World's oldest mummies were smoke-dried 10,000 years ago in China and Southeast Asia, researchers find

The world's oldest known human mummies were created by smoke-drying corpses 10,000 years ago in Southeast Asia and China, long before mummification became commonplace in Chile and Egypt, new research shows.

A study of dozens of ancient graves found in China, the Philippines, Laos, Thailand, Malaysia and Indonesia revealed that many skeletons that were found in a tight fetal position were treated by an extended period of smoke-drying over fire before being buried. The research was published Monday (Sept. 15) in the journal PNAS.

"Smoking likely carried spiritual, religious, or cultural meanings that went far beyond simply slowing decay," Hsiao-chun Hung, a senior research fellow at the Australian National University and lead author of the study, told Live Science in an email.

The researchers had been puzzled by the high number of burials in China and Southeast Asia from 4,000 to 12,000 years ago in which the skeletons were "hyperflexed," or contorted into unnatural tightly crouched positions. A similar skeleton found in Portugal in 2022 was interpreted as evidence of mummification because it was hyperflexed — likely bound up so the arms and legs could be moved beyond their natural limits as the body decomposed.

But in many of the ancient Southeast Asian burials, the researchers found, there was evidence of burning on the skeletons and not in the graves, which suggested some sort of ritual treatment of the body that included fire and smoke.

The researchers used X-ray diffraction, a nondestructive technique that allows scientists to investigate the internal microstructure of a material, and infrared spectroscopy to assess whether the bones had been exposed to heat. Many of the skeletons revealed evidence of low-intensity heating and discoloration from soot, rather than evidence of direct combustion such as a cremation. This suggests that a specialized mortuary practice involving the smoking of a corpse was likely practiced widely in pre-farming communities across southern China and Southeast Asia, the researchers wrote.

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Smoke-dried mummies are still being made today in parts of Southeast Asia, according to the researchers. They traveled to Papua, a province of Indonesia, in 2019 and observed the Dani and Pumo people creating mummies of their deceased ancestors by tightly binding the corpses, setting them over a fire, and smoking them until they turned entirely black. Drawing on these examples, the researchers concluded that ancient individuals were tightly bound after death and smoked for long periods over low-temperature fires.

Although the deceased individuals the researchers investigated in their study are only bones — with no skin, soft tissue or hair preserved — they consider the remains to be mummies because they were deliberately mummified through smoke-drying.

"The key difference from the mummies we typically imagine is that these ancient smoked bodies were not sealed in containers after the process, and therefore, their preservation generally lasted only a few decades to a few hundred years," Hung said. In the hot and humid climate of Southeast Asia, smoking was likely the most effective way of preserving the bodies, she said.

But how these ancient hunter-gatherers discovered that smoking a human body could preserve it "remains a fascinating and thought-provoking mystery," Hung said, and "we cannot say with certainty whether smoking the body was first conceived as a way to preserve it." It's possible that ancient people discovered smoking accidentally, as a by-product of some kind of ritual practice, or that they discovered smoking animal meat first and then applied it to dead humans.

"What is clear is that the practice prolonged the visible presence of the deceased, allowing ancestors to remain among the living in a tangible way, a poignant reflection of enduring human love, memory, and devotion," Hung said.

Two-layer model of migration

The mummies may also support a "two-layer" model of early migration into Southeast Asia. This model rests on the idea that ancient hunter-gatherers came as a wave of migrating people as early as 65,000 years ago and were distinct from the later Neolithic farmers and their burial traditions who did not arrive until 4,000 years ago. The ancient hunter-gatherers who used the smoked burial practices may have given rise to modern-day human populations in Southeast Asia, such as the Dani and Pumo people who still practice this form of funeral ritual.

Ivy Hui-Yuan Yeh, a biological anthropologist at Nanyang Technological University who was not involved in the study, told Live Science in an email the new findings support the two-layer model and "are consistent with the patterns of early human migration, distribution, and interaction in Asia."

If hyperflexed burials identified throughout Southeast Asia can be interpreted as smoked mummies, this suggests that "smoked mummification might have originated earlier, and been more widespread, than is currently identified in the archaeological record," the authors wrote in the study.

In fact, the process of smoke-drying a dead body may go back as far as the early expansion of Homo sapiens from Africa into Southeast Asia, and potentially as far back as 42,000 years ago, showcasing a "deep and enduring biological and cultural continuity," the researchers concluded.

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