A new study published in the journal PLOS ONE, has revealed that a unique burial method performed during the 15 th to 18 th centuries in eastern Japan may be associated with social stigma against certain infectious diseases, such as leprosy, tuberculosis or syphilis.

The Nabe-kaburi burial method involved covering the heads of the deceased with iron pots or mortars, the purpose of which has been shrouded in mystery. To date, a total of 105 Nabe-kaburi burials have been excavated in Japan. Various types of pots were used to cover the heads, including iron pots, earthenware pots and mortars; however, iron pots were most frequently used.

One theory regarding the practice is that Nabe-kaburi burials were performed for someone who died during the “Bon” period in Japan. The “Bon” is the Japanese ritual ceremony to welcome the souls of ancestors back from heaven during a 3-day period each summer. Since dying during the festival was considered bad luck, the ancestors beat the head of a descendant when they encountered each other on the way to and from the next world. Therefore, relatives of the descendant might have been trying to protect the head of the deceased at burial.

Depiction of Nabe Matsur (“pot festival”) in Maihara, Japan. Photo credit.

However, according to Japanese folklore, the reason the deceased were buried with iron pots on their heads was to symbolically “block” the spreading of particular diseases, such as leprosy, tuberculosis or syphilis, which plagued the deceased when they were alive. In many societies, infectious diseases brought public stigmatization and exclusion.

“Leprosy-associated deformities have been responsible for such social stigmatization and discrimination, and in some countries, the stigma is promoted by legislation against patients,” wrote the researchers. “This commonality between Nabe-kaburi and leprosy burials led to speculation that Nabe-kaburi burials could to some extent reflect the discrimination against leprosy during that time period.”

Early research, dating back as many as 100 years ago, does give some credence to this perspective due to the identification of leprosy-specific lesions among some of the excavated remains. However, no molecular testing had been done to confirm the presence of leprosy. In the present study, a team of scientists from Japan sought to explore the theory by carrying out DNA testing on archaeological skeletal remains of Nabe-kaburi to determine if they were indeed infected with disease. Three sets of skeletal remains were analysed and M. leprae DNA fragments were detected in two of the remains, providing the first definitive evidence that some of the Nabe-kaburi burials were performed for people affected by leprosy.

It is not yet known whether the other individuals with Nabe-kaburi burials were infected with other types of diseases, like tuberculosis or syphilis, as no testing has been done yet for those markers. This would help to unravel the mystery of why Nabe-kaburi burials were performed in medieval Japan and confirm whether the burials reveal the reality of social stigma against particular diseases in a village from the late Middle Ages in Japan.

Featured image: A Nabe-kaburi burial. Photo credit .

By April Holloway