An African Eve may have been mother to us all. Our kind might have come to life independently in several places. In and Out of This World. The means by which we first expanded meaning. The Last Big Biological Step, Complete Language.
Some indirect answers are intriguing.
There's reason to believe it was children. In many places, probably. When we might have brought language into being. Why, from a Darwinian viewpoint, we may have chanced on language. Sapiens Societies Develop The Quest For More.