Duncan Watts is principal research scientist at Yahoo! Research, where he directs the Human Social Dynamics group. He is also professor of sociology at Columbia University, and an external faculty member of the Santa Fe Institute. His research on social networks and collective dynamics has appeared in a wide range of journals, from Nature, Science, and Physical Review Letters to the American Journal of Sociology. He is also the author of Six Degrees: The Science of a Connected Age (W.W. Norton, 2003) and Small Worlds: The Dynamics of Networks between Order and Randomness (Princeton University Press, 1999). He holds a B.Sc. in Physics from the University of New South Wales, and Ph.D. in Theoretical and Applied Mechanics from Cornell University.