The ancient Japanese used to deform skulls, intentionally

The site was excavated numerous times, initially from 1957 to 1959 and then again from 2005 to 2006.

The painful procedure was carried out at young age 

In this painful procedure, an individual's head was forcibly pressed or tied, generally at a young age, to permanently deform the skull structure. 

As per the official release, the practice predates recorded history, and evidence of it has been discovered in various ancient cultures throughout the world.

The study authors posit that it was likely conducted to “signify group affiliation or demonstrate social status.”

One notable finding was that cranial modification among Hirota community females and males was largely the same, with no significant differences. This shows that both sexes engaged in deliberate cranial deformation. 

“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," added Seguchi. 

However, it remained unclear if these cranium changes were deliberate or the inadvertent consequence of other practices. They concluded the purposeful skull alteration practice after undertaking extensive 2D and 3D examinations of the skull pictures. This allowed them to determine the contour of the skulls. 

The images were then compared to crania data collected from other archeological sites in Japan, including the Doigahama Yayoi people in Western Yamaguchi and the Kyushu Island Jomon people. 

"Our results revealed distinct cranial morphology and significant statistical variability between the Hirota individuals with the Kyushu Island Jomon and Doigahama Yayoi samples," mentioned 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."

The researchers suggest that the Hirota people distorted their crania to retain group identification and maybe allow long-distance shellfish trade, confirmed by archaeological data uncovered at the location.

Further examination will be able to provide more insights into the social and cultural relevance of this practice in East Asia and even in other parts of the world.

The study results were reported in the journal PLOS ONE. 

Study abstract:

Intentional cranial modification has a long history, being a ubiquitous practice in many cultures around the world for millennia. The crania excavated at the Hirota site on Tanegashima Island, Kagoshima Prefecture, Japan, has been previously noted to have a marked tendency toward a short head and a flattened occipital bone, which has been suggested to be the result of artificial cranial deformation. However, whether this deformation was intentional or caused by unintentional habits remains unclear. This study aimed to investigate the characteristics of the cranial shape of the Hirota site to clarify whether the crania were intentionally modified. In the examination of Hirota crania, Kyushu Island Jomon and Doigahama Yayoi crania were added as comparative data and contrasted with three-dimensional (3D) surface scan imaging and two-dimensional outline-based geometric morphometric analysis, combined with objective assessments of potential cranial modification. The results showcased Hirota’s short and flattened cranial morphology, indicating clear alignment with our hypothesis that Hirota samples are morphologically different from Doigahama and Jomon samples. No sex-based differences were found. Morphological abnormalities in cranial sutures were visually assessed utilizing novel 3D visualization methods of cranial outer surfaces. Based on a comprehensive review of the results, we concluded that Hirota site crania were intentionally modified. Although the motivation of the practice is unclear, the Hirota people may have deformed their crania to preserve group identity and possibly aid in the long-distance trade of shellfish, as seen archaeologically.