Quote from piezoe:
This is key: "were [the emergence of life] not an obligatory manifestation of the combinatorial properties of matter, it could not possibly have arisen naturally."
Which I quote from Jem's post above, although, curiously, Jem doesn't seem to understand what this means.
A very satisfactory and rigorous proof that entropy is the driving force for evolution has already been published by Vogel. Therefore both organisms and virus must evolve. They have no other choice. Furthermore, Orgel's experiments proved unequivocally the evolution of organisms. Left to be yet determined are the details of the transition from inanimate components to simple lifeforms. Though viruses are not organisms, they may hold the key to understanding this transition. Some think that earliest lifeforms were based on RNA rather than DNA, and the NIH is funding research aimed at finding RNA catalysts, which may have early on in evolutionary time served the roles later played by protein enzymes. Quite a number of RNA catalysts have already been found.
There is good evidence for the existence of multiple, parallel evolutionary pathways, and the number of these may be, or have been, astronomically high. At this point in our knowledge, there is no reason to suppose that new life forms, most of which would be virtually identical to those already existing, are not currently, spontaneously arising on Earth .
It is virtually certain that life very similar to that on Earth exists on other planets in other solar systems and that all lifeforms are carbon based. Dewar showed in his paper provocatively entitled "Why Life Exists" that life based on elements other than carbon is unlikely.
One must bear in mind that the combining of chemical elements is not haphazard, but rather highly organized and specific, so that the laws of Chemistry and Physics are obeyed. Recognition of this takes us full circle back to the Quote, originally quoted by Jem, that began this post.
Things are not nearly so complex and unfathomable as supposed by those 21st Century believers in the supernatural, that is to say those with irrational faith in religious concepts.
The "details of the transition from inanimate components to simple lifeforms" is the whole crux of the matter. You can't sweep that under the rug as if it was some minor issue. Yes, the laws of chemistry must be obeyed. Which is precisely the problem. In a laboratory one could synthesize each of the amino acids, lipids, sugars, etc. that make up a living organism. You need very different conditions to create each of these. Then, with sufficient equipment and skill, you could in principle stitch them all together to make a living organism. But when you imagine an early earth with air, rocks, water, lightening, rain, thermal vents, and so forth no one has yet come up with a plausible set of scenarios where life would pop into existence. In a laboratory you have many advantages -- for example, you can produce reasonably pure ingredients. In a natural setting a reaction that can produce simple amino acids will also produce many tars (random hydrocarbons) that poison later reactions. (As just one example of the many problems of trying to transition your chemistry from a lab bench to a thermal vent.)
Frankly, I don't see what relevance viruses have to the problem. Viruses have no metabolism. They can't reproduce without taking over the machinery of an existing prokaryotic or eukaryotic cell. You can't have viruses until after you have independently living cellular life.
"There is good evidence for the existence of multiple, parallel evolutionary pathways, and the number of these may be, or have been, astronomically high. "
As my previous post made clear, terms like "astronomically high" are useless. A number like 10^60 is "astronomically high". It's also no where near enough trials to create a living cell by throwing simple molecules together and hoping they'll hook up the right way.
I see no evidence at all that new life forms are spontaneously springing into existence today. Which does present a conundrum for protobiologists -- if the creation of life is inevitable, we <i>would</i> expect new life forms to be coming into existence from inanimate matter all the time. This conflicts with observation. For example, if DNA based life kept arising from inanimate matter throughout geologic time there would be no common evolutionary descent of life forms. There's a lot of arbitrariness about life -- for example, which DNA triplets code for which amino acids. Why do all organisms have the same encoding? It's as if we discovered intelligent beings from another part of the galaxy and found that they used ASCII too. Why aren't there organisms that have switched all the left handed and right handed enantiomers?
But most importantly, if you really believe that life arises spontaneously today then prove it -- put some rocks and water in a box, sterilize it thoroughly with extreme high temperatures, and show how a few months later you have a new species of bacteria growing. Do this several times and demonstrate that in fact about half of the new bacteria species <i>do</i> have switched enantiomers. (Or explain why this can't happen.)
