Oh those salty little tears. They are fantastic really. They keep your eyes lubricated, flush out toxins from your body, help to de-stress, and they can get rid of those pesky little "something" in your eye. But scientists are at a loss to explain just why humans are the ONLY species (to date) that uses tears for emotional purposes. Yes we need tears to lubricate our eyes but why on earth do salty streams of tears run down our face making us blurry eyed and red faced when we are emotional? Scientists who study evolution say crying probably conferred some benefit and did something to advance our species — because it's stayed with us. Sounds a little vague to me. One new theory is that crying developed as a kind of valuable signal that you were in need of help and it could only be picked up by those who were closest to you. Or maybe it's a little bit more...tears come from all sorts of emotion not just pain. The gamete runs from happiness to joy to sorrow to frustration. They are cathartic and serve as a great sense of release. In a sense they are what make us human. Think about the last movie you watched that brought you to tears or the video of the wreckage from a natural disaster...witnessing tears and pain moves us to feel an emotional response. This is because as humans, one of our signature abilities is that we're able to put ourselves in someone else's shoes to feel what someone else is feeling and predict how they might react — something academics call having a "theory of mind." Theory of mind is more easily explained as empathy and its something that even a 3 year old has. It is fundamental in everything that we do from forming close relationships to live in proximity to others. One of the great things about tears is that they don't often lie...think back to when Tiger Woods got caught in his cheating scandal and started to cry during his public plea for sympathy. No one believed them. That's because along with our tears we have developed a great sense for interpreting them.