Assembly of Replicating Protocells with Primitive Metabolism

Evolution on Earth often follows unpredictable pathways for the emergence of new species that are dependent upon the environment. Therefore, we can assume that the chemical origins of life and Darwinian evolution began with processes that are not apparent today. In this review, we highlight recent progress toward elucidating such pathways and mechanisms that led to the emergence of life-like behavior in prebiotically plausible chemical systems. To this end, we focus on the growing and dividing of protocells that encapsulated genetic materials and the ways in which functional protocells could have adapted to their environment by forming a rudimentary metabolism out of prebiotic chemistry. We highlight the importance of genotype-to-phenotype coupling and possible cooperative or competitive pathways for evolutionary mechanisms to build upon. We consider coacervation by liquid-liquid phase separation as an emerging crucial element and argue that in order to study a system's chemistry at the onset of Darwinian evolution, we must involve the protocellular populations early on. By examining and drawing analogies from the physical and chemical dynamics that are at play in extant life, we provide a perspective on how the differences between nonliving and living entities on early Earth may have faded away gradually.