The Multitude of Abiotic Membranes: Selection and the Transition to Biological Membranes

The origin of biological membranes remains a fundamental unresolved problem in the transition from abiotic chemistry to cellular life. Although amphiphilic self-assembly can generate micelles, vesicles, and other supramolecular structures, membrane formation alone does not explain the emergence of functionally integrated and heritable cellular compartments. This review introduces the Abiotic Membrane Selection Principle (AMSP), a proposed mathematical and physicochemical framework in which biological membranes could have emerged through selection among numerous chemically distinct abiotic membrane populations rather than through the progressive evolution of one uniquely favorable lipid architecture. The model assumes the availability of chemically diverse amphiphiles, environmentally dependent self-assembly, differential molecular persistence, and the possibility of functional interactions between membrane composition and internal chemical networks. Representative sulfur-containing, sulfated, sulfonated, borate-associated, glycolipid, and ether-linked molecular architectures illustrate the potential diversity of primitive membrane systems. Combinatorial calculations demonstrate that nine amphiphilic components can generate 43,758 distinct compositions at 10 mol% increments and 3,108,105 compositions at 5 mol% increments, although only a subset may be physically capable of forming membranes. The proposed mathematical framework integrates thermodynamic mixing, membrane curvature, chemical stability, selective permeability, electrostatic properties, environmental robustness, growth, and compositional continuity into a multidimensional membrane-suitability landscape. Particular emphasis is placed on competing functional requirements, including the permeability–retention dilemma, the relationship between membrane persistence and chemical productivity, and the possibility of multiple environmentally dependent optimal compositions. Mathematical models further examine how environmental cycling, differential molecular retention, and reciprocal membrane–reaction network coupling could generate compositional memory and potentially support primitive heredity. The transition toward biological membranes is interpreted as a hypothetical process of progressive functional integration, eventually involving genetically regulated lipid biosynthesis and specialized membrane architectures. Sensitivity analysis, robust optimization, and experimentally falsifiable predictions are proposed to distinguish spontaneous membrane assembly from evolutionarily consequential compartmentalization. The central conclusion is that abiotic membrane diversity may have provided multiple physicochemical pathways toward cellular organization, whereas the emergence of biological membranes required the selection of systems capable of combining structural persistence, selective transport, chemical productivity, and hereditary continuity.