(K)not Writing?

This came across in the NYT science pages a few days ago, a story by John Wilford titled "String, and Knot, Theory of Inca Writing" (NYT subscription req.). Up to this point, Incan civilization has proven to be a stubborn exception to the dictum that writing is a prerequisite for civilization. But Gary Urton at Harvard is claiming that khipu, originally thought to have only been a numerical system, may also have served as a writing system:

The knots are unlike anything sailors or Eagle Scouts tie. In the conventional view of scholars, most khipu (or quipu, in the Hispanic spelling) were arranged as knotted strings hanging from horizontal cords in such a way as to represent numbers for bookkeeping and census purposes. The khipu were presumably textile abacuses, hardly written documents.

But a more searching analysis of some 450 of the 600 surviving khipu has called into question this interpretation. Although they were probably mainly accounting tools, a growing number of researchers now think that some khipu were nonnumerical and may have been an early form of writing.

Problem is that we have khipu without translation, and translations without the original khipu, so it's difficult to substantiate this possibility. Urton argues that the knot sequences function in something akin to 7-digit binary code which, given variations in color and weave, could have supported a language roughly on a par with Sumerian cuneiform and with double the expressive characters of Egyptian hieroglyphics.

I can't help but find this fascinating, both for the issues that it raises about the materiality of writing systems, and for the possibility that binary code might have existed alongside phonetic and pictographic systems as far back as the Bronze Age.

Now, excuse me while I go find some string...