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It's Not the "Complexity"

Cosmologist Paul Davies writes in The Guardian about the mystery of life's origin, in a way that is absolutely pregnant with implications.

One of the clich�s popular with journalists who try to explain intelligent design to their readers holds that ID is all about how life is "too complex" to have originated or evolved without direction from some source of intelligence. As Davies points out, though, it's not the complexity of life that really sets it apart but rather the information content. He observes that while it's been mainly chemists who have done research into trying to explain how life came about, chemistry itself is hopelessly inadequate as a framework for understanding what happened. It's not the chemistry but the information -- specifically the direction of information flow and the digitalization of information -- that is really vital.

Most research into life's murky origin has been carried out by chemists. They've 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.

But 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 organisation. 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.

Between biology, which is the study of infused information, and chemistry there is a basic disconnect. Or in Davies's expression, a fundamental "discontinuity." More:
Information theory has been extensively applied to biological systems at many levels from genomes to ecosystems, 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 organisation of information flow.

Sara Walker, a NASA astrobiologist working at Arizona State University, and I have proposed that the significant property of biological information is not its complexity, great though that may be, but the way it is organised hierarchically. In all physical systems there is a flow of information from the bottom upwards, in the sense that the components of a system serve to determine how the system as a whole behaves. Thus if a meteorologist wants to predict the weather, he may start with local information, such as temperature and air pressure, taken at various locations, and calculate how the weather system as a whole will move and change. In living organisms, this pattern of bottom-up information flow mingles with the inverse -- top-down information flow -- so that what happens at the local level can depend on the global environment, as well as vice versa.

Life as software, as an infusion of information. Much of this will be familiar to readers of Stephen Meyer's Signature in the Cell. Something that strikes me in Davies's description is the suddenness of the transformation in matter that made life spring into existence.
Walker and I propose that the key transition on the road to life occurred when top-down information flow first predominated. Based on simple mathematical models, we think it may have happened suddenly, analogously to a heated gas abruptly bursting into flame.
On top of this there is "the transition from analogue to digital," which it's also hard to see occurring other than suddenly, as in the analogy to "heated gas abruptly bursting into flame." All this was involved in the quantum leap from chemistry to biology. Let there be light. Let there be life. What does that sound like to you?