Mahadevan deciphered the earliest Tamil-Brahmi inscriptions, and has tentatively suggested a derivation of Brahmi from the Indus script rather than the conventional hypothesis which derives Brahmi from the Aramaic script.
Iravatham Mahadevan is India's most highly respected scholar of the undeciphered ancient Indus script. He is also the first to acknowledge that nothing is certain, even his own interpetations. A Tamil speaker, he has used historical linguistics and statistical studies to examine the Dravidian components in Vedic Sanskrit, and how these might point to interpretations of the Indus Valley script. Known for his breakthrough decipherments of the earliest Tamil Brahmi writing, his thoughts on the relationship between ancient Indus writing and Brahmi writing bear weight. A longtime civil servant, he used a fellowship opportunity to put together the first script concordance of Indian seals in 1970. His publications include The Indus Script: Texts, Concordance and Tables (1977). Dr. Gregory Possehl calls Mahadevan a "careful, methodical worker, taking care to spell out his assumptions and methods. . . 'Tentative conclusions' and 'working hypotheses' are more his style than set ideas and fait accompli" (Indus Age: The Writing System, p. 130).
Iravatham Mahadevan is a National Fellow of the Indian Council of Historical Research.
An exclusive interview with Mahadevan including audio excerpts is also available. http://www.harappa.com/script/mahadevantext.html#4