hi! this answer might have better luck in /r/linguistics or /r/AskAnthropology, but you'll find that the answer is "we don't know"

/r/linguistics FAQ:

• Language and Age

a few posts in /r/AskAnthropology

• At what point did we develop language? Could other hominins have had language?

• How did Language develop, and how quickly did it do so?

• What was the last civilization to not have language?

• Some questions about the birth of language.