The Origins of Life on Earth A Retrospective on Ideas

Recent ideas about the origins of life are becoming less parochial. It is no longer taken for granted that the original forms were caricatures of the simpler existing organisms and that the problem, in essence, is to devise means by which proteins, and small molecules of the types which dominate contemporary biochemistry, could have appeared. Possible roles for mineral crystals, tars and gums, either primordial or made by the action of ultraviolet light on components of the original ocean, now receive attention. Although the tendency of organisms to use molecules of only one chiral type can be explained by natural selection operating on small accidental biases, several mechanisms which could have created more general biases have been suggested.