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Owen Freeman

One Archaeologist's Quest to Prove that Ancient People Practiced Trepanation

Original image
Owen Freeman

We may be biased, but we think the human brain is pretty special. All this week, is celebrating this miracle organ with a heap of brain[y] stories, lists, and videos. It all leads up to Brain Surgery Live With mental_floss, a two-hour television event that will feature—yes—live brain surgery. Hosted by Bryant Gumbel, the special airs Sunday, October 25 at 9 p.m. EST on the National Geographic Channel.

Ephraim George Squier was a year into his journey across Peru when he reached the city of Cuzco. Evidence of his trek clung to his body: skin tattooed with mud, armpits ripe from the humidity, clothes so soiled their original color was obscured. It was 1864, and the 42-year-old American was hell-bent on finding something that would make him a legend among archaeologists.

What lured Squier to Cuzco is still a mystery—an invitation, a tip, instinct? But after months in the wilderness, the city must have beckoned to him. Squier compared the sight of the city’s palace to the decadent houses on the Grand Canal in Venice. Inside, amid the usual trappings of wealth, the walls were lined with statues, weapons, pottery. Squier had collected similar items in the jungle. But now he had stumbled into an abundance.

The head of the house, Señora Zentino, dressed the part: formal gowns, often augmented with a Peruvian scarf or, given her love of antiques, a necklace of Incan tokens. Next to such finery, the skull she cradled should have startled Squier.

The whole thing sounds like a fable: a wandering adventurer, a mysterious, aging beauty in a jungle palace, a stolen head. In a pulp novel, a skull such as this would have been cursed. But as Squier turned it over in his hands like a diamond in the sunlight, he marveled at its defining feature—a square-shaped hole on its top left side.

Archaeologists across the world had unearthed skulls with holes before, in quarries or mass graves. Some argued that ancient tribes had mutilated them postmortem, perhaps to make drinking vessels or amulets. Most academics simply dismissed the marks as the results of infections, birth defects, or animal bites.

But as Squier looked closer, he became convinced this hole was not natural: Nature doesn’t work in right angles. Peering at the squarish 15-by-17-millimeter hole, he could see healing scars and signs of new bone growth. This person had not only been alive during the cutting—he or she had survived. A startling idea occurred to Squier: Could this be evidence of ancient neurosurgery?

In proposing that Incans practiced brain surgery—something even the best European and American doctors struggled with—and positing that ancient American civilizations were as advanced as ancient Egypt and Rome, Squier was gambling with his reputation. At the time, there was a pervasive prejudice against Amerindian tribes, who had long been dismissed as loin-clothed savages wielding crude tools. This was tangible proof otherwise. And Squier was willing to do anything—cross colleagues, forgo his dignity, sacrifice his marriage—to make the rest of the world understand.

The Guano Problem

The funny thing is, Squier hadn’t traveled to South America to learn more about ancient neurosurgery or to combat stereotypes. No, Squier had come to South America to settle something far more serious: an argument about bird poop.

Throughout the 1800s, farmers used natural fertilizers to grow crops. The best fertilizers came from islands off South America, where mountains of guano had piled up over eons. Guano proved so important to global health and economics—millions of dollars were at stake, not to mention the health of millions of hungry people—that Chile, Bolivia, and Peru actually went to war over bird excrement in 1879.

For most of the 1800s, the U.S. imported thousands of tons of guano per year, and with the outbreak of the Civil War in the 1860s, securing fertilizer to help guarantee a steady supply of food became a necessity. But a number of international incidents (one involving Confederate pirates seizing Peruvian ships and destroying guano cargo) had angered Peru, and the government was threatening to cut off the pipeline. The situation forced Abraham Lincoln to address the United States’ guano deficit head on. He dispatched a delegation to Peru in July 1863, and Squier, who had served as a diplomat in Central America, was a natural choice.

Squier spent five months untangling the legal claims in Peru. Having succeeded, he then sent his wife, Miriam, home to New York and set out to explore his real interest, the country’s buried artifacts and vine-choked ruins. Over the next 18 months, he traveled everywhere from the coast of Peru to the peaks of the Andes deep in the interior. He saw mountain fortresses, llamas, and statues and artifacts of every kind. The trip culminated with a visit to Señora Zentino, which was when the idea of ancient neurosurgery grabbed him.

Squier saw the holes as evidence of trepanation—a procedure in which surgeons cut out a pocket of the skull to relieve internal pressure and remove sharp fragments of bone. Western doctors had been trepanning skulls as far back as ancient Greece, and it had a brutal reputation. Medieval doctors plugged patients’ ears with lint so they couldn’t hear their own heads being sawed open. Few people who endured trepanation survived. By 1700, most clinics had abandoned the procedure. As one British surgeon declared in 1839, any doctor who proposed trepanning someone “ought to be trepanned in turn.”

Squier’s claim, then, seemed iffy—if the best European surgeons couldn’t pull off trepanations, how could so-called primitive jungle tribes? But Squier was convinced. After returning to New York in 1865, he showed the skull to colleagues and outlined his theory. In the debate that followed, some sided with Squier, while others derided the idea.

Undeterred, Squier appealed to the highest scientific authority around, French neurologist Paul Broca. Broca had recently achieved worldwide fame by discovering the first-known language center in the brain, now called Broca’s area. The Frenchman shared Squier’s passion for archaeology, especially for skulls, and in 1867, he snapped up Squier’s offer to examine the Incan skull.

Broca’s conclusions were unequivocal: Squier was correct. The shape of the hole could not have been natural or accidental, and he confirmed that new bone had grown around the rim. Broca’s medical eye also found signs of inflammation, further evidence that the patient had survived.

Broca forced scientists in Europe to confront the possibility that ancient people had developed their own sophisticated medical practices. Soon, other archaeologists started to notice trepanned skulls in their collections, some potentially dating back 10,000 years. Most of the holes were small and circular, but some gaped as wide as five inches across. Many had rims completely smoothed over by new bone growth, indicating that the patients had lived for years after. Skulls with multiple trepanations even turned up. One unlucky Incan fellow had seven separate holes in his head, all perfectly healed. But as archaeologists embraced Squier’s theory, a bigger mystery emerged: Why were civilizations performing trepanations in the first place?

Trepanation: A How-To Guide

Before they could tackle why, archaeologists needed to understand how. Over the years, Incan pots with images of trepanations had turned up. Additionally, evidence from rural Kenya, New Guinea, and similarly remote areas showed that other tribes were also proficient in the practice.

The procedure looked something like this: Imagine a young warrior hit in the head with a slingshot stone, which left a crater of mangled bone. A surgeon would clamp the young man’s head between his knees, crack open a coconut, and pour the juice on the scalp. The doctor, meanwhile, would dab fresh-cut leaves on the wound to dull the pain.

Then he’d get to work, using a shark tooth or something sharp to cut into the skull, grooving it round and round the depressed fracture, carefully working the incision deeper. Throughout the process, the warrior would gulp alcohol or consume tobacco to quell the discomfort. He would feel almost nothing after the initial pain: just the friction of the shark tooth against his skull. At last, the warrior would experience a slight sucking sensation as a plug of skull bone came free. With bamboo fashioned into forceps, the surgeon would pick out the bone splinters and wash the wound with coconut milk. He’d sew up the scalp with a needle and thread made of bat bones and banana fibers. A dressing of leaves and a plaster of pepper, lime, and betel nut might seal the wound. Finally, the patient would be instructed to eat soft foods for a week and minimize the movement of his head.

As with today’s procedures, managing pain and infection were the biggest concerns, but surgeons had measures to combat these. The coca leaves helped anesthetize the skull. Similarly, wild plants like balsam killed bacteria, as did washing wounds with coconut milk. In fact, ancient surgeons did a remarkable job with sterilization: In one study of 66 trepanned skulls, just three showed any signs of infection. These surgeons had a better track record than their counterparts in industrialized countries. In one survey from London in the 1870s, 75 percent of neurosurgical patients died, mostly due to infections. Compare that to the New Guinea tribes, where surgeons lost just 30 percent of their patients.


Why ancient cultures performed neurosurgery remains controversial. After years of studying skull holes, Broca concluded that doctors had trepanned skulls primarily to release spirits trapped inside the brain. Moreover, he hypothesized that they operated mostly on children, a claim he based on a macabre experiment. Using sharp glass, Broca managed to open the skull of a recently deceased 2-year-old in four minutes. Cutting a similar hole in an adult skull required 50 minutes, and his hand ached. Broca concluded that ancient surgeons lacked the patience and tools to cut through adult skulls and therefore must have limited the procedure to children, who grew up with holes in their heads.

But most scientists doubt Broca’s conclusion, partially because few trepanned child skulls have ever turned up. Broca’s theory that trepanation released evil spirits, however, proved enormously influential. This idea played into stereotypes of ancient people. And, in truth, many tribes—despite wildly different supernatural beliefs—probably did trepan people to treat epilepsy and hallucinations, maladies often associated with spirits.

Squier and other archaeologists always doubted the spirit theory, however. They promoted an alternative: that ancient neurosurgeons were removing bone fragments from injuries sustained during combat. Modern research has provided strong evidence for this, especially among the Inca. For one thing, far more males than females had trepanation holes, likely because most warriors were males. For another, the holes were usually located on the left side of the skull—where a right-handed assailant would aim a slingshot or smash his club.

From a modern medical perspective, the idea makes sense: Doctors today still trepan people to reduce pressure on the brain after injury. The practice is meant to reduce swelling and the buildup of blood and other fluids, which can kill brain cells.

In the end, Squier bested Broca in the debate over why ancient neurosurgeons cut open skulls. But while Broca continued to have a glorious career, Squier’s unraveled not long after his discovery—as if the skull really were cursed.

Sad State of Squier's Affairs

It all started when Squier sent his wife, Miriam, home from Peru after the guano affair. Alone and resentful, Miriam accepted a job editing magazines for publisher Frank Leslie, and the two became inseparable. After his divorce in 1866, Leslie moved in with her and Squier. This seemed suspicious enough, but things really turned nasty in 1867 when the trio took a trip to Liverpool. Squier had some outstanding debts in England, and, humiliatingly, the police arrested him the moment he stepped ashore. An “anonymous” tipster—likely Leslie—had wired ahead to alert his creditors. With Squier out of the way, Leslie and Miriam’s affair began in earnest.

In May 1873, Miriam finally divorced Squier after publicly accusing him of sleeping with two prostitutes. Free of her husband, Miriam married Leslie in July 1874—a betrayal that broke Squier’s spirit. Just one month later, he had deteriorated to the point that a judge temporarily committed him to an insane asylum. Squier died at his brother’s home in Brooklyn in 1888. He was 67.

It was a sad, sordid end for one of America’s greatest archaeologists. Still, Squier did accomplish his life’s goal. He hadn’t thought much of Lincoln’s assignment in 1863, grumbling that guano “has contributed more towards the corruption of [Peru] than any one other thing.” But his trip to South America—and his willingness to take seriously a funny-looking hole in an old skull—revolutionized our understanding of ancient medicine, showing the world that, sometimes, a hole in the head is a sign of sophistication.

This story originally appeared in an issue of mental_floss magazine. Subscribe here.

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techbint, Flickr // CC BY 2.0
7 Famous Human Brains and Brain Collections You Can Visit
Original image
techbint, Flickr // CC BY 2.0

We may be biased, but we think the human brain is pretty special. All this week, is celebrating this miracle organ with a heap of brain[y] stories, lists, and videos. It all leads up to Brain Surgery Live With mental_floss, a two-hour television event that will feature—yes—live brain surgery. Hosted by Bryant Gumbel, the special airs Sunday, October 25 at 9 p.m. EST on the National Geographic Channel.

Scientists have been collecting human brains ever since the techniques to preserve them were perfected in the mid 19th century. These days, many of those collections languish in basements and back rooms—thanks to imperfect preservation, lack of funding, and the decreased need to study actual specimens in an age where we can scan the brains of living patients with sophisticated techniques.

Fortunately, a few of the world’s most interesting brains and brain collections are on view to the public. Some of these collections were amassed to study neurological issues, while others were put together in a failed attempt to correlate brain size with race, sex, and intelligence. (Despite what many scientists once thought, humans with larger brains aren’t necessarily more intelligent.) Below, seven collections to help you create your own brain-based travel itinerary:


It seems fitting that you can see the brain of the man who became practically synonymous with the term during the 20th century: Albert Einstein. Since 2011, the Mütter Museum in Philadelphia has owned 46 slides of Einstein’s gray matter, stained with cresyl violet and mounted on glass slides. Neuropathologist Lucy Rorke-Adams donated them to the museum in 2011, after receiving them from a colleague in the 1970s. 

Ironically, Einstein might have balked at the idea of having his brain on display. He told friends and family he wanted to be cremated after his death, so no one would “worship at his bones.” Most of his body was cremated, but the pathologist on duty during his autopsy, a man named Thomas Harvey, decided to take the brain in order to study. He wanted to see if he could find any kind of neuroanatomical evidence of what make Einstein so brilliant. (Einstein’s family was furious, and Harvey only received retroactive permission to keep the brain for scientific analysis. He’s frequently been portrayed as a thief, but pathologists at the time often saved organs from autopsies.) Since then, it’s been a long, strange trip—and the research about whether Einstein’s brain had anything to do with his intelligence is still inconclusive. (Later this week we'll talk to Dean Falk, a researcher who studied Einstein's brain, about the evolution of the human brain.)  


The Musée Dupuytren in Paris’ Latin Quarter is crammed to the ceiling with hundreds of skeletons, wax moulages of skin diseases, and organs floating in glass jars. It’s also home to two of the most famous brain specimens in the history of science.

In 1861, the eminent French surgeon and anthropologist Paul Broca was the first to prove the doctrine of cerebral localization—the idea that a particular part of the brain could be responsible for a particular function. Broca’s autopsies on two aphasic patients, a Mr. Leborgne and a Mr. Lelong, showed a link between lesions in the third convolution of the left frontal lobes and speech loss (patients with the lesions couldn’t form articulate speech, but only repeat a few basic words or syllables). Broca’s research paved the way for modern neuroscience, and the speech production center of the brain is now named Broca’s Area.

Today the brains of Leborgne and Lelong sit alongside the other eerie anatomical oddities at the Musée Dupuytren, housed in what was once a 15th-century refectory. Even Broca’s own brain is sometimes said to be inside the museum, but staff claim that’s not the case; the whereabouts of the scientist’s own brain seem to be something of a mystery. For now, visitors have to be content with seeing the brains of his most famous patients.


Babbage's brain at the Science Museum in London. Image credit: Anne-Lise Heinrichs, Flickr // CC BY 2.0

English mathematician, inventor, and engineer Charles Babbage is often credited as the “father of the computer”—his Difference Engine No.1, invented in 1821, was the first successful automatic calculator, and his later “analytical engines” shared characteristics with today’s computers. Babbage is also frequently remembered for his work with Ada Lovelace, Lord Byron’s daughter, who some consider the first computer programmer.

Always a forward-thinker, Babbage also donated his brain to science. Today it’s on display in two places in London: half is at the Science Museum, and the other half at the Hunterian Museum in the Royal College of Surgeons. You can see a video of it here.


The Cornell Brain Collection was assembled by the noted anatomist Burt Green Wilder, creator of Cornell University’s anatomy department and founder, in 1889, of the Cornell Brain Society, devoted to collecting the brains of "educated and orderly persons.” Wilder hoped to show how such brains differed from those of criminals, minorities, the mentally ill, and women. Research showed they didn’t—at least not in ways observable by 19th-century technology.

At its peak, the collection included hundreds of specimens. Today, while 70 unidentified brains are housed in a Cornell basement, eight identified specimens are on display at the university’s Uris Hall alongside text explaining their biographies. Notable items include the brain of Helen Hamilton Gardener, an author, activist, and civil servant who donated her brain intending to prove that women were just as intelligent as men—and that their brains could be just as big.

Wilder even donated his own brain to the collection, and it remains on display. Also on view: the brain of murderer Edward H. Rulloff, turned a minty green thanks to poor preservation techniques.


 For decades, the brains in Yale’s Cushing Center collection languished in the basement of the Harkness Dormitory, where breaking in to see them was a ritual among medical students. Today, the brains sit in a well-appointed display that cost $1.5 million to create—a somewhat rare concentration of resources for a brain collection, which these days often stay hidden in storage rooms.

The brains were collected by Dr. Harvey Cushing, a neuroscience professor at Yale and a pioneer of modern neurosurgery, who willed them to the school upon his death. The most famous specimen belonged to Leonard Wood, who served as the personal physician to two presidents as well as Army Chief of Staff. Cushing successfully removed a large tumor from Wood’s brain in 1910, ending his seizures—one of the few such successful operations at the time. Sadly, Wood died in 1927 after an operation to remove a second tumor.

The brains are also notable for being displayed with before-and-after photos of the patients—less harrowing and more fascinating than they sound. Cushing’s journals, surgical instruments, and other specimens complete the exhibit.


The little-known Brain Museum at the Institute of Neurological Science in Lima, Peru, contains close to 3000 specimens, many of which show the marked effects of Alzheimer’s, alcoholism, tumors, or stokes. One of the star brains belonged to someone who suffered from Creutzfeldt-Jakob disease, sometimes called “human mad cow disease,” and which has been caused by some tribes eating human brains as part of their funerary practices. (On the other hand, at least one tribe appears to have developed a genetic resistance to the disease thanks to its former brain-eating ways.) The museum has been collecting specimens since 1947 and is one of the few large collections of brains that’s regularly open to the public.


The National Museum of Health and Medicine in Washington, D.C. holds eight different neuroanatomical collections—but the specimens are off-limits except for researchers with an appointment. However, if brains are your thing and you don’t have a PhD., you can still check out the museum’s Traumatic Brain Injury exhibit, which is open to the public. The exhibit features 30 specimens with a host of brain damage, including hemorrhages, blunt force trauma, and bullet wounds, as well as the surgical tools used to treat said injuries. It sounds fascinating, but maybe don’t visit right after lunch.

Trepanation: The History of One of the World's Oldest Surgeries

During the 1860s, a United States diplomat named E.G. Squier traveled to Cuzco, Peru. While visiting the home of a wealthy woman who collected antiquities, he was shown an ancient skull. Discovered in an ancient Inca cemetery in the Valley of Yuca, the skull dated to pre-Columbian times and had a large, rectangle-shaped hole near its top front.

Squier—a well-educated polymath whose areas of expertise also included archaeology and Latin American culture—was immediately intrigued. So in 1865, Squier brought the skull to New York, where he presented it to members of the New York Academy of Medicine.

Squier believed that the skull was clear evidence that Peru’s ancient people had performed prehistoric brain surgery. The hole’s cross-hatched outlines were the work of a human hand; Squier noted that they were most likely made with a burin, a tool used by engravers on wood and metal. Even more shockingly, he observed, the skull showed signs of healing—meaning the patient had survived the procedure for at least one to two weeks before they died.

Members of the medical community were skeptical, and didn't believe that the cuts were made prior to death. So Squier sought the opinion of renowned French surgeon and anthropologist Paul Broca. In turn, Broca looked at the skull, and concluded that early indigenous societies had been performing “advanced surgery” long before Europeans arrived.

The practice of drilling or scraping a hole into the skull’s cranial vault to expose the brain’s dura mater and treat brain injuries is called trepanation. First mentioned by the Hippocratic corpus, it’s one of the world’s oldest surgeries. (In fact, the word trepanation comes from Greek, and means “auger” or “borer.”) Today, the medical community would refer to it as a craniotomy.

Throughout history, trepanation has been practiced in nearly every part of the world. It was performed in ancient Greece and Rome, and is today even reportedly used in parts of Africa, South America, and the South Pacific. In ancient Greece, it was used to relieve pressure, remove skull fragments from the brain after a traumatic accident, and for drainage. From the Renaissance until the beginning of the 19th century, trepanation was routinely used to treat head wounds, and into the 18th century, it was used to treat epilepsy and mental disorders.

The Victorian physicians of Squier and Broca's time had never considered that “primitive” cultures throughout history may have attempted the procedure. Also, since survival rates from the surgery were so poor due to hospital-acquired infections, they doubted that ancient patients could have lived for long following the operation.

After Broca acknowledged Squier’s find, scientists began discovering trepanned skulls across the globe, dating back to the Neolithic period. Hole-filled heads were discovered in Western Europe, South America, and the Americas. Over the years, it became clear that trepanation was attempted by many societies across the globe, starting in the late Paleolithic period.

Techniques varied from culture to culture. Prehistoric trepanations performed in early Peru were done with a ceremonial knife called a tumi, which was used to scrape or cut through the bone. The Hippocratic school invented the trephine drill, which bored holes into the skull. In the South Pacific, they sometimes used sharpened seashells; in Europe, flint and obsidian. By the Renaissance period, trepanation was routinely performed, and a range of instruments had been developed. However, due to the high infection rate, the practice soon waned.

Trepanation was performed on young and old, male and female. In many instances, the prehistoric patients had lived for years after the surgery. According to writings by Charles Gross, a professor of neuroscience at Princeton University, estimates for survival range from 50 to 90 percent. However, in many cases, the surgeon's motive for performing trepanation remains unclear.

John Verano, a professor of anthropology at Tulane University who studies trepanation in Peru, tells mental_floss he's convinced that “in Peru, the South Pacific, and many other parts of the world, trepanation began as a very practical treatment for head injuries. Say somebody has a head wound that’s torn up their skull. You’d clean it out and remove little broken fragments and allow the brain to swell a little bit, which it does after injuries.”

In some instances, trepanned skulls show clear evidence of trauma—meaning there must have been an underlying reason why the procedure was performed. However, archaeologists have also uncovered trepanned skulls that don’t show depressed fractures. Squier's famous skull, for instance, didn't indicate any signs of a head wound. Skulls with multiple holes have also been unearthed, revealing that patients sometimes had—and survived—more than one surgery.

According to Verano, modern eyewitness accounts from Africa and the South Pacific state that trepanation is still used to treat head wounds, headaches, or pressure on the brain. In other parts of the world, it’s thought that trepanation might have once been used to release evil spirits, or to treat insanity or epilepsy. But without any written record, we’ll never quite know why these kinds of surgeries were performed in the absence of obvious injury.

Individuals who underwent trepanation weren't administered anesthesia. Did the procedure hurt?

As Verano points out, they might have likely been unconscious during the surgery if they had suffered a head wound. Otherwise, they would have been awake. “The scalp has a lot of nerves, so it hurts to cut your scalp,” Verano says. “It also bleeds a lot, but then it stops. But the skull has very few nerves, and the brain has no nerves.” But Verano also points out that ancient trepanners weren’t cutting through the brain’s dura mater. (If they did, the patient would have gotten meningitis and died.) 

In today’s modern Western hospital, trepanation is no longer viewed as its own curative procedure. It’s used to debride a wound (remove dead or infected tissue), relieve pressure in the skull, or perform exploratory surgery. However, it’s fascinating to realize that the surgery survived many millennia—and that as early as prehistoric times, humans were already connecting the brain’s functioning to the body. We can only wonder what people of the future will think of our own modern brain surgeries

Additional Sources: A Hole in the HeadTrepanation (Studies on Neuropsychology, Development, and Cognition)


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