Here's some interesting notes that may connect up to my origin scenario. 1. Collision is important for hybridization. If, as I suggest, there was an h-bond world where the sun cycle was exactly that which denatured nucleotide strands completely at the high end and then annealed them into novel hybrids at the low end. And selection was on the variant best able to survive. THEN Where there was the most nucleotides, there would be the most chance for collision and annealing. 2. Also any paired strand that did not completely denature in the highest heat of the day, would be the first to anneal or zip up. And it would do so very quickly - thus giving it a selective advantage. 3. Complimentary bases will zip up faster in the annealing part of the cycle. That suggests that whatever was the most repetitive code in the nucleotides would also be the more likely to anneal, and more likely to anneal quicker and more often. 4. There are different levels of thermal stability. Molecular Bio by Friefelder lists three in order from most to least stable: double stranded DNA, single stranded DNA, free bases. That suggests that each is more likely to survive a heat cycle than that that follows it on the list 5. One phenomenon of DNA is breathing in which double stranded regions frequently open to become single stranded bubbles. The same text says, "Note that since a GC pair has 3 hydrogen bonds and an AT pair has only two, breathing occurs more often in regions rich in AT pairs than in regions rich in GC pairs." A good ex. of this is tRNA today. Note the GC rich stems and the AT rich loops. What this suggests to me is that in a thermal cycle the most often open or denatured areas would be those that are AT rich and the most often bonded areas would be those GC rich. Also if coding is more from the bubble areas then it would be more heavily AT. 6. Salt levels can help or hinder denaturation. Thus if one could determine the temp. range of this h-bond world, then would could probably figure out the amount of salt. Or vice versa - if one knows the probable level of salt, one could suggest a reasonable temp range of denaturing or annealing variants. (Note the annealing temp needs to be about 25-30 C below the denaturation temp) 7. Because polynucleotides tend to have a '3D structure that maximizes the contact of the highly soluble phosphate group with water and minimizes contact between bases and water', It would suggest that the obvious, that nucleotides were selected in a water environment. Yet it doesn't rule out that there was a dry part to this cycle. Comment?