An article in The Boston Globe  explores how a scholarly idea can take off -- and then come under sustained scrutiny. The idea is that certain traits such as smoking, obesity and loneliness are contagious and spread through social networks. It was promoted in 2007 articles by Nicholas Christakis of Harvard University's medical school and James Fowler, a political scientist at the University of California at San Diego. But while the article captured considerable attention beyond academe at the time, it has come under much questioning of late in a series of scholarly papers. Among the criticisms: that the original work didn't adequately rule out explanations beyond social networks for the spread of these traits.