In the context of language evolution, the study of emerging sign languages has taught us a lot about the process of how new (sign) languages emerge, but it is still unclear when (i.e. under what conditions) they emerge. The following research focuses on shared sign languages, sign languages that are shared by deaf and hearing members of communities. They typically emerge in rural areas with a high incidence of hereditary deafness (de Vos & Pfau, 2015). As shared sign languages vary on many levels (Zeshan & de Vos, 2012), researching the conditions allowing for their emergence requires an interdisciplinary approach: this includes studying the genetic foundations for deafness, the cultural transmission of language, and the sociocultural context in which interactions occur. So which variants of these features facilitate their emergence and evolution? The present agent-based model is inspired by Aoki & Feldman’s (1991) mathematical model of sign language persistence. In their model, persistence and transmission of deafness is determined by deaf alleles and by marriage patterns, while whether individuals are deaf or hearing determines the probability of sign language transmission from parents to offspring. In the current research, these components are implemented in an agent-based model, allowing us to observe random fluctuations and more easily incorporate community structure. To understand which conditions permit shared sign languages to emerge and evolve, we analyze a variety of scenarios using the agent-based model. Focusing on marriage patterns (specifying the likelihood that deaf individuals will marry another deaf individual) and sign language transmission types (vertical, horizontal, oblique), we find that these two components affect the persistence of sign language and the number of signers in the population. This methodology flexibly allows for the investigation of influences on the persistence of sign languages. Through this, we can better understand the conditions under which languages emerge and evolve.
Original languageEnglish
Publication statusPublished - 5 Mar 2019
EventISLE Inaugural Workshop: The Evolution of Language: Bridging the natural and cognitive sciences - University of Zürich, Zürich, Switzerland
Duration: 4 Mar 20195 Mar 2019


WorkshopISLE Inaugural Workshop
Internet address

ID: 44696220