At the beginning of the last Ice Age, 31,000 years ago, a community in what’s now Eastern Indonesia buried a young person in the dry floor of a mountainside cave painted with handprints. The people lived on the edge of what was then a low continent called Sunda, and they were likely part of the same group of early seafarers who crossed to Australia. They were sophisticated in other ways, too: According to a description of the burial published today in the journal Nature, the young adult is the oldest human known to have survived a surgical amputation.

Caring for the sick and wounded is an essential part of human evolution. To tend to a critically injured person requires communities to develop medicinal knowledge and have spare resources to devote to their recovery. Human and Neanderthal skeletons both show evidence of healed traumatic injuries going back tens of thousands of years, and some anthropologists argue that the ability to provide medical care allowed hominids to spread across the planet.

A successful surgery takes even more sophistication. “Surviving an amputation is a recent medical norm for most western societies,” said Tim Maloney, an archaeologist at Griffith University and the paper’s lead author, at a press briefing, made possible by the development of effective antiseptics in the late 1800s.

As Maloney and his team excavated the burial site, hoping to learn more about the people who had painted the cave at least 40,000 years ago, they noticed something odd: The skeleton was missing its left foot, while the delicate bones of the right foot were well-preserved. When they looked closer at the tip of the left leg, they saw that the tibia and fibula had been cut off, and the ends of the bone healed over.

Archaeology photo
A close examination of the tibia and fibula showed years of healed bone over an amputation. From T. Maloney et al., Nature, 2022.

When the researchers examined the tips of the bones, they didn’t find signs of an animal attack or rockfall, which would have left fracture or crush marks around the edges. The wound’s clean nature suggested that it had been made intentionally. Based on the age of the skeleton—about 19 at death—and the healed-over bone, the researchers believe that the surgery happened when the individual was a preteen, six to nine years before their death. Not only did they survive, but they managed to keep living in their rugged mountain home.

[Related: Skull research sheds light on human-Neanderthal interbreeding]

Even if this loss of a limb was accidental, “it is still significant that they managed to keep the person alive,” says Rebecca Gowland, an expert in human skeletal remains at Durham University who was not involved in the research. But she says she doesn’t have any reason to doubt the interpretation of the amputation. “I’ve seen a number of amputated limbs, and it looks like it could well be a healed amputation.” she says. 

A surgical procedure such as this, and the child’s survival, suggests experience, medical knowledge, and confidence. “You cannot survive the removal of your lower leg, particularly as a child, without managing shock, blood loss, and infection,” Maloney says.

Gowland agrees. It also indicates “that there are people within that community who say, ‘This is what we need to do in order to take the really drastic action of cutting someone’s leg off,’” she says.

Why exactly the child required amputation is a mystery. Because it happened so long before the individual’s death, no evidence from the actual procedure survives. It’s possible that they had an infection that had become dangerous, or suffered a catastrophic crushing injury to their foot and ankle.

But by comparing the wound to successful amputations in more recent history, the archaeologists can make some guesses about the details of the operation. The surgeons had to control bleeding, either with pressure bandages, tourniquets, or cauterization. The researchers believe that the cut was made with stone tools, which, though fragile, can be incredibly sharp—obsidian scalpels are used in some specialized medical procedures even today.

Maybe most surprisingly, the bone showed no signs of infection in an environment where it’s hard to avoid—even the excavation team regularly dealt with infected cuts. The answer might have to do with knowledge of medicinal plants. “It’s an open question whether this was a unique development associated with communities living in [the biodiverse] tropics,” says Maloney, “or whether it’s a combination of trial and error within a community that cared for their children, like most of us all do around the world.”

[Related: Modern medicine still needs leeches]

Gowland says that it’s important not to think of the surgery through a modern medical lens. People might have understood how to control bleeding and care for the wound without detailed information about blood vessels, veins, and limb anatomy. “People have had very different beliefs about healing and the body in the past,” she says. But “they absolutely had to have had an understanding that they had to stop blood loss, and they had to stop infection, and that’s pretty impressive.”

The skeleton was discovered in the central chamber of a limestone cave on the eastern edge of the island of Borneo, overlooking the headwaters of the nearby Amarang River, in a valley full of ancient rock art. “It is very cathedral-like,” Maloney says. The grave itself was marked by carved stones, and accompanied by stone tools and a bead of red pigment.

The individual’s unusual burial marked by the paint bead is, to Gowland, just as interesting as the actual amputation. “It might be that they had some kind of special status before the amputation,” which made them eligible for the surgery, she says. “Or maybe the amputation made them special.” 

Maxime Aubert, who specializes in dating rock art at Griffith University, and a coauthor on the study, notes that there’s still very little information about the culture the individual belonged to—the dig was part of ongoing work to understand who made the rock art. What the researchers do know is that the culture valued artwork. By the time the person was buried in the cave, some of the paint on its walls had been there for at least 10,000 years.

The amputation adds color to the technological and cultural sophistication of the artistic people, whoever they were. The second-oldest known surgical amputation is from 7,000 years ago, in Neolithic France, after the advent of settled farming. A favored model among archaeologists assumes that sophisticated technology must have accompanied sedentary life and agriculture. “This very much challenges, if not completely overturns the idea,” Maloney says, “that advanced medicine was beyond the capacity of these early foraging and hunting societies.”

Correction (September 15, 2022): A previous version of this article misstated Rebecca Gowland’s last name. Popular Science regrets the error.