Scientists have developed a new method based on artificial intelligence (AI) for mapping the dynamics of a smile that can automatically distinguish between men and women. Researchers from the University of Bradford in the UK mapped 49 landmarks on the face, mainly around the eyes, mouth and down the nose. They used these to assess how the face changes as we smile caused by the underlying muscle movements – including both changes in distances between the different points and the'flow' of the smile: how much, how far and how fast the different points on the face moved as the smile was formed. They then tested whether there were noticeable differences between men and women – and found that there were, with women's smiles being more expansive. "Anecdotally, women are thought to be more expressive in how they smile, and our research has borne this out. Women definitely have broader smiles, expanding their mouth and lip area far more than men," said Professor Hassan Ugail from the University of Bradford.