Why life on Mars may help change the paradigm
There has been growing speculation this weekend that NASA has discovered complex organic molecules in the soil of Mars, or perhaps made an even more significant discovery. See this article on space.com. I've asked people around me whether they thought the possible confirmation of microbial life on Mars would be a paradigm-breaking event. The response was mostly on the 'no' camp. This is completely understandable, for scientists have been acknowledging for years that life may be common and widespread in the universe. So why would the discovery of life in a neighboring celestial body break any paradigms? Yet, I think we are missing something here. Below, I will argue that such a discovery would not only be extraordinary, it would also pose difficult questions to our reigning scientific paradigm.
Our culture's mainstream view is that life is a mechanistic phenomenon explainable entirely by the known laws of physics. In other words, life is not a fundamental aspect of nature, but an epiphenomenon of dead matter. There is supposedly nothing to life but the movements of subatomic particles; the same kind of movements behind erosion, crystallization, the weather, etc. As such, life is supposedly no different from erosion or crystallization, except in that metabolism operates a little faster. Biological organisms are supposedly mere 'robots,' entirely analogous to the computer or handheld electronic device you are using to read this. Life supposedly arose by mere chance, through the random collisions of atoms and molecules in a primordial chemical soup on primitive Earth. So the question is: If life were to be discovered in a planet next door, would that raise new and difficult questions for such a mechanistic view of life? I think it would.
Nobody knows today how life could have emerged from dead matter. There are dozens of theories and even more avenues of speculation, but no one has ever managed to create life from dead matter in a laboratory. Therefore, there isn't even proof-of-principle that life could arise from non-life through purely mechanistic means – so-called 'abiogenesis' – let alone proof that abiogenesis actually happened in the remote past. Yet, abiogenesis is essential for the paradigmatic view that life is merely a mechanistic epiphenomenon of physics. Otherwise, the implication would be that there must necessarily be something extra – something fundamental, irreducible – behind the phenomenon of life.
The problem is that not only all the structures absolutely necessary for the processes of life – like metabolism – need to arise together in an organism, but very complicated mechanisms for the replication of all these structures – that is, reproduction – need to arise along with them. Otherwise, life would arise and disappear within one generation. Francis Crick, the Nobel Prize laureate and co-discoverer of DNA, once thought it impossible for the self-replication mechanisms essential to life to arise spontaneously, by chance, from a chemical soup on primitive Earth. He thought the complexity required was just too great. Although Crick later felt that he had been a little too pessimistic in his original assessment, the key point stands: Abiogenesis, if at all possible, is extraordinarily unlikely by pure chance. Anyone willing to disagree with this statement has an enormous burden of justification, worth of a Nobel Prize.
Now, how does all this tie in with our story about the possible discovery of microbial life on Mars? Well, if we were to find independently-arisen life on our immediate cosmic neighbor – right here, next door – the obvious implication would be that the rise of life is a very common occurrence in the cosmos. After all, what are the chances that a hugely unlikely event would happen, independently, twice within the distance between the sun and the asteroid belt? This would make it yet more difficult to defend the notion that life is merely a chance, mechanistic epiphenomenon of matter, for all scenarios behind such notion require exceedingly unlikely circumstances on Earth, let alone on Mars. It would just compound an already excruciatingly difficult problem. As such, if the independent rise of life is indeed a common affair in nature, one would be forced to take seriously the possibility that life isn't merely an epiphenomenon of mechanistic physics, but is itself built into the fabric of nature as a primary, fundamental aspect of the cosmos. This, by any measure, would be a paradigm-breaking notion.
Naturally, a possible way out would be if it could be shown that life on both Mars and Earth had a common origin. This is not unthinkable, for planetary impact could theoretically have thrown life-infested rocks into space, seeding life from one planet into the other. But such scenario would itself be yet another layer of speculation and contrivance necessary in order to argue for the validity of the current paradigm. As it is today, the argument seems to have enough layers of speculation and contrivance already.
This article is, in a way, jumping the gun: There is no official discovery yet of microbial life on Mars. As such, I am just speculating about the implications of possible future developments. Be it as it may, if the independent rise of life can eventually be shown to be commonplace in the universe, it will certainly pose yet more serious challenges to the reigning view that life is but a chance, mechanistic organization of dead matter. For this reason, I believe that a possible announcement in the coming weeks or months may indeed bear significance to the question of whether a new scientific paradigm may be imminently required.
UPDATE 3-Dec-2012 ~19:00h CET: I am watching the live broadcast of the AGU Fall Meeting in San Francisco, where NASA is announcing the much-hyped 'historical discovery on Mars,' as I write this. As most people, I had expected at least a conclusive measurement of various, complex organic compounds in multiple soil samples. Instead, they announced inconclusive trace measurements of very simple carbon compounds, whose origin they can't even determine to be really Mars yet. These results aren't even interesting, for we knew from previous missions that simple organics exist on Mars (as well as in many other places in the solar system). Now, I understand that what a scientist considers amazing is not necessarily what lay people would find even interesting. I also understand that scientists get carried away in their enthusiasm sometimes. But even taking all this into account, I cannot wrap my ahead around why lead investigator John Grotzinger would have described these results as 'one for the history books,' as he did in an earlier interview a few days ago. If the results presented today are all there is, there is just no conceivable reason for Grotzinger's original assessment. He has just been confronted by a journalist about this and his answer was, frankly, more evasive and hollow than political rhetoric. He looks uncomfortable and awkward on that podium. I am at a loss, but will stop here not to get carried away myself into a kind of speculation that I don't like to touch even with a ten-foot pole...
Space.com just released their own update here.