Who made these knotted records during the Inca Empire?

The Inca Empire in South America, one of the most powerful pre-Columbian societies, was known for many innovations — such as the architecture of Machu Picchu, an extensive road network, and a system of terraces for agriculture. Perhaps most unique, though, was the society's method of keeping records known as khipu, which involves a system of tying knots to encode information.

It's long been assumed that khipu production was the domain of this civilization's ruling elites, but a new analysis of a cord made out of human hair finds that even low-class commoners may have engaged in this tradition.

The discovery may help researchers rewrite their understanding of this aspect of Incan civilization, and propel more scientists to test other khipus sitting in museum collections.

"The Incas had t