smiles in yearbooks predict marriage success later?

This is an interesting story, even though we don't know whether correlation here means causation:


"If you want to know whether your marriage will survive, look at your spouse's yearbook photos.
Psychologists have found that how much people smile in old photographs can predict their later success in marriage."

http://news.yahoo.com/s/livescience/20090414/sc_livescience/smilespredictmarriagesuccess