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Author Topic:   Is Earth old enough for DNA to evolve?
bcoop
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From: Maine
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 Message 1 of 60 (668086) 07-17-2012 4:15 AM

Thank you for considering my post. I have revised it to eliminate the reference and replace it with a general statement of my own. That should eliminate this issue and still allow the conversation to continue. Here is the revised post:

Short question or statement: There is not enough time available in the acknowledged age of the earth for the human genome to have formed. The hypothesis is that the math doesn’t work for DNA to have developed because the earth isn’t old enough.

Basis:

1. The acknowledged age of the earth is about 4.5 billion years, with the simplest life forms arriving only 2 billion years ago.

2. The human genome has approximately 3 billion base pairs of DNA arranged into 46 chromosomes.

3. Evolutionary theory holds that the human genome developed through a series of DNA replication errors.

4. The base pairs are the building blocks of DNA. If I follow evolutionary theory correctly, if there are 3 billion base pairs then it took 3 billion replication errors to arrive at the current DNA structure ( unless multiple simultaneous positive replication errors occurred).

5. If there was a successful DNA replication error each generation then it would take 3 billion reproductive generations to arrive where we are today.

Problems:

a. 3 billion generations would take 60 billion years if each female reproduced at the age of 20.
b. It is stated that life on earth is only 2 billion years old.
c. It would take longer if any of the errors were not advantageous. Most replication errors are not advantageous.
d. This assumes that each and every mutation was the exact necessary mutation needed in the right order. Each block of the genome has to be built in the right order. ( You don’t need the lens of the eye before the optic nerve exists for example).
e. It also assumes that each generation got the opportunity to successfully reproduce and didn’t die first or something.
f. The replication error of a single base pair out of the 3 billion pairs can result in a genetically transmitted disease. We need 3 billion positive consecutive errors with no negative errors along the way, or it would take even longer.
g. There is no provision at all here for natural selection because that would exponentially add much more time.

6. I am sure this has been studied and discussed – can you point me to literature or web sites where I can read about this issue?

{Note: This message 1 is message 6 of the "Proposed New Topics" version of this topic - Adminnemooseus}

Edited by Adminnemooseus, : Red note.

 Replies to this message: Message 2 by Minnemooseus, posted 07-17-2012 4:27 AM bcoop has responded Message 3 by Dr Adequate, posted 07-17-2012 5:26 AM bcoop has responded Message 4 by caffeine, posted 07-17-2012 6:00 AM bcoop has responded Message 5 by Panda, posted 07-17-2012 6:05 AM bcoop has responded Message 6 by PaulK, posted 07-17-2012 8:25 AM bcoop has responded Message 29 by Tangle, posted 07-17-2012 4:08 PM bcoop has responded

Minnemooseus
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 Message 2 of 60 (668088) 07-17-2012 4:27 AM Reply to: Message 1 by bcoop07-17-2012 4:15 AM

Generation lengths bogus
The advantage of me promoting the topic is that I get first whack. I'm just going to whack one item.

 a. 3 billion generations would take 60 billion years if each female reproduced at the age of 20.

In the great chain of evolution, generation lengths have not been constant. First of all, for a long time reproduction was asexual. Early life forms may have had "generation" lengths measured in minutes.

Not remotely a biologist - Others can correct me and/or elaborate on this.

Moose

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 (5)
 Message 3 of 60 (668092) 07-17-2012 5:26 AM Reply to: Message 1 by bcoop07-17-2012 4:15 AM

 4. The base pairs are the building blocks of DNA. If I follow evolutionary theory correctly, if there are 3 billion base pairs then it took 3 billion replication errors to arrive at the current DNA structure ( unless multiple simultaneous positive replication errors occurred).

You've not followed evolutionary theory correctly. There are plenty of known mechanisms that increase the length of the genome other than single nucleotide insertions. This alone completely ruins your argument.

 a. 3 billion generations would take 60 billion years if each female reproduced at the age of 20. It is stated that life on earth is only 2 billion years old.

I don't think you've thought about this very carefully. HUmans may have a generation time of ~20 years; but you're trying to talk about the whole evolutionary process from single-celled organisms onwards. Prokaryotes, for example, typically have generation times of between 1 and 3 hours. A single-celled eukaryote, such as yeast, 90 minutes. This is something you'd have to take into account.

 b. It would take longer if any of the errors were deleterious and not advantageous.

Again, you haven't thought this through.

Remember, a mutation is something that happens in the first place to an individual and not a population. So long as there are beneficial mutations coming along and being fixed by natural selection at the necessary rate (whatever that is) it doesn't matter how many deleterious mutations are coming along and being removed by natural selection.

 (In summary, it is generally accepted that the majority of mutations are neutral or deleterious, with rare mutations being advantageous.

Do bear in mind that a neutral mutation which made the genome longer can go on to be fixed by genetic drift just as a beneficial one can be fixed by natural selection. Since your argument relates to the length of the genome rather than its function, you can't discount neutral mutations.

 c. This assumes that each and every mutation was the exact necessary mutation needed in the right order.

Not really. A mutation in the wrong order would not be beneficial. Once we've noted that not all mutations are beneficial, the point doesn't need making twice.

 d. It also assumes that each generation got the opportunity to successfully reproduce and didn’t die first or something.

Well, since life is still here, this would appear to be a valid "assumption". If, by analogy, I was to try to estimate the time it took for you to type your post, I should do so under the "assumption" that when you wrote it you were not dead. It is true that if you were then your typing speed would drop to zero, but I can be fairly sure that you weren't.

Of course, some things did go extinct, but we know that none of our ancestral species went extinct, because here we are.

 e. The replication error of a single base pair out of the 3 billion pairs can result in a genetically transmitted disease. We need 3 billion positive consecutive errors with no negative errors along the way.

See the answer to b. There were doubtless lots of negative errors along the way. The proportion of them that got fixed in the gene pool must have been tiny; also, it has nothing to do with your argument, which is about the size of the genome. Perhaps we do have some deleterious mutations fixed in our gene pool. What of it?

 f. There is no provision at all here for natural selection

And that's only one of the things that is wrong with your argument. Yes, you left natural selection out of an atempt at analyzing an evolutionary process, thus leading to several of your more egregious errors. Next time, try leaving it in.

 6. I am sure this has been studied and discussed – can you point me to literature or web sites where I can read about this issue?

Or just textbooks.

If you don't know that there are mutations other than single nucleotide insertions that increase the length of a genome, then you haven't really tried to understand the basics, have you? You could have gotten hold of a book called something like Introduction To Genetics and read it, but you didn't, did you?

Now, don't get me wrong, I like your style. It's a nice try. Only ... you're basing your argument not on facts that scientists have discovered, but on things that you vaguely think are true but you can't really say where you got your "facts" from. Every time I do that, I make a fool of myself --- and just 'cos you think God is on your side ... well, God won't save you from making mistakes.

---

Let me give you a non-religious example. I talked with a woman who was going to completely destroy the idea that bad diet is a major cause of heart disease. Her argument was that the people of New Guinea have more heart disease than anywhere in the world, and they don't eat a western diet.

A couple of minutes with google would have been her friend. The people of New Guinea have the unhealthiest diet in the world, they shovel down corned beef and buffalo wings like there's no tomorrow. They eat fat and salt like there's no tomorrow ... which in many cases there isn't.

Before she cited her "fact" she should have made sure that it was a fact. Otherwise her argument might have convinced her, and it might have convinced people ignorant of the facts, but it's never going to convince people who know the facts.

---

You've got to get it right. I'm not closed-minded, maybe if you try really hard to debunk evolution you will succeed. I'm rooting for you. But you have to do so with respect to real facts that are actually true, not by appealing to stuff that you kind of think that you're fairly sure that you've heard somewhere.

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caffeine
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 Message 4 of 60 (668095) 07-17-2012 6:00 AM Reply to: Message 1 by bcoop07-17-2012 4:15 AM

 1. The acknowledged age of the earth is about 4.5 billion years, with the simplest life forms arriving only 2 billion years ago.

This bit isn't an important, but I thought I'd correct it in the interested of accuracy. Life on Earth is estimated to be almost twice as long as that. It's difficult to tell, because there aren't so many rocks remaining from the distant past to find traces of life in, and when the life you're looking for is simple, single-celled organisms, it's hard to identify exactly when you've found it. Clear evidence of microbes has been found from about 2.7 billion years ago, and controversial evidence goes as far back as 3.4 billion. The consensus is that the earliest life arose somewhere between 3 and 4 billion years ago.

Now, on to some of the more important mistakes!

Dr. Adequate already alluded to this, but you're framing this question all wrong. You seem to be thinking about only one organism having these mutations, but there is a lot more than one organism out there. To take one arbitrary example, one study of Lake Mendota in Wisconsion, estimated the density of heterotrophic bacteria to be between 300,000 and 3,000,000 per ml, depending on season. The volume of Lake Mendota is approximately 505 million cubic metres. Taking the lower range of bacterial density, that means about 151,500,000,000,000,000,000 bacteria in the lake.

Now, in favourable conditions, some bacteria can produce a new generation in a few minutes, but even allowing for a much longer (arbitrarily chosen) average generation time of 12 hours, you're still talking about 606 trillion new bacteria produced every day. And each new bacterium will carry more than one mutation.

This is why natural selection is important, despite your dismissal of it as taking too long. Natural selection is simply the process by which, out of the trillions and trillions of mutations that happen in this single lake every day, the deleterious ones are eliminated.

Time doesn't look a problem to me, here.

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Panda
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 (1)
 Message 5 of 60 (668096) 07-17-2012 6:05 AM Reply to: Message 1 by bcoop07-17-2012 4:15 AM

 bcoop writes:Problems:a. 3 billion generations would take 60 billion years if each female reproduced at the age of 20.b. It is stated that life on earth is only 2 billion years old.

I think if you answer these questions you will see one of the the flaws in your argument...

Q: How many people are alive today?

Q: How many children were born in the 200,000 years since homo sapiens evolved?

CRYSTALS!!

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PaulK
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 (1)
 Message 6 of 60 (668100) 07-17-2012 8:25 AM Reply to: Message 1 by bcoop07-17-2012 4:15 AM

quote:

4. The base pairs are the building blocks of DNA. If I follow evolutionary theory correctly, if there are 3 billion base pairs then it took 3 billion replication errors to arrive at the current DNA structure ( unless multiple simultaneous positive replication errors occurred).

The issue you raise here is length. Evolutionary theory does not claim that the genome increases in length by a single base at a time. A single gene duplication event would typically add thousands of bases.

quote:

5. If there was a successful DNA replication error each generation then it would take 3 billion reproductive generations to arrive where we are today.

Problems:

a. 3 billion generations would take 60 billion years if each female reproduced at the age of 20.
b. It is stated that life on earth is only 2 billion years old.
c. It would take longer if any of the errors were not advantageous. Most replication errors are not advantageous.
d. This assumes that each and every mutation was the exact necessary mutation needed in the right order. Each block of the genome has to be built in the right order. ( You don’t need the lens of the eye before the optic nerve exists for example).
e. It also assumes that each generation got the opportunity to successfully reproduce and didn’t die first or something.
f. The replication error of a single base pair out of the 3 billion pairs can result in a genetically transmitted disease. We need 3 billion positive consecutive errors with no negative errors along the way, or it would take even longer.
g. There is no provision at all here for natural selection because that would exponentially add much more time.

As has been pointed out the assumption of a 20 year generation time is absurd.

At the molecular level, especially if we consider the whole genome, neutral change dominates. There are so many neutral mutations that they are have far more effect than the positive mutations. And since a very large proportion of the genome is not under any selective constraint at all, neutral mutations will constitute a large majority of the mutations involved.

Point d) is even more wrong. To the extent that selection is relevant it is already covered by point c). It might be appropriate if you were making the argument that it is unlikely that humans specifically would evolve (an argument which has the fatal flaw that it would be true of any complex life form), but it really has nothing to do with the length of the human genome, much of which seems to be unnecessary.

Point e) seems to have the same flaws but even worse.

Point f) is likewise irrelevant

Point g) is bizarre because points c and d are all about natural selection! How can you say that you didn't take natural selection into account when you make points which do take it into account ?

Might I suggest that you take care to work out which argument you wish to make ? If you wish to focus on the length of the human genome then don't drag in points about the a priori probability of humans evolving exactly as they are now. Do research how the length of the genome increases instead of assuming that it occurs one base at a time. Try to make an informed and coherent argument. It will serve you and this forum much better.

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bcoop
Junior Member (Idle past 2005 days)
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 Message 7 of 60 (668101) 07-17-2012 8:33 AM Reply to: Message 2 by Minnemooseus07-17-2012 4:27 AM

Re: Generation lengths bogus
Yes of course the lengths are bogus, but it makes the point that there are a lot of generations needed and they add up to a long time. It is difficult to articulate the point I am trying to make and over simplifying it makes it easy to communicate the concept. I knew when I wrote this I would be pilloried but through that I will learn a lot. You mentioned the front end of the process but is it known how long it takes for a positive change to prevail in the human population today? It is probably a long time.
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 (1)
 Message 8 of 60 (668102) 07-17-2012 8:43 AM Reply to: Message 7 by bcoop07-17-2012 8:33 AM

Re: Generation lengths bogus
 Yes of course the lengths are bogus, but it makes the point that there are a lot of generations needed and they add up to a long time. It is difficult to articulate the point I am trying to make and over simplifying it makes it easy to communicate the concept.

But your concept is trying to be quantitative. Your concept is that so-and-so many generations have passed, and so such-and-such an amount of evolution can't have taken place.

So if your numbers are no good --- if, as you yourself admit, "of course the lengths are bogus", then you don't have an argument. You don't have a quantitative argument against evolution if you yourself admit that your numbers are "bogus".

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bcoop
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 Message 9 of 60 (668107) 07-17-2012 9:09 AM Reply to: Message 3 by Dr Adequate07-17-2012 5:26 AM

Not so fast
“Has mathematical modeling been conducted of the amount of time it would take to generate the human genome”?
Yes, my simplistic model is full of errors, which you correctly point out, but you do not really address the underlying question, which is has someone modeled this process over time.
Yes – a yeast cell may reproduce in 90 minutes but how long does it take for a positive change to end up in the human DNA on the the end of the chain where we are now, taking into account natural selection and the host of other factors? Five hundred years? This is why a model of this process would be interesting.
The point about Deleterious mutations was only that it would add more time to the process to overcome them.
As far as your comments about reading a textbook, I did know that there were other methods that increase the length of the genome, but I was writing a one paragraph model of a concept I wanted to discuss. Your criticism is a little harsh, and maybe a little bit knee jerk to my post. I am not trying to debunk evolution, I am asking a legitimate question about how long it took to generate the human DNA.
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bcoop
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 Message 10 of 60 (668108) 07-17-2012 9:12 AM Reply to: Message 8 by Dr Adequate07-17-2012 8:43 AM

Re: Generation lengths bogus
I don't have an argument so much as a question - the question being "what would a mathematical model of the time needed to generate the human genome look like"? The professionals seem to quickly revert to these examples about bacteria and yeast cells but not so much about how much time it would take for a mammal to develop an functioning vision system or something like that. It would be fascinating to read someone who has worked this issue back through as much as possible!
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bcoop
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 Message 11 of 60 (668109) 07-17-2012 9:18 AM Reply to: Message 6 by PaulK07-17-2012 8:25 AM

I stand corrected
again - these things are difficult to articulate - especially knowing the level of people that are reading this. However, it was probably a child that said the king had no clothes on. I believe that asking the question how long did it take to generate the human genome is a legitimate one, and I am not really seeing a lot of answers to that so far. At the end of the day the math has to work. I trust that by the time this is done I would have posted a really different starting point but so far so good.
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bcoop
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 Message 12 of 60 (668110) 07-17-2012 9:24 AM Reply to: Message 5 by Panda07-17-2012 6:05 AM

probably is a flaw
I think you are saying that it is not a consecutive process but that if there are a million people reproducing any number of them may have a positive mutation all at the same point in time. This would indeed be a flaw - that this would allow multiple positive mutations at the same point in time, and then that natural selection would help get those diverse separate mutated humans back together into the subsequent gene pool. I would agree.
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bcoop
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 Message 13 of 60 (668112) 07-17-2012 9:28 AM Reply to: Message 4 by caffeine07-17-2012 6:00 AM

well said
You articulate this very clearly, but I wonder what this looks like down the road a ways when we become mammals and are much more complex. The facts made about all of this seem to revert quickly back to the simple creatures - how about an example of how this works in much more complex life forms and how long it takes a mutation to establish itself in the genome when it is more complex?
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NoNukes
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 (1)
 Message 14 of 60 (668113) 07-17-2012 9:30 AM Reply to: Message 10 by bcoop07-17-2012 9:12 AM

Re: Generation lengths bogus
 what would a mathematical model of the time needed to generate the human genome look like"?

If you want to assume that human genome was created completely from scratch, then perhaps it is okay to ignore calculations regarding lower life forms. But given that the theory of evolution is common descent, such an assumption would not address the theory of evolution as it is understood.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison

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bcoop
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 Message 15 of 60 (668114) 07-17-2012 9:37 AM Reply to: Message 14 by NoNukes07-17-2012 9:30 AM

Re: Generation lengths bogus
In all honesty - I was not entirely sure how to ask the question. The proposition that I posted got right to the heart of the matter though, and I will be curious to see the response. I would presume that a model that answers this question would be quite complex.
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