3 Quarks Daily and The Dragon's Tales each linked to Andrew Robinson's Nature article on the progress made in the decipherment of the Indus script. The problem, as yet, is that little is known of the Indus script, with no long passages, no agreement on what the underlying language is, or even how many symbols there are.
At optimistic best, Robinson's conclusion that we may be on the verge of starting to figure things out is worth noting.
Views vary on how many signs there are in the Indus script. In 1982, archaeologist Shikaripura Ranganatha Rao published a Sanskrit-based decipherment with just 62 signs4. Parpola put the number at about 425 in 1994 — an estimate supported by the leading Indus script researcher in India, Iravatham Mahadevan. At the other extreme is an implausibly high estimate of 958 signs, published this year by Bryan Wells, arising from his PhD at Harvard University in Cambridge, Massachusetts.
Nevertheless, almost every researcher accepts that the script contains too many signs to be either an alphabet or a syllabary (in which signs represent syllables), like Linear B. It is probably a logo-syllabic script — such as Sumerian cuneiform or Mayan glyphs — that is, a mixture of hundreds of logographic signs representing words and concepts, such as &, £ and %, and a much smaller subset representing syllables.
As for the language, the balance of evidence favours a proto-Dravidian language, not Sanskrit. Many scholars have proposed plausible Dravidian meanings for a few groups of characters based on Old Tamil, although none of these 'translations' has gained universal acceptance.
A minority of researchers query whether the Indus script was capable of expressing a spoken language, mainly because of the brevity of inscriptions. The carvings average five characters per text, and the longest has only 26. In 2004, historian Steve Farmer, computational linguist Richard Sproat (now a research scientist at Google) and Sanskrit researcher Michael Witzel at Harvard University caused a stir with a joint paper comparing the Indus script with a system of non-phonetic symbols akin to those of medieval European heraldry or the Neolithic Vinča culture from central and southeastern Europe.
At optimistic best, Robinson's conclusion that we may be on the verge of starting to figure things out is worth noting.