The RNA World

In his letter to the editor, Howard Deutsch writes that he has never heard anyone claim or conjecture that “ribonucleic acids were the first molecules of life” (C&EN, May 14, page 5). In fact, this idea has a very long history in the literature regarding the origin of life, and the idea has driven considerable experimental research in the field since the 1960s. A complete citation list would fill several pages, but see, for example, Leslie E. Orgel’s 1968 “Evolution of the Genetic Apparatus” (J. Mol. Biol., DOI: 10.1016/0022-2836(68)90393-8) and Francis H. C. Crick’s 1968 “The Origin of the Genetic Code” (J. Mol. Biol., DOI: 10.1016/0022-2836(68)90392-6).

The RNA World model is based on observations of modern biochemistry and the central role of RNA in translation. In its “weak” form, the RNA World model suggests that RNA came before DNA as an informational storage molecule; in its “strong” form, the model suggests that RNA was the original, evolvable, self-replicating form of life.

As there have proven to be numerous experimental difficulties with the prebiotic synthesis of RNA, it has been postulated that a simpler or simply different nucleic acid-like replicator preceded RNA during evolution (Proc. Natl. Acad. Sci. USA1987, 84, 4398; and Cleaves, H. J. and J. L. Bada, “The prebiotic chemistry of alternative nucleic acids,” in “Genesis: Origin of Life on Earth and Planets,” J. Seckbach and R. Gordon, editors, Berlin: Springer, in press).

The work described in this article does indeed inform research into these topics.

Although some hold that since the origin of life is a historical event that no one was around to witness, nothing regarding it can ever be proven. The creation of a novel living system in the laboratory would certainly be a remarkable scientific accomplishment.

Keep up the good work, editors!

By Henderson (Jim) Cleaves
Washington, DC