Before revision:  We find that the metabolic backbones of URLanisms in minimal medium are mainly composed of a core of reactions belonging to ancient pathways, meaning that reactions in the early stages of the life of URLanisms still remain at present significant for biomass production.
After revision:  We find that the metabolic backbones of URLanisms in minimal medium are mainly composed of reactions in ancient pathways, meaning that reactions in the early stages of the life of URLanisms still remain at present significant for biomass production.