According to a new Wayne State University study, people who smile a lot are usually happier, have more stable personalities, co-exist in more stable marriages, have better cognitive skills and have better interpersonal skills than those who don’t. Moreover, science just realized that happy faces live longer!

After examining the enlarged photos of 230 professional baseball players who started their careers before 1950, and rating them for smile intensity: small, none, partial smile . . .  the ratings were compared with mortality data from 2006 through 2009. The researchers then corrected their analysis to account for other factors associated with longevity, such as body mass index, career length, career precocity and college attendance. Among those who had died, the researchers found longevity ranged from an average of 72.9 years for players with no smiles (63 players) to 75 years for players with partial smiles (64 players) to 79.9 years for players with big smiles (23 players).
This isn't a bunch of psycho-hooey, the authors said. Smiles reflect positive emotion. Positive emotion has been linked to both physical and mental well-being. They added a caveat to their study: "The data source provided no information as to whether expressions were spontaneous or in response to a photographer's request to smile." Still, big smiles are more likely to reflect true happiness than partial smiles.
Maybe the non-smilers were thinking about batting averages?  The study is published in the journal Psychological Science.