This issue features groundbreaking study on Incan Khipus. Khipus, an Incan method of record-keeping, recorded data using knotted strings. In the past, khipus have proven nearly impossible to decipher and there was a very limited understanding of what they represented. In this article, Manuel Medrano and Gary Urton share what has been discovered: the khipus were used to represent names of villagers in a census. Read the article
, made freely available.