ABSTRACT
Is it rational to expect proteins such as insulin, relaxin, hemoglobin, or cytochrome to have followed the evolutionary route o f the organisms from which they were taken? O f course it i s , but it does not follow a priori that protein structures would reveal relatedness between species.1,2 The Genomic Potential Hypothesis predicts no branching o f either species or proteins and since proteins within species are the same there is harmony between proteins, species, and reality. In contrast, the old model starts with a single origin and produces variety by continuous branching (changing genomes and hence proteins under continuous mutational pressure). While the proteins within species should still be alike, the proteins from neighboring species must show sequence differences proportional to the phylogenetic distance deduced from the fossils. O f course, the purpose o f molecular genealogies is to deduce species’ relations from proteins and it is easy to imagine the turmoil created when proteins, such as pig relaxin, project a pattern o f relatedness that is totally incompatible with the old branching model. Since an animal and its proteins are going through evolu tion (by any model) together, all proteins must give the same pattern o f branching or no branching at all. Failure to meet this criterion means that no part o f that hypoth esis can survive.
