A phylogenetic methodology for determining gene duplication times showing how recent and ancestral gene duplication events can be differentiated. Marc Robinson-Rechavi (Ecole Normale Superieure de Lyon, France) has found four gene families that give the top tree, in which two duplicated genes in one species (Fish1, genes α and β) group with different genes from other species (Fish2 and Fish3), and eleven families that give the bottom tree, in which the two duplicated genes from the same species group together. The time of gene duplication is indicated by a bar on each tree. According to their two talks at this meeting, Robinson-Rechavi believes that this analysis does not support a genome duplication in the fish lineage, whereas Yves Van de Peer (University of Konstanz, Germany), who has undertaken a similar analysis, believes that it does. Figure kindly provided by Marc Robinson-Rechavi.