We investigate the evolution of homophones and its relation to the evolution of syllable number
of words, based on the quantitative analysis on the historical data and simulation. We suggest that
homophones are the outcome of arranging form-meaning associations according to Zipf’s law to
maximize the referential power under effort for the speaker constraints. We also discuss the neural
bases of ambiguity and the relation between ambiguity and robustness in language evolution.
Furthermore, we show that homophones are stable and cumulate with the times. To avoid creating
homophones, syllable number of words increases, with more recent entry dates of words
associated with more syllables. We also explore stability of homophones and instability of synonyms
in children’s acquisition process. The mechanism of the evolution of homophones and
syllable length of words works cross-linguistically from the emergence of language and goes on
at present