Spontaneous evolution of linguistic structure - An iterated learning modelof the emergence of regularity and irregularity

A computationally implemented model of the transmission of linguistic behav ior over time is presented. In this model [the iterated learning model (ILM )], there is no biological evolution, natural selection, nor any measuremen t of the success of the agents at communicating (except for results-gatheri ng purposes). Nevertheless, counter to intuition, significant evolution of linguistic behavior Is observed, From an initially unstructured communicati on system (a protolanguage), a fully compositional syntactic meaning-string mapping emerges. Furthermore, given a nonuniform: frequency distribution o ver a meaning space and a production mechanism that prefers short strings, a realistic distribution of string lengths and patterns of stable irregular ity emerges, suggesting that the ILM is a good model for the evolution of s ome of the fundamental features of human language.