In 1964 my friend Seppo Koskenniemi asked me whether I wanted to try a computer for some research tasks. In 1952, it had been possible to decipher the Linear B script without translations by studying such things as the sequence of script signs and the density of their occurrence. The computer assisted in collecting such data on the undeciphered writing system of the Indus Civilization, which now became our pastime. My brother, the Assyriologist Simo Parpola, brought his expertise on the Middle East and its writing systems to the project. We converted 2500 short texts into numbers and then drew Indus symbols above the numbers on the printouts. We assumed that what we had was a word/syllable script based on a Dravidian language. We got really started with our investigation when my teacher Pentti Aalto encouraged us to try and read certain symbols. My rashly prepared initial reports (1969–70) were received both positively and critically. The criticism helped me to eliminate mistakes, but did not manage to dispirit me.

We published the first concordance of Indus symbols in 1973 and with Kimmo Koskenniemi an improved version in 1979–82. The works contained 400 previously unpublished texts, which I had discovered in Indian and Pakistani museums in 1971. In 1973 I initiated an international photographic publication of Indus seals and texts, of which there has been three large volumes, in the years 1987, 1991 and 2010. From Finland Virpi Hämeen-Anttila and Petteri Koskikallio and the photographers Erja Lahdenperä, Jyrki Lyytikkä, and Arto Vuohelainen have taken part in the project.

In my book Deciphering the Indus script, which was released in 1994, I developed the ideas from those early years further. Even after this I have still been able to carry on the investigation: my new views are contained in my work The Roots of Hinduism (2015), which has been supported by BAULT.