Hirota’s motivation for intentionally skull modification, but archeological evidence suggests it could be linked to cultural identity and to facilitate the trade in shellfish between distant communities.

"Our findings significantly contribute to our understanding of the practice of intentional cranial modification in ancient societies," says Seguchi. "We hope that further investigations in the region will offer additional insights into the social and cultural significance of this practice in East Asia and the world."

Reference: Seguchi N, Loftus JF, Yonemoto S, Murphy M. A hybridized two-dimensional/three-dimensional study of the Hirota site, Tanegashima, Japan. PLOS ONE. 2023. doi: 10.1371/journal.pone.0289219

This article is a rework of a press release issued by Kyushu University. Material has been edited for length and content.