ChaosKnight wrote:I’ll say your pet theory is very telling. You probably know I’m going to say this: it totally evades the question of how cells formed, and instead changes the question to how that alien life came about in the first place. As long as the alien is not divine, I don’t have a problem with that. But lets speculate more. In your imagination, how did the alien life form come about?
Since I know nothing about the alien life that created life on earth, I would not speculate. After all, the possibilities for alien life are unlimited! They need not be carbon life forms - they could be composed of any known and unknown elements. or could be nebulous energy lifeforms. Who knows? I will leave the question of 'who created the aliens' to the aliens themselves! Or maybe there is no beginning for the aliens? They could have existed since eternity past - I suspect our minds have difficulty dealing with infinity and therefore is always looking for the beginning of something, that is why Hubble's Law was so well received.
Welcome to the real world. Scientific procedure does not always follow your prescribed “practical” list.
Well, our R&D lab uses the standard procedures which I described. I would like to think we are living in the real world - or maybe this is all virtual reality as in the 'Matrix'? 8-)
To me it’s more like a study using MD. But I’m curious. What does a “hypothesis-generating” paper mean? What does it do, and to what extent is it useful? Does a "hypothesis generating" paper give usable results? What about computational models? How much can you trust the results?
To me, a hypothesis-generating paper basically lays down the framework on how something is supposed to work based on incomplete data available currently. If used correctly, it could direct research efforts to critical areas that need experimental data. If used incorrectly, it is just an instrument for the proposer to 'be the first' to suggest a mechanism that would later proved to be 'true' and thus become famous. A hypothesis-generating paper thus does not give results, but gives direction to where the results may be found.
As regards to computational models, we use them a lot, but all of them for exploratory' purposes, never 'confirmatory' (I'm talking about life sciences, of course). Even just this week, we have a paper in Nature that showed that the number of genes in humans are closer to 20,500 (anyone remember the 200,000 gene estimate put forth just a few years ago?) based on computational methods. Is this number confirmed then? No, but it gives an idea on where the ultimate answer might lie. No matter how much you compute, you need to assign each gene and only when all that had been done and totaled up, then you have the 'right' answer. Would you take a drug that has been developed based on computational models but never tested on humans?
Yes, Szostak et. al.’s paper is quite interesting in that it communicates what the authors think are necessary conditions for a primitive, artificial cell, based on principles of current, real, hard science, and the author’s opinion that it is very much possible to create such a “cell”.
I think that is attributing too much to Szostak's 4-page paper. This paper is not about presenting new experimental results, but about hypothesizing about the spontaneous creation of cells based on existing data published elsewhere. A few quotes from his paper:
- "... to imagine a collection of molecules that is simple enough to form by self-assembly, yet sufficiently complex to take on the essential properties of a living organism."
- "We must look to simpler systems if we hope either to synthesize a cell de novo or understand the origin of life on Earth."
- "We believe that within this framework structures can be found that are both indisputably alive and yet simple enough to be amenable to total synthesis. We note that solutions found in the laboratory need not be chemically similar or even directly relevant to the actual molecular assemblies that led to the origin of life on Earth."
- "Defining life is notoriously difficult; its very diversity resists the confines of any compact definition."
- "Although there is considerable debate about the nature of the first genetic polymers...A growing body of experimental work points to the feasibility of evolving and/or designing in the laboratory an RNA replicase — an RNA molecule that can act both as a template for the storage and transmission of genetic information, and as an RNA polymerase that can replicate its own sequence."
- "...the easiest way to construct our simple protocell is to surround it with a lipid membrane. This also makes it easier to imagine how a simple cell could evolve into more complex cells, similar to present-day cells, without major architectural transitions."
- "...the protocell as a whole could self-assemble."
- "Such simple protocells would be nearly, but not quite, alive....For this to happen, an RNA-coded activity is needed that imparts an advantage in survival, growth or replication for the membrane component."
- "No natural ribozymes are known that can catalyse the required chemistry and use nucleoside triphosphates as substrates. As this is a complex enzymatic function, attempts to evolve an RNA polymerase ribozyme experimentally have proceeded incrementally."
- "What further improvements are required to obtain an RNA replicase suitable for incorporation into an artificial cell?... A ribozyme that can recognize the primer–template using non-sequence-specific contacts would enable more extensive and general RNA synthesis. The next hurdle will be to improve the fidelity and efficiency of polymerization."
- "A potential solution comes from the finding that active ribozymes can be reconstituted by the spontaneous self-assembly of two or more oligonucleotides; the separate oligonucleotides can be more or less unstructured, while the assembled complex can be stable and enzymatically active."
- "A better understanding of the kinetics of RNA folding will be required to predict sequences that will be reasonably stable as unpaired + and - strands when packaged in the same vesicle."
- "An attractive alternative strategy is replication by strand-displacement on a duplex template..."
- "Spontaneous vesicle growth could in principle occur either gradually by the incorporation of single lipid molecules or micelles, or stepwise by fusion with other vesicles."
- "An intriguing possibility is that the process of division could be highly favoured, or even become spontaneous, with lipid compositions that yield vesicles of optimum size for thermodynamic stability."
- "An alternative approach to feeding the replicase small-molecule substrates would be to encapsulate the substrates within vesicles, which could then be delivered to the replicase by vesicle fusion."
etc.. What he had presented was a few possible ways of generating a cell, which is currently still a hypothesis. There are no criteria to speak of, just conjectures based on limited data. Which brings to the next item...
It actually set the stage for Irene Chen's research, which suggests it is possible, at present, to fulfill at least some of Szostak's criteria.
Suppose my hypothesis is that cars are created 'spontaneously'. And then I devised a possible solution based on the self-assembly of different motor parts. Now, if I observe that when I placed the cylinder of the engine and the piston close by, and without external intervention, the piston spontaneously slid into the cylinder of the engine. Is this proof of my hypothesis? Not yet, but it is a step. But science demand that the experiment be independently verified, (remember the South Korean Cloning saga?) or it is not a universal principle. Better still if the confirmatory data comes from a camp that opposes your theory! This did happen in Medicine - it is called the HOPE trial, when the investigators set out to disprove the efficacy of one drug and ended up with positive results instead.
Is it lazy? Or is it because we really do not know the cause? What if we do know at least part of the cause? If I say, “When I heat water till it boils, the average distance between molecules spontaneously increase”, in what way am I being lazy?
There is a term for 'unknown' - it's called "idiopathic".
In that case why don’t you just bet on the wrong horse, get proven wrong, and make yourself a joyful man?
It is not possible to bet on the 'wrong' horse if the truth is not known yet. And if I know the truth, then it's not called betting because I know it IS the wrong horse. So when I bet, I do not know whether the horse is the 'right' or 'wrong' one. Which means I can be proven right or wrong either way. So, to a scientist, it is a win-win situation: if I am proven correct, I win because I am a step towards the truth; if I am proven wrong, I win because I am also a step towards the truth. Purposely betting on a horse which you know does not lead to the scientific truth is counter-productive and in sociology is known as a 'trouble maker".
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
