Why Isn’t Sign Language Ubiquitous? February 26, 2011Posted by federalist in Language, Open Questions.
Deaf children instinctively develop sign languages during the same critical periods for language development as other children develop spoken language. And these sign languages have complete analogs to the linguistic characteristics that distinguish and define all spoken human languages. (My favorite book on this is Pinker’s The Language Instinct.)
Given this innate instinct why don’t humans develop full-fledged sign languages unless they are deprived of hearing? The advantage of having a gesticular language to back up a spoken language seems compelling, as Matt Ridley suggests:
At loud parties, on trains or during ambushes, we could resort to signing, instead of having to shout, distract fellow travelers or alert our quarry.