Don’t talk to me about life

Prof Steve Jones’s recent column in the Daily Telegraph has a dig at Stephen Hawking’s belief that life, statistically, must exist elsewhere in the Universe. He cites Nick Lane’s biochemical case for the improbability of life arising – indeed, he says it’s unlikely that eukaryotic life exists anywhere else.

In doing so, to my mind he glosses over important points. He makes abiogenesis sound easy – all you need is a membrane containing some inefficiently self-reproducing “small” molecules (easily made from materials falling from space). After that, natural selection has no trouble making the first cells.

He makes bacteria sound easy, too:

However, that earliest existence stagnated for a billion years – and their descendants, today’s bacteria, are still pretty torpid. They went nowhere because they could not generate enough energy to impose a decent dose of order on their internal being.

“Went nowhere” would be a phrase strongly challenged by bacteriologists both in its geographical and evolutionary meanings. Have a look at videos of DNA replication, protein formation, cell division, flagellar function, proton pumps etc, and then you’re informed enough to start bemoaning the lack of decent order in bacteria. For Jones, however, the main sticking point is the transition to eukaryotic life, a process he sees as so unlikely that all the resources of the Universe have failed to achieve it more than once.

This “bacteria easy, animals hard” approach is the same as that taken by Ward and Brownlee in their excellent book Rare Earth, only their emphasis is on the conditions necessary to maintain eukaryotes and allow them to evolve rather than what was necessary to make them in the first place. Jones’s angle is that advanced life itself is an extremely unlikely event. “Unlikely” meaning a one-off freak.

Ever since my youth I’ve been underwhelmed by the celebrated Drake Equation, used to estimate the number of cases of life in the Universe from multiplying a number of parameters together, the values of only one of which is known. This spurious maths enables people to be taken seriously when they say the Universe must be teeming with life. Jones shows how by a no more rigorous process you can arrive at the extreme opposite answer. Good science is guessing an answer somewhere between 1 and infinity, folks.

Jones’s problems also appear diametrically opposed to the concerns of most biologists. The general feeling seems to be that once you’ve got life, eukaryotes or their equivalent will arise by the irrepressibly creative forces of evolution … that is by random variation and differential survival, if these strike you as irrepressible and creative. The real problem is explaining the origin of life in the first place, despite both Jones’s and Ward and Brownlee’s gung-ho attitude to abiogenesis.

Everyone’s united in knocking Steve Meyer’s negative assessment of the state of origins-of-life science, but if there was as much confidence about its plausibility as is claimed, you’d expect a universal consensus in favour of life’s cosmic universality. Even astronomically low probabilities happen at astronomical scales. Cosmologically low odds are what raise doubts, and what are in fact indistinguishable from miracles.

The RNA-world gets tossed around as a solution, despite the inability to make or explain the first necessity – spontaneous generation of genuinely self-replicating RNA, especially at that all-important “simple” scale that decreases the odds to the merely cosmic. “PNG”, posting on a BioLogos thread on “junk DNA” says this  (#67347):

Bob Shapiro said to me 25 years ago that, having worked with RNA for years, he was pretty sure there never was a naked replicating RNA and I’m inclined to agree. RNA is just too unstable for it to work. If there was an RNA world, that RNA was enclosed in and protected by something, so functionally I would say that was a cell of some sort.

It was obviously not Shapiro himself who overtly admitted the need for a cell as the first RNA-life (RNA-life itself being a mere speculation), but PNG’s logic is inescapable and very far removed from Jones’s view of the cell as the culmination of an evolutionary process. So what are the odds for self-replicating RNA, enclosed in a membrance and able to metabolise energy, spontaneously arising? Remember, RNA is the simplest seriously proposed self-replicator, and so the first conceivable subject for natural selection. Before that, everything has to arise by pure chance.

For Eugene Koonin, it is the replication of DNA that is the sticking point, and despite being one of the world leaders in the field he can’t see a mechanism for it to happen short of multi-cosmological odds. I could multiply the more-than-lucky coincidences that seem necessary to explain chirality, the origin of the genetic code and the other early achievements of life. But maybe I’ve shown enough to suggest that there are three levels at which the origin of life both here and elsewhere in the Universe is assessed.

First, one must see in the background “worldview” a scientific “natural origin of life myth”: the basic assumption that we know how life started, but are not quite there yet on the details. At the lowest level within this mythology are the workers who achieve some dubious success in one piece of the jigsaw like this  paper (see Meyer’s critique in Signature in the Cell). They then generalise over-optimistically and suggest that the whole problem is nearly cracked.

Then there are those who, like Bob Shapiro or Eugene Koonin, see the possibilities within their own areas of concern as incalculably slight. In some cases, it seems they assume that everybody else’s areas must be problem-free – some such idea must surely have informed Steve Jones in his any-one-can-make-bacteria argument.

Then at the highest level there are the people like Hawking, Jones, Sagan and the SETI crowd making wild guesses reasoned predictions about the question of the frequency of life across the Universe. For a subject about which absolutely nothing is known, it’s astonishing how many high-profile scientists are prepared to stick their necks out on the matter. I guess it’s easy to stick your neck out if there’s no axe in prospect. Where these people put their vote seems to depend on whether they’re more aware of any of the many sticking points (in which case, life is rare) or whether they’re persuaded by the myth in general (in which case it’s abundant). But with the best will in the world, it’s still science fiction, based on scientific origins myth.

Do you suppose that I could get an article in the Daily Telegraph by presenting my Modern Extraterrestrial Life Synthesis, which states that there is a medium amount of advanced life in the cosmos as a whole. What could be more reasonable?

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About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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