A fine-tuned grin

Recently on the street, I encountered a smile-fest. There was the lady who glanced at my shoes, caught me looking, and flashed a grin. I myself mustered the widest beam I could when I splashed tea on someone in a café. There was the genuine smile I directed at a friend, and the heartfelt, grinned apology of a man who walked into me as I boarded a train. (That last one, I confess, is an outright fantasy. Chivalry is dead on the subway.)

But really, this day happens everyday. It’s just that a sudden hyper-awareness to smiling left me pondering a seemingly basic question: What is it about a smile that is so perfunctory, and yet so particular? Considering this, what is it about Mona Lisa, or the Cheshire Cat, each grinning perpetually, that is so unnerving? The answer, I would venture, is in the immobility of each.

Humans identify and respond to smiles because facial expressions are the chief indicator of human emotion. The changeability of a smile – its presence or absence, and the subtle gradations in between – is what points to the grin’s evolutionary roots.

There is a mishmash of science on the topic, much of which examines the parallels between the facial expressions of humans and chimpanzees. There is a similar theory behind why we laugh. You only need consider the giggles of young apes to recognize this, researchers say.

The accepted idea is perhaps not altogether unforeseen: we smile or beam or grin or smirk or sneer for social reasons. The work of one social psychologist, Paula Niedenthal, shows that specific social situations dictate the need for a particular type of smile. Drawing on this observation, she suggests that we take our cue from the types of smiles we see in chimpanzees.

By showing the teeth in a child-like beam, chimps show their submission in threatening situations. They also have a ‘play’ smile, which denotes genuine pleasure and social bonding, while in competitive scenarios, they express dominance through a garish grin, complete with bared teeth. There are a host of other categories.

While these particular signals aren’t necessarily matched in human smiles, in one article, Niedenthal says we have our own set of visual clues to connote similar sentiments. Raised eyebrows and a lowered chin accompanying a smile signal appeasement or embarrassment, for example, but a raised chin shows confidence, a projection of superiority or strength. There are a multitude of cues, and each is familiar to us on an entirely subconscious level.

Facial signals fine-tune a smile, molding it appropriately to a social situation. Thus, smiling demonstrates evolutionary adaptation in a strikingly pure form: we do it to progress socially; to ensure a basic, and yet essential, type of success.

If too many people have played you like a ping-pong ball on the subway already this week, here’s a song to consider. The next time you get pushed around, flash a warning smile. You know you’ve got it in you.