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 a core of reactions belonging to ancient pathways, meaning that those reactions still remain at present significant for biomass production.