It’s Life, Jim, but not as we know it…
Todays post is a welcome return of guest blogger:
Ed Rybicki, Department of Molecular and Cell Biology, University of Cape Town, South Africa.
It’s Life, Jim, but not as we know it…
Which could well apply to viruses, my very own favourite organisms – after all, they don’t respire, grow, excrete or any of those other good things that classical organisms supposedly do – but that’s not the point of this piece. Rather, I’d like to speculate on an interesting convergence of articles I’ve seen recently, on (1) extrasolar planets, (2) water on same, and (3) the possibility of novel lifeforms. Some of this is an accident of the irregular timing of receipt of my New Scientist and Nature subscriptions, but serendipity has played a large role in my life and will doubtless continue to do so.
It is amazing that, just a few years ago, the concept of planets outside of our own solar system was still a matter for debate – now we know of more than 200 of these, with an exponentially increasing number being discovered each month. Of course, most of these are weird: the very way we look for them guarantees that, with big objects very close to their parent stars being the most easily findable. Even so, we are down to about five Earth masses as the lowest yet described, and one of the newest has water – albeit as water vapour at a temperature of over 500oC. Extrapolating from there to smaller planets with liquid water gives you…well, us, or a reasonable facsimile, galactically speaking. And given the fact that we have found so many planets in such a short time of looking augurs well for there being uncounted millions of them, in our galaxy alone – and many would look like ours.
Meaning that there would be a very good chance of similar chemistries having a similar chance of ascending the scale of negative entropy to give…well, nothing like us, probably, but quite possibly carbon-based lifeforms, dependent on water as a solvent, with some form of information storage which allows replication of itself and its accompanying phenotype. It is also highly likely that there, as here, microbiology would precede and dominate macrobiology, and single-celled or single-unit lifeforms would predominate in the biosphere. It is also quite possible that Earth itself was seeded by bacteria from Mars, given that that planet cooled down quicker than ours, had a similar early chemistry and therefore potential to develop life, and that Earth and Mars have regularly exchanged pieces of their surfaces following asteroid impacts. For the same reason, there could well be familiar sorts of organisms on Europa and other Jovian and Saturnian moons with liquid water beneath thick ice cover.
Indeed, some have speculated that there may even be more than one type of life on Earth (of course there is; viruses and everything else B-) and that we may simply have missed the other types because we don’t know what to look for yet. In fact, so-called nanobacteria could well be another type of life, for all that Alan C doesn’t like them… B-)
But why stop there? The New Scientist issue of 9th June has a most intriguing picture on its cover, of a sandy humanoid shape rising up through bricks and sand, with the caption “Why life doesn’t need DNA, carbon or water“. A case could be made for silicon-based organisms using liquid ethane or methane as solvents, which would open up all sorts of niches in our own solar system, let alone outside it. The Sirens of Titan could well be real, albeit a little slow and definitely not as we know them.
Anyone who has read any science fiction – and as I tell my classes, if you don’t then you should! – will have seen many examples of what is considered possible in terms of life. Some of the more interesting possibilities are self-aware electronic entities derived from computer programs (see Charles Stross’s “Accelerando!” for a wonderful recent example), and replicating, self-aware clouds of organised plasma.
Which is why I push my definition of life: which is “The phenomenon associated with the replication of self-coding informational systems” © E.P. Rybicki, 1996. Incidentally, I find another person with a Polish name has said something very similar, in 2001 – which means it must be true. Bernard Korzeniewski describes life as: “A network of inferior negative feedbacks subordinated to a superior positive feedback.” Which – um – means the same thing, doesn’t it?
And if there are other forms of life, there will be other forms of viruses…indeed, Steven Hawking is on record as saying that computer viruses can be considered a form of life: they are obligate parasites which exploit the “metabolism” of the host computer they infect, they replicate in the form of their source code [=genome], and they newest and nastiest can mutate while they do so.
Which means that there will be other versions of entities like Alan and I, spending our lives studying the invisible, for little reward other than simple fascination. As that late lamented student of chronosynclastic infundibula would have said, so it goes …
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