@kaputotter Yeah, exactly! We can puzzle out plenty of things it's useful for, but there are so many of them, and they have so little to do with each other on the surface.
It's just so damn _versatile_ compared to other emotions. It's even a good irony detector, and I can see how it would have been useful for early hominids to have an more advanced "whoa this does NOT make sense, WTF" instinct than less adaptable mammals...