1. Researchers at Wayne State University conducted the study
2. The sponsor was not specifically mentioned, although Wayne State University most likely paid for it.
3. The sponsors of the study probably had little economic interest in whether smiles prolong life or not. I suppose the particularly smile or frown prone researchers may have taken a specific interest for health reasons.
4. The study used photographs of 230 players from the 1952 Baseball Register. The article did not say that the players were chosen randomly. Five people looked through the photos and rated each player’s expression as having no smile; a partial smile; or a full smile. The researchers controlled for a number of variables including the length of the players’ careers, education, and body-mass index.
5. Yes. The survey concluded that, of those players that had died, those with no smile lived an average of 72.9 years (63 players), those with partial smiles lived an average of 75 years (64 players), and those with full smiles lived an average of 79.9 plays (23 players).