James Fowler, Friend of a Friend of a Friend ...
Social networking usually makes us think of Mark Zuckerberg, but how and why people connect have been central questions of social science for centuries. More recently, James Fowler, professor of medical genetics and political science at the University of California, San Diego, has been lighting up the field. In 2007, Fowler teamed up with Harvard University researcher Nicholas Christakis to study the effects of social networks on health outcomes.
What they discovered mesmerized scientists and laypeople alike: that a person's friends can profoundly affect that person's health. They started with obesity, reporting in The New England Journal of Medicine that a person's chance of becoming obese increased 57 percent if a close friend became obese at the same time. The effect held even when a direct friend wasn't involved; obesity in a friend of a friend also increased the odds of a person becoming obese.
In 2008, Fowler and Christakis followed up with two additional studies examining the effects of social networks on smoking and levels of happiness. They discovered similar patterns in both health measures. If someone's friends quit smoking or described themselves as happy, then that person was more likely to quit smoking or to be happy himself. In 2011, the two researchers summarized their discoveries in "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives," a best-selling book that has since been translated into 20 languages.
Fowler has gone on to research overconfidence as an evolutionary trait. His findings suggest that overconfident people outcompete realists in many situations, even though those folks could hurt the group as a whole.