The late Leslie Orgel, a pioneering researcher in pre-biotic evolution, has an interesting essay in the most recent issue of PLoS Biology. A long-running debate in origins-of-life research has been over what came first: genetic material, or a self-organizing metabolism.

The self-organizing metabolism theory has been most prominently argued by Stuart Kauffman. Orgel doesn't rebut Kauffman's theoretical work, but he does claim it makes unrealistic assumptions about peptide chemistry, and thus is unlikely to be what happened on earth 4 billion years ago.

Orgel makes some reasonable arguments, but what is really needed is more experimental work to figure out just how plausible this self-organizing metabolism idea really is.