Question: why do we cry when we're in pain, angry or upset?

Marianne Baker answered on 21 Jun 2010:

I commented on a crying question in one of the other zones actually, but I can’t find it!

So, we have tears for lots of reasons, one of the main ones being to protect the eyes from infection; lacrimal glands (that make tears) also produce enzymes that kill bacteria.
We need to keep our eyes moist, so we’re always making tears and blinking to do that.

If we get hurt (physically or emotionally), I guess the extra production of tears can serve as a warning to others; the sound and sight of people crying is distressing to us, so it can help us to learn what not to do, to protect ourselves from harm! In an evolutionary sense, that is.

In terms of emotional pain I guess it’s a bit more complicated. Perhaps again it’s just part of the defense mechanism; seeing people cry is usually unpleasant so could help stop whatever it is that’s happening to you that hurts.

There are probably better explanations than that around, from (evolutionary) psychologists for example 😀