Even the toughest of us admitted they teared up during the end of Toy Story 3, and few can deny not crying after breaking up for the first time. But why? Why do we cry when we’re sad, asks Asap SCIENCE.  

Tearing up when our eyes are irritated, or just to keep them moist, is normal, and other animals also automatically perform this eye maintenance task.

But only humans cry when we are sad, and it may have to do with how social of beings we truly are.