Thu, Jan 17, 2013 - Page 9 News List

Chemistry alone cannot explain the origin of life

By Paul Davies  /  The Guardian

The origin of life is one of the great outstanding mysteries of science. How did a non-living mixture of molecules transform themselves into a living organism? What sort of mechanism might be responsible?

A century and a half ago, Charles Darwin produced a convincing explanation for how life on Earth evolved from simple microbes to the complexity of the biosphere today, but he pointedly left out how life got started in the first place. “One might as well speculate about the origin of matter,” he said.

However, that did not stop generations of scientists from investigating the puzzle.

The problem is, whatever took place happened billions of years ago, and all traces long ago vanished — indeed, we may never have a blow-by-blow account of the process. Nevertheless we may still be able to answer the simpler question of whether life’s origin was a freak series of events that happened only once, or an almost inevitable outcome of intrinsically life-friendly laws. On that answer hinges the question of whether we are alone in the universe.

Most research into life’s murky origin has been carried out by chemists. They have tried a variety of approaches in their attempts to recreate the first steps on the road to life, but little progress has been made. Perhaps that is no surprise, given life’s stupendous complexity. Even the simplest bacterium is incomparably more complicated than any chemical brew ever studied.

However, a more fundamental obstacle stands in the way of attempts to cook up life in the chemistry lab. The language of chemistry simply does not mesh with that of biology. Chemistry is about substances and how they react, whereas biology appeals to concepts such as information and organization. Informational narratives permeate biology.

DNA is described as a genetic “database,” containing “instructions” on how to build an organism. The genetic “code” has to be “transcribed” and “translated” before it can act. And so on. If we cast the problem of life’s origin in computer jargon, attempts at chemical synthesis focus exclusively on the hardware — the chemical substrate of life — but ignore the software — the informational aspect. To explain how life began we need to understand how its unique management of information came about.

In the 1940s, the mathematician John von Neumann compared life to a mechanical constructor, and set out the logical structure required for a self-reproducing automaton to replicate both its hardware and software.

However, Von Neumann’s analysis remained a theoretical curiosity. Now a new perspective has emerged from the work of engineers, mathematicians and computer scientists, studying the way in which information flows through complex systems such as communication networks with feedback loops, logic modules and control processes. What is clear from their work is that the dynamics of information flow displays generic features that are independent of the specific hardware supporting the information.

Information theory has been extensively applied to biological systems at many levels, but rarely to the problem of how life actually began. Doing so opens up an entirely new perspective on the problem. Rather than the answer being buried in some baffling chemical transformation, the key to life’s origin lies instead with a transformation in the organization of information flow.

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