Wednesday, 30 May 2012

The Myth of Abiogenesis

     In discussions or debates about the development of life on Earth, I often hear a remark from the evolutionist side that "Evolution doesn't tell us how life began; it just explains how it evolves from simpler to more complex forms," or words to that effect. I suspect this is an attempt to be conciliatory, by leaving room for the creationists to attribute the first living thing to God.

     It's a nice sentiment, I suppose, but flawed in two ways. First, it's not going to satisfy the creationist who takes issue with evolution in the first place, since such creationists generally want to insist on a literal Biblical account. But second, it's just not true. It turns out that Darwin's principle of natural selection actually does account for the origins of life itself. Not the precise molecular details, of course, but a broad outline of the principle involved. 

     To explain, I first need to ask you to set aside a distinction that doesn't really exist: that between living and non-living material. Now, it seems obvious that there is a difference, and on the scale that we interact with the world, it's a practical distinction to make, but on the scale of molecules, there's just molecules, and no difference between a living or a dead one. A water molecule in my blood is no different from one my my coffee, or one in the cloud I see through my kitchen door as I type this. Likewise more complex organic molecules like proteins and DNA: they're just molecules, ordinary, non-living matter.

     I should also make explicit what the theory of natural selection is all about, at its most basic, abstract level. It's about replication of information patterns, and which patterns will tend to become more common over time.  Natural selection is often expressed as a principle governing what happens when three basic assumptions are true. Those assumptions are as follows:

     (1) There is variation among a population, and those variations affect the likelihood of the individual successfully reproducing.
     (2) Offspring tend to resemble their parent(s).
     (3) More offspring are produced than can survive to adulthood and reproduce themselves.

     This is expressed in terms that assume we're already dealing with living creatures (which isn't surprising, because the theory is almost exclusively used for understanding biological phenomena), but as a Law of Nature, natural selection applies all the time to everything everywhere, and makes no distinction whatsoever between "living" and "nonliving" matter. So just bear in mind that the words "parent" and "offspring" should be understood more as "original" and "copy". What's really being copied with each generation is an information pattern, and subsequent generations are simply copies of copies of copies.

     Now, there are also two concepts concerning replication of patterns we need to be aware of: fecundity and fidelity. Fecundity relates to the number of copies made; a highly fecund creature will have lots and lots of babies. Fidelity relates to the accuracy of the copy, how closely it resembles the original. A duplicate with very high fidelity will be almost identical to the original, while one with very low fidelity might not even be recognized as a copy at all.

     Patterns of information exist in everything, although most of the time we'll not recognize them as particularly useful information, just random arrangements of things. Patterns also give rise to subsequent patterns all the time, simply by the operation of the laws of nature. A pattern characterized by lots of water molecules in clouds may lead to a pattern of liquid water droplets falling as rain, leading to a pattern where water molecules are arranged as standing or flowing water on the ground, and so on.
     This process, of patterns producing new patterns, is in fact a kind of replication. It's just that the value for fidelity tends to be very, very low; almost none of the original pattern of information is recognizable in the offspring. But not always. In fact, patterns are duplicated with surprisingly high fidelity quite naturally, and in ways that we don't often think of as replication. For example, a shadow of a mountain is actually a rather high-fidelity replication of the profile of the mountain itself from a particular perspective. Layers of ocean sediments record climate patterns over time, and so on. In most of these cases, the fecundity of the next generation is very low, however; there are few ways for a shadow to copy itself.

     But there are ways for simple, non-biological patterns to duplicate with both fidelity and fecundity. Consider a rock cleaving in two. The two newly exposed surfaces will have all sorts of random bumps and pits, but they will correspond to each other almost exactly so you can fit the two pieces back together perfectly. Each piece contains a very high fidelity copy of the inverse of the contours of the other piece, and if you were to press one half into some clay, the imprint left would be a pretty good copy of the other half. What's more, you'd be able to reuse the stone to make more copies. So both fidelity and fecundity are well above zero for this process. One can easily imagine, without any human intervention at all, scenarios where a pattern like this is duplicated many times. A rock, rolling down a hill, leaving multiple impressions of itself in the soft earth along its path.

     This process of cleaving to produce mirror-image duplicates can happen on a molecular level, as well. In fact, DNA is very much like the cleaving rock. Each side of the double helix is a sort of inverse copy of the other side. We know very little about how the first DNA molecule came to be, but we do not need to know the precise pathway to see that natural selection would be at play every step of the way. Any pattern of information that, when encoded into matter in some way happens to increase the fecundity and fidelity of the subsequent generation of patterns, will tend to become more common over time. It need not be particularly high in fidelity or fecundity to begin with; it merely needs to be slightly better than the other patterns around it. Its own copies will tend to vary as well (a lot, if the fidelity is low), but whichever pattern has the highest fidelity/fecundity will eventually win out.

     So there is, was, and always will be a natural selection pressure operating in the universe on all matter in every form everywhere, tending to select for higher fecundity and fidelity. In most places, there's not a lot of potential for other, but in some places, particularly planets with rich chemistry and just the right temperature range, there will be enough random patterns that some crystal, some organic polymer, or some other chemical reaction will have a fecundity/fidelity advantage. And that's all it takes to get started. The molecule that is just slightly better at preserving its information by copying will become more common than the next, and over time, ever more sophisticated systems of molecules will accumulate more and better ways to improve fidelity and fecundity.
     There is no point at which the spark of life suddenly appears and matter becomes living, no point at which maggots spontaneously appear in rotten flesh. Every organism, every pattern of matter arises as the result of some previous pattern of matter that it resembles in some way, which in turn arose from an earlier arrangement of matter, and so on back to the beginning of time.


  1. There's one major problem with your model: when a chemical reaction occurs, producing a DNA base, that's not reproduction with low fidelity. There's a reason chemists don't think like that. The fecundity of gases like methane "reproducing" themselves (into something like adenine no less) is so low that methane is not thought of as reproducing itself.

    There's a another problem. "Any pattern of information that, when encoded into matter in some way happens to increase the fecundity and fidelity of the subsequent generation of patterns, will tend to become more common over time." It would be easy to develop a model where fecundity is be favoured by selective mechanisms, but not fidelity. Selection against fidelity is more reasonable if the original is not a very viable prototype. Considering all the permutations of the DNA letters in even the "simplest" bacteria, the argument for selection in favour of fecundity is dubious.

    Finally, you haven't dealt with a mechanism of reproduction. Splitting a rock or having it tumble down a mountain are highly plausible within naturalistic assumptions; DNA or even RNA reproducing itself is not. If your model of abiogenesis is "everything replicates itself, albeit with low fecundity or fidelity, and these two variables were favoured by selection", it would be necessary at some point to establish a replicating mechanism apart from self-replication.

    If course, if you want to ignore scientific findings, you have your case. Evolutionists have been doing that for over a century - the contradiction between entropy and polymerization, the chirality problem, and the one I mentioned, the replicator-DNA chicken-and-egg, are plenty of evidence against the very possibility of abiogenesis.

  2. Thank you for your comment. I'll respond to your paragraphs in order.

    First, my point is rather abstract, and I'm not talking specifically about methane reproducing. I'm talking about instances of patterns of information becoming more common by ANY means, as the example of the mountain's shadow. So I'm not referring simply to methane mutating into adenine, but more broadly to patterns which in any way influence the likelihood of being "echoed".

    Second, with respect to selection pressures for fecundity and fidelity, fidelity is by far the stronger pressure, especially over multiple generations. Most low-fidelity copies simply won't be improvements, and those that are will benefit from higher fidelity copying to preserve the improvement. Of course, the pattern that has both high fidelity AND fecundity will be even better off.

    Third, I didn't deal with a mechanism of reproduction because I don't have one, but that wasn't my purpose here. My point was not to explain precisely how we ended up with DNA replicators, but to show how natural selection tends to favour ANY kind of configuration of matter that happened to have a higher probability of replication. Yes, DNA as it currently operates is a highly sophisticated replicator, but that system has had three billion years of refinement. Nobody knows what the earlier versions of the system looked like.

    Finally, on ignoring scientific findings: Er, no. These problems have not been ignored by evolutionists. Ilya Prigogine won the Nobel Prize for his work on entropy and self-organizing structures. Chirality isn't a major problem because one of the two alternatives will eventually become established as the universal standard, and it can be arbitrary which one. And as for the chicken-and-egg thing, I'm actually denying abiogenesis as a meaningful concept. That is, I'm saying that evolution's been happening since the Big Bang, that there's no meaningful distinction between living and non-living matter when you get down to the molecular level where it all happens.