Early Medical Techniques

New Light Shed on Prehistoric Surgery

September 17, 2000 - National Geographic

Ancient humans recognized that sometimes a hole in the head was exactly what was needed.

Skulls with holes bored in them have been found by archaeologists in virtually every region of the world, and scientists have debated for more than a century about the motivation for the holes. Are they evidence of an emerging medical technology or an artifact of practices involving magic, ritual, warfare, or religion?

"Good evidence exists to show that trepanation was performed as a treatment for skull fractures," says John Verano, a physical and forensic anthropologist at Tulane University in New Orleans, in the September 16 issue of the journal New Scientist.

Verano, who specializes in the prehistoric cultures of the Andes, has compiled a data base documenting the physical characteristics of nearly 700 trepanated skulls from Peru and Bolivia.

Evidence of trepanation - deliberately cutting or drilling a hole in the skull - dates back to 3000 BC, and possibly as far back as 10,000 years ago. Trepanation is discussed in medical texts of ancient Greece; Hippocrates (c. 460 to 355 BC) wrote extensively about when, why and how to perform trepanations.

Until the mid-1800s, though, the received wisdom among archaeologists and anthropologists held that prehistoric trepanations were performed only after death. Scientists attributed the holes to burial rituals or war practices, parading the head of an enemy on a stick or hanging it by a string. Among some early cultures, pieces of bone were carved from the skulls of the fallen mighty and worn as amulets.

In the 1860s, anthropologist Paul Broca recognized signs of healed bone surrounding a hole in a prehistoric skull. This convinced him that surgery had been performed on the living. As old evidence was reviewed and new evidence found, the idea that prehistoric humans practiced trepanation became widely accepted.

The argument as to motivation, however, remained.

Evidence of the Andes

While evidence of trepanning has been found around the world, the most skulls - about 1,000 - have turned up in South America.

Verano's data base includes skulls from Peru and Bolivia spanning nearly 2,000 years, from 400 BC to 1500 AD. These were violent times for the peoples of the Andes. The weapons of choice were slingshots and clubs, and skull fractures were a fact of life. Among skulls found in the central highlands region of the Andes dating from 900 to 1500 AD, more than half the men had at least one skull fracture, as did 32 percent of the women and 27 percent of the children, according to the New Scientist report.

"There was probably a lot of village warfare in which everyone got involved," says Verano.

Verano's data shows not only that trepanned skulls were highly associated with skull fractures but also that surgical techniques improved over time. "The holes got smaller over time," he says. "The earliest were quite large; 4 inches by 4 inches, (10 centimeters by 10 centimeters) or even larger, while some of the later ones are no larger than a single drill hole. It looks like they figured out that they didn't have to take quite so much bone. "

With improved techniques, survival rates also improved.

Surgeons on the southern coast of Peru around 400 BC scraped away the bone around a head wound with stone tools, and had a survival rate of about 40 percent. By 1350 AD, Inca surgeons in the central Andes had developed a range of techniques for performing the surgery - and appear to have had a survival rate of more than 80 percent. Anthropologists can tell whether a patient survived the surgery because, given time, the rim around the hole becomes smooth.

The improved success rate, the development of several techniques for performing the surgery, and evidence that surgeons made choices about which technique to use, combine to show that the surgery was part of an emerging medical repertoire, says Verano.