Watch: Why Do We Cry? The Three Types Of Tears

Humans cry. A lot. New parents cry the first time they see their child. Children cry when they fall down. People cry when they are going through a divorce and when they chop onions. Sad movies and pain and love. It all makes us cry. And sometimes we even cry for no reason. Ultimately, our eyes are constantly producing tears. Here, Alex Gendler tracks a particularly watery day in the life of Iris (the iris) as she cycles through basal, reflex and emotional tears.