The 'Fish' Signs
Fig. 1: Number and Fish Signs
The 'fish' sign: Starting Point
As the starting point for his linguistic decipherment Parpola accepts the famous rebus (Fig. I a) first suggested by Father Heras half a century ago. In almost all Dravidian languages the word for 'fish' is meen. Many Dravidian languages have also the homophone meen meaning 'star' (derived, in this case, from the root meen, 'to shine'). It can be reasonably inferred from the widespread occurrence of the homopones that they must have been present in Proto-Dravidian with similar meanings. This is the linguistic basis for reading the 'fish' sign as meen, but interpreting it as 'star'. This interpretation has gained popularity among the Dravidianist scholars on account of its simplicity even though it has remained unverifiable.
'Number + fish' signs: Asterisms
This hypothesis is seemingly corroborated by the occurrence of 'number + fish' sequences (Fig. I b-d) interpreted as asterisms first by Heras and further elaborated by the Soviet scholars and Parpola. It is interesting to note that the numerical names for the three asterisms are actually attested in Old Tamil. There is however no proof that these interpretations are the only correct ones. There are, in the Indus texts, several sets of 'number + sign' sequences. The interpretation of 'number + fish' signs as asterisms would make this set unique among such sequences.