A writer, who has traveled the world searching for the secrets of a long life, is now working to fight obesity in children. In partnership with MPR's Sound Learning, Dan Buettner is launching the Blue Zones Challenge. It is named for the so-called blue zones, places in the world where people live longer than the rest of us. Buettner is the author of "Secrets of Long Life" which was the cover story in November's National Gegraphic magazine. Dan Buettner joins me this morning in the studio.