Preface/Front Matter

Abstract

This book invokes a prebiotic RNA world that existed some 3.8 billion years ago, only 50 times more ancient than the dinosaur era. The essence of this RNA world was RNA-catalyzed replication, which ultimately gave rise to the predecessor of the DNA-based organisms of modern life.

The notion that prebiotic evolution absolutely depended on RNA replication has intrigued many since the early suggestions by Woese, Orgel, and Crick. Those of us with interests in the current function of RNA were especially fascinated as we, of course, hoped that RNA was the pivotal molecule. However, no one predicted the richness of apparent "relics" from the RNA world that have been discovered in present-day organisms. In fact, the overwhelming stimulus for the new wave of interest in the RNA world comes from discoveries of catalytic functions and structural diversity among contemporary RNAs. Experiments with catalytic RNAs reveal the potential for RNA to possess the plasticity of functions needed for complex evolution — functions which could have resulted in the “breakthrough organism” that was the predecessor of all life. The plasticity of RNA is critically dependent on 2′-hydroxyl groups; it is remarkable that this distinction between RNA and DNA can so dramatically influence versatility of function.

New technologies allow iterative selective examination of large numbers of RNA sequence variants with altered binding properties, novel catalytic activities, or perhaps even replicating functions, opening the door to real-time exploration of RNA molecular evolution. If the current rate of experimental progress continues, we anticipate, in the near