SFI Postdoctoral Fellow Elhanan Borenstein and SFI External Professor Marcus Feldman introduce the concept of a metabolic network’s “seed set” and provide a methodological framework to computationally infer the seed set of a given network. The seed sets’ composition significantly correlates with several basic properties characterizing the species’ environments. Their findings suggest that the seed state is transient and that seeds tend either to be dropped completely from the network or to become non-seed compounds relatively fast. The “reverse ecology” approach presented lays the foundations for studying the evolutionary interplay between organisms and their habitats on a large scale. See “Large-scale Reconstruction and Phylogenetic Analysis of Metabolic Environments,” E. Borenstein, M. Kupiec, M. W. Feldman, and E. Ruppin, Proceedings of the National Academy of Sciences of the U.S.A. 105(38) (2008): 14482-14487.