Clustering and preferential attachment in growing networks - art. no. 025102

We study empirically the time evolution of scientific collaboration network s in physics and biology. In these networks, two scientists are considered connected if they have coauthored one or more papers together. We show that the probability of a pair of scientists collaborating increases with the n umber of other collaborators they have in common, and that the probability of a particular scientist acquiring new collaborators increases with the nu mber of his or her past collaborators. These results provide experimental e vidence in favor of previously conjectured mechanisms for clustering and po wer-law degree distributions in networks.