Maybe, for this planet. Still, panspermia requires abiogenesis somewhere else, so it does not solve the problem, just shifts it.Saidin said:
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Astonishing Scientific Discovery:Majority of Human DNA is "Off-world" in origin-Human Geno
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Infundibulum said:
This is not logically correct. It says abiogenesis could be the cause of life, but in no way reqires it. How can we take a theory that is based upon theoretical early conditions on this planet and apply them to the entire cosmos?
For abiogenesis to work, one needs an incredible amount of time, and an incredible amount of chance, such that the odds of it happening are near impossible. Therefore the building blocks would be rare, and not as ubiquitous as it appears from panspermia evidence.
I do not understand this. In case of panspermia how the spreading and seeding life particles form? They must have formed somehow, so abiogenesis is implied somewhere in the (or "a" ) universeSaidin said:
As for abiogenesis, I do not know how impossible the odds are; do we have any handy calculations or is it gut feeling guesstimate?
Blundering_Novice
Rising Star
Richard Dawkins has satisfied my curiousity on the subject. No Gods or divine beings are required to explain how life came to be on our planet.
That is NOT to say that I don't like to use my imagination in regards to the more fanciful explanations, though.
That is NOT to say that I don't like to use my imagination in regards to the more fanciful explanations, though.
Infundibulum said:
Abiogenisis is the theory of how life may have formed on this planet. That does not logically infer that it occurs anywhere else by those means. It could, but to say that abiogenesis (which is an unproven theory) is the mechanism for the formationn of life throughout the universe is not possible.
A few calculations:
A ribozyme:
"Assume that the ribozyme is 300 nucleotides long, and that at each position there could be any of four nucleotides present. The chances of that ribozyme assembling are then 4^300, a number so large that it could not possibly happen by chance even once in 13 billion years, the age of the universe."
Amino Acids:
"The most compelling evidence is amino acids. The simplest known living organism has over 500 amino acids. When they form, they form with side groups of atoms. Scientist have found that all non-living amino acids form with 50% of side atoms on the right side of the acid and 50% on the left. This is true on all non-living amino acids. Living cells can ONLY contain amino acids on the left side. ALL amino acids found in every single living cell contains only left-sided amino acids. In the most favorable environment of scientific labs, this has never been duplicated. No scientist has ever created the left-handed amino acid that is critical to the formation of life. All amino acids always form with left and right sided atoms. If scientist in perfect conditions can't duplicate one single left-sided amino acid, how could the 500 necessary for life form by chance? The odds of even one left-sided amino acid forming by chance is 10^123"
So, just from those two examples we have 10^123, and 4^300.
Blundering_Novice
Rising Star
"to say that abiogenesis (which is an unproven theory) is the mechanism for the formationn of life throughout the universe is not possible."
How and why do you know that such is not possible? What are you aware of that I am not? (A genuine inquiry...)
How and why do you know that such is not possible? What are you aware of that I am not? (A genuine inquiry...)
Blundering_Novice said:
Its not possible in the sense that it is illogical to take a condition in a specific environment and apply it to an environment which is dissimilar. I am not saying its impossible, just not possible to take an experiment in a box and apply it to the univese as a whole.
Touche Guevara
Rising Star
You're missing an important part of the equation.Saidin said:
300 nucleotides long with each position having 1 of 4 possible components, times each occurrence of nucleotide combination ever to occur in the universe. Concurrent attempts makes even the generous 13 billion-year time frame irrelevant.
Blundering_Novice
Rising Star
13 billion years is a long fucking time, mate....
Blundering_Novice said:
It is a long time, until you consider the odds. Then it is not nearly long enough. And the time frame we are considering is in the space of hundreds of millions of years, nowhere near the entire age of the universe. According to Abiogenesis, life formed randomly on earth in the space of ~500 million years.
Blundering_Novice said:
It's unfortunate you have put so much stock into Dawkins. I have read a few of his books, even agreed with him for a time. Until...I started reading some of counter arguments to his ideas. Once you begin to, you realize that he is just a close minded blowhard that bases nearly all his arguments on unprovable assumtions and faulty logic. Just the same as what he claims for non materialists.
Felnik said:
I agree. Lots of definitive statements, but nothing to back them up. I was hoping for more "evidence" but instead got a lot of information that was not pertinent to the topic.
On a side note. If you want to understand how our DNA changes without the need for random mutations, look into Epigenetics. Random mutations over time is an outdated and false paradigm.
These calculations suffer from retrospective fallacy.Saidin said:
Evolution of molecules is not deterministic. These numbers give the impression that for one ribozyme or enzyme to occur all other combinations must have been tried and found suboptimal. This is of course not true and impossible. In practise, life evolves with what is available and if few combinations of nucleotides or aminoacids can perform some catalytic functions then they will be utilised.
The same goes for aminoacids, it is a matter of chance of whether left or right- aminoacids could be used. It appears that from all possible combinations of ribozymes the one that could utilise the left aminiacids appeared much before than the one that could utilise the right ones and was therefore utilised from primitive organisms. This "problem" with aminoacids would really be a problem in a situation of infinite possible useability of molecules and available enzymes. But as I said above evolution is not deterministic, primordial life utilised what was available around because it happened to be around.
Infundibulum said:
But there was no primordial life. It was just molecules floating in water with the only combinations being possible those that occur though chemical bonding.
Evidence suggests molecules are not deterministic, and therefore how can we talk about evolution in this context? We must rely on pure randomness, taking the chemicals that would be likely on the early earth, and what possible combinations they could create. There are very limited number of "good" combinations, and an universe of "bad" combinations. Conversely the "bad" combinations take the molecules out of the picture for future use. You said life evolves with what is available, but how does this mechanism start, such that inanimate matter begins to attract to itself the correct combinations of elements in order to spark what we would call life?
Lets reduce the odds of one ribozyme occurring. Lets say that we can throw out 2/3 of possible combinations. That still leaves us with 4^100. A number still making it highly unlikely for it ever to occur, anywhere in the universe thoughout its entire history. 1 in 16000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. Reduce even that in half, now you have 4^50. Still probalistically unlikely.
You seem to be making the point that since it occured, then the probability is 1. Valid logically, but very unsatisfying.
I think we need to start the argument anew before going into cycles.
Do we agree that macromolecules (e.g. ribozymes, proteins etc) can form in a primordial molecular soup? Macromolecules are molecules build by smaller molecules. Nucleotides make RNA and DNA and amino acids make proteins.
In a primordial environment nucleotides can combine with each other in all sorts of combinations to form a plethora of RNAs. You need not to go far off to start creating RNAs with enzymatic activity. Researchers have been randomly combining nucleotides to make long strands of RNAs and then trying to decipher whether any of them have catalytic activities. It turns out that from a random pool of RNAs some have important biological catalytic activities. And this is what was proposed to occur in the primordial soup. Out of a vast array of enzymatic activities some appear more helpful and fitting than others.
It is highly improbable that you will get an exact predetermined RNA strand from a pool of randomly combined nucleotides (as your calculations imply), but it is very probable that you will get some that do the same job as the predetermined. This is why I believe that your calculations are fallacious. There is nothing magical about a certain sequence and function in biology dictates more than mere sequence. The latter is called convergent evolution and there are numerous examples of that in the macromolecular world.
Do we agree thus far?
Do we agree that macromolecules (e.g. ribozymes, proteins etc) can form in a primordial molecular soup? Macromolecules are molecules build by smaller molecules. Nucleotides make RNA and DNA and amino acids make proteins.
In a primordial environment nucleotides can combine with each other in all sorts of combinations to form a plethora of RNAs. You need not to go far off to start creating RNAs with enzymatic activity. Researchers have been randomly combining nucleotides to make long strands of RNAs and then trying to decipher whether any of them have catalytic activities. It turns out that from a random pool of RNAs some have important biological catalytic activities. And this is what was proposed to occur in the primordial soup. Out of a vast array of enzymatic activities some appear more helpful and fitting than others.
It is highly improbable that you will get an exact predetermined RNA strand from a pool of randomly combined nucleotides (as your calculations imply), but it is very probable that you will get some that do the same job as the predetermined. This is why I believe that your calculations are fallacious. There is nothing magical about a certain sequence and function in biology dictates more than mere sequence. The latter is called convergent evolution and there are numerous examples of that in the macromolecular world.
Do we agree thus far?
I agree that macromolecules can form in a primordial soup. I also agree that Abiogenesis is theoretically possible, my problem lies with its probability.
I am having difficulty with the concept, "There is nothing magical about a certain sequence and function in biology dictates more than mere sequence."
It appears to me you are saying that the whole is no greater than the sum of its parts. If this is what you are saying, then I disagree. If this is not what you are saying, could you please clarify.
I am having difficulty with the concept, "There is nothing magical about a certain sequence and function in biology dictates more than mere sequence."
It appears to me you are saying that the whole is no greater than the sum of its parts. If this is what you are saying, then I disagree. If this is not what you are saying, could you please clarify.
What he's saying (i think) is that the problem with your probability analysis acts as though one (and only one!) Rna sequence can have the particular enzymatic activities that are needed. In fact, there are numerous Rna sequences that can have these enzymatic activities. Keeping this in mind, the probability is much higher than your calculation implies.
Also, remember that not every residue in the ribosome is functional. In some spots, it doesn't matter what residue is present (these are called non-conserved regions) so that throws off your calculation too.
On a different tangent, I think of abiogenesis as life arising from non-living molecules, regardless of whether it happened on earth. I believe that's what he meant that panspermia doesn't solve the problem of how life arose, it just shifts the problem to another planet. The life with which earth was seeded (according to panspermia) still had to have arisen from somewhere.
Also, remember that not every residue in the ribosome is functional. In some spots, it doesn't matter what residue is present (these are called non-conserved regions) so that throws off your calculation too.
On a different tangent, I think of abiogenesis as life arising from non-living molecules, regardless of whether it happened on earth. I believe that's what he meant that panspermia doesn't solve the problem of how life arose, it just shifts the problem to another planet. The life with which earth was seeded (according to panspermia) still had to have arisen from somewhere.
Yes, the sentence needs clarification. I believe that the whole is more than the sum of the parts. What I was trying to say in my sentence is that what is more important in biological function of macromolecules is the tertiary structure (or their 3D conformation). Or, a protein or ribozyme does what it does because it has a specific shape. In molecular biology terms these are called domains; so we have DNA binding domain, acetylation domain, lipid binding domain etc. Within domains the 3d conformation is far more conserved than amino acid (or nucleotide in ribozymes) sequence. That means that many different combinations of building blocks can make enzymes with the same function.Saidin said:
The analogy with everyday work is, say tools. We can make screwdrivers from all sorts of different materials or combinations of materials but it is the shape we are ultimately interested in.
Coming back to the argument, in the primordial soup most likely all enzymes/ribozymes that could sustain extremely basic life-like functions could form, thus giving the potential to take things to the next level. And as I said in my previous post, people today do the exact thing with ribozymes; they randomly combine nucleotides to generate as diverse sequences as possible and in the end they get (after applying selection of course) functional enzymes.
970Codfert
Rising Star
That was a massive oversimplification of what I said, and what the Stoned Ape theory says (It never states mushrooms caused evolution human evolution, it simply states that mushrooms likely had a role). All I said was that it is much more likely to account for ancient people's myths and visions of space ships, aliens, etc.. than ACTUAL space ships and aliens.
Not to personally attack you Saidin, but why do you put so much faith in odds and randomness? What's so random about thermodynamics? IMHO, I don't think life randomly assembled itself, I think it followed very specific instructions from the laws of nature. Life can form on Earth; this is one thing, out of the many possible events, that can take place in the universe... why negate that possibility using the odds of it happening, which change constantly depending on new discoveries and our ever-expanding knowledge? Not to say that calculating odds cannot be useful in scientific endeavor.
I can't keep up with all the chemistry that everyone is discussing, but maybe you guys could watch this short video about Abiogenesis and shed some light on it, poke holes in it etc? I posted it a few months ago in the hyperspace tavern.
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