Perhaps I am misunderstanding (the article was fairly short and I haven't looked into this elsewhere) - but it seems to me that this is flimsy at best. I don't

Perhaps I am misunderstanding (the article was fairly short and I haven't looked into this elsewhere) - but it seems to me that this is flimsy at best. I don't run scientific studies so if anyone can correct or educate me I'd be happy to learn - but can you really get any solid scientific conclusions by examining a single smile at a single point of time, in a small group (one yearbook, 141 photos)? Certainly such an insignificant event such as a smile, in an uncontrolled environment without knowing any surrounding factors, in such a small set of people shouldn't be extrapolated and generalized this way?