The Lipid World

The continuity of abiotically formed bilayer membraneswith similar structures in contemporary cellular life,and the requirement for microenvironments in whichlarge and small molecules could be compartmentalized, support the idea that amphiphilic boundary structurescontributed to the emergence of life. As an extensionof this notion, we propose here a `Lipid World'scenario as an early evolutionary step in theemergence of cellular life on Earth. This conceptcombines the potential chemical activities of lipidsand other amphiphiles, with their capacity to undergospontaneous self-organization into supramolecularstructures such as micelles and bilayers. Inparticular, the documented chemical rate enhancementswithin lipid assemblies suggest that energy-dependentsynthetic reactions could lead to the growth andincreased abundance of certain amphiphilic assemblies.We further propose that selective processes might acton such assemblies, as suggested by our computersimulations of mutual catalysis among amphiphiles. Asdemonstrated also by other researchers, such mutualcatalysis within random molecular assemblies couldhave led to a primordial homeostatic system displayingrudimentary life-like properties. Taken together,these concepts provide a theoretical framework, andsuggest experimental tests for a Lipid World model forthe origin of life.