Who made these knotted records during the Inca Empire?

Brendan Smialowski / AFP via Getty Images

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 s