Emotional tears are a uniquely human behavior. Research suggests they evolved not for eye health but as a powerful social ...

Terminator: Why do you cry? John Connor: You mean people? Terminator: Yes. John Connor: I don't know. We just cry. You know. When it hurts. Terminator: Pain causes it? John Connor: Uh-uh, no, it's ...

Crying as an expression of emotion appears to be uniquely human behavior. Other animals may tear up because of irritants in their eyes, but only humans shed tears at times of extreme sadness or joy.