A Hole in the Head: Trepanation

Trepanation, or trephination, has fascinated the Western academic world since the mid-19th century when Ephraim Squier discovered a trepanned skull in Cuzco, Peru. “Trepanation is the removal of a bone piece of the skull of a living individual without penetration of the underlying soft tissue” according to Erdal and Erdal (2011). The word trepanation in latin means ‘to bore’, which fits the procedure perfectly. It can be done with a variety of methods, but all involve removal of a piece of skull. It appears to have been fairly widespread type of operation, and was likely independently invented in a number of cultures. Most frequently, trepanation is found in Peru, Bolivia, Africa and Central Europe. The earliest trepanation dates to 6500 BCE and is found in France. This type of surgery, now known as craniometry, is still practiced today for cranial trauma.

Trepanation is easily identified by large holes in the skull of an individual, usually in the parietal or frontal bones. Based on the technique used to remove the bone, the hole can be either circular or rectangular. The first type of trepanation involves drilling small holes in a circular pattern which will connect and allow for removal of a section. This produces a circular pattern of smaller circles.

Brothwell 1981

The second technique involves scraping away in a circular pattern until the inner table is penetrated. This creates a more clean circular pattern.

Brothwell 1981

The third technique involves sawing at the bone in long canoe shaped lines to create a rectangular pattern. This leaves a rectangular hole in the skull.

Brothwell 1981

The bone can be removed through drilling with a trephine or drill, scraping with an abrasive instrument, cutting with an incisive instrument, or using a combination of tools. Trepanation is done for a number of reasons such as the treatment of cranial injury, as a cure for insanity or epilepsy, or in some cases was done with religious or ritual motivation. While trepanation is a major surgery that is potentially fatal, a large number of individuals throughout history have evidence of healing. In a number of trepanned skulls we see that the edges of the wound are rounded and new bone has built up, showing that the individual recovered from the incident.

In a recent article by Erdal and Erdal (2011), trepanation in Anatolia is reviewed. They examined 40 individuals from 23 different regions in Anatolia and that span over 10,000 years from the Aceramic period to the Ottoman Empire. The purpose of this paper was to look at the patterns of trepanation over a long period of time in a small area to see what patterns emerged. The results of their analysis revealed that trepanation was only conducted on adults, and half of them showed long term healing. Healing was most likely to occur when using the scraping technique, however the lowest was in the rectangular technique. There was variation by time period on whether more males or females were trepanned, but overall it was more often found in males. All three types of trepanation were found in this region, with a variety of possible tools. The earliest cases were primarily drilled, and later cases were scraping and rectangular techniques. Boring multiple holes to create one larger one was only found in the Iron Age. Based on the other pathological indicators, they concluded that the majority of trepanations occurred as a reaction to cranial trauma. There was no clear evidence that religious or magical reasons were the purpose of trepanation, but these would be hard to prove without clear burial context and supporting artifacts.

When we study populations it is important to not study them in a void. We need to look both horizontally at the wider region, and vertically at the ancestral and descendant populations. Erdal and Erdal (2011:508) note that one of the problems of these expansive reviews is that there is very little evidence given the space and time, and that studies like these are only a first step towards a fuller understanding of the processes occurring. Despite that, it is an important step to synthesize what we know about the world. A large percentage of bioarchaeology studies focus on singular populations, or singular pathologies, or even a single individual. While these are a necessary step, we also need to look at the bigger picture to see what was occurring in the region and how it fits into the more general temporal trends. The only downfall of this study is that they are primarily descriptive in their study. What we need know is the social processes that are guiding these changes. This will require combining the Erdal and Erdal (2011) study with studies on the culture in general.

Works Cited

Y.S. Erdal and O.D. Erdal (2011). A Review of Trepanations in Anatolia with new Cases International Journal of Osteoarchaeology, 21, 505-534

12 responses to “A Hole in the Head: Trepanation

  1. One of my former students, Lara Frame, wrote a master’s thesis on the topic: “Drilling Away the Spirits: a Worldwide Study of Trepanation” (East Carolina University, 2010). There is definitely a need for a synthetic article on the worldwide practice of trepanation, though… maybe I can bug Lara to revise her thesis and submit it somewhere.🙂

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  3. I am a member of an amateur archaeology group. In our latest dig (supervised by our local University Archaeo Dept) we uncovered a full skeleton with the unusual feature of a perfectly triangular hole in the skull. The dig is not yet finished and we are awaiting appropriate permissions before we complete the skele excavation. Until this is finished we won’t have a full view of the skull (it is still buried in the trench wall). Any ideas please about triangular holes in skulls. Stratified evidence points to Iron Age, Roman or 12th Century possibilities for identifying a period.

    Sincerely Liz

    • First off, I would need to know how the edge of the hole appear. If they are jagged or bent it could indicate trauma with a triangular weapon or object. If the edges have kerf marks it would indicate sawing associated with medical procedure.

      Second, look for healing and other marks around the wound as these may help with identification. I would also check the color of the bone to make sure it isn’t a taphonomic change.

      Finally, you probably need a better handle on the time period you are dealing with to determine how the wound appeared. I would look up weapons from the time period, as well as medical procedures to see what is common.

      Hope that helps!

      • Many thanks for your thoughts Katy. The edges of the hole are quite sharp. There is no evidence of radial breaks or cracks which is why the enigma began. We close the site on Friday but I will try and take close up photos before we lay the soul to rest once more. As for historical period, the skele is lying in the same strata as one King Alexander of Scotland silver coin and several French and English coins belonging to the King Edward II period (1300’s) . When I’ve done some more ‘digging’ (pun intended) I’ll make another post here.
        Once again many thanks.

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