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Is the range of languages we observe today explainable in terms of which languages can be learned easily and which cannot? If so, the key to understanding language is to understand innate learning biases, and the process of biological evolution through which they have evolved. Using mathematical and computer modelling, we show how a very small bias towards regularity can be accentuated by the process of cultural transmission in which language is passed from generation to generation, resulting in languages that are overwhelmingly regular. Cultural evolution therefore plays as big a role as prior bias in determining the form of emergent languages, showing that language can only be explained in terms of the interaction of biological evolution, individual development, and cultural transmission.

No abstract received.

Language learning is an iterative process, with each learner learning from other learners. Analysis of this process of iterated learning with chains of Bayesian agents, each of whom learns from one agent and teaches the next, shows that it converges to a distribution over languages that reflects the inductive biases of the learners. However, if agents are taught by multiple members of the previous generation, who potentially speak different languages, then a single language quickly dominates the population. In this work, we consider a setting where agents learn from multiple teachers, but are allowed to learn multiple languages. We show that if agents have a sufficiently strong expectation that multiple languages are being spoken. we reproduce the effects of inductive biases on the outcome of iterated learning seen with chains of agents.

Identifying the evolutionary forces that we need to appeal to in order to explain aspects of human languages requires having a clear understanding of the effects of those forces. Evolutionary biologists use neutral models to characterize how systems evolve in the absence of selection (e.g., Kimura, 1983). Neutral models are valuable as a means of obtaining insight into the effects of evolutionary forces other than selection – mutation and genetic drift – and as a null hypothesis that can be used when testing for the presence of selection…