Marcus Alexander, PhD, MPhil, is a research scientist in Yale Engineering. He studies biological and social aspects of human networks in the Human Nature Lab directed by Professor Christakis in the Yale Institute for Network Science, Department of Biomedical Engineering, Department of Ecology and Evolutionary Biology and the Department of Sociology, Yale University. MA acknowledges funding support from the Howard Hughes Medical Institutes, Memorial Sloan-Kettering Cancer Center, National Science Foundation, Russell Sage Foundation, Stanford University, Harvard University, the Clarendon Fund, Fox Fellowship, and the Merkle Foundation.