So what if crying is our body's futile attempt to flush out the microscopic invaders responsible for our sadness? Like, at some point in our evolutionary history crying became a thing. And for crying to become a thing emotions had to be a thing first. Therefore at some point some unlucky bastard was the first humanoid thing to experience crying. That must have been fucking wild.
Anyways imagine that your body doesn't know how to cry yet. All the while you are feeling this intense despair. You biology is confused, there is no immediate cause to this phantom pain haunting your mind. The biology panics! It must flush everything! Eyes water. The Nose Drips. Even nausea may set in to bring about the ultimate cleansing.
Our bodies blame the pain of sadness on possible parasites and plagues, and does what it usually does when presented with miasma. However that energy is misguided, the pain is ethereal, separate from the body, but flooding the mind. This probably only increases our body's desperation to be rid of despair.
We cry because our body's are too stupid to handle emotions.
