“It’s not that Russians don’t smile, [cross-sultural studies professor Maria] Arapova explains. They do smile, and a lot. ‘We’re not such gloomy, sad, or aggressive people,’ she tells me. But smiling, for Russians — to paint with a broad brush — is an optional component of a commercial or social exchange and not a requirement of politeness. It means something different to smile — in fact, smiling can be dangerous.”