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You see the difference between this argument and what you wrote above though? Perhaps I'm reading your original post too strongly, so please correct me if so.

by Cogito 6y ago

You see the difference between this argument and what you wrote above though? Perhaps I'm reading your original post too strongly, so please correct me if so. In the first post you compare the number of valid DNA chains to the space of all possible chains, you mention the number of different proteins in the human body, and you draw an analogy to a random sequence of bits forming a valid program. None of these talk to the probability of a reproducing molecule arising through physical processes, nor do they talk to the probability of DNA as a descendant of that original reproducing molecule (or potentially multiple original molecules). I get that you understand the gaps in our knowledge of how these systems came to be; my point is that your original argument is misleading in the exact same way you claim the argument "Billion of years passed since the Big Bang. If some chemical process can create life it's very likely that somewhere it did." is a "kind of hand-wavey statement [that] seems to convince most people. Universe is hella-old, and really big. Ergo, incredibly rare stuff has happened basically infinitely many times. Life everywhere, etc." (this was a reply to a different post, but I think it holds to the comment you originally replied to). In fact, I find the argument that "things reproduce, and have been reproducing for a long time in a large environment, so we expect to see complexity in those things" much more reasonable than "most random arrangments of this molecule are useless, and we can see lots of useful arrangements, therefore time and randomness can't explain them".

erichocean 6y ago
We're discussing how to get those "things that reproduce" in the first place. I agree that once you have useful things that reproduce, it's easy to keep it going. Similarly, if I have a running copy of Linux, I can use the tools (and source code) to produce another copy of Linux. But how do we get the first copy, the "original reproducing molecule" as you put it? The usual explanation is that the "first copy" arose randomly, and then kept going. Do you believe that? I suspect not—but most people do. We know that it can't have been random (which is the argument I gave, and I suspect you agree with). We should tell people "it wasn't random, something about the fundamental nature of these molecules caused better and more complex molecules to emerge." But we have no mechanism for that, just a (valid) belief that it has to be true. I think we should find those mechanisms, and simultaneously, stop telling people that random chance + vast universe + long timespan is sufficient.
- Cogito 6y ago
  > The usual explanation is that the "first copy" arose randomly, and then kept going. Do you believe that? I believe a variation of that. I believe that the first copy arose through physical processes. Evoking 'randomness' is unnecessary and misleading. Do you not believe this? To my knowledge, we don't yet have a mechanism for how such a molecule came in to being (though there are ideas). We also don't have any reason to think that it must be some random single choice from a large possibility space, and we don't have any evidence at all that it could have arisen from non-physical processes (what would that even look like?).
  - erichocean 6y ago
    This is what I mean by random: no DNA sequence is privileged over any other, and no (known) physical process produces anything but random DNA sequences (excluding, of course, copying already useful DNA sequences). DNA has about as much structure as bits on a disk (with coding for one of 20 amino acids as the "bits"). No DNA sequence is more likely than any other to exist. I think that means we need to identify strong physical processes that produce useful DNA strands; you, apparently, aren't as concerned about it. Maybe you're right, but from where I'm sitting, it's hard to imagine what those physical processes might be since the strands they must produce are extremely, unimaginably rare in practice. DNA is basically information[0], and we literally have no example of a chemical process producing valid DNA information, nor is it all obvious how such a process might work in practice. In the past, large amounts of time + equal likelihood of producing random DNA was considered sufficient to think "well, useful DNA stands could appear randomly." We now know that's extremely unlikely to the point of being effectively impossible, statistically-speaking. [0] https://www.nature.com/scitable/topicpage/dna-is-a-structure-that-encodes-biological-6493050/ https://www.nature.com/scitable/topicpage/dna-is-a-structure...
    - Cogito 6y ago
      But some DNA sequences are privileged over others! The mechanisms for producing new DNA sequences involves copying existing DNA sequences. Thus, the ones that exist are privileged over the ones that do not exist (yet), and the adjacent sequences are privileged over a random sequence. > No DNA sequence is more likely than any other to exist. It is far more likely for a DNA sequence very similar to my own to exist than a random sequence. > we need to identify strong physical processes that produce useful DNA strands We have already identified those processes! We know quite well how the machinery of DNA replication works. If we care about the first DNA molecule to ever exist it's a very different question. We don't need to find a physical process that produces a modern DNA molecule from 'raw parts', rather one that takes not-quite-DNA and converts it into DNA. > it's hard to imagine what those physical processes might be since the strands they must produce are extremely, unimaginably rare in practice. Can you imagine slightly simpler DNA? Say just a bit shorter? What's the simplest molecule we might still call DNA, that is reproducing? Can we imagine machinery that would produce that? I think it's very reasonable to think such machinery could exist, even if we don't know the exact mechanisms involved. We know that RNA can self-reproduce, and also produce proteins, so it's reasonable to think that machinery to produce RNA strands could evolve to produce DNA strands (for example). The only involvement randomness has in this whole process are (relatively) rare and infrequent changes to self-replicating molecules, and (potentially) the initial formation of a self-replicating molecule. It is irrelevant how many possible DNA sequences there are, or how much information is stored within them, as we know new sequences are derived from previous ones.

by Cogito 6y ago

erichocean 6y ago

We're discussing how to get those "things that reproduce" in the first place. I agree that once you have useful things that reproduce, it's easy to keep it going. Similarly, if I have a running copy of Linux, I can use the tools (and source code) to produce another copy of Linux. But how do we get the first copy, the "original reproducing molecule" as you put it? The usual explanation is that the "first copy" arose randomly, and then kept going. Do you believe that? I suspect not—but most people do. We know that it can't have been random (which is the argument I gave, and I suspect you agree with). We should tell people "it wasn't random, something about the fundamental nature of these molecules caused better and more complex molecules to emerge." But we have no mechanism for that, just a (valid) belief that it has to be true. I think we should find those mechanisms, and simultaneously, stop telling people that random chance + vast universe + long timespan is sufficient.

Cogito 6y ago
> The usual explanation is that the "first copy" arose randomly, and then kept going. Do you believe that? I believe a variation of that. I believe that the first copy arose through physical processes. Evoking 'randomness' is unnecessary and misleading. Do you not believe this? To my knowledge, we don't yet have a mechanism for how such a molecule came in to being (though there are ideas). We also don't have any reason to think that it must be some random single choice from a large possibility space, and we don't have any evidence at all that it could have arisen from non-physical processes (what would that even look like?).
- erichocean 6y ago
  This is what I mean by random: no DNA sequence is privileged over any other, and no (known) physical process produces anything but random DNA sequences (excluding, of course, copying already useful DNA sequences). DNA has about as much structure as bits on a disk (with coding for one of 20 amino acids as the "bits"). No DNA sequence is more likely than any other to exist. I think that means we need to identify strong physical processes that produce useful DNA strands; you, apparently, aren't as concerned about it. Maybe you're right, but from where I'm sitting, it's hard to imagine what those physical processes might be since the strands they must produce are extremely, unimaginably rare in practice. DNA is basically information[0], and we literally have no example of a chemical process producing valid DNA information, nor is it all obvious how such a process might work in practice. In the past, large amounts of time + equal likelihood of producing random DNA was considered sufficient to think "well, useful DNA stands could appear randomly." We now know that's extremely unlikely to the point of being effectively impossible, statistically-speaking. [0] https://www.nature.com/scitable/topicpage/dna-is-a-structure-that-encodes-biological-6493050/ https://www.nature.com/scitable/topicpage/dna-is-a-structure...
  - Cogito 6y ago
    But some DNA sequences are privileged over others! The mechanisms for producing new DNA sequences involves copying existing DNA sequences. Thus, the ones that exist are privileged over the ones that do not exist (yet), and the adjacent sequences are privileged over a random sequence. > No DNA sequence is more likely than any other to exist. It is far more likely for a DNA sequence very similar to my own to exist than a random sequence. > we need to identify strong physical processes that produce useful DNA strands We have already identified those processes! We know quite well how the machinery of DNA replication works. If we care about the first DNA molecule to ever exist it's a very different question. We don't need to find a physical process that produces a modern DNA molecule from 'raw parts', rather one that takes not-quite-DNA and converts it into DNA. > it's hard to imagine what those physical processes might be since the strands they must produce are extremely, unimaginably rare in practice. Can you imagine slightly simpler DNA? Say just a bit shorter? What's the simplest molecule we might still call DNA, that is reproducing? Can we imagine machinery that would produce that? I think it's very reasonable to think such machinery could exist, even if we don't know the exact mechanisms involved. We know that RNA can self-reproduce, and also produce proteins, so it's reasonable to think that machinery to produce RNA strands could evolve to produce DNA strands (for example). The only involvement randomness has in this whole process are (relatively) rare and infrequent changes to self-replicating molecules, and (potentially) the initial formation of a self-replicating molecule. It is irrelevant how many possible DNA sequences there are, or how much information is stored within them, as we know new sequences are derived from previous ones.