Ancient Symbols, Computational Linguistics, and the Reviewing Practices of the General Science Journals

Few archaeological finds are as evocative as artifacts inscribed with symbols. Whenever an archaeologist finds a potsherd or a seal impression that seems to have symbols scratched or impressed on the surface, it is natural to want to “read” the symbols. And if the symbols come from an undeciphered or previously unknown symbol system it is common to ask what language the symbols supposedly represent and whether the system can be deciphered. Of course the first question that really should be asked is whether the symbols are in fact writing. A writing system, as linguists usually define it, is a symbol system that is used to represent language. Familiar examples are alphabets such as the Latin, Greek, Cyrillic or Hangul alphabets, alphasyllabaries such as Devanagari or Tamil, syllabaries such as Cherokee or Kana, and morphosyllabic systems like Chinese characters. But symbol systems that do not encode language abound: European heraldry, mathematical notation, labanotation (used to represent dance), and boy scout merit badges are all examples of symbol systems that represent things, but do not function as part of a system that represents language. Whether an unknown system is writing or not is a difficult question to answer. It can only be answered definitively in the affirmative if one can develop a verifiable decipherment into some language or languages. Statistical techniques have been used in decipherment for years, but these have always been used under the assumption that the system one is dealing with is writing, and the techniques are used to uncover patterns or regularities that might aid in the decipherment. Patterns of symbol distribution might suggest that a symbol system is not linguistic: for example, odd repetition patterns might make it seem that a symbol system is unlikely to be writing. But until recently nobody had argued that statistical techniques could be used to determine that a system is linguistic.1 It was therefore quite a surprise when, in April 2009, there appeared in Science a short article by Rajesh Rao of the University of Washington and colleagues at two