A special issue of Chemical Communications was recently published, investigating mixtures of molecules that exhibit emergent properties. Martha Grover's paper, "Model identification of a template-directed peptide network for optimization in a continuous reactor," was featured there. Living systems are built from diverse chemical species, which have been optimized through an evolutionary design process. In this paper, a model of peptide assembly and catalysis is optimized, to find the composition that maximizes production of a desired peptide. The optimal design contains diverse species, demonstrating the value of chemical cooperation.