Modeling cultural evolution. A parallel investigation of changes in bird song and human language
Prof. dr. C.J. ten Cate en Prof. dr. A. Verhagen
a) Human language and birdsong are both culturally transmitted vocal communication systems. Both vocal signals consist of units, organized in specific ways. For both it has been observed that the vocalizations change over time in phonology, structure, and meaning. We examine whether the mechanisms underlying such changes in language and birdsong share common features which may indicate general characteristics of the process of cultural transmission. We combine empirical studies of song change and language change with agent based simulation models of change. Our comparative approach has led to mutually beneficial interactions, which are already having an impact on our fields. The incorporation of agent based models of evolutionary change in studies of language change is introducing a new approach in the area which is attracting attention at conferences. We have been presenting birdsong studies on several predominantly linguistically oriented conferences and this has fostered interest in birdsong as a model for language evolution. At the same time the studies of birdsong are addressing the issue of structural changes in birdsong syntax. Both the theoretical approach and the methods are strongly influenced by linguistic concepts and techniques. We see the frequent and active exchanges among the four scientists involved in the project (Lachlan, Landsbergen, ten Cate & Verhagen) as instrumental to our success. We feel our project fulfills the goals of stimulating mutual interaction and knowledge exchange between the fields of linguistics and animal communication, not just for the researchers involved, but also their research communities.
b) Apart from a continuation of the current research, the next phase of the project will be one in which we will increase the visibility of our project and its results by concentrating on publicizing our results and by furthering the interaction between social and natural sciences by expanding our modeling to more general aspects of cultural evolution in non-human species. Until fairly recently, culture was thought of as the sole preserve of humans. A more nuanced current view would state that non-human animals possess the building blocks of culture: the method of transmission (social learning). However, anthropologists have emphasized that human culture also encompasses the complex and hierarchical interactions between multiple cultural traits, while most examples of animal “culture” consist of isolated behavior that happens to be socially learned. We are challenging this view by exploring the hierarchical cultural evolution of bird song. Our current results document how “elements”, “syllables”, and “songs” (three hierarchical levels of organization within a song) culturally evolve at different paces, and how rules governing this differ between populations. We will use this system to work on a cultural evolutionary model that aims to generate hypotheses about how hierarchical patterns of organization originate. This model will then be tested against the empirical data we have collected from chaffinch populations, as well as data about linguistic changes.