Why are so many networks disassortative

A wide range of empirical networks—whether biological, technological, information‐related or linguistic—generically exhibit important degree‐degree anticorrelations (i.e., they are disassortative), the only exceptions being social ones, which tend to be positively correlated (assortative). Using an information‐theory approach, we show that the equilibrium state of highly heterogeneous (scale‐free) random networks is disassortative. This not only gives a parsimonious explanation to a long‐standing question, but also provides a neutral model against which to compare experimental data and ascertain whether a given system is being driven from equilibrium by correlating mechanisms.