Prebiotic Gels as the Cradle of Life

We outline the “prebiotic gel-first” framework, which considers how the origin of life (OoL) could have potentially emerged within surface-attached gel matrices. Drawing on concepts from soft-matter chemistry and using modern microbial biofilms as a framing device, we review the physicochemical features of prebiotic gels and discuss how prebiotic gels could have provided the means for localized environments conducive to chemical complexification and evolutionary potential well before cellularization. Such prebiotic gels may have allowed primitive chemical systems to overcome key barriers in prebiotic chemistry by enabling molecular concentration, selective retention, reaction efficiency, and environmental buffering. Furthermore, we explore how gel matrices could have supported proto-metabolic activity through redox chemistry, light-driven processes, chemo-mechanical coupling—and proto-replication via autocatalytic networks or template-directed synthesis. We then briefly extend this model into the domain of extraterrestrial life detection, discussing the potential existence of “Xeno-films,” i.e., alien biofilm-like structures composed of non-terrestrial (or with some terrestrial) building blocks, and emphasize the relevance of agnostic life-detection strategies in the search for life as we know it, and do not know it.