An opposing hypothesis that has been offered by Michael Witzel and Steve Farmer, is that these symbols are nonlinguistic signs, which symbolise families, clans, gods, and religious concepts and are similar to components of coats of arms or totem poles.[25] In a 2004 article, Farmer, Sproat, and Witzel presented a number of arguments stating that the Indus script is nonlinguistic. The main ones are the extreme brevity of the inscriptions, the existence of too many rare signs (which increase over the 700-year period of the Mature Harappan civilization) and the lack of the random-looking sign repetition that is typical of language.[26]