Dissertation

Creating a sign language out of everything and everywhere: An example from the deaf people of Bissau

On the 19th of February, Mariana Martins successfully defended a doctoral thesis. Leiden University Centre for Linguistics congratulates Mariana on this achievement!

Author: Mariana Martins
Date: 19 February 2026
Links: Leiden University Repository

This thesis traces the formation of a deaf community in Guinea-Bissau and the emergence of its sign language, Língua Gestual Guineense (LGG), providing rare real-time documentation of language development from gestural roots. The relative absence of medicalised approaches to deafness enabled a free-signing environment in schools and informal meeting places. Within two decades, the first generation of signers in Bissau formed a proud community and developed an autochthonous sign language.Analysis of gestures reveals three main pathways of incorporation into LGG: direct incorporation, incorporation of variants, and incorporation through overlapping networks of polysemous and synonymous gestures. Although many gestures entered the lexicon with minimal formal change, signers exploited variation in form and meaning to drive lexical growth. Innovative methods based on small-group elicitation and deaf participants’ metalinguistic insights reveal the degree of gesture conventionalisation in Bissau. Gestures provided crucial linguistic starting capital, particularly in kinship terms. The research also shows that male-dominated social dynamics shaped semantic domains, such as colour and country name signs, motivated by football references.Linguistically, LGG expands rapidly through compounding, derivation, and grammaticalisation. Overall, LGG reflects both universal processes and local insights driving language emergence, showing how new languages are created out of everything and everywhere.