The Mechanisms of Evolution: Natural Selection and Natural Conventions

The mechanisms of evolution have been one of the most controversial issues in Biology and the great debate about them has culminated, in the 1930s and 1940s, in the Modern Synthesis, the theoretical framework where natural selection is regarded as the sole mechanism of evolutionary change. Here it is shown that a new approach to these great problems is provided by two concepts that are firmly based on the evidence of molecular biology. The first is the idea that all biological objects are artifacts, in the sense that they are manufactured structures. Genes and proteins, for example, are produced by molecular machines that physically stick their subunits together in an order provided by external templates. The second concept is the idea that there are two different ways of producing biological artifacts, two distinct mechanisms that here are referred to as copying and coding. The copying of templates is the process that accounts for heredity and, in the long run, for natural selection. Coding is the process that establishes rules of correspondence between two independent worlds, thus giving origin to natural conventions. Copying and coding account, respectively, for the origins of genes and proteins, i.e. for the first two Major Transitions of the history of life. As for the other transitions, it is generally assumed that natural selection has been their sole mechanism, but here it is proposed that a key role was also played by natural conventions, i.e. by the origin of new organic codes. More precisely, it is proposed that natural selection and natural conventions are complementary mechanisms of evolution, the first accounting for the gradual transformation of existing objects and the second for the origin of absolute novelties. This conclusion is a direct consequence of the difference between copying and coding and of the existence of many organic codes in Nature, a fact for which an increasing amount of evidence has been accumulating in recent years.