What you say about the experiment results is true. I don't know if this one is any better, but the guy who gave this TED talk found similar results when looking for communities having people with the longest life spans:

http://www.ted.com/talks/dan_buettner_how_to_live_to_be_100....

One of the places with a lot of centenarians was a place near Okinawa, Japan, where people form life long friendships. They also eat healthy and I'm sure other variables are different. I find the correlations interesting even if they are not conclusive.