Smiles are also a signal of subservience and acquiescence. When you want to appear non-threatening, you smile, even at animals. I am no expert in social signals but I might hypothesize that by being friendly without smiling first, Russians are subconsciously sending the signal that they are not to be trifled with and that they will deal with others on their own terms. Maybe that's why Russians are so shitty to the service sector. If there's a culture of salesmen giving you the shaft, you cease to smile like a monkey and laugh at everyone's jokes.It made me wonder a lot, as a kid, why would people do kind things to one another but not smile at them at the same time. It made sense to me even at 11 that a smile is a natural indication of good will and friendliness, and if you're helping someone, you're being friendly, so it should follow that you would smile to express so.