Smile intensity in photographs predicts longevity

We came across this paper that tweaked our interest and perhaps will make you smile too!
230 photos were collected from The Baseball Register for 1952 and
enlarged to twice their original size. They were rated for smile intensity by five assessors and dates of death
investigated. The Register allowed various factors influencing longevity to be controlled, including body mass
index, career length (continued fitness and performance), marital status and education. Players giving the
biggest grins in the photographs lived 5 years longer than those who kept a straight face.
Comment: This study is the first to link smile intensity to a biological outcome – longevity. Previous studies have
revealed that smile intensity in childhood photographs and school yearbooks correlates with marriage stability
and satisfaction. Perhaps even a forced smile stimulates the brain in a similar way to real happiness?