An Inca 1040?

Think accounting is the invention of modern minds? Not likely. Two Harvard researchers are convinced that ancient Incas tracked inventory and taxes through a three-tiered accounting system using knotted bundles of threads.
The researchersand many scholars pondering their reportbelieve the colorful knotted quipu strings found at a 13th century archaeological site near Lima, Peru, formed an early abacus system the Incas used to track the units of labor and time upon which taxes were based. The first two tiers of knots are double-entry accounts, they think, and the third is a summary of the numbers.

If their interpretation is accepted by the academic community, it will put to rest the Inca paradoxthe question of why these early Americans had the only complex empire with no written form of communication. They may have had no novels, it seems, but they did indeed have books.