(2017-12-07, 01:45 AM)Paul C. Anagnostopoulos Wrote: [ -> ]First, of course, we don't know how many times life started on the primordial Earth. I can think of two reasons why it wouldn't start up again today: (1) the conditions aren't right; (2) there is too much competition from current life.
If we reset the Earth to its primordial conditions, I see no reason life wouldn't start again. It might come out the same or it might not. I believe the two papers Steve linked will suggest that it would come out more or less the same.
~~ Paul
I think that Crick and others are saying that life originated once and once only. Hence the "frozen accident". Here's what Crick said:
Quote:The Frozen Accident Theory
This theory states that the code is universal because at the present time any change wovld be leihal, or at least very strongly selected against.
This is because in all organisms (with the possible exception of certain virases) the code determines (by reading the mRNA) the amino acid sequences of so many highly evolved protein molecules that any change to these would be highly disadvantageous unless accompanied by many simultaneous mutations to correct the “mistakes” produced by altering the code.
This accounts for the fact that the code does not change.
To account for it being the same in all organisms one must assume that all life evolved from a single organism (more strictly, from a single closely interbreeding population).
In its extreme form, the theory implies that the allocation of codons to amino acids at this point was entirely a matter of “chance”.
Should we dismiss Crick as some kind of religious nut too? Let's consider what you are saying:
1. Conditions are pretty good for life to survive and prosper but not for life to get started. Doesn't that strike you as counter intuitive?
2. Even if life could start under today's conditions, it would be snuffed out by life itself. So presumably the steps leading from lifeless chemicals to cellular life forms would be recognised by other life forms and the prebiotic forms eaten? No prospective life form could possibly escape this fate?
3. The earth would have to return to primordial conditions even though we are not sure what they were. For example, one popular theory is that life could have started in the deep ocean around hydrothermal vents. But hang on - we still have such vents. Exactly what is to prevent abiogenesis happening around them right now?
Kamarling Wrote:I think that Crick and others are saying that life originated once and once only. Hence the "frozen accident". Should we dismiss Crick as some kind of religious nut too?
What does the frozen accident hypothesis have to do with being a religious nut? He might simply be wrong. If Wills and Carter are right, it's no accident.
Quote:Let's consider what you are saying:
1. Conditions are pretty good for life to survive and prosper but not for life to get started. Doesn't that strike you as counter intuitive?
No. Perhaps the Earth had to be warmer. Perhaps a fortuitous piece of space material landed on the Earth. Perhaps there is too much competition. Anyway, I'm not claiming that it couldn't start again if we disappeared all extant life.
Quote:2. Even if life could start under today's conditions, it would be snuffed out by life itself. So presumably the steps leading from lifeless chemicals to cellular life forms would be recognised by other life forms and the prebiotic forms eaten? No prospective life form could possibly escape this fate?
There could be competition for resources that might rule out the new kids on the block.
Quote:3. The earth would have to return to primordial conditions even though we are not sure what they were. For example, one popular theory is that life could have started in the deep ocean around hydrothermal vents. But hang on - we still have such vents. Exactly what is to prevent abiogenesis happening around them right now?
Competition from other organisms living around the vents?
This is a complex issue. I certainly make no claim to have a definitive answer.
~~ Paul
(2017-12-07, 02:47 AM)Paul C. Anagnostopoulos Wrote: [ -> ]What does the frozen accident hypothesis have to do with being a religious nut? He might simply be wrong. If Wills and Carter are right, it's no accident.
No. Perhaps the Earth had to be warmer. Perhaps a fortuitous piece of space material landed on the Earth. Perhaps there is too much competition. Anyway, I'm not claiming that it couldn't start again if we disappeared all extant life.
There could be competition for resources that might rule out the new kids on the block.
Competition from other organisms living around the vents?
This is a complex issue. I certainly make no claim to have a definitive answer.
~~ Paul
Religious nut seems to be the go-to accusation around here but, no, of course there is no reason to suppose that Crick, right or wrong, had religious motives. I wish that some of the Darwin doubters were given similar latitude.
The rest of you post is not very convincing as, I think, you concede.
(2017-12-07, 01:30 AM)Paul C. Anagnostopoulos Wrote: [ -> ]Hang on. The peptides are generated at random, but some are useful and some are not. So the chemical processes that produce the useful ones remain and the other processes disappear. So over time, various processes stick around.
Sorry, I didn't mean to suggest that the processes are completely uniformly random. That is confusing. There would be various chemical processes, some producing useful products and some not. There would have to be some way to "hang onto" the useful ones and ignore the useless ones. That rudimentary system is subject to natural selection.
The question is, how does the system hang onto the useful products? Check out the next post for one possibility.
Who says there were modern ribosomes when the 3-base code evolved? Perhaps there was a proto-ribosome that stepped along the RNA by 3 bases but paid attention to only 2 of them. Again, see the next post.
~~ Paul
If the odd 'useful' molecule is generated, there isn't any way to select it (unless perhaps there is an intelligent observer
) this is the real core of the problem.
I'll take a look at the second paper you cited, but I obviously can't comment on it immediately:
https://www.biorxiv.org/content/biorxiv/...9.full.pdf
[url=https://www.biorxiv.org/content/biorxiv/early/2017/05/17/139139.full.pdf][/url]
If you have digested this paper, or the other one that derives rate equations, you could do everyone a favour by summarising the steps that are being proposed to get to the genetic code, or anything else that is revealed in them.
Your idea of a 2-base reader that conveniently always skips the third base is ingenious, but I must say that would be an extraordinarily lucky accident (an act of God perhaps) for such a system to arise. Note also that if the third base was irrelevant, suddenly giving it meaning would still do enormous damage to an existing genome.
One problem I have with this, is that there is an unfortunate tendency to assume that any intelligence is omniscient - basically because people think of God. That doesn't need to be true, and if the intelligence is finite there are more interesting possibilities.
A finite intelligence may need to experiment to produce some desired result.
Maybe a finite intelligence really did assemble a 2-base reader that skipped the third base (just in case it became useful).
Think of native people in a jungle. They acquire knowledge about the many plants that surround them. They say that some of that knowledge is acquired from dreams and visions (maybe rather as Ramanujan acquired some of his mathematical ideas). The trouble is in these discussions, that one side sees an acceptance of ID as being total defeat, so they use none of their ingenuity in exploring exactly what finite intelligence might be doing. J. Scott Turner makes a good case that purposeful action (intelligence?) operates all the way through biology. You can see that even in single cell macrophages chasing down their prey. I think it is an intelligence of that sort that might have been operating even mack in the pre-biotic era. Of course, such an intelligence would not have to be supported by life, but by an existence in another realm - the same realm that people seem to re-enter when they have an NDE (my thought, not JST's).
David
(2017-12-07, 03:06 AM)Kamarling Wrote: [ -> ]Religious nut seems to be the go-to accusation around here but, no, of course there is no reason to suppose that Crick, right or wrong, had religious motives. I wish that some of the Darwin doubters were given similar latitude.
Some would be if they didn't have a history of being religiously motivated and also bad at math. The problem is that there is no research program in Intelligent Design. Look at the sparsity of papers:
https://www.discovery.org/id/peer-review/
Here is the 2017 volume of
BIO-complexity, the ID journal:
http://bio-complexity.org/ojs/index.php/...ue/current
Quote:The rest of you post is not very convincing as, I think, you concede.
I do; how could I know? Eventually we might reproduce the start of life in the lab. It's also possible that there are places where it is starting up again, but how would we know? We certainly aren't going to see a parallel ecosystem develop.
~~ Paul
DaveB Wrote:If the odd 'useful' molecule is generated, there isn't any way to select it (unless perhaps there is an intelligent observer ) this is the real core of the problem.
Why isn't there any way to select it? Is the environment out to lunch? Perhaps you mean there isn't any way to create a gene for it.
Quote:If you have digested this paper, or the other one that derives rate equations, you could do everyone a favour by summarising the steps that are being proposed to get to the genetic code, or anything else that is revealed in them.
I read through page 10 last night. It's a long, slow read and the authors are murky writers. The idea centers around an ancestral gene that codes for one end of the tRNA synthetase when translated in one direction and the other end when translated in the opposite direction. The system starts out with only two amino acids, one in synthetase class I and the other in class II. It bifurcates from there. The evidence includes much highly technical chemistry. It does rely on an ancestral gene translation system.
I'll report back when I get through the paper.
Quote:Your idea of a 2-base reader that conveniently always skips the third base is ingenious, but I must say that would be an extraordinarily lucky accident (an act of God perhaps) for such a system to arise. Note also that if the third base was irrelevant, suddenly giving it meaning would still do enormous damage to an existing genome.
It's not my idea.
Quote:One problem I have with this, is that there is an unfortunate tendency to assume that any intelligence is omniscient - basically because people think of God. That doesn't need to be true, and if the intelligence is finite there are more interesting possibilities. A finite intelligence may need to experiment to produce some desired result.
I'm willing to listen to all sorts of squirming about how the ID did the job. Then problem is that there is no research program to discover this and I very much doubt there ever will be.
Quote:They say that some of that knowledge is acquired from dreams and visions (maybe rather as Ramanujan acquired some of his mathematical ideas). The trouble is in these discussions, that one side sees an acceptance of ID as being total defeat, so they use none of their ingenuity in exploring exactly what finite intelligence might be doing.
As far as I can tell, it is a total defeat. Saying that an ID did it is like saying "I don't know and I dont care." Nevertheless, it's the job of the folks making the ID hypothesis to do the research program. There is no research program, because there is no concrete evidence with which to get started. There is no way to bootstrap. So it's not much more than an appeal to probability by people who aren't particularly good at math.
~~ Paul
(2017-12-07, 01:09 PM)Paul C. Anagnostopoulos Wrote: [ -> ]Why isn't there any way to select it? Is the environment out to lunch? Perhaps you mean there isn't any way to create a gene for it.
Let's focus for a bit on this idea that a molecule would be selected for out of random chemistry.
Can you elaborate on what that would consist of, in the absence of any living cells.
If I had a test tube of residual 'tar' after running an organic chemistry reaction, how would such a molecule become apparent?
David
(2017-12-07, 05:19 PM)DaveB Wrote: [ -> ]Let's focus for a bit on this idea that a molecule would be selected for out of random chemistry.
Can you elaborate on what that would consist of, in the absence of any living cells.
If I had a test tube of residual 'tar' after running an organic chemistry reaction, how would such a molecule become apparent?
David
I'd like to know why you phrase the question in such as way as to imply intelligence of any sort is at work?
(2017-12-07, 12:56 PM)Paul C. Anagnostopoulos Wrote: [ -> ]Some would be if they didn't have a history of being religiously motivated and also bad at math. The problem is that there is no research program in Intelligent Design. Look at the sparsity of papers:
https://www.discovery.org/id/peer-review/
Here is the 2017 volume of BIO-complexity, the ID journal:
http://bio-complexity.org/ojs/index.php/...ue/current
I do; how could I know? Eventually we might reproduce the start of life in the lab. It's also possible that there are places where it is starting up again, but how would we know? We certainly aren't going to see a parallel ecosystem develop.
~~ Paul
There are some prominent
doubters of Darwinism who are not religious and there are probably many more who would rather keep their jobs than voice their doubt.
As for research and peer review, it seems to me that for peer review to work, there should be peers with an unbiased approach. This is an old complaint about peer review when it comes to anything outside - or at the fringes - of orthodoxy. Peer review is effectively cut off at the outset because ID is deemed to be not scientific, therefore not eligible for scientific review. Not scientific because most scientists adhere to methodological naturalism, as defined here by Keith Augustine:
Quote:Methodological naturalism, by contrast, is the principle that science and history should presume that all causes are natural causes solely for the purpose of promoting successful investigation. The idea behind this principle is that natural causes can be investigated directly through scientific method, whereas supernatural causes cannot, and hence presuming that an event has a supernatural cause for methodological purposes halts further investigation.
ID proposes an intelligent agent which, as David suggested above, might be considered to be beyond what scientists deem to be natural (part of the physical world). If science must be restricted to materialism (as Lewontin and others maintain) then ID will never be accepted as science, therefore never accepted for peer review. The people at the DI might put forward a few papers that challenge neo-darwinism but don't directly violate naturalism but any inference to an intelligent agent would have to be avoided.
I can't see a way around this impasse. It is a matter of base assumptions and it seems to me that the scientific community has, for the most part, decided a philosophical question and ordained that materialism is absolute and incontestable.
(2017-12-07, 05:19 PM)DaveB Wrote: [ -> ]Let's focus for a bit on this idea that a molecule would be selected for out of random chemistry.
Can you elaborate on what that would consist of, in the absence of any living cells.
If I had a test tube of residual 'tar' after running an organic chemistry reaction, how would such a molecule become apparent?
David
There would be some sort of proto-organism. Perhaps a bag of chemicals with a simple membrane. Perhaps a group of tightly bound molecules that were difficult to separate. If these organisms could replicate, then some kind of rudimentary selection would occur. Note that no genes are required in the conventional sense.
But, again, I make no claim to understand how things started. If I did, I'd be a famous biologist.
~~ Paul