Anyone familiar with the RNA World can see why it is so alluring. According to the model, since RNA can serve as both catalysts & genomes, they could have been progenitors to DNA (as carriers of hereditary info) & protein enymes (as organic catalysts in metabolic processes). Indeed RNA does seem to be just about everywhere in modern biochemistry, from polymerases, to retrotransposons; from co-factors (NAD/H, FAD/H, & ATP; the universal energy currency of the cell), to RNA viruses. The sole exception to the rule that all terrestrial life must have a DNA-based genome seems violated for those who consider viruses to be living organisms. Fairly straightforward, right?

Evolution aways generates complexity, according to creationists who adore dragging probability into arguments without consideration for the laws of thermodynamics! Still, this logical flaw precisely illustrates one assumption made by some of the supposed best & brightest in the field about the origins & early evolution of life on Earth. In fact, there is no consensus within the scientific community as to the biochemical nature of the earliest microbes for a very simple reason. Biochemists tend to perceive the intricacies of evolution through the eyes of (of course) biochemistry, so most of what they propose when it comes to the RNA World is based on knowledge gleaned from within their own specialty-- knowledge which only places chemical parameters on whether or not a given molecule could persist under a given set of circumstances. Here, indirect, circumstantial evidence substitutes for direct observation of physical evidence from remnants of that age.

Unlike the highly observant geochemist in his/her element out in the field, biochemistry is remarkably out of touch with the outdoors & often fails to consider the ramifications of building incredible models over shaky foundations which do not reflect the actual environment in which life was supposed to have originated. The result is a deep divide between 2 fields which directly contradict each other. Geochemists have been able to extract a remarkable amount of info from isotopic studies & tiny zircon crystals. Their data is often supported by work conducted by planetary scientists. Together, experts from these 2 fields have been able to arrive at a reasonable approximation of what Earth was like during the Hadean period. The bottom line is simply this: The catalytic capacity of RNA relies heavily on flexibility. That same malleable molecular structure however, makes it extremely fragile in extreme environments like those of Hadean Earth.

So why are biochemists so slow to accept the notion that despite RNA's versatility, it could not possibly have existed at or even near the origin of life? Many RNA World proponents have accepted the fact that RNA may not have been the 1st genetic/catalytic molecule but their search tends to be restricted to "simpler" nucleic acids & nothing else. Many also limit the study of RNA polymerization to montmorillonite clay which in contrast to pyrite (a far more common mineral found to hydrolyze the phosphodiester backbones of nucleic acids), offers the best chance for RNA polymerization in the absence of ice. Even that requires some reasonable degree of topography upon which to desiccate (under damaging UV light, no less!). RNA is vulnerable to a wide variety of environmental hazards & immature plate tectonics may not have provided sufficient landmass; restricting dry areas to volcanic islands.

If the RNA World is such a risky proposition, why is it so popular? How many of you have ever heard of Thomas Cech? He & Sidney Altman (at Yale) were awarded the Nobel prize for the discovery of ribozymes. Dr. Cech heads HHMI; a major source of funding for biochemical research. Furthermore, when one searches the HHMI roster, we find many RNA World supporters, but none against it! Consider Lasker laureate Jack Szostak! Was the truth sold to Cech & HHMI for research funding? Grant $?

Personally RNA world and viruses as the ancestor of everything makes sense to me. Nevertheless, I can't see how these concepts have much significance outside the world of pure science.