Put those pearly whites away for the photo, because rather than make you look younger, smiling actually makes you look older – according to Israeli scientists.

Turning a smile into a frown whilst turning conventional wisdom on its head, researchers at Ben-Gurion University in the Negev, together with Canadian colleagues, found that smilers came across as older than grumps.

“Popular media promotes the idea that smiling makes you look younger,” said Prof. Tzvi Ganel, head of the Laboratory for Visual Perception and Action at BGU’s Department of Psychology. In fact, it’s the opposite.

In research published this week in the May edition of Psychonomic Bulletin and Review, Ganel’s team explained how they conducted experiments comparing age perceptions of smiling faces to those showing surprise or no emotion.

To their surprise, participants ranked smiling faces as the oldest, followed by neutral expressions. Those looking surprised were judged to look the youngest. It’s all to do with the wrinkle lines that form when smiling, researchers said, and the motion of lifting and pulling the skin backwards when looking shocked.

In a quirky second finding, participants erroneously recalled the smiling faces as those they had judged youngest, when asked after the experiment.

“Ironically, we discovered that the same person can believe that smiling makes you appear younger and judge smiling faces older than neutral ones,” said co-author Prof. Melvyn Goodale from Western University in Canada.

The researchers at Ben-Gurion University of the Negev in Israel and Western University in Canada conducted a series of experiments intended to gauge age perception based on facial expressions. Forty student participants were shown images of people and asked to rank them from oldest to youngest. They were shown pictures of smiling faces, neutral expressions and surprised looks. The participants ranked the smiling faces as the oldest, followed by neutral expressions, and surprised expressions as the youngest.