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Vanished Inca may have used binary code language

The vanished Inca civilisation of the Andes, long thought to have no writing, invented a seven-bit binary code to store information more than 500 years before the invention of the computer, argues an American anthropologist.

Begun in the Andean highlands of Chile and Colombia around 1200 AD, the Inca ruled the largest empire on Earth by the time their last emperor, Atahualpa, was garroted by Spanish conquistadors in 1533.

But the voice of the Inca has never been heard; it has long been considered the only major Bronze Age civilisation without a written language.

Professor Gary Urton, an anthropologist at Harvard University in Boston and a specialist in Pre-Columbian studies, is now challenging that assumption in a new book, Signs of the Inka Khipu. He argues the Incas had a written language disguised in the form of elaborate knotted strings known as khipu.

Derived from the word for 'knot' in the Quechuan language of the Inca - still widely spoken in the the Andes highlands - these decorative objects consist of one main cord to which are attached several pendant strings. These, which can carry subsidiary or tertiary strings, bear clusters of knots.

In 1923, science historian L. Leland Locke proved that the khipu were more than decorative; they were a sort of textile abacus, their knots used to record calculations.

But Locke's rules decoded only a small percentage of the existing 600 khipu that survived the Spanish destruction, failing to take into account even one-half of the total information encoded in them, Urton said.

"The most convincing evidence for this three-dimensional writing system is the khipu. Their complexity would have been unnecessary if they were just mnemonic devices understood only by their makers," Urton said.

In the book, published by the University of Texas Press, Urton has for the first time systematically analyses the khipu's essential elements. It emerged that there are seven points in making a khipu, where the maker chooses between two possibilities.

The binary choices include the type of material (cotton or wool), the spin and ply direction of the string, the direction (forward or reversed) of the knot, and so on. A strict seven-bit code would produce 128 permutations (or 27). But Urton calculates that there were 24 possible colours that could be used in khipu making.

Thus the khipu code can store 1,536 units of information (26, multiplied by 24). This is comparable to the Sumerian cuneiform symbols used between 1000 AD and 1500 AD, and more than twice the Egyptian and Maya hieroglyphic signs.

A definitive way to crack the intractable code would be the discovery of what Urton calls a 'Rosetta khipu', something similar to the deciphering of Egyptian hieroglyphics from the Rosetta stone: a basalt slab unearthed in Egypt in 1799 with text in Greek and Egyptian hieroglyphs, allowing linguists to decode the language.

"We have a sizeable number of khipu, and we have about a dozen documents that are written up from the khipu. What we don't have yet is a match between a document and a khipu," said Urton.

While searching, Urton is attacking the khipu code with 21st century technology, creating a database packed with any possible data on each khipu: length of the main string, number of pendants, details on the knots, spin, ply of each string, and so on, in order to search for common patterns.

"Just 10 days ago, I discovered three khipu that share part of the information," he said. "This is a pretty strong evidence that they were not made by single people. On the contrary, there was a shared code."

"It is an interesting study," said Professor Laura Laurencich-Minelli, a specilaist in Pre-Columbian studies at Bologna University and author of several books on the Inca and the khipu. "Certainly, khipu were much more than mnemonic devices."