What Rao and his associates did was compare the relative disorder of the glyph positions to that of five types of known natural languages (Sumerian, Old Tamil, Rig Vedic Sanskrit, and English); four types of non-languages (Vinča inscriptions and Near Eastern deity lists, human DNA sequences and bacterial protein sequences); and an artificially-created language (Fortran).
They found that, indeed, the occurrence of glyphs is both non-random and patterned, but not rigidly so, and the characteristic of that language falls within the same non-randomness and lack of rigidity as recognized languages.
It may be that we will never crack the code of the ancient Indus. The reason we could crack Egyptian hieroglyphs and Akkadian rests primarily on the availability of the multi-language texts of the Rosetta Stone and the Behistun Inscription. The Mycenaean Linear B was cracked using tens of thousands of inscriptions. But, what Rao has done gives us hope that one day, maybe somebody like Asko Parpola may crack the Indus script.
Sources and Further Information
Rao, Rajesh P. N., et al. 2009 Entropic Evidence for Linguistic Structure in the Indus Script. Science Express 23 April 2009
Guide to the Indus Civilization
Bibliography of the Indus Civilization
Study of the Indus Script at Harappa.com includes an article by Asko Parpola, essential reading to understanding this issue.
Steve Farmer, Richard Sproat, and Michael Witzel. 2004. The Collapse of the Indus-Script Thesis: The Myth of a Literate Harappan Civilization. EJVS 11-2: 19-57. Free pdf to download
