How come we cry when we are in pain, upset, laughing etc. Is there any benift of crying?
There is if it gets you a piece o’ pie!! 
[WAG]
We developed the tendency to cry sometime during our evolution. Shortly thereafter, we developed the ability to recognize what it looked like when someone cried, and what it meant. Since we still have both of these, we still react with sympathy and perhaps physical affection when someone cries. And friendship and family bonds and teamwork, etc. can’t be bad for our evolution.
[/WAG]
Obviously, your eyes water to clean themselves out. But that’s not exactly what you’re asking.
Are humans the only higher animal that cries? Do apes and chimps cry? I don’t know the answer to the OP’s question, just thought I’d add to the mystery. 