It’s well known that much of the organic material from outer space to reach the prebiotic Earth came in the form of flat, sturdy molecules called polycyclic aromatic hydrocarbons, or PAHs. Platts began to see how PAHs could have been energized by solar radiation and self-assembled into stacks in the ancient ocean. Small, flat amino-acid molecules would begin to stick to the outside of this “stack of plates,” and the whole array would begin to look “for all the world like the information-rich genetic sequence of DNA or RNA.” This would have been nothing more than an intriguing, left-field notion if not for the fact that the space between these PAH layers is 0.34 billionths of a meter, which just happens to be precisely the distance between the ladder-like rungs of a DNA or RNA molecule. Somehow—and Platts doesn’t propose exactly how—this interesting but haphazard assemblage of molecules became a coherent vector of biochemical information, broke free of its PAH host and folded over on itself to become a “true pre-RNA genetic molecule.”
Andrew O’Hehir writes about Robert M. Hazen’s book Genesis: The Scientific Quest for Life’s Origins.