THE Incas left no doubt that theirs was a sophisticated, technologically savvy civilisation. At its height in the 15th century, it was the largest empire in the Americas, extending almost 5000 kilometres from modern-day Ecuador to Chile. These were the people who built Machu Picchu, a royal estate perched in the clouds, and an extensive network of paved roads complete with suspension bridges crafted from woven grass. But the paradox of the Incas is that despite all this sophistication they never learned to write.
Or did they? The Incas may not have bequeathed any written records, but they did have colourful knotted cords. Each of these devices was called a khipu (pronounced key-poo). We know these intricate cords to be an abacus-like system for recording numbers. However, there have also been teasing hints that they might encode long-lost stories, myths and songs too.
In a century of study, no one has managed to make these knots talk. But recent breakthroughs have begun to unpick this tangled mystery of the Andes, revealing the first signs of phonetic symbolism within the strands. Now two anthropologists are closing in on the Inca equivalent of the Rosetta stone. That could finally crack the code and transform our understanding of a civilisation whose history has so far been told only through the eyes of the Europeans who sought to eviscerate it.
The Spanish conquistadors, led by Francisco Pizarro, first encountered the Incas at the start of the 1530s. They were awestruck by the magnificent stone cities, the gold and treasure. But as the Spanish began to take over the Inca empire and impose their own customs, they became equally enthralled by the way the society was organised.
The Incas governed the 10 million people in their realm with what amounted to a federal system. Power was centred in Cusco, in the south of what is now Peru, but spread through several levels of hierarchy across a series of partially self-governing provinces. There was no money and no market economy. The production and distribution of food and other commodities was centrally controlled. People had their own land to farm, but every subject was also issued with necessities from state storehouses in exchange for labour, administered through an impressive tribute system.
“Break the khipu code and we might finally read an indigenous Inca history”
Historians have argued variously that the Inca empire was a socialist utopia or an authoritarian monarchy. But no one disputes its efficiency. “It was an extraordinary system,” says Gary Urton, an anthropologist at Harvard University. “Administratively speaking, it was very sophisticated and it seems to have worked well.”
Key to that success was the flow of reliable data, in the form of censuses, tribute accounts and storehouse inventories. For that, the Incas relied on the khipumayuq, or the keepers of the khipus, a specially trained caste who could tie and read the cords.
The majority of surviving khipus consist of a pencil-thick primary cord, from which hang multiple “pendant” cords and, in turn, “subsidiaries”. The Spanish described how they were used to record all manner of information. The poet Garcilaso de la Vega, son of an Inca princess and a Spanish conquistador, noted in a 1609 account that they had “an admirable method of counting everything in the Inca’s kingdom, including all taxes and tributes, both paid and due, which they did with knots in strings of different colours.”
There are reasons to think khipus may record other things, including stories and myths – the sort of narrative information that many cultures write down. De la Vega was among many chroniclers who hinted as much, writing in one passage that the Incas “recorded on knots everything that could be counted, even mentioning battles and fights, all the embassies that had come to visit the Inca, and all the speeches and arguments they had uttered”. True, he was prone to ambiguity and contradictions. But about a third of the khipus in collections seem to have a more elaborate construction than the others, as if they contain a different sort of information. For decades the point was moot, however, because no one could read any of them.
The first hints of revelations from khipus came in the 1920s, when anthropologist Leland Locke analysed a bunch of them housed at the American Museum of Natural History in New York. He noticed that the knots are organised in rows almost like beads on an abacus (see diagram). He demonstrated that each row of knots at a certain height denoted units, tens, hundreds and so on. That made sense, fitting with the decimal system the Inca used to divide up groups for tribute purposes.
Hard knot to crack
The discovery sparked a wave of interest in khipus. By the 1990s, though, we still had no idea what the numbers meant. “Say you read off the number 76 – what does it refer to?,” asks Urton.
To answer that, you would ideally have a translation of a khipu into a familiar language. It would be an equivalent of the Rosetta stone, which contained a translation of Egyptian hieroglyphics into ancient Greek and unlocked that picture language. In the absence of that, Urton has spent the last 25 years tracking down and carefully digitising the details of every khipu he could find in museums and private collections across the world. Today, his Khipu Database Project contains details of more than 900 of them.
There are all sorts of varying factors in khipus: the colour of the strings, the structure of the knots and the direction in which they were hitched. Having spent countless hours poring over them, Urton began to think that binary differences in these features might be encoding information. For example, a basic knot tied in one direction could mean “paid”, while in the other it would mean “unpaid”. By 2012, he had developed a more specific hypothesis, proposing that the direction in which knots were tied, the colours of the strings, or some combination of the two, corresponded to the social status of the people whose tributes they recorded, and even individuals’ names. Without a khipu translation, however, the idea looked destined to remain untested.
Then in 2016, Urton was browsing his personal library when he picked out a book that contained a Spanish census document from the 1670s. It was what the colonists referred to as a revisita, a reassessment of six clans living around the village of Recuay in the Santa valley region of western Peru. The document was made in the same region and at the same time as a set of six khipus in his database, so in theory it and the khipus were recording the same things.
Checking it out, Urton found that there were 132 tribute payers listed in the text and 132 cords on the khipus. The fine details fitted too, with the numbers on the cords matching the charges the Spanish document said had been levelled. It seemed to be the match he had been looking for.
Even so, Urton was struggling to pick apart the detail of the connections between the Santa valley khipus and the Spanish documents. He ended up letting a Harvard undergraduate student named Manny Medrano take a look. He turned out to have the perfect complement of skills for the job. He was a native Spanish speaker and, majoring in economics, he was a whizz with spreadsheets. Medrano painstakingly generated tables of the khipu data and combed through them in search of matching patterns. This year, he and Urton showed for the first time that the way pendant cords are tied onto the primary cord indicates which clan an individual belonged to.
“It is a really important achievement,” says Jeffrey Splitstoser at George Washington University in Washington DC, who specialises in khipus from the Wari empire that preceded the Inca. “It gives us a new way to interpret these sources. Gary has made things a lot more tractable.” Yet the question of whether the khipus also contain stories still hung there.