Wintery Knight

…integrating Christian faith and knowledge in the public square

Paul Davies: the hard problem of the origin of life is not “complexity” – it’s information

Check out this column on the origin of life from the radically leftist UK Guardian, written by agnostic cosmologist Paul Davies. (The same Paul Davies who is occasionally quoted by William Lane Craig)


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?

[…]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.

[…]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.

[…]The way life manages information involves a logical structure that differs fundamentally from mere complex chemistry. Therefore chemistry alone will not explain life’s origin, any more than a study of silicon, copper and plastic will explain how a computer can execute a program. Our work suggests that the answer will come from taking information seriously as a physical agency, with its own dynamics and causal relationships existing alongside those of the matter that embodies it – and that life’s origin can ultimately be explained by importing the language and concepts of biology into physics and chemistry, rather than the other way round.

The point of me posting this is simple. The thing to be explained in the origin of life is not a cake, where you can jumble ingredients together and get something. The thing to be explained is information. The origin of life is a programming problem, not a cooking problem. Where did the software come from – the first basic program that allowed for the basic functions of life, like self-replication.

Dr. Davies is hoping for a naturalistic solution to the problem, because he is a naturalist. But at least he is clear about specifying the thing that needs to be explained. A lot more clear than the journalists who explain intelligent design as the belief that some things are too complex to have evolved. But that’s wrong. The real question is: where did the information come from?

Filed under: Polemics, , , , , , , , , , , , , , , , , ,

Is the set of 20 amino acids used in living systems finely tuned?

Jonathan has found a gem of a research paper and written about it at Evolution News.

Jonathan explains the question he is addressing:

An interesting research paper was recently published in the Journal Astrobiology by Gayle K. Philip and Stephen J. Freeland, which asks, “Did Evolution Select a Nonrandom Alphabet of Amino Acids?”

The article notes that there exists no strict limitation on the character or type of amino acids which can be used in living systems. Indeed, biology could conceivably have used a different amino acid alphabet, and there appears to be a fairly wide range from which it could have chosen. But is there anything special — is there anything unique or unusual — about the set of 20 amino acids (some organisms use one or two additional amino acids) that life does use? And, if there is, how might this fundamentally non-random contingency be explained?

Is there anything special about the set of 20 amino acids we see in virtually all living systems? There are about 80 of them in total, so why do we see only 20 of them being used?

Jonathan explains why the set of 20 we see in nature is finely-tuned:

The authors compared the coverage of the standard alphabet of 20 amino acids for size, charge, and hydrophobicity with equivalent values calculated for a sample of 1 million alternative sets (each also comprising 20 members) drawn randomly from the pool of 50 plausible prebiotic candidates.

The results?

The authors noted that:

…the standard alphabet exhibits better coverage (i.e., greater breadth and greater evenness) than any random set for each of size, charge, and hydrophobicity, and for all combinations thereof. In other words, within the boundaries of our assumptions, the full set of 20 genetically encoded amino acids matches our hypothesized adaptive criterion relative to anything that chance could have assembled from what was available prebiotically.

In the rest of the article, Jonathan assesses whether chance or law or a combination of chance and law are capable of explaining the selection of this optimized 20-character alphabet naturalistically. He also argues that once we have exhausted the explanatory powers of naturalistic mechanisms, that we are justified in appealing to intelligent causes, since we see intelligent agents choosing things for purposes all the time.

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