Sign language doesn’t need hearing or sound making!

I suppose language requires a means of communication and someone to communicate to at a minimum. Although actually we think in a language so I guess we don’t need someone to communicate to.

Then maybe language creation just requires the right sort of thoughts?

Edit:

I should have read the article first LOL!

They say as much:

> "Language is both a cognitive system and a communication system," Miyagawa says. "My guess is prior to 135,000 years ago, it did start out as a private cognitive system, but relatively quickly that turned into a communications system."