I guess what i'm suggesting is that we would all know this, we would all be aware that it's all fantasy, had we not, say for example, lost our ability to synthesize ascorbate.

I'm suggesting that it was parasites what caused us to lose this ability, or "turn it off", as they say, a very long time ago.

I'm wondering if we can turn it back on, and what would happen if we did.

Or is all of that stuff also fantasy?

Where do we draw the line between fantasy and not fantasy?