Evidence for a Human Language Instinct from Sign Languages

This paper examines whether evidence from sign language research supports the hypothesis that humans possess a language instinct. Drawing on studies of homesign systems, emerging sign languages, cospeech gesture in stuttering, and the neurobiological bases of sign language processing, it argues that linguistic structure cannot be explained solely by communicative interaction or environmental input. Homesign research shows that deaf children develop systematic structural patterns despite the absence of a conventional language model. Studies of Nicaraguan Sign Language further demonstrate how gesture-based communication can be reorganized into increasingly structured grammatical systems across cohorts of learners. Evidence from cospeech gesture and neurobiological research suggests that language relies on internally organized mechanisms that are largely independent of modality. Together, these findings indicate that language development is guided by a biologically grounded capacity for language, providing support for the hypothesis that humans possess a language instinct.