Here's why it's so difficult to get a precise number:
* Lack of research: Many sign languages, particularly those used by smaller deaf communities, haven't been formally documented or studied.
* Language variation: Sign languages often exhibit significant regional and dialectal differences, making it challenging to define what constitutes a distinct language.
* Emergence of new languages: Sign languages can develop over time as new communities form, leading to the emergence of new sign languages.
Despite the uncertainty, it's clear that sign languages are a rich and diverse form of communication, with each language possessing its own unique structure and vocabulary.