Entire families were sacrificed in Korea about 1,500 years ago in rituals to honour royalty, according to a new analysis of dozens of skeletons unearthed in Gyeongsan in the southeastern region of the Korean Peninsula.
The findings raise further questions about slavery, social mobility, and institutionalised violence in ancient Korean kingdoms.
They also offer the first large-scale scientific evidence of the social structure and customs of the era, proving close-kin marriages were common during the Silla Kingdom (57 BC to 935 AD).
In 1982, archaeologists first unearthed a burial complex in the region constructed some time between the 4th and 6th centuries.
It was thought to contain the graves of local ruling families with over 1,600 tombs and the remains of nearly 260 individuals unearthed from the site.
However, how people were buried in the region were related and the social hierarchy of the time had remained elusive.
In the latest study, scientists analysed genome-wide data from 78 human remains unearthed from 44 tombs at the Imdang-Joyeong burial complex in Gyeongsan.
At least 20 of the tombs displayed evidence of “sunjang”, a practice in which individuals were sacrificed and buried alongside the dead.
Scientists found that at least in three of the cases, closely related individuals, including parent-child pairs, were interred together in the same tomb.
One of the burial contained both parents and their child, researchers found.
“Our genetic findings are the first to confirm the acts of sunjang of an entire household,” they wrote in the study published in the journal Science Advances.
“If correct, the presence of what seems to have been a sacrificial caste in this regional polity outside of the Silla core has profound implications for how we understand Silla society,” Jack Davey, director of the Early Korean Studies Center in Cambridge, told Live Science.
The latest findings suggest people chosen for the sunjang ritual inherited their roles.
“Genetic relatedness among sacrificial individuals over generations may suggest the presence of families that served as sacrificial individuals for the grave owner class for consecutive generations,” researchers wrote.
Five of the individuals buried, both royal and non-royal, had parents who were closely related, scientists found, indicating that the Silla royal elites and the Silla people who were sacrificed practiced close-kin marriage.
Based on the evidence, researchers suspect there may have been a “sacrificial caste” in this region outside of the core political circle who inherited their roles to be buried along with the dead nobles.
Those selected to be sacrificed and buried may have been servants, retainers or dependents, reflecting a belief that the dead required attendants in the afterlife, scientists say.
Overall, the analysis “highlights a kinship structure distinct from those observed in ancient Europe and offer new insight into how local communities were organised” during this period, they said in a statement on Thursday.