The mechanism is chance. As I understand the article these are selection experiments which you can think of as fast evolution in a laboratory setting. I tried t

The mechanism is chance. As I understand the article these are selection experiments which you can think of as fast evolution in a laboratory setting. I tried to find a good reference for you but this was the best I could find [1]. Essentially they start with a large randomized pool of RNA molecules. They are then able to select out the catalytic RNAs through some process possibly involving a column. At first the number of RNA molecules that exhibit catalytic behavior is infinitesimal. But through PCR they are able to iteratively amplify each generation for the qualities they are looking for, in this case catalytic behavior. At the end of a few generations you have a pool of RNA molecules that exhibit the behavior you want. [1] http://www.lcg.unam.mx/frontiers/files/frontiers/Tuerk%20and%20Gold%201990.pdf http://www.lcg.unam.mx/frontiers/files/frontiers/Tuerk%20and...