Everyone knows that a duck face pout is the expression of choice for that perfect Instagram selfie, even if it is pretty damn irritating. 

But now it seems that those camera-lovers might actually be on to something in their refusal to smile, as a study has revealed flashing a grin makes you look older than you are by as much as two whole years. 

That’s right, although it seems contrary to popular belief, research has found that when we look happy, rather than maintaining a poker face, we age ourselves in the eyes of strangers.

Co-author Melvyn Goodale, who worked on the study, said: “We associate smiling with positive values and youth…think of all the skin-care and toothpaste companies that sell the same idea every day.

“It may seem counter intuitive, but the study shows that people can sincerely believe one thing and then behave in a completely different way.”

The team from the Brain and Mind Institute at Western University, in Canada, showed participants a series of pictures with three expressions – smiling, neutral and surprised.

And while the group perceived surprised faces as the youngest, smiling was consistently the oldest. 

Goodale speculates that this is caused by the simple fact that smiling causes wrinkles around our eyes to form, and people are “unable” to ignore this ageing effect. On the contrary a look of surprise, smooths any wrinkles. 

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Despite this clear preference for people to keep a neutral expression, Goodale says that one of the most shocking things was that people do not acknowledge the bias.

“The striking thing was that when we asked participants afterwards about their perceptions they erroneously recalled that they had identified smiling faces as the youngest ones.

“They were completely blind to the fact they had ‘aged’ the happy-looking faces. Their perceptions and their beliefs were polar opposites,” said Goodale. 

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