The square-drilled skull that confirmed the Incas performed complex surgeries

In 1864, the American Ephraim George Squier lived an unusual experience.

He held in his hands the first unquestionable evidence of something scientists had long thought impossible: ancient neurosurgery.

The discovery was an accident — and to some extent due to bird droppings.

With the outbreak of the US Civil War in 1861, securing fertilizers for growing food became a strategic necessity for then-President Abraham Lincoln.

And the best fertilizer in the world at the time was found in the mountains of some islands in South America, which for centuries had accumulated guano, a substrate that originates from animal feces and is rich in nitrogen and phosphorus.

It was because of guano that, in 1864, Lincoln sent a delegation to Peru, of which Squier was a member.

The lady ‘of the Grand Canal’

The fertilizer supply secured, the diplomat told the woman to return to New York alone. Passionate about archeology, he decided to stay in the country to dedicate himself to research.

After a year of traveling, traveling from the coast to the forests and scaling the peaks of the Andes, he arrived in Cusco, a “lofty but isolated mountain city”.

It was a place that took longer to reach and with four times more “discomfort and fatigue” from the Peruvian capital than traveling from Lima to New York, he wrote in the book “Peru: Exploration and Travel Incidents in Land of the Incas”.

After describing in detail the magnificent archaeological sites he found in the region, as well as the city, its history, population and modern appearance, he stopped at one place:

“I will refer especially to the residence of Mrs. Zentino, a lady who resided in the Plaza de San Francisco, whose attention to foreigners was proverbial, and who established an honorable reputation as a collector of the best and most valuable museum of antiquities in Peru.”

“This house would be called a ‘palace’ even in Venice, if it were not for its architecture, certainly for its extent. In the breadth of its rooms and in its rich and varied contents and decoration, it could commendably be compared with some of the most beautiful in the world. Grand Canal.”

museum of curiosities

The “señora Zentino” was María Ana Centeno de Romainville (1816/1817-1874), a woman enriched by “frequent reading” and who began collecting at a young age, with a “passion that bordered on madness”, according to the pioneer educator Peruvian Elvira García y García in her book “The Peruvian Woman Through the Centuries (1925)”.

This fascination led her to gather a treasure trove of pieces from different places, to the point of having a true “historical-archaeological museum, through which it was possible to learn about the entire history of Peru in its different eras”.

In addition to pre-Columbian antiquities made of stone, ceramics and precious metals, there was everything from a Roman mosaic and Japanese objects to stuffed birds and mysterious works. After all, his goal was not “to create an archaeological museum — but one of curiosities,” García y García wrote.

Mrs. Zentino’s “palace” was a meeting place similar to the salons that existed in Enlightenment Europe. It was where the Cusco elite and prominent foreign guests gathered to talk about science, art and literature.

One of them was Squier, and it was on one of those occasions that he got his hands on that unusual gem that would change the history of surgery.

“In some ways, the most important relic in Mrs. Zentino’s collection is the frontal bone of a skull, from the Inca cemetery in the Yucay Valley,” wrote the American.

the skull

What caught his attention in the piece was a 15 x 17 mm square hole. It wasn’t natural, he thought: nature doesn’t work at right angles.

He also thought he saw signs of new bone growth, indicating that the person was not only alive during the drilling, but had survived.

A startling thought occurred to him: Could it be the result of surgery, an opening made in the skull for curative purposes?

He concluded that there was no doubt that he was dealing with “a clear case of trepanation”, an ancient technique of cranial drilling.

“Ms. Zentino kindly lent me the piece for research. It was analyzed by the best surgeons in the United States and Europe, being considered by all as the most remarkable evidence of knowledge of surgery by native peoples ever discovered in this continent. Trepanning is one of the most difficult surgical procedures,” Squier described in his book.

But it wasn’t that simple.

The American’s report, published in 1877, omitted an episode that occurred shortly after his return, at a meeting of the Academy of Medicine in New York. Upon seeing the skull, those in attendance refused to believe that anyone had survived a trepanation procedure conducted by an indigenous Peruvian.

The idea that the ancient Incas could perform such delicate surgery without anesthesia or metal tools just seemed preposterous.

The survival rate of trepanations performed by the most skilled surgeons in the best hospitals in the region at the time rarely reached 10%.

What they did not take into account is that the percentage was similar to that observed in other types of procedure. The microbial theory, which revolutionized the treatment and diagnosis of diseases, was not yet in effect at that time, and many patients ended up dying from the infection.

Squier didn’t give up. He decided to take the skull to France for examination by Europe’s foremost authority on the human skull, Paul Broca, professor of external pathology and clinical surgery at the University of Paris and founder of the first anthropological society.

Broca became world famous in 1861 when he discovered the first known language point in the human brain, now called Broca’s area, the first case of brain localization of a psychological function.

Upon examining the square hole, the scientist concluded that it had been deliberately made. After examining it under a microscope, he found evidence of bone growth around the puncture – which indicated that the patient had survived the operation.

Despite Broca’s prestige, the Anthropological Society of Paris was skeptical of his conclusions.

But a few years later, his interpretation would finally be confirmed, with the discovery in the central region of France of skulls with rounded holes, scars on the edges and bone discs of the same size (perhaps used as amulets) belonging to the Neolithic – which confirmed that, since in that period, trepanning was successfully practiced.

Scientists had no choice but to consider the possibility that they had underestimated older civilizations in this respect until then.

The Inca skull spurred a change of heart among anthropologists, who began digging through their own collections and examining holes that had been interpreted in the past as the result of war injuries, accidents or animal attacks. And they found more trepanned skulls, some of which date back to 8000 BC.

Today it is known that it was a widespread practice and that different cultures around the world used a variety of tools to cut skulls: sharp stones, animal bones, red-hot irons and even shark teeth.

In the case of Peru, cemeteries usually contain a “tumi” —a curved metal ceremonial knife—, which seems appropriate for carrying out the procedure.

Studies also indicate that these ancient surgeons were even able to prevent infections. A survey of 66 trepanned ancient skulls showed that only three had signs of infection.

The result is similar to that of a report produced in London in the 1870s. While 75% of neurosurgical patients in the English city died, in New Guinea, where surgeons still drilled into skulls with traditional methods, the mortality rate was 30%.

What is not known for sure is why ancient cultures practiced trepanation, as there was nothing written about the procedure.

Broca always argued that they trepanned the skulls to release what they believed to be evil spirits trapped inside the brain. He claimed that this association was common, especially in cases involving epileptic seizures or hallucinations.

It was something that actually happened in Europe, but there is no evidence that it also happened in the more distant past.

Squier and other archaeologists have always questioned theories that refer to the supernatural.

They argued that ancient neurosurgeons were doing exactly what they appeared to be doing: treating head injuries, primarily from falls and those resulting from combat.

Modern research points more in that direction, especially in the case of the Incas.

Skulls with perforations were found more in males than in females, which is interpreted as a result of the fact that there were more male than female warriors.

These holes are usually on the left side of the skull, where a right-handed opponent would strike with his weapon.

Trepanning would have been a way to clean the wounds and prevent blood from accumulating.

Superstition may have played a role in early trepanations. But it’s also possible that those ancient neurosurgeons used the procedure to save people’s lives, as their colleagues still do today.

This text was originally published here.