Friday, September 12, 2008

Origin of life: But is being greedy enough?

A recent article in Nature by Katharine Sanderson suggests that "Greedy molecules could be behind the emergence of life" because an "Artificial system shows how a molecular soup could be exploited by a single self-replicating complex."
Douglas Philp, a chemist at the University of St Andrews, UK, has previously shown that a molecule made of two halves that recognise and bind to one another can then act as a template for its own replication1. Along with his colleague Jan Sadownik, he has now discovered that this template molecule can drive its own formation in a bigger pool of many more reactants, quickly taking over the processes in that pool and dominating the system so that almost no other products have a chance to form.

This kind of self-replicating system has been proposed as an explanation to how complex molecules such as DNA could have formed, ultimately triggering the emergence of life. Artificial versions of these systems, however, have remained elusive.
This, Philp says, "... shows that you can bring order from chaos."

Yes you can - but only over a limited range. And the fundamental problem we tend to run into is that further instances of order become astronomically less probable.

For example, if I dump the Scrabble letters, the ones face up can probably form some words. But if I must form a specific sentence - for example, "You better all move your cars because I can see the parking hornet from my window," my chances are very much lower. Origin of life is far more like that than it is like finding some letters that will form words.