Tuesday, January 24, 2012

Spontaneous combustion! How life began, how life begins.... Part I.

How did life begin?  People who don't find the answer in the Bible often believe they'll find it in Darwin's Origin of Species, but of course Darwin doesn't touch on the origin of life at all.  In fact, he doesn't even explain the origin of species.  But that's a story for another day.

For centuries it was viable to speculate that life arose by spontaneous generation. Stuff in the soil, for example, came together to produce organisms.  Of course, the knowledge at that time did not permit definitive study of the question.  But one example was the apparent spontaneous appearance of maggots in dead meat. Ugh!


However,  in 1784 Lazzaro Spallanzani performed a famous experiment (duplicated below by Ken a few years ago, as he described here) that showed these maggots only arose if the meat was exposed to flies, who laid their tiny, unobserved eggs on it.


The maggots did seem to appear spontaneously, but Spallanzani showed that if gauze were placed over the meat, no maggots (Whew!).  Thus, we needed another explanation, and in the age of science another type of spontaneous generation, Creation of species as individual acts of God, wasn't acceptable either.  Now, anyone who argues for spontaneous generation is gently ushered to the psychological services center.  But the story isn't quite so clear cut!


In our book, The Mermaid's Tale, we point out that people no longer believe in spontaneous generation .... except at the beginning, when organic life sprang spontaneously from inorganic elements.  Of course we were not the first to notice this inconsistency.  In fact, Thomas Mann wrote of it much more eloquently 85 years before we did.

In his beautiful book, The Magic Mountain, Mann tells the story of Hans Castorp, a young naval engineer just embarking on his career.  He pays a visit to his cousin in a TB sanatorium, intending to stay for 3 weeks and then return to work, but he ultimately spends 7 years there.  Being set as it is in a place of illness, where both healing and death are integral parts of life, the book is full of musings about the meaning of life, death, time, work, illness, science, art and much more.

Here's Mann on the origins of life (from the John E Woods translation).
What was life?  No one knew.  No one could pinpoint when it had emerged from nature and struck fire.  Nothing in the realm of life was self-actuated or even poorly actuated from that point on.  And yet life seemed to have actuated itself.  If anything could be said about it, then, it was this: life's structure had to be so highly developed that nothing like it could occur in the inanimate world.  The distance between an amoeba--a pseudopod--and a vertebrate was minor, insignificant in comparison to that between the simplest form of life and inorganic nature, which did not even deserve to be called dead--because death was merely the logical negation of life.  Between life and inanimate nature, however, was a yawning abyss, which research sought in vain to bridge.  people endeavored to close that abyss with theories--it swallowed them whole, and was still not an inch less broad or deep.  In the search for some link, scientists had stooped to the absurdity of hypothesizing living material with no structure, unorganized organisms, which if placed in a solution of protein would grow like crystals in a nutrient solution--whereas, in fact, organic differentiation was simultaneously the prerequisite and expression of all life, and no life-form could be proved that did not owe its existence to propagation by a parent.  What jubilation had greeted the first primal slime fished from the sea's deepest deeps--and what humiliation had followed.  It turned out that they had mistaken a precipitate of gypsum for protoplasm.  But to avoid one miracle (because it would be a miracle for life spontaneously to arise out of and return to the same stuff as inorganic matter), scientists had found it necessary to believe in another: archebiosis, that is, the slow formation of organic life from inorganic matter.  And so they went about inventing transitional and intermediate stages, assuming the existence of organisms lower than any known form, but which themselves were the result of even more primal attempts by nature to create life--attempts that no one would ever see, that were submicroscopic in size, and whose hypothesized formation pre supped a previous synthesis of protein. 
Mann goes on to answer the question of what is life poetically, as warmth produced by instability attempting to preserve form, the existence of that with no inherent ability to exist, and so on.  Mann needs no proof to support his answer, he can simply write it and it's there for as long as we can read.

Scientists, though, still struggle with their assumed transitional forms and submicroscopic particles. We claim not to believe in spontaneous generation, but we accept that it occurred (but only once!) in the primordial soup.  That starting event wasn't an act of God, as deists might claim, but the fluke (spontaneous, not pre-ordained) coming together of the right chemicals, perhaps plus some lightning bolts, to start the reaction that we know today as 'life'.

The idea that this occurred only once is preposterous.  It is far more likely that similar conditions in a similar span of time occurred trillions upon trillions of times within and among ponds, tides, shores, seas, rivers, lakes or wherever the magic soup occurred.  What we mean in science is that all of today's life came from one origin.  It leaves its trace of that single start-up.  More on that in a moment.

If we speculate on whether there are little green men (or even little red bacteria) on Mars, as a way of justifying costly tourist adventures there, then that's an acknowledgment that life arose by spontaneous combustion at least twice even within our own solar system!  (Unless of course we believe it was seeded on Earth by a meteor from Mars.) And if, as we discussed in previous posts on life in the universe, there are billions of habitable planets, even just thinking of earth-like life, then spontaneous generation of life is a downright everyday occurrence.  And if one thinks there are nearly infinitely many such planets, spontaneous generation is necessarily occurring somewhere, right this very minute (can you feel it?)!

So, it's not mysticism of any kind to argue for spontaneous generation.  And can we say that it is not still occurring, even here on earth?  One would have to rule out any possibility of the same chemical ingredients being present in right amounts anywhere on earth.  That seems at least somewhat unlikely (though, we think it is widely thought  that the actual origin of life was in an earth with oxygen-free atmosphere, so the question isn't so simple, and perhaps it's not occurring anywhere here any longer).

How can we as scientists deny, much less denigrate, Creationism if we then in our next breath, adopt  Darwin's final metaphor in the Origin, say that life was breathed into an otherwise inanimate earth?  The answer is simple, and relates to what is spontaneously being generated, and to the nature of life not just as a chemical phenomenon, but as a polymer phenomenon, as we described in earlier posts.  In part II of this short series, we'll elaborate.

2 comments:

Torbjörn Larsson, OM said...

As a part time student of astrobiology I find this a curious post. It sets up strawmen only to knock them down or in some cases not, so consistently as it seems like tropes rather than descriptions.

Just for the record, spontaneous generation has been duly rejected. Instead astrobiologists recognize the ubiquiteness of chemical evolution, which can't exactly repeat generation of worms. (I assume that is what the next post will describe.)

And the transition from chemical to biological evolution is rarely if at all claimed to have happened once. In fact I believe already Darwin, who speculated in a "warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. present", recognized that " "at the present day such matter would be instantly devoured or absorbed".

Darwin left the question of universal common ancestry open, because at that time it couldn't be tested as it has been today (common genetic machinery, say). Even so, most astrobiologists recognize that many early abiogenesis attempts were likely to have happened before or during the one or ones that alone or mutually combined to originate our established UCA.

Ken Weiss said...

If I understand your comment, there are no straw men, tropes, or disagreements, really. Spontaneous generation is life emerging where there was no life. We were attempting a bit of humor in this post.

Modern science would argue as you have, that this is strictly a chemical phenomenon arising whenever the right combination of molecules, energy, etc. are present.

Many religious groups ('deists' for example) have argued that God started everything and let it thereafter run its course.

Nobody nowadays thinks that ready-made organized life arises spontaneously, as it was speculated for a long time, in the past, was the case. And I agree that any new rudimentary life would be absorbed, assuming it were the same kind of life we're made of. And I've said elsewhere if not also in this series that the idea of a single location for life's terrestrial origin (ponds and pools).

As to what Darwin said, I'd have to go back and check.