This article from the Weizman Institute has a very interesting report on a new model for the phenomenon known as abiogenesis. The language is not all that technical, and I would be interested in knowing if anyone else finds it as interesting as I did.
You see, the argument against the natural science description of the origins of life are based, in part, at times, when other tactics fail, on the “unlikelihood” of the spontaneous creation of replicating molecular structures without a specific design, and intent. That argument does have flaws, since the number of iterations cannot be evaluated, nor can the results of all partial replications be assessed. The absence of probility values for the unlikely event happening is simply an exercise in choices by the person making the assesment.
In this model, the structural elements of cellular life are already in place, and the iterative separation of trials is inherent in the model. Since multiple cases will be created in similar structures over long periods of time, the essential probability of replicating molecular elements are contained, and recreated in successive iterations. This is an environment which would conserve incomplete elements, without successful replication by the proto-DNA. Partial success becomes an element of the process, and the very unlikely one step event is not necessary.
<p align=center><b>Tris</b></p>
<font face=webdings size=5 color=#ff1CAE> <b>-</b> </font> “I taught that boy everything he knows. . . and I’m really sorry.”
Thats interesting. Perhaps I don’t get it, but how could a lipid droplet, granted, one that can carry a kind of information and self-replicate become the cell of today? When does the RNA and DNA come in?
Perhaps someone more knowledgable then I can answer my questions.
The DNA and RNA need not come in until much later, in fact. The particular advantage in this model is (if it does reflect the history of life) there were many many small, encapsulated sets of chemicals. Each one was able to replicate itself in general content, and each one able to alter the specific chemical nature of the lipid “cell wall” and the contents within that barrier. It is a mutational chemical factory that can conserve its own form, and change over time. The changes within the bubble can include failure after failure for protein replication, and still continue to happen. When a successful replication of the proteins does take place, it is conserved by the action of the lipid structure, which is not dependent upon protein replication.
The conservation of near misses in the process of replication changes the fundamental likelihood of the eventual outcome by many orders of magnitude. The whole probability argument is undermined if this mechanism is possible. While it is only a model for now, the route is clear for the eventual experimentation to assess the possibility that it is a true reflection of abiogenetic process. While it may never be possible know if it did occur, it is an excellent example of how something might have occurred by random process, and the conservation of successful replication becomes a powerful force, overwhelming the odd against the so called accident of DNA based life.
But it’s all still just a theory, a computer simulation. Is there any way of testing it IRL? Or will they just have to wait for more funding to do that?
My big problem with computer simulations is that they don’t leave any room for “accidents”, for the lightning strike or the asteroid impact. What’s the Stephen Hawking thing, “punctuated equilibrium”? You can sit there and run simulations till the cows come home, but how do you factor in the random event?
P.S. All I know about abiogenesis is what I see on NOVA, so be gentle.
Ahh, I see so basically each of these pseudo-cells has a self-contained, self-replicating environment for protein replication. Then they would merge and the diversity withen a single environment grows. Then eventually one will finnally produce Rna and reverse transcriptase to create DNA . Correct? That one would have an evolutionary advantage(eventually) and would be able to basically take over correct? Hrm… interesting.
Punctuated equilibrium, who’s biggest proponent is Gould, does not suggest instantaneous random events. It suggest long periods of stability in an environment, then some instability allowing evolution/adaptation to occur at a normal pace.
Punctuated equilibrium diagrams suffer from a sort of compression of the time axis. Major changes occur from time to time, but the time it takes for the changes to occur is well in the bounds of normal rates of mutation.
From what I gather, very little is known about abiogenesis. There are hypotheses based on extrapolations of the fossil record (nothing that far back!), evidence of the conditions of the early Earth, and knowledge of chemical properties. But there are no strong theories with direct evidence. A good website to check out is http://www.talkorigins.org
Good question. I wish I had a good answer for it. I can give you some speculation, though.
I don’t think it favors either the RNA world theory, or the direct DNA world for any particular reason. What causes the separation of the lipid walled bubbles is not a protein function, but rather the consequence of the solubility and insolubility of various components of the liquid in which the bubbles evolve. They could, I think (or wild ass guess, if you prefer) provide the same structure for isolation of environments for the development of either RNA or DNA. It is worth noting that other chemical combinations might well develop as well, and survive until one or more of the bubbles developed a great enough advantage in replication ability to overwhelm them.
Another chemical basis for life, in fact might have existed. Not particularly likely, but not incompatible with the concept. Later examples would consume the raw materials of the other forms, and soon leave no trace of them. In that way, the “false starts” of the abiogenesis process become a resource for the final successful examples. This model is not well enough developed to answer real detailed analysis on every question. (At least not by me!) I do find it very heartening to have some inkling that there are answers to the vexing question of partial development for the extraordinarily complex combination of chemicals necessary for either RNA or DNA. Other possibilities might well exist. This is only one of the possible answers, and it might well be another wrong answer. Science needs wrong answers, that is part of the process of learning new things.
