Why we respond to sneezes

When someone sneezes, common courtesy in every culture on earth is to wish a divine blessing upon them ("Bless you!") or, alternatively, good health ("Gesundheit!"). My friends over at Snopes do a fine job of explaining the whys and wherefores of this custom.

Unlike the vapid "Hi! How are you doing?" greeting , which is offered without sincerity or conscious thought by over 99% of those who say it, and whose response is usually ignored, the sneeze wish acknowledges the sneezer's existence as a person. It says, "I offer you this bit of caring, no matter how small, for your equally small discomfort."