The RNA World at Thirty: A Look Back with its Author.

Thirty years ago, molecular biologist Walter Gilbert published his RNA world hypothesis, which posited that early in evolution living systems were composed entirely of RNA. Proposed in the immediate wake of the discovery that certain RNA molecules were capable of catalyzing biological reactions, the hypothesis ascribed both of life's essential functions, namely carrying information and catalysis-respectively, performed by DNA and proteins in most modern life systems-to RNA, which were labeled as ribozymes. In the years since its inception, the RNA world has been greeted with equal parts enthusiasm and opposition from the origins of life research community, of which Gilbert neither was, nor really became, a part. For this special historical issue of the Journal of Molecular Evolution, Gilbert agreed to revisit his hypothesis and share his memories about the theory's origins and his insights into its fate in the years since he first published his idea.