Medieval Croatian skulls indicate that people intentionally modified their head shapes. But why?

A reconstruction showing what researchers believe was intentional cranial deformation.
A reconstruction showing what researchers believe was intentional cranial deformation.PLOS ONE

Imagine that a time machine transports you back 1,500 years to a forest road in what is now Croatia. You get up, dust yourself off, and look around. You’re in the Early Middle Ages.

A local inhabitant approaches you, and you see something you didn’t expect. You’re immediately struck by the shape of their head. It’s extremely elongated toward the back, resulting in an egg shape.

As a curious crowd gathers, you see that there are other people in the crowd whose heads are deformed in a different way. Their foreheads have been flattened, and their skulls have grown upward higher than normal.


Researchers, after looking at evidence from skeletons in a mysterious burial pit found in 2013 near the town of Osijek in eastern Croatia, say people who practiced artificial cranial deformation appear to have lived in the area at the time.

But the reason they changed the shape of their heads is still a matter of speculation.

“The impetus behind why these things were done can’t really be deciphered by the kind of data we have,” said Kendra Sirak, a postdoctoral fellow at Harvard Medical School in the Reich Lab of Medical and Population Genetics. Sirak was one of the lead authors on a new paper on the skeletons, which was published last week in the journal PLOS One.

“We think it could be some sort of visual indicator of group membership,” she said. The people who did it may have thought, she said, that “it sets us apart. It makes us unique. It allows us to identify other members of my same group.”

Practiced for some 5,500 years by cultures around the world, artificial cranial deformation involves binding the growing heads of infants and children with bandages, planks, boards, or bricks. As the skull grows under constant pressure, it becomes misshapen, resulting in oblong heads and other unusual shapes. Anthropologists have documented this practice on every inhabited continent, but it isn’t common. Today it continues in only a few remote tribes.


Skulls unearthed in the burial pit near Osijek were the first with artificial cranial deformation found in Croatia.

The pit contained three sets of human bones, as well as animal skeletons and broken pottery. Two of the skulls were deformed, but in different ways — one resembled an elongated egg, and the other had a flattened forehead, causing the cranium to grow higher.

Researchers, led by Mario Novak, an archeologist at the Institute for Anthropological Research in Croatia and Ron Pinhasi of the University of Vienna, examined the bones, scanned and reconstructed the skulls, and analyzed their DNA.

The findings suggested that between the fifth and sixth centuries, during the Migration Period, people of starkly different cultural backgrounds may have interacted more than previously thought. The study also provides the earliest genetic evidence of the presence of people from East Asia in Europe.

The Migration Period was the time in Western European history around and after the fall of the Roman Empire. It was marked by frequent warfare, a virtual disappearance of urban life, and the movement of so-called barbarian peoples into what had been the Western Roman Empire, according to britannica.com.

The researchers found that the skulls belonged to three malnourished males, between the ages of 14 and 16, who had lived between A.D. 415 and 560. There were no signs of violent death.


DNA testing deepened the mystery. It revealed the flat-foreheaded skull belonged to someone from somewhere in the Middle East, northern Africa, or southeastern Europe. The egg-shaped skull belonged to someone from East Asia. The unaltered skull likely came from a person of West Eurasian ancestry. Their genes were relatively unmixed, suggesting they had moved from these places or their parents had.

“Based on the presented data, it seems that different types of ACD [artificial cranial deformation] (or the lack thereof) might be associated with affiliation with a particular cultural group (at least in the case of Osijek), leading us to consider that populations with different ancestries and potentially different cultures were interacting intimately” in the area at the time, the study said.

Novak speculated to The New York Times that the youths may have died as part of a ritual sacrifice, because the contents of the pit were similar to those found in other cases of sacrifice from the same period.

Sirak said researchers don’t know what technique was used to deform the youths’ skulls, but the effects were obvious.

“We can definitely see the direction in which they were deforming the skull even if we don’t know exactly what they were using to do so,” she said.

Researchers looking at the remains in the pit “found something that was unexpected,” she said.

She said they were puzzled by the similarities among the three and the differences. The youths were buried in the same pit, were around the same age, and had the same history of nutritional deficiency, for example. But at the same time, they had different ancestral backgrounds and had different forms of cranial modifications.


“There was something more going on there that we really don’t understand,” she said.

Material from The New York Times was used in this report.