Energy-harnessing problem solving of primordial life: modeling the emergence of catalytic host-parasite life cycles

Abstract

All life forms on earth ultimately descended from a primordial population dubbed the last universal common ancestor or LUCA via Darwinian evolution. Extant living systems share two salient functional features, a metabolism extracting and transforming energy required for survival, and an evolvable, informational polymer - the genome - conferring heredity. Genome replication invariably generates essential and ubiquitous genetic parasites. Here we model the energetic, replicative conditions of LUCA-like organisms and their parasites, as well as adaptive problem solving of host-parasite pairs. We show using the Lotka-Volterra equations that three host-parasite pairs - individually a unit of a host and a parasite that is itself parasitized - are sufficient for robust and stable homeostasis, forming a life cycle. This catalytic life cycle efficiently captures, channels and transforms energy, enabling dynamic host survival and adaptation. We propose a Malthusian fitness model for an original quasispecies evolving through a host-parasite life cycle.