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Author Topic:   Mutation
Enchanted
Inactive Junior Member


Message 151 of 171 (107152)
05-10-2004 3:19 PM
Reply to: Message 150 by NosyNed
05-10-2004 3:10 PM


Re: Mistakes are common
ok. fair point. So if the mutations are common surely a mutation still involves a loss of data. Common or not it is according to modern evolution that all complex organs and joints in creatures and plants have evolved by an accumilation of slight changes where each slight change was the result of a genetic mistake.

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Replies to this message:
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JonF
Member
Posts: 6174
Joined: 06-23-2003


Message 152 of 171 (107154)
05-10-2004 3:23 PM
Reply to: Message 150 by NosyNed
05-10-2004 3:10 PM


Re: Mistakes are common
Mutations are common. How many are harmful (I'd guess half based on humans). How many are waiting in the wings for the right selective pressue -- the other half.

I don't have figures to hand, but the majority of mutations are neutral and the remainder are somewhat more harmful than beneficial.


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JonF
Member
Posts: 6174
Joined: 06-23-2003


Message 153 of 171 (107158)
05-10-2004 3:29 PM
Reply to: Message 151 by Enchanted
05-10-2004 3:19 PM


Re: Mistakes are common
So if the mutations are common surely a mutation still involves a loss of data.

Does not follow. Calculating a meaningful change in data or information as the result of mutations is a challenge at which nobody to date has been successful (although a few have claimed success).

Common or not it is according to modern evolution that all complex organs and joints in creatures and plants have evolved by an accumilation of slight changes where each slight change was the result of a genetic mistake.

Almost ... "mistake" is definitely the wrong word to use. It implies that there is a right way and a wrong way and the wrong way is the mistake. But there's no right or wrong, there's just better or worse equipped for reproduction and survival in the current environment (which, of course, implies that what's better in one environment can be worse in another environemnt). Mutations are not mistakes, they're just changes. You could substitute "difference":

Common or not it is according to modern evolution that all complex organs and joints in creatures and plants have evolved by an accumulation of slight changes where each slight change was the result of a genetic difference.

Yeah, that's reasonable.


This message is a reply to:
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Enchanted
Inactive Junior Member


Message 154 of 171 (107162)
05-10-2004 3:40 PM
Reply to: Message 153 by JonF
05-10-2004 3:29 PM


Re: Mistakes are common
Ok... so "difference"... however it is still a random accident.
Im still learning! lol

How then can mutation explain the developement of an irriducible mecanism such as the knee joint?

The knee joint is irreduceable and cannot evolve as it requires four complex parts (Posterior cruciate ligament, Anterior cruciate ligament, Tibia and fuma) to exist simultaniosly and i complex assembly to be able to praform a useful function.


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Loudmouth
Inactive Member


Message 155 of 171 (107169)
05-10-2004 4:01 PM
Reply to: Message 154 by Enchanted
05-10-2004 3:40 PM


Re: Mistakes are common
quote:
Ok... so "difference"... however it is still a random accident.

Which is kept or removed from the population gene pool due to natural selection, a non-random, non-chance process.

quote:
Im still learning! lol

We all are in a constant mode of learning. All we can do is help each other learn more, which is the attitude I try to bring to this forum. Right attitude=more knowledge.

quote:
The knee joint is irreduceable and cannot evolve as it requires four complex parts (Posterior cruciate ligament, Anterior cruciate ligament, Tibia and fuma) to exist simultaniosly and i complex assembly to be able to praform a useful function.

Before we go down the irreducibly complex path, perhaps you should check out the thread entitled Behe's Irreducible Complexity Is Refuted. This thread shows the evolution of an IC system found in the middle ear. This example shows how jawbones of a reptile became the small middle ear bones in mammals. It shows how each step in the evolutionary pathway gives an increase in function. This is what we would expect to see in the evolution of the knee as well.

This message has been edited by Loudmouth, 05-10-2004 03:02 PM


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NosyNed
Member
Posts: 8963
From: Canada
Joined: 04-04-2003


Message 156 of 171 (107170)
05-10-2004 4:04 PM
Reply to: Message 152 by JonF
05-10-2004 3:23 PM


Neutral or Beneficial?
I don't have figures to hand, but the majority of mutations are neutral and the remainder are somewhat more harmful than beneficial.

I deliberately chose to avoid the words neutral or beneficial. It is probably not to difficult to tag a mutation as harmfull. Certainly if it kills the individual before birth it is.

However, in the bigger picture, I don't think that one can be so sure about beneficial or neutral. Sure, it may be clear that a mutaion helps an individual and maybe that it doesn't. But from an evolutionary standpoint any of the so-called neutral mutations could be beneficial. It is just a matter of them hanging around in the population till the "right" conditions arise. It would seem to me that just having genetic variability is a darn good thing in itself.


This message is a reply to:
 Message 152 by JonF, posted 05-10-2004 3:23 PM JonF has responded

Replies to this message:
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JonF
Member
Posts: 6174
Joined: 06-23-2003


Message 157 of 171 (107171)
05-10-2004 4:11 PM
Reply to: Message 154 by Enchanted
05-10-2004 3:40 PM


Re: Mistakes are common
How then can mutation explain the developement of an irriducible mecanism such as the knee joint?

Well, first you have ignored the effect of selection, which is a powerful filter that makes evolution definitely not a random process.

Second, there are many ways in which "irreducibly complex" systems can arise through evolution. One that comes to mind is scaffolding; system A+B+C may not be irreducibly complex, but remove system B and you may still have an operating system that is now "irreducibly complex" (similar to how an "irreducibly complex" arch is built with scaffolding). Another is co-optation; a system may perform a particular function and mutations may produce a new system that is "irreducibly complex" and performs a different function.

Third, it may be that the knee requires those four complex parts to exist to operate as a human knee but you are going to have to do some serious arguing to convince me that they all have to be present to function as a joint.

There should be a discussion of the knee at http://www.philoonline.org/library/shanks_4_1.htm ("Behe, Biochemistry, and the Invisible Hand", Niall Shanks & Karl Joplin) but that seems to be down, perhaps forever.


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JonF
Member
Posts: 6174
Joined: 06-23-2003


Message 158 of 171 (107174)
05-10-2004 4:17 PM
Reply to: Message 156 by NosyNed
05-10-2004 4:04 PM


Re: Neutral or Beneficial?
However, in the bigger picture, I don't think that one can be so sure about beneficial or neutral. Sure, it may be clear that a mutaion helps an individual and maybe that it doesn't. But from an evolutionary standpoint any of the so-called neutral mutations could be beneficial. It is just a matter of them hanging around in the population till the "right" conditions arise. It would seem to me that just having genetic variability is a darn good thing in itself.

Agreed. You probably didn't note that I carefully never describe the italian anti-atherosclerosis mutation as "beneficial" without a caveat; we like the idea but whether it contributes to, detracts from, or has no effect on reproductive success remains to be seen.

However, "neutral" properly means "currently not subject to selective pressure" and can be detected with a high degree of confidence; just by pure statistics most mutations take place in "junk" DNA which seems as best as we can tell to have no function (and some obviously does not have any function), and therefore are neutral. A neutral mutation incoding DNA could possibly become another type in another environment.


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Replies to this message:
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Enchanted
Inactive Junior Member


Message 159 of 171 (107180)
05-10-2004 4:26 PM
Reply to: Message 157 by JonF
05-10-2004 4:11 PM


Re: Mistakes are common
ok. then how can evolution explain:

the process by which two ligaments became crossed at the centre of a pivot joint precisely at the same time at the same time that a space is formed to accomidate them and precisely at the same time that a complex and comparitable rolling motion is formed. I can not see how there can be an intermediate stage.

My argumentmay be flaued as i am not an expert yet (im only 15). I would appreciate constructive arguments that would improve my knolage...


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 Message 157 by JonF, posted 05-10-2004 4:11 PM JonF has responded

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NosyNed
Member
Posts: 8963
From: Canada
Joined: 04-04-2003


Message 160 of 171 (107212)
05-10-2004 7:28 PM
Reply to: Message 158 by JonF
05-10-2004 4:17 PM


Re: Neutral or Beneficial?
However, "neutral" properly means "currently not subject to selective pressure" and can be detected with a high degree of confidence;

Agreed. I wasn't thinking it through carefully enough. So in the mix of changes we have those which are clearly detrimental (the organism spontaneously aborts), those which are clearly neutral (not expressed as far as we know), those which appear to be beneficial (but it's hard to be sure over the short terem), those which appear to be neutral (but could be beneficial or harmful as the selective pressures change) and those which appear to be harmful but might be reevaluated with selective changes.

It seems that we end up with a lot which are neutral, a significant number which are harmful and another bunch which come down to
"dunno for sure".


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 Message 158 by JonF, posted 05-10-2004 4:17 PM JonF has responded

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JonF
Member
Posts: 6174
Joined: 06-23-2003


Message 161 of 171 (107222)
05-10-2004 7:52 PM
Reply to: Message 159 by Enchanted
05-10-2004 4:26 PM


Re: Mistakes are common
ok. then how can evolution explain:

the process by which two ligaments became crossed at the centre of a pivot joint precisely at the same time at the same time that a space is formed to accomidate them and precisely at the same time that a complex and comparitable rolling motion is formed. I can not see how there can be an intermediate stage.

I don't know. That's not one of my areas of expertise. Perhaps someone else can help you. Knees evolved very early, in the first tetrapods. We have lots of examples of tetrapod fossils with primitive knees. You might look up Acanthostega and Eusthenopteron and Sterropterygion.

I do hope you realize that your inability to think up an intermediate stage does not mean that there cannot be an intermediate stage.

You might also consider how poor a design our knees are for carrying our weight in an upright stance.


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Brad McFall
Member (Idle past 3964 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 162 of 171 (107223)
05-10-2004 7:58 PM
Reply to: Message 159 by Enchanted
05-10-2004 4:26 PM


Re: Mistakes are common
try temporal hierarchies that SHIFT functionally from a physiological past to an ecological reality. If that doesnt do it for you you will have to wait for a response from me in detail as I am busy just now.

This message has been edited by Brad McFall, 05-10-2004 06:58 PM


This message is a reply to:
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moon
Inactive Member


Message 163 of 171 (107270)
05-10-2004 9:22 PM
Reply to: Message 159 by Enchanted
05-10-2004 4:26 PM


Re: Mistakes are common
Hon, I don't know it for exactly 'coz i'm also just a student, but I'm sure that there are some advantages for intermediate stages. Let's say it needs a, b, c, d to form a perfect knee joint. First, there was no knee joint, and then b by mutation, a particular orgnism had an 'a'. There would be some advantages for having 'a' rather than not having any of them. So, that guy got selected for. In this way, the gene that codes for 'a' allele became dominant in population. then 'b' allele might arose from mutation. If 'a' and 'b' allele came from the same species, sex will help the combination of these two alleles and they would outcompete the guys which had only either'a' or 'b' alleles.

"The eyes of moles and some burrowing rodents are quite covered up by skin and fur. This state of eyes is.....aided perhaps by natural selection". (Darwin)


This message is a reply to:
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moon
Inactive Member


Message 164 of 171 (107272)
05-10-2004 10:01 PM
Reply to: Message 158 by JonF
05-10-2004 4:17 PM


Re: Neutral or Beneficial?
Yup,agree. As far as I know, mutations in junk DNA are neutral. So do the third codons of the DNA/ RNA, genes that codes for inactive sites of the proteins. Whatever genotypes which can't be seen by natural selection.

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Replies to this message:
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moon
Inactive Member


Message 165 of 171 (107273)
05-10-2004 10:05 PM
Reply to: Message 151 by Enchanted
05-10-2004 3:19 PM


Re: Mistakes are common
What do u mean by "a loss of data"?

This message is a reply to:
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