A paper just published online in Science magazine (subscription required for full text) makes a significant contribution to the debate about whether the Indus Valley “script” was really a script for a language, or was a mere nonlinguistic symbol system. They consider the statistical properties of texts in known languages and non-languages (in particular, the conditional entropy) and compare with a large corpus of Indus Valley text. The conclusion is that the Indus Valley symbols indeed encode a language. It looks extremely convincing. Now the task remains to decode the thing.
I’m a bit slow to blog on this because I wanted to read the paper first: it turns out it’s very short (barely a page plus references and figures in the ScienceExpress format, and no doubt the final published version will be even more compact.) One of the authors is my colleague Ronojoy Adhikari and I had a brief lunch-room summary from him which pretty much covers the paper. (A longer summary from Ronojoy is here, courtesy Rahul Basu.) It has attracted a fair bit of media attention (km has a nice summary and a couple of links).
A couple of points are striking: first, of the languages compared, the conditional entropy for the Indus scripts seems closest to Old Tamil, which is suggestive given the belief that the Indus Valley residents may have been Dravidians and thus the ancestors of the ancient Tamil people. (Rig Vedic Sanskrit is plotted in only one of the two sub-figures, unfortunately — the one on relative conditional entropy. Given its geographic, though probably not temporal, proximity to the Indus Valley civilisation, it would have been nice to see it in the other plot too.) Second, when comparing with non-linguistic systems, the difference is extremely stark. And convincing. One could imagine a primitive linguistic system falling somewhere between the “real languages” and Fortran, or between the “real languages” and Vinca. But in this case, the Indus script curve is bang on top of the other “real language” curves, and well separated from everything else.
I’m one of those who believes that “interdisciplinary research” will tell us more and more in the future, and this is an example of computer scientists, physicists and linguists succeeding in putting together a few simple ideas that tell us a great deal. (It is not Ronojoy’s only recent interdisciplinary foray; primarily a “soft condensed matter” physicist, he also recently published an article [free arxiv preprint] on the harmonics produced by loading the membrane in Indian drums. The topic is of interest to me — I did a project on it long ago as an undergraduate — but will perhaps talk about it some other time.)