for National Geographic News
Known for its intricate textiles and spectacular architecture, the Inca Empire ranks among the world's great civilizations. Yet the ancient Inca apparently lacked a written language.
To record information, the ancient Inca used enigmatic devices called khipus, mop-like textiles. Made from cotton or animal hair, the objects consisted of multiple knotted strings hanging vertically from a single horizontal string.
Khipus were probably used for more than just recording numbers. Some experts say they may have been a medium for recording historical informationpossibly as a form of writing.
Now a new study shows that khipus were used as documents in a sophisticated accounting system passed up through the Inca bureaucracy.
"They're quite complex, and there's a tremendous amount of information in them," said Gary Urton, a professor of pre-Columbian studies at Harvard University in Cambridge, Massachusetts. "They are beautifully structured to take care of what was a hierarchical organization overseeing activities in the Inca Empire."
The study, by Urton and co-author Carrie Brezine, is published in tomorrow's issue of the academic journal Science. The researchers analyzed 21 khipus found in an urn under the floor of a house adjacent to the Inca palace of Puruchuco on the central coast of modern-day Peru.
Tribute in the form of a labor tax was imposed on subjects of the Inca Emipre, who were assigned to work a certain number of days each year on state projects.
Urton says the khipus that he analyzed, which were organized in a three-tier hierarchy, show how census and tribute data were assembled and transferred among different levels of authority within the Inca administrative system.
The khipus on the lowest level of the hierarchy may have represented contact between the khipu keeper and local laborers. While the top level probably represented contact between the palace of Puruchuco and a central authority.
"What we may have represented is that the khipus on top, containing the most aggregated data, came into the local palace as commands on the organization of activity on the local level," Urton said.
"And then that information was subdivided into the middle level and then further subdivided into the lower level."
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