Language Evolution and Computation Bibliography

A unique hallmark of human language is that it uses signals that are both learnt and symbolic. The emergence of such signals was therefore a defining event in human cognitive evolution, yet very little is known about how such a process occurs. Previous work provides some insights on how meaning can become attached to form, but a more foundational issue is presently unaddressed. How does a signal signal its own signalhood? That is, how do humans even know that communicative behaviour is indeed communicative in nature? We introduce an experimental game that has been designed to tackle this problem. We find that it is commonly resolved with a bootstrapping process, and that this process influences the final form of the communication system. Furthermore, sufficient common ground is observed to be integral to the recognition of signalhood, and the emergence of dialogue is observed to be the key step in the development of a system that can be employed to achieve shared goals.

The 'developmental stress hypothesis' attempts to provide a functional explanation of the evolutionary maintenance of song learning in songbirds. It argues that song learning can be viewed as an indicator mechanism that allows females to use learned features of song as a window on a male's early development, a potentially stressful period that may have long-term phenotypic effects. In this paper we formally model this hypothesis for the first time, presenting a population genetic model that takes into account both the evolution of genetic learning preferences and cultural transmission of song. The models demonstrate that a preference for song types that reveal developmental stress can evolve in a population, and that cultural transmission of these song types can be stable, lending more support to the hypothesis.

Vocal learning is a key component of the human language faculty, and is a behaviour we share with only a few other species in nature. Perhaps the most studied example of this phenomenon is bird song which displays a number of striking parallels with human language, particularly in its development. In this paper we present a simple computational model of bird song development and then use this in a model of evolution to investigate some of the ecological conditions under which vocal behaviour can become more or less reliant on cultural transmission.

One of the most distinctive characteristics of human language is the extent to which it relies on learned vocal signals. Communication systems are ubiquitous in the natural world but vocal learning is a comparatively rare evolutionary development (Jarvis, 2004). In this paper we take one example of this phenomena, bird song, which displays some remarkable parallels with human language (Doupe \& Kuhl, 1999), and we focus on one particular case study, that of the Bengalese finch (Lonchura striata var. domestica), a domesticated species whose song behaviour differs strikingly from its feral ancestor in that it has complex syntax and is heavily influenced by early learning (Okanoya, 2002). We present a computational model of the evolutionary history of the Bengalese finch which demonstrates how an increase in song complexity and increased influence from early learning could evolve spontaneously as a result of domestication. We argue that this may provide an insight into how increased reliance on vocal learning could evolve in other communication systems, including human language.