Facial gestures expressing emotions are commonly understood to be universal to human beings. The increasing use of emojis in our correspondence is evidence of this and yet, it seems, there are differences in the way we use these universal gestures. So while we all smile the same, what a smile conveys might vary from culture to culture.

When McDonald’s entered Russia in the 1990s, it had to train its employees how to smile. Smiling didn’t come naturally to them. A former employee told the TV show Invisibilia: “In Russia, if somebody looks at us, we look the other way, unless we about to fight or something. But in America, when you making eye contact, you smile.’’ In another instance, Walmart had to tell its sales clerks in Germany not to smile, because male customers interpreted it as flirting.

Smile scientists have been trying to unravel the smile’s anatomy for years. In the 19th century, Charles Darwin argued in The Expression of Emotion in Man and Animals that the universal human smile evolved from similar ‘precursor actions’ in our animal ancestors. The prototype of a genuine smile is known as the Duchenne smile—named after the 19th century neurologist who first noticed that a phony smile was limited to the mouth, whereas a genuine one emanated from the eyes.

We know that some cultures smile more than others. A recent report in The Atlantic claims that this might have something to do with rates of immigration. Americans smile more because they have so many nationalities in America. You use the smile to break the ice, since you don’t know the other’s language. Countries like India and China, with relatively stable populations, apparently smile less. One might argue against this, because India has witnessed waves of immigration over the centuries, much more than the United States. In fact, the diversity of languages and cultures points to the opposite. We should be smiling a whole lot more but, for some reason, we don’t.

Indians can be a grumpy lot. When we travel in groups, we are noisy and outwardly happy, but in our one-on-one transactions, we apply the straight face with distressing regularity. In a shop situation, the north Indian style is to look through the customer. There is no welcome greeting. The shop keeper has made an art of staring uselessly into space; it’s a pretend-occupied look. The wordless, emotionless transaction is par for the course, even with grocers one has known for years. The buying and selling happens in comfortable, comforting boredom and ennui.

It’s different in Mumbai. If I ask: “Gillette Sensor Excel hoga?”, the Mumbai shopkeeper will say, “Milega na, kyon nahin milega?” It’s a touch that softens the transaction, adds a hint of a smile to it. In England, one gets both word and gesture. As a student at Oxford, I went to Oxfam and bought a coffee mug, a dictionary and some cutlery. The lady at the counter flashed a smile and said: ‘I can see you’re settling in, love.’ Her cheery wink and smile brightened me up. One can forget about smiling in any transaction where haggling is involved; it’s a game of one-upsmanship, where a smile means that your guard is lowered, which is not a good strategy if you want to clinch a great deal.

Smiles come in an assortment of shapes. The batsman smiles after ducking a bouncer, to show he’s not afraid. The talking head on television smiles caustically to express disagreement. The telephone linesman or the postman will smile only if they want to touch you for a little festival bakshish. Our prime ministers don’t smile much. Manmohan Singh and Atalji avoided smiling altogether, unless absolutely necessary, though Rajiv Gandhi had a nice smile.

We are suspicious of men who smile excessively or display too much enthusiasm—it’s considered child-like, a dispensable trait. In fact, in India, smiling at strangers often elicits a scowl or a quizzical frown. I’ve tried smiling to defuse situations with strangers, but it doesn’t work. It’s better to crack a joke. Beaming for the sake of it just won’t cut it.