Has Platts solved this problem? Hazen would like to think so, but he's far too cautious to say anything definitive. On a flight back to Washington after a scientific conference in Italy to commemorate the 50th anniversary of Stanley Miller's experiment, Platts began to scribble ideas on his airplane ticket. 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."

If this isn't how life began, Hazen argues, then it's probably the kind of guess that moves us in the right direction. In the end, he suspects that the dichotomy between metabolism and genetics is as misleading as that between life and non-life. Hazen admires the chemical plausibility and conceptual simplicity of Platts' hypothesis, but more important, it points toward the possibility that a crude genetic molecule and a crude metabolic cycle could have developed jointly, with evolution rapidly favoring those molecules that protected their genetic code better and metabolized more efficiently. On Platts' primordial earth, one could argue, every scientist gets a piece of the action, and none of the hypotheses propounded ("clay life" perhaps excepted) is completely wrong.

What makes Hazen's scientific cum philosophical theorizing so appetizing, especially to humanities-based readers like myself, is his refusal of dogmatic opposition and his desire to encompass apparently opposing positions. Along with his wholehearted embrace of emergence, with its faintly squishy odor, this may not endear him to hard-science types less eager to leaven the biochemistry lecture with God or Napa Valley cabernet or scientific sexism or Chaucer or the other peripheral issues Hazen drags in from time to time. Like most readers of this book, I don't have any real idea whether Hazen is right that life is emerging all around us, in a faintly deistic universe pregnant with immanent possibility. But given the time and place of this book's publication, it sure is nice to think so.

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