It's interesting to wonder about the sequence of events that led to the discovery of salt as a food additive.

A woman is walking along when she comes upon a white, crystalline rock.

She thinks to herself, "Hmmm.. I wonder what that rock tastes like."

After a moment's hesitation, she picks up the rock and gingerly presses her tongue against it. A moment passes, and an expression of bliss transforms her face. She gathers as much of the rock as she can carry, rushes back to her tribe, and begins frantically crumbling the delicious mineral into the communal cooking pot. She is tackled by a nearby member of the community who is startled by her seemingly deranged actions, and she begins to babble about the taste of the rock until someone else confusedly picks up and licks one of the fragments of salt that the woman dropped.

Within days, an entire tribe of humans is regularly crushing rocks and adding them to its meals. Time rolls on.