Language as an Exaptation
Much of the recent computational research into the evolution of language has concentrated on explaining the origins of compositionality and syntax in language. In such models, the ability of syntax to allow generalisation leads to it naturally emerging in the resulting language to capture structural properties of the semantic space under discussion. However, while such models can explain why protolanguages may have gained in structural complexity to become fully-fledged languages given the opportunity, they do not explain how the ability of individuals to handle composition of linguistic fragments evolved: while existing models may explain the emergence of syntax in the language, they presuppose a syntax-handling capability in the brain. It is the evolution of this capability that my research seeks to address.
My work lays out one possible explanation for the evolution of this linguistic ability and develops from it a computational model to assess its feasibility. Specifically, the biologically plausible idea is examined that the ability to handle compositionality in language is derived from a similar, and earlier, ability to handle compositionality in navigation and that the same underlying neural mechanisms are used. A second, supplemental, theory is also proposed, that one of the original purposes of language may have been for use in navigation. Communication in this case would be a form of inherently cooperative social behaviour which could lead to evolutionary benefits for groups of individuals possessing this trait. To assess the ability of these theories to explain the evolution of the capability of individuals to handle compositional language, a multi-agent simulation is created in which populations of agents with a variety of linguistic and foraging policies are tested for their abilities to survive and reproduce.
In addition to using the model to essay the relative successes of these behaviours, the role of the environment structure in determining the benefit of a behaviour is also examined. By varying parameters of the landscape, it is established that populations able to communicate can grow faster and be more resilient to volatility of resources than those unable to do so. In some situations, communication even provides the ability for a population to survive when resources are too scarce or volatile for a non- communicating population to do so. Such results point towards a possible source of evolutionary pressure for the ability to use language.
This work was carried out as part of my PhD which was supervised by Dimitar Kazakov
Adapted from the abstract to my thesis