The culture of the "sons of cliffs" is alive: descendants of the creators of suspended coffins found by DNA

The work, led by Dr Hui Zhou and colleagues, is published in the journal Nature Communications.

Who are the bearers of the hanging coffin tradition

Some of the earliest hanging coffins have been discovered in southeast China, in the Wishan Mountains of Fujian Province. Radiocarbon analysis dates them to about 3,445 ± 150 and 3,370 ± 80 years ago, coinciding with the arrival of the first agriculturalists in the region. From here the practice is thought to have spread to other areas - Yunnan, Sichuan, Hunan, present-day Thailand and Taiwan.

The ritual involved lifting wooden coffins containing the remains and placing them on steep cliffs, in caves or crevices, usually near rivers, mountain slopes or the seashore.

Among the peoples who practised this custom, the Bo took a special place. In folklore they were called "conquerors of the sky" and "sons of cliffs", and legends attributed to them almost the ability to fly - so inaccessible seemed the places where they managed to place the coffins.

How exactly this was done is not entirely clear. One of the authors of the work, Dr Xiaoming Zhang, cites three hypotheses most recognised by archaeologists:

• timbers and planking - temporary wooden structures made oftimbers and beams to lift coffins and insert them into pre-cut nests in the rock;

• rope system - raising or lowering coffins using thick ropes (hemp or rattan), possibly with blocks, from above or below the slope;

• rock ledges and trails - the use of natural ledges or carved paths along which coffins could be dragged horizontally to niches.

By the end of the Ming period, the tradition of suspended coffins had largely disappeared from written sources. The Bo people were persecuted, many fled to neighbouring regions and probably mixed with the local population over time.

Who were compared by DNA

Today, Bo descendants live in the Wenshan Zhuang and Miao autonomous region of Yunnan province - that's 42 natural villages. For the study, the scientists analysed the DNA of 32 modern Bo representatives, but because of their close kinship, they chose 21 genomes for statistically correct comparison.

The team also examined 14 ancient genomes of people associated with the hanging coffin tradition from several archaeological sites in southeastern China and from northern Thailand.

The analyses showed that ancient groups of pendant coffin bearers, especially from Yunnan and Guangxi, were genetically very close to each other - and to ancient coastal populations in southeast China. This strengthens the idea that the early "birth point" of the tradition was precisely the coastal areas of southeast China, such as Mount Wishan, from where the rite then spread to southern China and mainland Southeast Asia.

An interesting detail: the people of the Log Coffin cultures in Thailand have almost no mitochondrial DNA (mtDNA) in their genome, inherited from the pendant coffin bearers. Since mtDNA is only maternally transmitted, this indicates a migration of predominantly males from southern China who married local women and brought the tradition of hanging coffins with them.

The modern Bo are the genetic heirs of the "sons of cliffs"

Genome comparisons have shown that the modern Bo have derived the bulk of their ancestry from the ancient practitioners of hanging coffins. This is evidenced by the large number of common "drift" alleles - genetic variants whose proportion varies randomly in populations - that modern Bo share with ancient Yunnan speakers of the culture.

The authors emphasise that this reinforces patterns of ethnic continuity: despite persecution, migration and cultural assimilation, the genetic lineage of pendant coffin bearers has not disappeared, but continues in modern Bo communities.

What scientists will study next

According to Dr Zhang, new areas of research have already been outlined that will provide a deeper understanding of the history of the Bo people and the practice of pendant coffins in general.

Scientists are planning a multi-omic approach:

• isotope geochemistry (to study nutrition and migrations),

• ancient proteomics,

• more precise dating,

• advanced genomic analysis.

This should help to reconstruct not only the routes of settlement and the origin of the groups, but also how they lived, what they ate, how they interacted with their neighbours, and how exactly they treated their dead.