Self-replication of molecular systems is often viewed in the context of information content. Many scientists believe that life began with the spontaneous emergence of biopolymers, such as proteins or RNA, where information is stored in the sequence of chemical units. Experiments mimicking the conditions on Earth billions of years ago have shown how such chemical units, e.g. some of the building blocks of proteins and RNA, could appear spontaneously. Yet, the emergence of proteins or self-replicating RNA molecules remained enigmatic. They have developed a model, suggesting a new route for the origin of life, based on lipid molecules.
Lipids are oily substances, known as chief ingredients of the cell's membranes.
They get readily synthesized under simulated prebiological conditions, and because of their bipartite nature, have the tendency to spontaneously form supramolecular structures made of thousands of molecular units. The model proposed by Lancet and colleagues offers a solution. They surmise that early on, lipid-like compounds existed in a very large diversity of shapes and forms. They show mathematically that under such conditions, lipid assemblies could contain almost as much information as an RNA strand or a protein chain. Information would be stored in the assembly's composition, i.e. in the exact amount of each of its compounds, rather than in a sequence of molecular 'beads' on a string.