A research published in 'Proceedings of the National Academy of Sciences' rejects the theory that the origin of life originated as a system of autocatalytic molecules capable of experimenting Darwinian evolution without the need of replicating RNA or DNA. According to the study, then, life as a system capable of experimenting Darwinian evolution began when it was able to store genetic information and transmit it as it happens with RNA and DNA.
Scientific theories about the origin of life revolve around two main ideas: one, genetics, with RNA or DNA replication as an essential condition for Darwinian evolution to take place, and the second which says that first there was the metabolism. Both situations had to have starts, of course, from simple organic molecules formed by prebiotic processes. The point of disagreement between them is that replication of RNA or DNA molecules is a too complex process which requires a proper combination of monomers in the polymers to produce chains of molecules arising from the replication.
There is even a plausible chemical explanation about how those early processes could have occurred. Proponents of the 'metabolism first' argue that the required evolutionary paths would have needed a primordial metabolism. This network is envisioned as a chemical network that carries a high degree of mutual catalysis amongst its components to allow eventually the adaptation and evolution without molecular replication.
In the study Mauro Santos participated, a researcher at the Department of Genetics and Microlobiology of the Autonomous University of Barcelona (UAB). It concludes through the analysis that some researchers have called 'composite genomes', that these chemical networks cannot be considered evolutionary units because they lose the essential properties for Darwinian evolution when they reach a critical size and greater complexity. The 'composite genomes' are so named because they represent a set of chemical components that store information about its composition, which can be duplicated and transmitted to offsprings.
In other words, from the 'composite genomes', inheritance does not require information to be stored in the RNA or DNA molecules. These, then, seem to meet the conditions required to be considered as units of evolution.
