Trepanation: The Evidence for Ancient Skull Surgery

The Short Answer

Trepanation is the deliberate removal of a piece of bone from the skull of a living person. It is the oldest surgical procedure with clear archaeological evidence, going back at least 7,000 years in Europe. It was also practiced widely in ancient Peru. Healed bone around many openings proves that patients survived, often for years. The most consistent documented reason is the treatment of head injuries. Spiritual and other motives remain possible but are harder to prove.

• Oldest secure case: A skull from Ensisheim, Alsace, c. 5000 BCE, with two trepanations, one fully healed
• Largest body of evidence: The Andes of Peru, from about 400 BCE to the Spanish conquest
• Survival in the Inca period: Roughly 75 to 83 percent long-term survival, according to Kushner, Verano and Titelbaum (2018)
• Prehistoric tools: Flint, obsidian and later copper or bronze blades, used to scrape, groove or cut the bone
• Earliest medical text: The Hippocratic treatise On Wounds in the Head, late 5th century BCE
• Modern descendants: Burr holes and craniotomies in neurosurgery

What Trepanation Is and How Archaeologists Identify It

The word comes through Medieval Latin from the Greek trypanon, meaning “borer” or “auger.” “Trephination” is used as a synonym. Strictly, a trepanation removes a disc or plate of bone from the cranial vault and leaves the dura mater intact. The dura is the tough membrane covering the brain.

A hole in an ancient skull is not automatically surgery. Archaeologists have to rule out other causes, such as:

• Weapon wounds
• Tumors or infections that erode bone
• Damage from burial or excavation
• Cuts made after death, for example to make trophy skulls

The signs of deliberate surgery are tool marks running in a controlled pattern, a bevelled or stepped edge, and an opening that does not follow the shape of a fracture. The decisive evidence is healing. Living bone reacts to injury. Within weeks the sharp cut edges begin to round off. After months or years they become smooth and dense. A skull with smoothly remodelled margins belonged to someone who survived the operation.

The Oldest Trepanned Skulls

Trepanned skulls have been found in Europe, North Africa, the Near East, Central and South Asia, Siberia, China, the Pacific and the Americas. Because of that spread, scholars usually treat the practice as something several societies developed independently, not a single invention that traveled.

The earliest dates are contested. Some researchers have proposed cases from late Ice Age or Mesolithic sites, such as Taforalt in Morocco. These identifications are debated, so claims of “10,000 years” of trepanation rest on weak ground.

The firmest early case comes from a Neolithic cemetery at Ensisheim in Alsace, France. In 1997 Kurt Alt and colleagues published in Nature the skull of a man of about 50, dated to around 5000 BCE. He had two large trepanations. One had healed completely, and the other showed partial healing. He survived both operations.

Neolithic Europe has produced many more examples, especially in France, in the third and fourth millennia BCE. Most belong to adult men, but women and children also appear. Some sites have also yielded skull discs, called “rondelles,” that were cut from skulls and perforated, apparently to be worn. Whether all of these were taken from living patients or some from the dead is not always clear.

One animal case is unusual. A cow skull from Champ-Durand in western France, dated to about 3400 to 3000 BCE, has a surgical-looking opening with no healing. Researchers Fernando Ramirez Rozzi and Alain Froment, who published it in 2018, suggested it may have been practice on an animal. If the animal was alive at the time, it did not survive.

How Ancient Surgeons Opened the Skull

Before metal tools, surgeons worked with flaked flint or obsidian. In the Andes, copper and bronze blades came into use later. Scholars who study the skulls describe several distinct techniques. Some cultures favored one over the others.

Scraping

The surgeon abraded the outer table of the skull over a wide oval area until the bone thinned and broke through. This leaves a broad, bevelled opening. It was slow, but it gave fine control over depth.

Grooving

The surgeon cut a circular or oval groove repeatedly until the central disc of bone came free.

Rectangular intersecting incisions

Four straight cuts, crossing at the corners, outlined a square or rectangle of bone that was then lifted out. The skull that E. George Squier brought from Peru in 1865 shows this technique.

Boring and cutting

The surgeon drilled a ring of small holes close together and then cut the bridges between them.

The crown trephine is a different instrument. It is a cylinder with a toothed rim, rotated by hand or with a bow. It belongs to Greek and Roman medicine, not prehistoric practice. Celsus describes it, along with a drill, in Book VIII of De Medicina in the 1st century CE.

A popular claim holds that Peruvian surgeons used the ceremonial crescent-shaped knife known as the tumi. The tumi does appear in Andean art, but no study has tied the skull marks specifically to that tool.

Why Ancient People Performed Trepanation

No prehistoric society left a written explanation, so motives have to be inferred from the bones and their context. The evidence supports several explanations, with different strengths.

Treatment of head injuries

This is the best-documented reason. In Peru, many trepanations sit beside or directly over depressed skull fractures. They cluster on the left front of the skull, where a right-handed opponent’s blow would land. They are also more frequent in adult men. Anthropologist John Verano of Tulane University, who has examined hundreds of Andean examples, argues that the practice began as practical treatment for head wounds. The aim was to remove bone fragments, clean the wound and relieve pressure from bleeding or swelling. Sling stones and star-headed maces were common Andean weapons and could cause exactly such fractures.

Other medical complaints

Some trepanned skulls show no fracture. The surgeons may have been treating headaches, seizures, infections or symptoms that leave no mark on bone. In the 1860s and 1870s Paul Broca suggested that Neolithic trepanation treated convulsions in children. This was a reasonable guess, but it cannot be tested directly.

Ritual or spiritual motives

The idea that trepanation released evil spirits is common in popular accounts. It draws on later ethnographic reports and on the perforated skull discs found in some Neolithic graves. It is plausible for some societies, but there is little direct evidence for it. In practice, the line between “medical” and “spiritual” treatment may not have existed for the people involved.

Did Patients Survive? Healing and Survival Rates

Many did, and the bone records it. Scholars sort skulls by the state of the cut edges:

• No healing: death during or shortly after surgery
• Early healing: survival for weeks
• Complete remodelling: long-term survival

The largest study comes from Peru. In 2018, David Kushner, John Verano and Anne Titelbaum compared Andean trepanations across time:

• Earliest cases, roughly 400 to 200 BCE on the south coast: about 40 percent of patients showed long-term survival
• Middle periods: survival rose to around half
• Inca period, roughly 1400 to 1532 CE: long-term survival reached about 75 to 83 percent

The authors compared this with the American Civil War, when mortality after cranial surgery in military hospitals ran between about 46 and 56 percent. Infection was the main killer in 19th-century hospitals.

The Peruvian sample also shows the technique changing over time. Openings in later periods tend to be smaller. Scraping and circular grooving largely replaced the riskier rectangular cuts. Surgeons appear to have avoided the midline of the skull, where a large venous sinus runs beneath the bone. Some individuals had several trepanations, many of them healed, so they survived more than one operation.

Survival estimates for prehistoric Europe vary by site and method. Neuroscientist Charles Gross summarized published estimates as ranging from about 50 to 90 percent. These figures depend heavily on how each researcher reads the healing evidence.

Healing does not mean the hole closed. The edges remodel and seal, but the skull rarely regrows across a large opening. A permanent defect remains, protected only by scalp and membrane. Coca has been proposed as a pain reliever in the Andes, but nothing in the skulls confirms its use. Verano notes that the scalp is sensitive, while the skull itself has few nerves. A patient with a serious head injury may already have been unconscious.

Trepanation in Greek, Roman and Medieval Medical Texts

Writing about the procedure begins thousands of years after the earliest skulls. The Egyptian Edwin Smith Papyrus, copied around the 17th century BCE, describes many head injuries but does not describe trepanation.

The first detailed surgical account is the Hippocratic treatise On Wounds in the Head, written in the late 5th century BCE. It classifies skull injuries and recommends trepanning certain fractures and contusions. Its practical advice includes avoiding the sutures and stopping before reaching the membrane. It also tells the surgeon to withdraw the trephine often and cool it in water so the bone is not overheated.

Celsus described Roman instruments and methods in the 1st century CE, and Galen discussed the operation in the 2nd century. In the Islamic world, Abu al-Qasim al-Zahrawi (Albucasis, d. c. 1013) described drills fitted with collars that stopped them from plunging into the brain. In Europe, surgeons continued to trepan skull fractures through the Renaissance and into the 18th and 19th centuries.

Some named individuals carry the evidence. Vespasiano Gonzaga, Duke of Sabbioneta in Lombardy, died in 1591. His remains were exhumed in the late 1980s, and his skull shows a healed trepanation, so he lived for a significant time after the surgery. Accounts of exactly when and why it was performed differ, so those details are best treated with caution.

How Trepanation Was Rediscovered: Squier and Broca

For a long time, European scholars did not recognize trepanned skulls for what they were. Bernard de Montfaucon described a perforated skull from Cocherel, France, in 1719, but no one understood it as surgery. In 1839 Samuel Morton illustrated a Peruvian example without grasping its significance.

The turning point came in the 1860s. E. George Squier was an American diplomat, journalist and archaeologist. In the Cuzco region of Peru he was shown a skull from a pre-Columbian burial with a rectangular opening. He concluded it was “a clear case of trepanning before death.” In 1865 he presented it to the New York Academy of Medicine, where physicians were skeptical. Squier then sent it to Paul Broca in Paris.

In 1867 Broca told the Anthropological Society of Paris that the edges showed reactive changes. The patient had therefore survived for days or weeks. Many colleagues doubted that “primitive” people could achieve what Paris hospitals struggled to do. In the following years, physician Prunières and others reported trepanned Neolithic skulls and skull discs from the Lozère region of southern France. Those finds confirmed that the practice was ancient and that patients survived. Squier later described the skull in Peru: Incidents of Travel and Exploration in the Land of the Incas (1877).

The “Stone of Madness” and Other Misconceptions

Several popular ideas about trepanation mix real history with later imagery.

• “Medieval doctors cut stones of madness out of skulls.” This image comes mainly from late 15th to 17th century Netherlandish art. The best-known example is The Extraction of the Stone of Madness in the Prado, attributed to Hieronymus Bosch, though its date and attribution are debated. Painters such as Jan Sanders van Hemessen repeated the theme. These works usually satirize quacks and gullible patients. The incision shown is a shallow scalp cut, not a trepanation. Whether such operations were actually performed, perhaps with a hidden pebble, is uncertain.
• “Trepanation was mainly for letting out demons.” In the best-studied region, Peru, the skeletal evidence points first to head trauma. Spiritual motives are possible elsewhere but are seldom demonstrable.
• “Ancient survival rates were 80 percent.” That figure applies to the Inca period specifically. Earlier Andean surgery was far riskier.
• “Prehistoric surgeons used drills like modern ones.” Most prehistoric openings were scraped, grooved or cut. Rotating trephines belong to the classical world and later.

Trepanation in the Modern Era

In the 1960s, the Dutch writer Bart Huges developed a theory that adults could raise their brain’s blood volume, and so their consciousness, by opening the skull. He trepanned himself in 1965. His British followers included Joey Mellen and Amanda Feilding. In 1970 Feilding drilled into her own forehead with a dentist’s drill under local anaesthetic, using a mirror, and filmed the procedure as Heartbeat in the Brain. She survived. She later stood for Parliament promoting trepanation and went on to found the Beckley Foundation, which funds research on psychedelics. Medical authorities regard elective self-trepanation as dangerous and see no evidence that it raises consciousness.

Modern neurosurgery still opens the skull, for specific, diagnosed conditions:

• Burr holes: to drain chronic subdural hematomas and to insert pressure monitors or drains
• Craniotomy: a bone flap is temporarily removed to reach tumors, aneurysms or bleeds
• Decompressive craniectomy: after severe brain swelling, a section of skull is left off for a period to relieve pressure

The underlying principle matches what the Hippocratic and Andean surgeons appear to have grasped from experience. Bleeding or swelling inside the rigid skull can kill, and removing bone can relieve it. The modern difference lies in imaging to locate the problem, sterile technique and anaesthesia.

Frequently Asked Questions

What was trepanation in ancient skull surgery?

Trepanation was the removal of a piece of bone from a living person’s skull by scraping, grooving, cutting or drilling. It is the oldest surgery with clear archaeological evidence, dating back at least 7,000 years in Europe. It was also widespread in ancient Peru. Healed edges on many skulls show that patients often survived the operation.

Does the skull heal after trepanation?

Partly. Within weeks the cut edges begin to remodel, and over months to years they become smooth and rounded. This healing is how archaeologists know a patient survived. However, the bone rarely grows back across a large opening, so a permanent hole usually remains, covered only by the scalp and the membranes beneath.

Why did ancient people do trepanation?

The best-documented reason is treating head injuries: removing fragments of fractured bone and relieving pressure from bleeding or swelling. Many Peruvian cases sit beside skull fractures. Other suggested motives include headaches, seizures and spiritual beliefs about releasing harmful forces. Without written records, those other motives are much harder to prove.

What was the survival rate of trepanation?

It varied by time and place. In ancient Peru, a 2018 study found about 40 percent long-term survival in the earliest cases, around 400 to 200 BCE. That rose to roughly 75 to 83 percent in the Inca period. For prehistoric Europe, published estimates range from about 50 to 90 percent, depending on the site and how healing is assessed.

Do doctors still use trepanation?

Not under that name or for ancient reasons, but its descendants are routine. Neurosurgeons drill burr holes to drain blood clots and insert pressure monitors. They perform craniotomies and decompressive craniectomies to reach tumors or relieve dangerous brain swelling. These are done only for diagnosed conditions, with imaging, anaesthesia and sterile technique.