Sneezing

I sneezed a couple of times on the train this morning, and as one expects, the guy across from me said "God bless you" or some variant. It occurred to me that it's very odd that sneezing is the only thing you can do where you absolutely expect any random bystanders to respond to. And they do.

Apparently the traditional reponses in European languages derive from an ancient belief that one's soul is leaving one's body during a sneeze, or somesuch, which is all good and well. But that doesn't really explain why people respond to sneezes so reflexively in the 21st century. It's so automatic that it's utterly emblematic of culture, the things people do because they do them.