I missed the “most” because I thought I was reading a response by someone else. Following some of these threads is like being lost in a maze of twisty little passages.
[quote=“Bill_II, post:105, topic:35086”]
I missed the “most” because I thought I was reading a response by someone else. Following some of these threads is like being lost in a maze of twisty little passages.
[/quote]Hooray! It works! Now who’d have guessed that? Anyway, I agree with Bill_II - at least the bit about the ‘maze of twisty little passages’!
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Which ones? I don’t know of any.
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Neither did I until I saw William DJ’s claim and ran off to Google it.
William DJ’s link to the Nobel Academy gives us: “Given the size of the human genome and the large number of cells in a human body (about 3.7 × 1013) mistakes will inevitably accumulate during the lifetime of an individual. Most of these errors will remain silent, but they can also cause serious diseases.”
Wikipedia (Mutation) goes for “Naturally occurring oxidative DNA damages arise at least 10,000 times per cell per day in humans and 50,000 times or more per cell per day in rats.”
A nature.com article called ‘DNA Replication and Causes of Mutation’ gives: “[DNA polymerase] enzymes do make mistakes at a rate of about 1 per every 100,000 nucleotides. That might not seem like much, until you consider how much DNA a cell has. In humans, with our 6 billion base pairs in each diploid cell, that would amount to about 120,000 mistakes every time a cell divides!”
A paper on the American Journal of Clinical Nutrition website (‘Why and how should we measure oxidative DNA damage in nutritional studies?’ by Barry Halliwell) says: “Estimates suggest an average of at least a few hundred “oxidative hits” per day on the DNA of each of the ≈5 × 1013 cells in the human body” for which he gives two further sources.
I dare say one could find many more.
Before we start arguing at cross-purposes, however, it is obvious that the vast majority of these mistranscriptions are repaired, and by some definitions only those which are not repaired can properly be called mutations at all. I only mentioned the others because it seemed to be William DJ’s argument at the top of the thread that every one of the mistranscriptions is repaired, and that none of them ‘survive’ to become the kind of mutation that could cause harm or benefit - or evolution.
Your sources mention DNA damage and mistranscription, not mutation. The DNA damage or mistranscription can result in mutations, but they are not mutations themselves. Please read this to learn the difference between damage and mutation.
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Yes, I know. The difference is largely semantic and different dictionaries differ in nuance. If a mistranscription is not corrected, then it can be passed on by subsequent replication. The exact point at which it stops being a mistranscription and becomes a mutation does not alter its nature, only its name. William DJ, to whose comments I have been continuously referring, said: “In every cell, every day hundreds of thousands of mutations of the DNA occur, which are fortunately largely repaired by mutation repair mechanisms”, so I have continued to use his terminology. Similarly, the word “damage” is open to interpretation, and largely subjective. If damaged DNA leads to the increased reproductive success of its organism, is it really damaged?
But it isn’t just semantic. You can’t point to DNA damage and mistranscription and claim that’s actually mutation.
That is the problem; his terminology is wrong.
No, it really isn’t. If it was, then talk of “DNA repair” would be meaningless.
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Words, eh? I think we both understand each other, so that’s OK by me.
No, your writing suggests conceptual confusion. It’s not “semantic” to point to the difference between DNA replication errors (“mistranscription” isn’t even about DNA – you should look up ‘transcription’) and mutations. As you seem to understand, DNA replication errors are corrected by proofreading machinery. Some tiny number escape proofreading and become permanent, and those are mutations. As I hope you know, there are several other modes of mutation that don’t have anything to do with copying errors.
If your point is that William DJ is wrong about mutations, great, but your writing is muddled enough that it looks like you don’t understand the basic biological concepts. I’m always glad to recommend some basic reading to get you started.
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And mention that there are some great online courses available (free or cheap).
No. Not correct.
I was not attempting to make any comment at all about alleles. I was discussing a single point about mutations. And so when Ben started criticizing me and my post, I asked a simple question to see how Ben would answer it. It was evidence enough that Ben and I are not really suited to discuss together or to share our little evolutionary gossip with each other.
I certainly prefer your description over Ben’s:
I doubt if Ben could ever be happy using those words himself. But as we all know, miracles do happen.
[quote=“sfmatheson, post:113, topic:35086”]“mistranscription”[/quote]Sorry; yes of course you’re right - a senior moment. As to the rest, yes, that’s fine too.[quote=“sfmatheson, post:113, topic:35086”]Some tiny number escape proofreading and become permanent, and those are mutations.[/quote]That’s just what I meant. Thank you for clarifying.[quote=“sfmatheson, post:113, topic:35086”]your writing is muddled enough that it looks like you don’t understand the basic biological concepts.[/quote]I’m sorry you found it so. I hope it was clear enough for others. And if it wasn’t - well, thanks again for your assistance.
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It’s evidence that you lack a basic understanding of evolution, as shown by this nonsensical assertion:
Mutations create new alleles, so they necessarily have a lot to do with alleles. You don’t seem to grasp this basic fact.
How does “. . . evolutionary change typically relies on standing (i.e. previously-existing) genetic variation, as opposed to just-in-time mutation,” differ from "… evolutionary mechanisms operate far more on existing variation than they do on new variation’?
I don’t see any difference.[quote=“gbrooks9, post:116, topic:35086”]
I doubt if Ben could ever be happy using those words himself.
[/quote]
I’m perfectly fine using those words myself.
In other news, you denied this when you described evolution to Greg, who predictably seized on mutation, instead of seeing that selection works primarily on existing variation.
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Ben spends way too much time arguing with people he doesn’t have to argue with … about things he doesn’t have to argue about.
[EDITS TO POSTING]
Maybe it would help to re-post the very beginning of Ben’s concern for my well-being. I wrote a post supportive of Ben in his discussion with WilliamDJ:
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[Post #56 by GBrooks9 (approx 7 days ago)]
Don’t get sucked into a useless semantic gambit. It doesn’t matter whether genetic molecules do or don’t suffer damage and are repaired. That is irrelevant to the important issues.
All evolutionary science is based on the idea that perfect replication of chromosomes would yield virtually no mutations.
Some populations have survived because they have cells with less perfect powers of genetic replication… otherwise, the population (never changing) might have been wiped out by environmental factors that their original genetics were not capable of handling.
@WilliamDJ is investing all this effort in discussing Distinctions that do not produce a Difference!
[END OF POST]
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Reply from benkirk
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Quote from gbrooks9:
Some populations have survived because they have cells with less perfect powers of genetic replication… otherwise, the population (never changing) might have been wiped out by environmental factors that their original genetics were not capable of handling.
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Hello George,
I’m sorry, but you’re just as confused as William, but in a different, far more common way.
As I’ve explained to you before, evolutionary mechanisms operate far more on existing variation than they do on new variation. William promotes a false dichotomy, while you have yet to grasp the teeny-tiny ratio of new variation to existing variation.
If you disagree, perhaps you could name some of those alleged populations that you so vaguely cited?
Then I’ll cite those that are endangered because their genetic polymorphism is low. They can’t be rescued by new mutations.
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GBrooks9 Quote: "@WilliamDJ is investing all this effort in discussing Distinctions that do not produce a Difference!
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No, he’s discussing distinctions that simply aren’t true.
[END OF QUOTE]
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New Post by gbrooks9
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Quote from benkirk:
As I’ve explained to you before, evolutionary mechanisms operate far more on existing variation than they do on new variation. William promotes a false dichotomy, while you have yet to grasp the teeny-tiny ratio of new variation to existing variation.
If you disagree, perhaps you could name some of those alleged populations that you so vaguely cited?
Then I’ll cite those that are endangered because their genetic polymorphism is low. They can’t be rescued by new mutations.
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The problem here is that you like to pick too many fights in any given post. I was restricting my discussion PURELY to genetic mutations… (not evolution of a population by means of changes in allele ratios).
I’ve already heard your sp[i]el on allele ratios. And that’s why I very carefully avoided making any references to something that you might interpret as that. And yet … you still manage to do it.
I wrote 3 paragraphs:
[1] It doesn’t matter whether genetic molecules do or don’t suffer damage and are repaired. That is irrelevant to the important issues.
^ No mention of alleles here. And presumably you don’t find anything unacceptable in that sentence.
[2] All evolutionary science is based on the idea that perfect replication of chromosomes would yield virtually no mutations.
^ I suppose you could argue this point … but I’m not trying to say mutations are more important than changes in allele ratios… I’m merely pointing out that if all the first single celled animals never experienced genetic mutations… there would still only be single celled life. Would you agree with that? Or do you really think we could get a whale out of a single celled life form by juggling the existing alleles of a single celled animal a billion years ago?
And finally, [3]:
Some populations have survived because they have cells with less perfect powers of genetic replication… otherwise, the population (never changing) might have been wiped out by environmental factors that their original genetics were not capable of handling.
^ Ben, do I really need to name a specific example of a life form that whose genes were too stable to adapt to their changing environment, Won’t Terror Birds do? They became extinct, and most scientists think it was because of the merger of the North and South continents, which allowed brand new predators from the north to compete with the Terror Birds of South America - - competing for declining food stocks, or directly predating on their chicks. Terror Birds left no successor population (that we know of). So… not enough changes (in alleles OR in mutations) to save the future of the entire population. Isn’t that a pretty clear example?
Ben, all you really had to think about was my last sentence: “@WilliamDJ is investing all this effort in discussing Distinctions that do not produce a Difference!” And you agreed with that.
George B.
[END OF POST]
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And the rest is history …
No, what would help is this: stop posting at all so that this utterly inane “conversation” can end with some shred of your credibility intact.
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Of course you realize that your innuendo that my credibility is not intact is counter-productive, yes?
First, it’s allele frequencies, not ratios.
Second, mutations create new alleles. Whether you’re using the word or not, the concepts (which you clearly don’t understand) are inseparable. Again, you repeatedly ignore the far greater role that existing differences, recombination, etc. play in Darwinian evolution. Here’s an example:
ONLY WHEN, eh? Please explain why recombination can’t divide one part of a population from another part.
One of the classic signs that a conversation should be closed is that we are talking about talking about talking. Which is definitely happening here.
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