Abiogenesis

First off I would modify DNAunions construct as follows:

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1) when the universe began there was no life
2) there is life now
Absent any evidence of a supernatural creation of life one is lead to the conclusion that life must have arisen from nonlife somehow.

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Even if one assumes that a god created the universe in a beginning moment and then left it on its own we are stuck with assuming abiogenesis, as this event occurs 10 billion years after a 13.7 plus billion year old beginning.

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Next, when it comes to the "building blocks" there is ample evidence that highly complex organic molecules were prevalent in the universe at large early on and that formation of higher complexity has been demonstrated in experiments simulating early earth conditions. I have listed a number of these in an essay on my website at:
http://mywebpage.netscape.com/AbbyLeever/Building-Blocks.htm

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with this conclusion:

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From these building blocks it should be clear to a rational mind that the building blocks needed for the creation of life were plentiful, not just on Earth but in space in general and from the earliest of times. Probably they have been around since long before even the Earth formed from the cosmic debris left behind by the life and death cycle of previous stars and planets, back to the beginning of time. These "seeds of life" no doubt extend through the far reaches of the universe as well as the depths of time (cue Crosby, Stills, Nash and Young ... "We are star dust ...").

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It also should be clear to a rational mind that the natural processes for forming more complex structures from those basic building blocks were prevalent on the earth at least 3.5 billion years ago in a variety of forms and locations. We are left with a scenario that has a random combination of plentiful and multitudinous organic molecules forming amino acids all over the earth, with a second scenario that has random combination of plentiful and multitudinous amino acids into peptides and proteins, and a third scenario that has random combinations of plentiful and multitudinous peptides and proteins into the first "replicators" (the predecessors to RNA and DNA), a simple 3 step process where the probability of a successful combination is almost inevitable: it is no longer a matter of "if" but of "when" it will occur under these conditions ... and once self replication occurs the frequency of replication will necessarily outpace the random action, replicators that are faster and stronger will outpace their competition ... life is inevitable when given the conditions for life.

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Finally, DNA can exist outside a living cell although it degrades with time -- no longer has the mechanic doing tune-ups ... but it is not the minimum requirement for abiogenesis to have occurred. Viruses use an abbreviated RNA that hi-jacks the cell mechanism to replicate its nefarious (to us) messages. Then we get to prions like the ones that cause mad cow disease, which are even less 'complete' than viral RNA ...

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Enjoy

fair enough (only an A???) ahahahaaaWhile I agree that abiogenesis has not been accomplished experimentally, I will not be surprised when it happens.

hmmm

"Even if life is created in the lab, it is still not PROOF (as in ultimate proof) that life arose via a precise mechanism. 3.5 billion years is a long time ago, and any models that we create are tentative and will not tell us the specifics of how life arose on Earth."

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That's a really good point: Just because something can happen doesn't mean it did. Guess that's something that both sides of the debate need to keep in mind.

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It would be proof that life can originate when the conditions of the experiment occur in the real world. Of course it will not be proof of how it actually happened, as there is (still) a lot of debate about what the conditions were like on earth at that time.What I would expect to see, is that once a self replicating element has been achieved, that a number of similar experiments would follow using different conditions --- if for no other reason than to see how easily life could evolve on other planets: what are the limiting factors?And as the number of extra-solar planetary systems has sky-rocketed since the discovery of the first one, I would expect to see many successful experiments using many varieties of conditions.That is a prediction based on the way science works and the innate inquisitiveness of humans.Enjoy.

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" Which requires DNA. The host cells wouldn't be alive without their DNA, and without living host cells viruses couldn't 'replicate'."

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Do we know the mechanisms of viruses outside a host environment re survival and replication? Are there conditions that would allow replication?

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" Second, there's no consensus as to whether or not viruses are alive."

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the definition of life is a tough one indeed. Do a google on [definition life] and there is a lot of reading with no clear end in sight. Morales gives it a pretty good whack (but too much about too little) at: Psychozoan: The Definition of Life

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"But since prions are not living, they're an irrelevant example. "

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Again they are able to replicate within a system.The [bottom up] question of abiogenesis is not life but the first replicator.The [top down] question of abiogenesis is what is the absolute simplest possible form of life. Dissecting DNA down to an absolute minimum for bacteria to still qualify as life brings us very close to virus type stuff at this point though controversy ensues.A professor at school mentioned the difference between practical and theoretical:

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Take a boy and a girl and stand them 10 feet apart. Every second, halve the distance between them. theoretically they never touch, but they get close enough for all practical purposes.

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the [top down] and [bottom up] approach is like that.

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we are limited in our ability to understand
by our ability to understand

I don’t think you are looking at this with a fully open mind. The evidence to date is that viruses do not replicate on their own within the environments that we know about. The absence of evidence is not evidence of absence however, and does not rule out that a certain environment may exist wherein viruses could replicate. That environment could be something closer to a primordial environment or one of the extremophiles type or depend on a random input of energy in a pre-bio soup. It is also possible that the viruses have lost mechanisms where they have found easier mechanisms to use from cells than from their [original development], even though that [original mechanism] may have differed significantly from modern cell biology. This would mean that they are not devolved bacteria but a separate form of life, perhaps one entirely based on RNA. ... we don't know. As mentioned regards prions, the development of a replicator is a relatively necessary first step whether it can be classed as [life by some definition or other] or not, even if that replicator uses a clay or crystal structure to form a molecular production [not so much Xerox as Widget building] machine. Perhaps "replicator" is the wrong word and we should be looking for "implicators" ("imps" for short?) first. Then one could look for how "imps" can be incorporated into proto-cell structures where they start to turn out product to maintain the proto-cells without necessarily replicating themselves.

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we are limited in our ability to understand
by our ability to understand

Whatever complexity is required, one thing is sure: the universe has already figured out what the solution is.

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we are limited in our ability to understand
by our ability to understand

Again, that information is limited to only certain environments and conditions. Only when every environment in all the pasts have been eliminated can you come close to making an absolute statement of that type. Of course Bio101 levels sometimes simplify things so as not to introduce too much at once ... you might want to try xenobiology 101 ... it may help. sorry I thought you would understand I was talking about extremophile environments not the extremophiles themselves.Notice that only a little while ago biologists were saying that life couldn't exist in such extreme conditions. Then they found it. Your argument against viruses is the same logic: we haven't seen it therefore it can't be true ... a limited argument.The question was (and is) whether something else can provide the missing elements that are currently provided by living cells to allow {viruses or close cousins} to reproduce. Could that have been how the first replicators worked. Your denial of possibilities is quite amusing. At some point in the search for the beginning of life you will have to get out of the cell as we know it ...Enjoy.

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we are limited in our ability to understand
by our ability to understand

what's wrong with this picture:
http://www.vivaria.net/experiments/notes/documentation/ahahahahaaa
(ps html no work in sig lines)

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we are limited in our ability to understand
by our ability to understandRebel American Zen Deist

html is turned off in the sig lines - you'd have to ask the adminfolks why.(and the answer is yes ... she'll find out about it anyway.)

go back and look and you will see if looking for the answers is what you want to beyou continue to misinterpret. not my problem.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist

one last chance to think:where do viruses come from?

you are full of yourself aren't you.bye.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist

I didn't claim that you made errorsjust that your views were incomplete.enjoy yourself.

Very curious indeed. But don't get sidetracked by DNAUnion's dogmatic misapprehensions of my position:http://EvC Forum: Abiogenesis http://EvC Forum: Abiogenesis http://EvC Forum: Abiogenesis http://EvC Forum: Abiogenesis http://EvC Forum: Abiogenesis You will note that nowhere do I state that I consider either viruses or prions to be alive or that they fit a definition of life, but raise them solely as examples of mechanisms by which replication occurs (such replication being classified as a condition for "quasi-life" in one of DNAUnion's citations). Replication which now depends on cell mechanisms for support, but may not have in the distant past if other similar mechanisms were available.I stand by what I said, consistently, here, and refuse to get into a one-upmanship contest.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist

Additional thoughts.(1) is it possible to have a proto-cell structure that is not self replicating but which is held together in a stable (relatively) form for considerable periods of time? ie - does the cell structure come before the replication process or the vice versa? a primordial chicken and egg question. Or do replicators and protocells develop independently ... there has been some research on the development of membranes as a first level of cell development.(2) is abiogenesis better aligned with xenobiology (earth as a special case) or with biology. Considering that the original environment on earth was quite alien to the environment that we know, I would place it with xenobiology.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist