Eleonora De Lazzari* published her findings on scaling laws for gene families. A striking quantitative invariant in evolutionary genomics is the scaling with genome size of the number of proteins sharing a specific function. E.D.L. showed that such scaling laws exist systematically at the level of single evolutionary families. This provides a novel view of the links between evolutionary expansion of protein families and gene functions.This work was performed in collaboration with J Grilli (U. Chicago) and S Maslov (U. Illinois).