Why did humans evolve self pity?

A thought occured to me just now. What is the evolutionary purpose of the emotion of self pity? I understand why an individual might benefit from some negative emotions like fear and anger. These get you out of danger or bring the danger to a deserving rival.

But I don't readily see a survival advantage to self pity or really any type of depression. How is wallowing in your own misery supposed to help you survive or get laid? Maybe it works in tandem with other human emotions like empathy and nurturing. "Oh, I feel so bad for you, here's some mutton and would you like to go lay down with me in the deer skin?"

Seems like a stretch though.