doi:10.1038/nindia.2009.128 Published online 8 May 2009
Using computational and statistical techniques to search for patterns in Indus writing, fresh research1 concludes that it fits the description of 'linguistic writing' – a system rigid enough to convey unambiguous meaning and yet flexible enough to allow expression of a large variety of information.
Since their first discovery more than 130 years ago, speculations about the meaning of the Indus script abound. None of these has found general acceptability.
The researchers compared the entropy of Indus writing with other writing systems representing Rigvedic Sanskrit, Old Tamil, Sumerian and English, and non-linguistic information like DNA and proteins as well as the artificially created computer language Fortran. Their results show that the conditional entropy of Harappan writing falls along with other linguistic writing and is different from non-linguistic information coding systems.
The researchers draw a parallel with languages such as English. "In English, the word 'the' can be followed by common nouns such as "man" or "woman" but not verbs such as 'walks'. Even within words, the alphabet 't' can be succeeded by many alphabets but not 'x', or 's' etc. This mix of flexibility and rigidity distinguishes linguistic writing from other writing," says Mayank Vahia, one of the researchers.
Indus texts exhibit the same type of flexibility in symbol order as many natural languages. Given the earlier identification of patterns in the Indus texts and the more recent conditional entropy results, the evidence for linguistic writing becomes very strong, the researchers feel.
However, deciphering the Harappan script will take a lot more effort, Vahia says, particularly in identifying its fine grammatical structure and other aspects which are not apparent yet. "The demonstration that Indus writing may indeed be linguistic only means that more intense work needs to be done before one can understand its contents," he adds.
The authors of this work are from: Department of Computer Science & Engineering, University of Washington, Seattle, USA; Department of Astronomy & Astrophysics, Tata Institute of Fundamental Research, Mumbai; Centre for Excellence in Basic Sciences, Mumbai; Dhus Wadi, Laxminiketan, Thakurdwar, Mumbai, India; The Institute of Mathematical Sciences, Chennai and Indus Research Centre, Roja Muthiah Research Library, Chennai, India.