Drilling holes in each other’s skulls: Why did our ancestors do this?

In prehistory, humans have practiced trepanation: drilling, cutting, or scraping away layers of bone with a sharp instrument to form a hole in the skull of a living person.

There have been thousands of skulls unearthed at archaeological sites throughout the world that show signs of trepanation.

Although trepanation seems to have been important to our ancestors, scientists are still unsure as to why they performed it.

Trepanation was at least performed in Africa and Polynesia to treat pain, such as that caused by skull trauma or neurological disorders, according to anthropological accounts.

A similar purpose may have been served by trepanation in prehistory. Often, the region of the skull where the trepanation hole was made includes signs of cranial injuries or neurological diseases.

Research has long suggested that ancient humans performed trepanation primarily for ritual purposes, in addition to treating medical conditions.

Around 7,000 years ago, the earliest clear evidence of trepanation was found. A wide range of cultures practiced it, including Ancient Greece, North and South America, Africa, Polynesia, and the Far East. In several locations, the practice probably developed independently.

Some of the best evidence of ritual trepanation has ever been discovered by archaeologists

In some isolated parts of Africa and Polynesia until the early 1900s, trepanation was still practiced. Most cultures abandoned the practice by the middle ages.

Ancient humans performed trepanation as part of initiation rites or to allow spirits to pass through the body, as scholars have claimed since the first scientific studies on trepanation were published in the 19th Century.

It is difficult, however, to find convincing evidence. Since some brain conditions leave no trace on the skull, trepanation can almost never be ruled out as a medical procedure.

Archaeologists have found some of the most compelling evidence for ritual trepanation in Russia, however.


1997 marks the beginning of the story. Near the northern reaches of the Black Sea, near Rostov-on-Don in the far south of Russia, archaeologists excavated a prehistoric burial site.

At the site, 35 human skeletons were scattered across 20 graves. In determining the date of the burials, archaeologists looked at the style of the burials, which indicated they were from the Chalcolithic or “Copper Age” between 5,000 and 3,000 BC.

It is estimated that fewer than 1% of all trepanations occur above the obelion point

An infant aged between one and two years, and a girl in her mid-teens were buried with five adults — two women and three men.

In prehistoric graves, it is not uncommon to find multiple skeletons. All four skulls had been trepanned, including those of the two women, two men, and the teenage girl.

There was a single hole in each skull, several centimetres wide and roughly elliptical in shape, with scraping around the edges. An important feature of the skull of the third man was a depression that appeared to have been carved, but it did not appear to be a hole. There was only one unblemished skull on the infant.

Elena Batieva, an anthropologist at the Southern Federal University in Rostov-on-Don, Russia, was assigned the job of analyzing the grave’s contents. Her immediate recognition of the holes was that they were trepanations, and she soon discovered that these trepanations were unusual.

There was almost exactly one location on the skull where they all were made: the “obelion”. Approximately where a high ponytail might be gathered, the obelion is located on top of the skull.

There was a risk of death and major haemorrhage if the skull had been opened here.

Trepanations above the obelion point make up less than one percent of all recorded trepanations. The ancient Russians were even less likely to perform such trepanations, according to Batieva. A skull unearthed in 1974 at an archaeological site surprisingly close to the one she was excavating was the only other example known of an obelion trepanation at the time.

It is clearly remarkable to find a single obellion trepanation. Batieva saw five people buried together in the graveyard. This is the first time anything like this has ever happened.

The danger of obelion trepanation is one of the reasons it is uncommon.

Located directly above the superior sagittal sinus, the obelion point gathers blood from the brain before flowing into its main veins. The risk of death and major haemorrhage would have been high had the skull been opened in this location.

Clearly, such trepanation procedures were performed by the Copper Age Russians for good reason. No injuries or illnesses were found in any of the skulls, either before or after the trepanation.

They found nine skulls with obvious holes among the 137

Thus, it appeared that all of these individuals had been trepanned while they were completely healthy. They trepanated as part of some ritual, wasn’t it?

There was something intriguing about it. The trail, however, was abandoned by Batieva. A few skulls, however enigmatic, could not afford to distract her from analyzing the vast number of skeletons from southern Russia.

To find out if any other strange obelion trepanations had been discovered but not reported, Batieva decided to check Russia’s unpublished archaeological records.

She got two hits, which surprised her. In 1980 and 1992, obelion trepanations were discovered in the skulls of two young women. There were no signs that either had been trepanned for medical reasons since they were discovered within 31 miles (50 km) of Rostov-on-Don.

A total of eight unusual skulls were found in Batieva’s study, all clustered in the same region of southern Russia. There were even more revelations a decade later.

Archaeologists from around the world examined 137 human skeletons in 2011. In the Stavropol Krai region of Russia, close to the modern-day border with Georgia, three Copper Age burial sites were recently excavated south-east of Rostov-on-Don.

Trepanations were not the archaeologists’ goal. Prehistoric inhabitants of the region were studied to learn about their health. They found nine skulls with obvious holes among the 137.

Ritual trepanation may have been practiced in southern Russia

There were five examples of trepanation among them. It is likely that the trepanations were performed to treat the injuries that caused the holes made in the skull at different locations around the front and side.

There were no signs of damage or disease on the other four trepanned skulls. A further notable feature of all four was that they had been trepanned exactly at the obelion.

An anthropologist at the German Archaeological Institute (DAI) — Julia Gresky — had read Batieva’s papers describing the unusual trepanations from Rostov-on-Don.

As a result of Gresky’s and Batieva’s collaboration, all 12 of the obelion trepanations have been described. The American Journal of Physical Anthropology published their study in April 2016.

It would have been a remarkable discovery wherever the 12 skulls had been discovered. A connection seemed likely, however, since they were all found in the same tiny corner of Russia. Without a link, it was extremely unlikely that a batch of such rare trepanations would appear exclusively in southern Russia.

The clustering of the unusual trepanations suggests, although it is difficult to prove, that southern Russia may have been a center for ritual trepanation.

There seems to have been no problem with the other skull owners.

Among the experts on Russian trepanation is Maria Mednikova of the Russian Academy of Sciences in Moscow. Some “transformations” may have been achieved through trepanations in specific, dangerous areas of the cranium, according to her. By trepanning in these places, people believed they could acquire unique skills not available to ordinary people.

The unusual and dangerous manner in which these 12 apparently healthy people were trepanned can only be speculated. It is possible, however, to infer a surprising number of things about the people’s fate from the trepanation holes themselves.

At one of the sites near Rostov-on-Don, one of the skulls belonged to a young woman under the age of 25. During or after trepanation, it did not show any signs of healing, making it likely that she died.

Other skull owners, however, appear to have recovered from their operations. Despite the fact that the bone never entirely regrew over the trepanation holes in their skulls, the edges of the holes showed signs of bone healing.

It appears that three of the 12 skulls survive less than eight weeks after their owners were trepannated, as only slight healing was seen around the trepanation hole in three of the skulls. There were two women between the ages of 20 and 35 among these individuals. It was not possible to determine the sex of the third individual, who was an elderly person between the ages of 50 and 70.

There was a greater degree of healing on the other eight skulls. After their operations, these individuals probably survived at least four years based on current knowledge of bone healing.

It appeared that all of these people were trepanned while they were perfectly healthy

Batieva was first drawn to the bizarrely-trepanned skulls of the mass grave near Rostov-on-Don almost 20 years ago after finding them in the grave.

One adolescent girl, two women, and two men had survived with their obelion holes for a number of years. It appears that she was trepanned when she was not older than 12, and possibly even younger. Her skeleton suggests she was between 14 and 16 years old.

There is still a possibility that these 12 people had diseases or injuries to their heads. Eight of them may have benefitted from the trepanning operation in that case.

Batieva and her colleagues may also be correct, and these individuals were trepanned for ritual purposes. The benefits they received over the rest of their lives can only be guesstimated if that is the case.



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