Big questions get big answers. - Francis Crick

The ultimate aim of the modern movement in biology is in fact to explain all biology in terms of physics and chemistry.

An honest man, armed with all the knowledge available to us now, could only state that in some sense, the origin of life appears at the moment to be almost a miracle, so many are the conditions which would have had to have been satisfied to get it going.

Life, as we know it on earth, appears as a synthesis of two macromolecular systems. The proteins, because of their versatility and chemical reactivity, do all the work but are unable to replicate themselves in any simple way. The nucleic acids seem tailor-made for replication but can achieve rather little else compared with the more elaborate and better equipped proteins. RNA and DNA are the dumb blondes of the biomolecular world, fit mainly for reproduction (with a little help from proteins) but of little use for much of the really demanding work. The problem of the origin of life would be a great deal easier to approach if there were only one family of macromolecules, capable of doing both jobs, replication and catalysis, but life as we know it employs two families. This may well be due to the fact that no macromolecule exists which could conveniently carry out both functions, because of the limitations of organic chemistry; because, that is, of the nature of things.