Researcher Ernest L. Abel (Wayne State University, Michigan, USA) and colleagues have found that smiling intensity is linked to life longevity.
The researchers analyzed photographs of 230 major league baseball players in the 1952 season. Each player's smiles in numerous photos were categorized for intensity. Then the life length of the 184 players who had already died was correlated with the level of their smile. The true and more genuine smilers tended to live the longest. Seventy percent of them lived to age 80 or more. Only fifty percent of the non-smilers survived to age 80.