Question: Why do we cry when we feel very sad or very happy?

Miranda Bane answered on 17 Nov 2016:

Hi Maddie, that’s a really interesting question. I don’t know the answer, and I’m not sure if anyone has discovered this but I have read some things about it. Some scientist think it comes from before very early humans were able to communicate with language. When you cry you clean out your eyes with your tears. This would normally need to happen in a danger situation so that your eyes are clear to see the danger. Over time we have associated the feeling of being scared or upset with crying so we cry even when there isn’t danger. When we are really happy we experience a similar surge of emotion to being really sad which is why we cry when we are happy too. We become overwhelmed with emotion and then the natural crying response kicks in.
I hope that helps. It’s not the answer for certain but on either that I read about and thought was quite good.