Asked by: Holly Nicholls, Aberdeen
There are three kinds of tears: those that lubricate the eye, reflex tears that wash away irritants, and emotional tears that contain more protein and hormones than the others. Facial expressions of sadness or grief are interpreted as much stronger when accompanied by tears.
These emotional tears blur vision and make someone who is crying far more vulnerable. Although this may seem dangerous, crying may have evolved as a genuine signal to others that you can’t attack or harm them. Crying can’t easily be faked and real tears are hard to wipe away to restore good vision. So this signal shows that you’re genuinely handicapped, telling others they can safely leave you alone or come and give you the help you need.