This exhibit is now closed.


Incomplete trephination using the drilling techniqueThe act and art of trephination have been practiced around the world for thousands of years. The Museum’s newest exhibition Skull Stories: The Art of Ancient Surgery focuses on the universality of this practice, the various methods and tools used to perform trephinations, and why the surgery is carried out. This important new exhibit opened to the public on Saturday, November 22, 2008.

All peoples, both ancient and recent, have used natural and/or supernatural healing methods to deal with varied illnesses. Trephining, or removing a piece of bone from the skull, is the oldest surgical procedure known from antiquity.

The practice has garnered intense interest because it represents an early form of cranial surgery performed well before the advent of modern medicine. Many trephinations are associated with skull fractures, suggesting that the treatment of head injury and its complications may have been a major motivation for the practice. Evidence also shows that ancient people may have believed trephination would cure various ailments such as epileptic seizures, migraines, and mental disorders. In addition to being used as a method to treat illnesses, trephination was practiced by some populations in order to let evil spirits escape from an individual. Furthermore, some individuals kept the bone that was trephined and wore it as a talisman or charm to keep evil spirits away.


Four basic trephination techniques were used by prehistoric surgeons: cutting, scraping, drilling, and grooving. The cutting technique usually consisted of four straight cuts at right angles (tic-tac-toe style) to remove a rectangular piece of bone. The cuts were made with a sharp stone knife and were deeper in the center than on either end. The scraping technique consisted of gradually scraping the bone with a sharp or abrasive stone until the outer, middle, and lower layers of the skull were worn away, exposing the membrane that covers the brain. The drilling technique required two steps. First, a circle of holes was drilled with a sharp instrument. Then the tiny of bridges of bone between the holes were cut with a stone knife, and the disc of bone was pried out to expose the membrane covering the brain. The grooving technique was accomplished using a sharp stone point to carve a circular piece of bone from the skull. The groove was drawn and redrawn until the central piece was loose.


Trephination using the classic "tic-tac-toe" cut 

Artist’s reconstruction of an Inca trephination at ancient Machu Picchu
(painting by Alton Tobey, courtesy of the Smithsonian Institution).

That the ancient surgeon enjoyed a considerable degree of success in trephination surgeries is proven by the fact that many of the skulls show some degree of healing in the wound. Trephined openings with no healing reveal a sharply cut edge or an abraded edge with no signs of change in the bone from such causes as inflammation or infection. Partial healing may show in bony changes such as new or fibrous bone. Scratch marks, probably from incising the scalp, may still be apparent, as well as fracture lines near the opening. In a well-healed trephination, the bone has consolidated and the diploe (the porous layer between the inner and outer layers) is no longer visible.

Copper and bronze tumi knives from prehistoric Peru.

Skulls exhibiting different degrees of healing after a trephination will be displayed, as well as skulls that have been trephined using different techniques. Peruvian skulls from the Museum of Man’s premiere Hrdlicka Paleopathology Collection will be showcased, and people from various cultures around the world who perform trephinations will be highlighted. Trephination tools and instruments such as obsidian blades, tumis, and chisels will also be displayed. The curiosity surrounding this subject as well as its historic appeal are sure to attract many visitors who are anxious to learn more about cranial surgery. Skull Stories: The Art of Ancient Surgery opened on the South Balcony of the Museum on November 22, 2008.

—Tori Heflin, Curator of Physical Anthropology

Sponsored by:

City of San Diego Commission for Arts and Culture

County of San Diego Community Enhancement Program