On: A Language That Linguists Thought Couldn’t Exist

[DenisM]

This phenomenon is treated as an example of phonology in the process of emergence in a very young language.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250231/

[athom → DenisM]

I was just thinking that "...a new sign language emerging..." would more likely consist of whole concepts embodied in independent expressions, which later get broken down into some parts that are more easily recombined into new words/concepts. Thanks for casting sharing this perspective!