Trepanation: The Ancient Practice of Drilling Into the Skull, and Who Survived It

Trepanation means opening the skull on purpose. In Spanish it is *trepanación*, and a skull with such an opening is a *cráneo trepanado*. The Diccionario del español de México defines trepanación as perforating the vault of the skull with a trephine to relieve compression from a fracture or from a collection of blood and pus.

The openings come in different shapes. Some are round, some are square or rectangular, and some are shallow, wide scrapes. The shape often tells you which technique was used, a point we will come back to.

A scholarly review by López and colleagues in the journal Anthropological Science reports European examples dating to about 10,000 BCE, with Mesolithic cases from Portugal and other regions. During the Neolithic, between about 4500 and 1800 BCE, trepanation became more common across parts of Europe and the Mediterranean.

One of the clearest early cases comes from Catalonia. The Gavà Museum keeps the skull of a man aged 30 to 40, buried at the Gavà mines and dated to 5600 to 5400 BCE. He had two trepanations, both made by abrasion, which means the bone was worn away rather than cut out. The museum states that he lived for six months after the operation.

In Denmark, the National Museum in Copenhagen holds the Næs skull, from a man aged 30 to 40, found at Næs, Falster, in a context dated to about 3500 to 3000 BCE. A photograph of it on Wikimedia Commons is openly licensed.

The earliest Peruvian examples cited by López and colleagues come from Paracas burials, dated between 200 BCE and 400 CE. From there the practice spread widely through Andean societies, including communities in the southern highlands, and continued into the Inca period.

Museums in Lima keep many of these skulls. The Museo Larco collection spans 1250 BCE to 1532 CE and includes trepanned skulls such as ML100679, ML101604, ML101614, ML101616, ML500089 and ML500092, some with healed openings and some without. At the Museo Nacional de Arqueología, Antropología e Historia del Perú, a Paracas skull shows a trepanation made over a fracture caused by a star-shaped club. That skull also carries a gold covering, and the museum is careful to say there is no evidence the gold sheet was implanted while the person was alive.

If you hope to see a particular skull in person, confirm its object number and display status with the museum before you travel, since collections rotate and not everything is on view.

Yes, many did, and the evidence is written in their bones. When a person lives for weeks or months after an opening is made, the bone around the edge reacts: it smooths over, regenerates and remodels. A skull with a smooth, rounded edge around the hole belonged to someone who survived long enough for that healing to happen. A sharp, unhealed edge is harder to read. It cannot by itself prove the operation killed the person, because they may have died of the original injury or of something else.

The most cited numbers come from Peru. Andrushko and John W. Verano examined 66 individuals from 11 burial sites in the Cuzco region and documented 109 perforations. They reported an overall survival rate of 83 percent, with little evidence of infection afterward, and they saw survival improve over time, which suggests that technique got better. Their study is summarized on PubMed.

A broader comparison by David S. Kushner and John W. Verano, presented in Neurology, tracked survival across centuries.

The American College of Surgeons summarizes the same line of work, reporting regional samples reaching 91 percent between 1000 and 1400 CE and an average Inca-period survival of 75 to 83 percent. Europe has its own figures: a Spanish study identified signs of survival in 95 of 127 published trepanned skulls, about 75 percent.

These percentages describe the skulls that archaeologists have studied, not every trepanation ever performed. Even so, they change the image of the practice. For many ancient patients, this was an operation they walked away from.

In ancient Peru, head injury is the leading documented reason. The Museo Larco describes trepanation as a way to remove hematomas, pooled blood under the skull, or fractured bone, especially after ritual combat or warfare, and it also mentions pain and other complaints of the head. Andrushko and Verano likewise concluded that cranial trauma was a major motive in their Cuzco sample.

In Greece, the Hippocratic treatise On Injuries of the Head, written around 400 BCE, describes trepanning for serious head wounds and conditions of the skull. Its instructions are detailed: where to place the opening, how to avoid the membrane covering the brain, how to examine the cut, and how to cool the trepan as it saws.

Medieval and early modern European texts describe trepanation mainly for skull fractures, head wounds and pressure beneath the skull. Later historical writing also linked it with epilepsy, convulsions and mental illness. For any single archaeological skull, though, the exact motive often cannot be known. Studying medieval skulls from Gormaz in Spain, López and colleagues note that trepanation was much less common in medieval Europe than in prehistoric times, and that the reason for an operation cannot be determined from the skeleton alone.

Museums and excavations record several ways of opening a skull, and the tool and the shape of the hole usually go together.

In the Cuzco study, circular cutting and scraping were the main methods. Peruvian collections identify knives of obsidian, copper and copper alloy. The Peruvian Ministry of Culture describes a Paracas operation made by scraping the bone with stone or metal, which left a relatively small opening with beveled edges.

The Hippocratic text names a serrated trepan, a perforator and a probe. It advises the surgeon who began treatment right away to stop before the instrument reaches the membrane, and to cool the trepan in water during sawing.

By the eighteenth century the tools had become a surgeon's kit. The Science Museum Group holds an English trepanning set dated about 1731 to 1770, with trephine crowns, a perforator handle, reaming tools, forceps, a skull elevator, a gouge and a fitted case. The University of Groningen Museum also lists a set of tools for boring into the skull.

For a long time, scholars debated whether holes in ancient skulls were surgery at all or simply damage that happened after death. One skull helped settle it. In 1865, Ephraim George Squier found an Inca skull in Cuzco, dated to about 1400 to 1530, with a trepanation opening. According to the American College of Surgeons, the skull helped establish ancient Peruvian trepanation as evidence of surgery rather than postmortem damage.

The skulls from Gormaz in Spain show how much, and how little, bone can tell. One woman's skull shows extensive regeneration around the opening, a clear sign she lived on. A man's skull from the same study lacks clear signs of survival. Neither one says why the operation was done.

These are the questions people ask most often about the holes in these skulls.

Trepanation is one of many ways the human skull has carried a story long after its owner died. For a nineteenth-century skull that taught doctors about the brain, read about Phineas Gage's skull. For another Neolithic tradition of working on the skull, this time to remember the dead, see the Jericho plastered skulls, and for the basics of the bone itself, start with human skull facts.