The handshake will return. It’s too much a part of who we are.

“We use greetings to mark ourselves as one of the group, one of the gang,” says Andy Scott, a former diplomat who has adeptly bowed and bussed on the international stage and who was reached at his home in southeast London. When we fumble a greeting, he says, it’s as if we’ve slipped out of bounds. For a brief moment, we’re on the sidelines.