Stone Age people built an artificial island of rock, bones, and wood.

In east-central Sweden, workers demolishing a railway that crossed the Motala Ström River discovered something bizarre. For roughly 7,500 years, a shallow, swampy lake in the area had hidden a pile of stones that contained the skeletal remains of at least 10 people and weapons made of stone and antler. They also found the bones of bears, deer, boar, and a badger. Two of the human skulls were mounted on pointed stakes.

Thousands of years ago, this semi-submerged burial ground must have been an imposing sight for the small settlements located nearby. A pile of rocks rose above the water, covered in weapons, wooden structures, and the grisly remains of fearsome animals—as well as the skulls of some carefully chosen people. Now dubbed “Kanaljorden,” the archaeological site has finally begun to yield some secrets about the people who created it. In a recent article for Antiquity, Stockholm University archaeologist Sara Gummesson and her colleagues explain what the evidence reveals about how this ritual site was used.

Though we’ve seen lots of heads on stakes in Game of Thrones and various movies, Kanaljorden is the first time anyone has found evidence in real life that Stone Age people in this area were mounting heads on stakes. And their reasons are not quite what you might imagine.

First, it’s important to dispel the myth that this site was for displaying the remains of enemies, killed violently and staked. Forensic analysis reveals a much more complicated story. Though a number of crania at the site showed trauma from weapons, there’s evidence that these injuries had healed over time. Most of these men and women had recovered from their wounds at the time they died. While this doesn’t rule out the idea that these were enemies, it seems more likely they were members of the community who fought battles and survived.

Gummesson and her colleagues note that the women had injuries mostly on the sides of their heads, while the men had injuries on the top. One possible explanation for this is that women occupied different positions from men in battle and thus got hit in slightly different spots.

Secondary burial

There’s another key indicator that these people may have been special members of the community rather than defeated bad guys put on display. Their bodies were given special treatment after death. In fact, they arrived on the artificial island as part of a “secondary burial” ritual, a term for what happens when bodies are moved from one burial site to another. All the people at Kanaljorden had been exposed or buried for a period of time, likely until most of their flesh was gone. After that, someone removed their heads, took off their lower jaws, and placed them in the middle of the lake—sometimes on a stake. In one case, the secondary burial came very quickly. One of the crania still had some brain residues clinging to the inside, which suggests the brain was in there during secondary burial.

Scientists working on the site have sequenced the DNA for several of the individuals—that’s how they figured out that two of the crania were female. They’ve also done isotope analysis on their bones, which reveals these people had a diet high in protein, mostly from fish. Remains from settlements near the river suggest these people were fisher-gatherers, eating aquatic animals, nuts, and berries. They probably lived in settlements in this area seasonally, setting up semi-permanent homes where they returned every year.

The Kanaljorden site may have been used for as long as 500 years and probably served as a ritual area for many different settlements that shared a common culture. There’s also evidence that the artificial island was used for a variety of rituals during that time. Clearly, the dead were being honored or at least memorialized there, though in diverse ways: some bodies were buried while others were staked. The animal bones and antler tools hint at still other kinds of rituals. Remains of wood hint at structures such as platforms or altars. Perhaps these objects were associated with funerals. More likely, this place was the site of many kinds of spiritual and social events.

Regardless of what those events were, they were clearly aimed at creating a striking image. Indeed, it’s so striking that we’re still marveling at it, thousands of years later.

At first glance, the Kanaljorden site might seem to represent the remains of a savage and violent event. But after examining the evidence, Gummesson and her team found the story was a lot more complicated than that. This artificial island of rock and bone was borne from centuries of ritual, shared among people in several local settlements. We may never know the specifics of what it meant, but we can still experience the awe it would have inspired in Stone Age people, as they looked upon this monument that brought together water and earth, animal and human, the living and the dead.