I imagine it as originating in knowledge about plants and animals. To know is to be able to separate one species from another, or one individual from the group. In the Genesis myth, the first thing Adam does is give names to different animals. And the Tree of Knowledge revealed the separation of nakedness from non-nakedness. This was before people "knew" things like history or math. I suppose this kind of knowing is similar to how the function `filter` separates things based on a predicate.