People who smile more, are happier in the long run. This study looked at baseball cards from the early 1950s and coded whether players were smiling or not. Players who did not smile at all on average lived for 72 years. Those who smiled a bit on average lived for 75 years. And those with big smiles on average lived for 80 years.
These researchers also analyzed 114 pictures from the 1958 and 1960 yearbooks of a women's college in the Bay Area. All but three of the young women were smiling, but the smiles varied. The researchers chose these particular pictures for analysis because the women in them were participants in a long-term study of important life events. Specifically, the researchers knew - decades after the yearbook photos - whether the women were married and if they were satisfied with their marriage. As it turns out, the degree of their smiles years earlier predicted both of these outcomes.