languages may have spread into the Indian subcontinent with the spread of farming. According to David McAlpin, the Dravidian languages were brought to India by immigration into India from Elam. In earlier publications, Renfrew also stated that proto-Dravidian was brought to India by farmers from the Iranian part of the Fertile Crescent, but more recently Heggarty and Renfrew note that "a great deal remains to be done in elucidating the prehistory of Dravidian." They also note that "McAlpin's analysis of the language data, and thus his claims, remain far from orthodoxy." Heggarty and Renfrew conclude that several scenarios are compatible with the data, and that "the linguistic jury is still very much out." In a 2021 study, Bahata Ansumali Mukhopadhyay presented a linguistic analysis to posit a Proto-Dravidian presence in the ancient Indus area, using Dravidian root words for tooth, toothbrush and elephant in various contemporary ancient civilisations. Possible writing system Between 400 and as many as 600 distinct Indus symbols have been found on stamp seals, small tablets, ceramic pots and more than a dozen other materials, including a "signboard" that apparently once hung over the gate of the inner citadel of the Indus city of Dholavira. Typical Indus inscriptions are around five characters in length, most of which (aside from the Dholavira "signboard") are tiny; the longest on any single object (inscribed on a copper plate) has a length of 34 symbols. While the Indus Valley Civilisation is generally characterised as a literate society on the evidence of these inscriptions, this description has been challenged by Farmer, Sproat, and Witzel (2004) who argue that the Indus system did not encode language, but was instead similar to a variety of non-linguistic sign systems used extensively in the Near East and other societies, to symbolise families, clans, gods, and religious concepts. Others have claimed on occasion that the symbols were exclusively used for economic transactions, but this claim leaves unexplained the appearance of Indus symbols on many ritual objects, many of which were mass-produced in moulds. No parallels to these mass-produced inscriptions are known in any other early ancient civilisations. In a 2009 study by P.N. Rao et al. published in Science, computer scientists, comparing the pattern of symbols to various linguistic scripts and non-linguistic systems, including DNA and a computer programming language, found that the Indus script's pattern is closer to that of spoken words, supporting the hypothesis that