The selfie-stick is changing the culture of the smile after decades of it being celebrated, according to a professor.

Colin Jones, who wrote The Smile Revolution, said that technology was changing how people presented themselves to the world, adding that the so-called duck face was now replacing the “Cheshire cat”.

The “duck face” has drawn comparisons to Ben Stiller’s character in Zoolander

The academic said that for almost the entire 20th century “the smile had carried on triumphant” — propelled into popularity by advertising, advances in dentistry and studio photography.

“Technology has made it interesting for the culture of the smile,” he told the Hay Festival. He said that in the early days of the selfie-stick people still smiled for photographs but then the duck face became popular. “The idea now is that you probably won’t smile. You will probably suck in and look very ironic and trendy and fashionable.” He described the duck face as “a caved-in look”, which was “incredibly common in the modern world”. Mr Jones, a professor of history at Queen Mary University of London and whose book analyses the history of the smile in society, said historians would “be very interested looking back at this era”.

“I think there is something going on contemporaneously that is going to affect how the smile is valued and what it means. A coda on the wonders of narcissism is to look back at how social media changes the way we present.”

He said it seemed like this was now a seminal moment such as the 1787 self-portrait by Madame Elisabeth Vigée Le Brun, which he described as the “radical transformation in the cultural significance of the smile”. Mr Jones said that prior to this, open-mouthed smiles were “seen as demeaning” and were traditionally only shown on portraits of “plebeians or the mentally deficient”.

The toothy smile then retreated again during the 19th century when paintings presented it as “gothic” but arose again with photography and the spread of western advertising.