Archaeologists working in southeast Asia have long been puzzled by pre-farming burials dating from about 12,000 to 4,000 years ago. Unlike later Neolithic graves, where people were typically laid flat, these older burials often show bodies tightly crouched or squatting, sometimes with patches of darkened bone. Such contorted postures are hard to achieve if a body is buried soon after death.

Now, a study in Proceedings of the National Academy of Sciences by scientists from across Asia has reported that many of these communities gently heated and smoked their dead to preserve them, much like practices recorded in recent times in the New Guinea Highlands. The findings explain the postures as well as pushes back the earliest evidence for artificial mummification by five millennia.

The team documented dozens of pre-Neolithic burials from 11 sites. Then they studied the bones using X-ray diffraction and Fourier-transform infrared spectroscopy. The team also compared results from different bones of the same person and used radiocarbon dating.

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About 84% of the tested bones showed elevated crystallinity and nearly a third reached values typical of stronger heating. Diffraction identified several samples heated to around 525º C or more. Burn traces clustered on the forehead, knees, and elbows while other parts showed only mild or no changes. Crucially, different bones from the same individual often recorded different heat levels, which was evidence against effects due to the soil. Together with the extreme crouching, which left no empty space for soft tissue, the results fit a scenario in which bodies were tightly bound and suspended over smoky, low fires for long periods, then kept for a time and finally buried.

The practice appeared at least 14,000 years ago, earlier than the Chinchorro (~7,000 years ago).

"Pushing back the earliest known case of artificial mummification by about 5,000 years shows that these early communities already had remarkable spiritual beliefs and technical skills," Australian National University senior research fellow and the study's first author Hsiao-chun Hung told The Hindu.

"It highlights their deep concern for the dead and their willingness to devote great effort to preserving the body as part of community life. This discovery changes how we understand early human culture: it shows that long before we thought, people had developed symbolic thinking, strong social bonds, and rituals that kept the living closely connected with their ancestors."

Dawn of artificial mummification pushed back 5,000 years