Incan civilization was a technological marvel. When the Spanish conquistadors arrived in 1532, they found an empire that spanned nearly 3,000 miles, from present-day Ecuador to Chile, all served by a high-altitude road system that included 200-foot suspension bridges built of woven reeds. It was the Inca who constructed Machu Picchu, a cloud city terraced into a precarious stretch of earth hanging between two Andean peaks. They even put together a kind of Bronze Age Internet, a system of messenger posts along the major roads. In one day, Incan runners amped on coca leaves could relay news some 150 miles down the network.
Yet, if centuries of scholarship are to be believed, the Inca, whose rule began 2,000 years after Homer, never figured out how to write. It's an enigma known as the Inca paradox, and for nearly 500 years it has stood as one of the great historical puzzles of the Americas. But now a Harvard anthropologist named Gary Urton may be close to untangling the mystery.
His quest revolves around strange, once-colorful bundles of knotted strings called khipu (pronounced KEY-poo). The Spanish invaders noticed the khipu soon after arriving but never understood their significance – or how they worked.
Once, at the beginning of the 17th century, a group of Spaniards traveling in the central Peruvian highlands east of modern-day Lima encountered an old Indian carrying khipu that he insisted held a record of "all [the Spanish] had done, both the good and the bad." Angered, the Spanish burned the man's khipu, as they did countless others over the years.
Some of the knots did survive, though, and for centuries people wondered if the old man had been speaking the truth. Then, in 1923, an anthropologist named Leland Locke provided an answer: The khipu were files. Each knot represented a different number, arranged in a decimal system, and each bundle likely held census data or summarized the contents of storehouses. Roughly a third of the existing khipu don't follow the rules Locke identified, but he speculated that these "anomalous" khipu served some ceremonial or other function. The mystery was considered more or less solved.
Then, in the early 1990s, Urton, one of the world's leading Inca scholars, spotted several details that convinced him the khipu contained much more than tallies of llama sales. For example, some knots are tied right over left, others left over right. Urton came to think that this information must signal something. Could the knotted strings also be a form of writing? In 2003, Urton wrote a book outlining his theory, and in 2005 he published a paper in Science that showed how even khipu that follow Locke's rules could include place-names as well as numbers.
