Experimental RNA evolution

The recent ability to select functional RNA molecules through combinatorial chemistry has ignited exobiological research by offering a set of tools for testing early theories of RNA evolution without the need for organisms. This process can retrieve molecules present in as few as one in 1 x 10(15) sequences, which suggests that careful design may allow 'resuscitation' of active RNA molecules that have been 'extinct' for over three billion years, if they ever 'lived' at all. These experiments now provide a wonderful setting for exploring the basic process of evolution at its most fundamental level - a single molecule - as well as providing a window onto the set of building blocks and constraints that would have defined many events in prebiotic evolution.