The Inca Empire in South America was one of the most powerful pre-Columbian societies. It was known for the architecture of Machu Picchu, an extensive road network and a system of terraces for agriculture. The society also kept records known as khipu, which involved a system of tying knots to encode sophisticated information.

Literacy in this form of writing was assumed to be something that only the highest levels of Inca society could do. But NPR science correspondent Nell Greenfieldboyce shares how a new analysis of a cord made out of human hair may change that assumption. 


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