This seems to need no explanation. I wonder if you could do the same analysis from the annual Lawrence faculty picture?
Smile Intensity in Photographs Predicts Longevity
Ernest Abel & Michael Kruger
Psychological Science, forthcoming
“Photographs were taken from the Baseball Register for 1952 (Spink, Rickart, & Abramovich, 1952). We restricted our analysis to players who debuted prior to 1950, and we included only photographs in which the player appeared to be looking at the viewer…Players with Duchenne smiles were half as likely to die in any year compared with nonsmilers, HR = 0.50, p = .006…In this model, smile intensity accounted for 35% of the explained variability in survival”