What's a smile got to do with it? A lot apparently. There are studies that show a subject's smile in a picture is highly predictive of longevity and even likelihood of divorce. Abel and Kruger from Wayne State University studied the "smile intensity" of baseball players as depicted in their baseball cards. Those with larger smiles, also known as Duchenne smiles (meaning a full smile where the corners of your mouth are raised and you have creases near your eyes), lived the longest.
Another study done by Matthew Hertenstein from DePauw University measured the smiles of individuals taken from college yearbooks. He found that 31% of the frowners divorced compared to only 11% of those with smiles.