Where did the genetic code come from?
In this fabulous scientific article, the authors scream from the roof tops, "WE DON'T HAVE A CLUE!"
THAT'S WHAT I'M TALKIN' ABOUT!
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"(In 40 years since Cricks' paper), despite extensive and, in many cases, elaborate attempts to model code optimization, ingenious theorizing along the lines of the coevolution theory, and considerable experimentation, very little definitive progress has been made."
"And then, there is, of course, frozen accident, Crick’s famous “non-explanation” that, even after 40 years of increasingly sophisticated research, still appears relevant for the problem of the code’s origin... "
"Before closing this discussion, it makes sense to ask: do the analyses described here, focused on the properties and evolution of the code per se, have the potential to actually solve the enigma of the code’s origin? It appears that such potential is problematic because, out of necessity, to make the problems they address tractable, all studies of the code evolution are performed in formalized and, more or less, artificial settings (be it modeling under a defined set of code transformation or aptamer selection experiments) the relevance of which to the reality of primordial evolution is dubious at best."
"Indeed, it stands to reason that any scenario of the code origin and evolution will remain vacuous if not combined with understanding of the origin of the coding principle itself and the translation system that embodies it."
"At the heart of this problem is a dreary vicious circle: what would be the selective force behind the evolution of the extremely complex translation system before there were functional proteins? And, of course, there could be no proteins without a sufficiently effective translation system. A variety of hypotheses have been proposed in attempts to break the circle, but so far none of these seems to be sufficiently coherent or enjoys sufficient support to claim the status of a real theory."
"(All) theoretical approaches lack the ability to take the reconstruction of the evolutionary past beyond the complexity threshold that is required to yield functional proteins, and we must admit that concrete ways to cross that horizon are not currently known."
"(W)e are unaware of any experiments that would have the potential to actually reconstruct the origin of coding, not even at the stage of serious planning."
"Summarizing the state of the art in the study of the code evolution, we cannot escape considerable skepticism. It seems that the two-pronged fundamental question: “why is the genetic code the way it is and how did it come to be?”, that was asked over 50 years ago, at the dawn of molecular biology, might remain pertinent even in another 50 years. Our consolation is that we cannot think of a more fundamental problem in biology."
Origin and evolution of the genetic code: the universal enigma
The genetic code is nearly universal, and the arrangement of the codons in the standard codon table is highly non-random. The three main concepts on the…
ncbi.nlm.nih.gov
ncbi.nlm.nih.gov |
