The hidden history of Inca rule, which extended up and down the Andes for 100 years before the Spanish conquest of 1532, may be contained in the Incas' famous knotted strings, called khipu, the latest research indicates.

Until now, khipu (also spelled quipu) were widely thought to be little more than accounting tools, with various knot combinations representing totals like beads on an abacus. Because no one has ever been able to decipher the knot patterns, many scholars have said khipu were the haphazard concoctions of individuals, and were not ''recording machines'' designed to be read universally. Some scholars have even dismissed khipu as mere ''reminders'' for their owners to do tasks or recite stories, like string tied around a person's finger.

But comprehensive study by an antiquities scholar at Harvard University suggests the patterns not only conformed to a universal standard, but represented a writing system that was the technological equivalent of systems developed by the Sumerians, the Egyptians, the Mayans and the Chinese.

While none of those systems is as versatile as an alphabet-based one, which can represent an infinite number of sounds, they were all early breakthroughs in mankind's ability to record his surroundings more efficiently than in pictures.

''When you think about it, the idea that the khipu is just a cacophonic or wildly chaotic system producing radically idiosyncratic records to account for the state of goods and resources just doesn't make sense,'' said Gary Urton, who joined Harvard faculty last year as professor of pre-Columbian studies. ''I believe it is based on a shared system of record-keeping whereby sign values are assigned to these khipu structures.''

Compared to the civilizations of ancient Greece or Rome, the Inca have been the focus of relatively few studies, so many mysteries surrounding them have yet to be resolved.

Deciphering khipu could yield answers to the Inca's other secrets, such as how they built precision-fit walls without a cementing material, or what use they made of their subsequently ''lost city,'' Machu Picchu.

Evidence suggesting khipu could be interpreted by anyone trained to read them came two weeks ago after hundreds of hours of painstaking analysis of 32 khipu discovered in 1997 among 225 mummy bundles in a rock overhang in northern Peru.

Mr. Urton and his team identified matching patterns or sequences, believed to convey numerical data, in three of the khipu.

''So we have the first evidence of a system of checks and balances,'' he said. ''With that new find, we're getting the first clear evidence that these people were not just keeping information in a way that only one official had the only record, and only he could testify.''

Mr. Urton has also begun arguing that khipu incorporated a binary code capable of conveying at least 1,536 pieces of information. For comparison, the earliest forms of Sumerian cuneiform had 1,300-1,500 signs, and Mayan and Egyptian hieroglyphics 600-800.

Mr. Urton bases his argument on the typical decisions a khipu maker had to make when constructing a khipu.

For example, khipu were invariably made from cotton or wool, tasking the khipu maker to choose one or the other when creating a knotted string. The maker would then have to decide whether to spin or ply in clockwise or counter-clockwise directions. Hanging the knotted string on the front or back of the main cord would also present two choices. In all, there were six sets of alternatives, plus a choice of 24 colours, Mr. Urton said. That permutates into 1,536 different ways to ''write'' a khipu sign.

If Mr. Urton is right, the Inca not only adopted a computer-age binary code at least 500 years before the invention of computers, but also gave the world its only known three-dimensional ''written'' language, given that writing to date has always been laid down on flat surfaces, such as paper.

Mr. Urton presents his conclusions in his just-released book, Signs of the Inka Khipu, using the spelling of Inca used today in Quechua, the official language of the Inca empire.

Confirming Mr. Urton's conclusions depends on being able to translate khipu, which would be simple with the discovery of a South American equivalent of the Rosetta Stone -- the basalt slab found at Rosetta, near Alexandria in Egypt, that allowed scholars to decipher an Egyptian hieroglyphic text from demotic and Greek translations.

Hope that a ''Rosetta khipu'' exists comes from evidence the Spaniards initially worked closely with khipu keepers as they tried to insert themselves into the Inca's administrative system without disrupting it too much, to avoid slowing the flow of wealth.

''There was a tremendous amount of production of documents on administrative matters in the early Spanish colonial state in Peru,'' Mr. Urton said. ''And the main source of information for the Spaniards as they set up a colonial empire was the khipu keepers, whom they would call in and say, 'Read me the information off your khipu.' ''

As in Canada under French colonial rule, Catholic religious orders such as the Jesuits were prodigious record keepers, and may have produced a translation of a khipu that has yet to be found.

But the closest to a match so far is only a complex khipu containing 3,005 knots that Mr. Urton has argued is reflected in Spanish documents mentioning a khipu keeper known as the ''Lord of the 3,000 Tribute Payers.'' Made up of 12 sections containing two sets of 365 strings, Mr. Urton said the khipu is clearly a two-year calendar recording the work 3,000 subjects did for the Inca state.

Mr. Urton said he is optimistic a khipu and a parallel document in a European language -- most likely Spanish -- will be found.

''One can't give a reasonable estimate of how long that might take, because there are not that many people working in this field, and thousands of documents to go through in archives,'' he said.

In the meantime, Mr. Urton and his team are mimicking wartime code breakers by trying to identify similarities in khipu patterns. Information is fed into a computer database as it is gradually collected from some 600 khipu held in museums.

The work of Mr. Urton and his team is at the ''cutting edge,'' according to Thomas Cummins, professor of the history of pre-Columbian and colonial art at Dumbarton Oaks, a research library in Washington, D.C., that is administered by Harvard trustees.

Mr. Urton's binary theory is drawn from the analysis and re-analysis of his own observations and the work of other scholars, including William J. Conklin, a research associate at the Textile Museum in Washington, D.C., who was the first to suggest, in 1997, that spinning, plying and colour-coding were an important part of the khipu system.

''Over the years, research has been ... fragmented,'' Mr. Urton said. ''My theory brings together the different features.''

June 30, 2003

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