July 27, 2007 | David F. Coppedge

Origin of Life: Speculation vs. Evidence

The European Astrobiology Magazine reviewed a book1 that tries to give “detailed scrutiny” the problem of “the transition from small, simple molecules to large, complex cells.”  The initial reaction by reviewer Toby Murcott points out glaring problems in origin of life research: uncertainty, lack of consensus, and lack of evidence:

What hits you immediately about this subject is the large amount of uncertainty and the many different possible scenarios.  Concerning the transition from prebiotic chemistry to life, there is no clear evidence of chronology.  There are many different pathways from pre-biotic soup to living organisms, and numerous possible intermediate stages with any number of complex organic and biochemical reactions en route.  It’s also clear that the biochemicals of today may have performed very different functions in the past.  For example, the majority of chemical reactions are today mediated by protein enzymes but some indications from biology suggest that RNA was widely used as a catalyst during early chemical evolution.

The tone of uncertainty was not mitigated by evidence in the article.  The word perhaps appeared 4 times, possible twice and impossible to say once, scenario four times, uncertainty twice, may and might a dozen times.  We know that today’s organisms rely on proteins, amino acids, fats and sugars, “But just what happened and in what order is a matter of much debate and likely to remain so for some time.”
    Specifically, “Three different scenarios for chemical evolution are discussed in the review; co-evolution; self-replicating peptides and the RNA world.”  How did these three fare?  About the co-evolution scenario, “It is the simplest of the models, requiring perhaps the least detailed explanation but it is not a particularly satisfying description.”  For self-replicating peptides, “There is, as yet, no convincing rationale for this transition and what’s more, there is no hint of PNA in any modern organism,” the reviewers said, adding this speculation: “While that does not rule it out, both biochemical and Darwinian evolution are expected to leave detectable traces of their heritage behind.
    That leaves the RNA world by default.  It gets the most attention, but a key step is a big hurdle: “However, an efficient prebiotic pathway for nucleotide synthesis remains to be found.”  In short, origin-of-life research is big on speculation and short on evidence.  Maybe astrobiology could help, Murcott said in conclusion, by actually finding some exotic life somewhere someday:

This book covers every element of the evolution of life from the emergence of simple organic molecules to theories on how the first cells might have got together.  How did groups of chemicals and their associated reactions become compartmentalised into prototype cells?  What was the involvement of inorganic matrices and, the big one, how did complexity arise from simple origins?  The authors painstakingly pore over the limited evidence and make intelligent, though guarded, speculations as appropriate.  Anyone who is not comfortable with biochemistry might struggle at times but the summaries are less intense and will allow virtually all readers to grasp the concepts and uncertainties.  In describing the problem of how life emerged the authors also illustrate why astrobiology might provide one of the few experimental opportunities to test the hypotheses.

1From Suns to Life: A Chronological Approach to the History of Life on Earth, edited by M. Gargaud et. al. and reprinted from Earth, Moon, and Planets, Vol. 98/1-4, 2006.

It’s all futureware, speculation, smoke and mirrors, bluffing and ignorance.  Don’t let anyone fool you into thinking this is scientific.  The use of scientific instruments does not justify calling this science.  Alchemists used the best instruments available and even came up with many useful techniques for physical chemistry.  Their findings about what did not make gold proved useful when the real science of chemistry supplanted alchemy.  But none of the effort, the experimentation, the writing, or the speculation justified the premise of alchemy at all.  Similarly, astrobiologists and chemical evolutionists are revising experimental methods and learning many things about chemicals while ruling out scenarios that prove hopeless for evolving life.  What remains is a bundle of raw speculation that has not yet been ruled out.  Speculation is not science.  If efforts to confirm the speculation result in some interesting scientific observations on the side, well and good for those observations, but the bundle of speculation itself is indistinguishable from modern alchemy – a fun trip on a dead-end road.  Someone quipped, if you don’t care where you are going, you ain’t lost.  We think people should care.  You may be lost and not know it yet.

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Categories: Origin of Life

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