How the unique properties of life originated from inert matter is still one of the great unsolved problems of biology. Creationists, of course, claim that our failure to solve it means that God did it: as Ingersoll noted in yesterday's quote, "Our ignorance is God; what we know is science."
And perhaps we'll never know precisely how life began, for it happened in the distant past and involved chemical reactions that could not fossilize. But I have confidence in three things: life originated naturally and not through God's fiat; that we will show that this was possible within 50 years or so by demonstrating the evolution of life-like systems in the laboratory under primitive Earth conditions; and that while life may have originated more than once, all living species descended from only a single proto-organism (lots of evidence for that one). If we can demonstrate the origin of life in the lab through realistic experiments, then—although we may not know how it really happened several billion years ago—we can say that it could have happened naturally, and therefore we need not invoke God.
Paul Davies is an astrophysicist who spends a lot of time promoting the comity between science and faith, and who won the Templeton Prize in 1995. As Wikipedia notes:
An opinion piece published in the New York Times,[2] generated controversy over its exploration of the role of faith in scientific inquiry. Davies argued that the faith scientists have in the immutability of physical laws has origins in Christian theology, and that the claim that science is "free of faith" is "manifestly bogus."[2] The Edge Foundation presented a criticism of Davies' article written by Jerry Coyne, Nathan Myhrvold, Lawrence Krauss, Scott Atran, Sean Carroll, Jeremy Bernstein, PZ Myers, Lee Smolin, John Horgan, Alan Sokal and a response by Davies beginning I was dismayed at how many of my detractors completely misunderstood what I had written. Indeed, their responses bore the hallmarks of a superficial knee-jerk reaction to the sight of the words "science" and "faith" juxtaposed.[3] While atheists Richard Dawkins[4] and Victor J. Stenger[5] have criticised Davies' public stance on science and religion, others including the John Templeton Foundation, have praised his work.
I've written about Davies' accommodationism several times on this site; one example, in which he finds God in quantum mechanics, is here (see also his 2007 New York Times article asserting that science rests on faith.) But, to give him credit, Davies is also something of a polymath, and has an interest not just in physics, but in the early Ediacaran fauna and especially in the origin of life ("abiogenesis"). He's apparently done technical work on the last issue, which I must confess I haven't read (the literature on abiogenesis is huge). But in yesterday's Guardian, Davies summarizes his work in a piece called "The secret of life won't be cooked up in a chemistry lab."
His basic claim is that science hasn't solved the origin-of-life problem because it's been left largely in the hands of chemists, and from-the-ground-up reductionist chemistry is not the way to solve it:
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.
Well, he doesn't mention that many biologists and biochemists have also worked on the problem, including Stanley Miller, Gerald Joyce, and Nobel Laureate Jack Szostak. But never mind. Davies goes on to say that the fundamental problem is not in the purview of chemistry, but in how biological information gets organized hierarchically:
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.
. . . 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.
. . . 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.
Now I have to say that this is either way above my pay grade, is too abstruse for the general public, or is simply wrong. And I'll take a chance here and say that the problem is not going to be solved using information theory or "top down" considerations. Yes, of course the environment played a role in the origin of life, but that doesn't mean that we can't take a reductionist approach. (As an example of "top down" control, Davies uses the fact that genes can be turned on by environmental factors, but of course that area of research progressed purely through reductionism, not through incorporating "environmental information theory.") To me, the problem of abiogenesis involves taking a set of original molecules that didn't contain any information for a replicator, and then figure out what kind of processes enabled them to gain the ability to replicate. Along with that is the formidable problem of how the replicator became connected with a phenotype, in other words, how that replicator evolved to produce proteins and cells—and that is information. All this can, I think, be attacked without any importation of "information theory" from the beginning. Information is a consequence of, rather than an a priori requirement for, understanding abiogenesis.
In fact I don't know what Davies is suggesting here, and maybe his technical work has insights that are fruitful. The Guardian article, though, is simply opaque, and there are hints from other work that Davies' approach may not be fruitful.
One of these is a new book by chemist Addy Pross, What is Life? How Chemistry Becomes Biology. (The title, of course, is borrowed from Erwin Schrödinger's famous book that had such a huge influence on the pioneers of molecular genetics.)
I have just received this book and have only glanced through it, but it's a short volume describing the latest thought on the origin of life, and Pross's own speculations on how it started. And it's pure chemistry: no information theory needed. It does, in fact, what Davies says hasn't been done: meshing the language of chemistry with that of biology.
I'm told by those who have read it that Pross has an intriguing and possibly correct idea about how a population of molecules can, through a process of biochemical natural selection, become replicators that get hitched to metabolism. The "information" of life then is a result of the process, not something that, as Davies asserts, needs be modeled in from the beginning. As Pross notes on p. 152:
A moment's thought suggests therefore that the term "information" in its biological context is just "specific catalysis" when considered in a chemical context.
I'll be reading this book in the next month or so, and will report back, but I wanted to say four things now:
1. If you're interested in the origin of life, read Pross's book.
2. I suspect that Davis is wrong and that the reductionist approach, based on chemistry, is the way to solve the problem of life's origin.
3. But I may be wrong, too, and somehow, in ways I don't understand "top down information flow"—whatever that means—may be the key to the problem. But if the history of science is any guide, the problem will yield to chemists starting with a population of molecules existing under realistic early-Earth conditions.
4. The Guardian article is completely opaque to the nonscientific reader (indeed, to me as well), and seems more like p.r. for Davies' work than a genuine attempt to explain to the layperson how life might have originated.
h/t: Michael
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