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Pentadactyl Design


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#1 Springer

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Posted 22 November 2005 - 04:28 PM

I have tried six or seven times on this forum to get an evolutionist to answer the problem of homologous structures coming about by non-homologous means. There are numerous examples of this in nature. I have never received a decent rebuttal. I’ve been asked for scientific evidence of ID and have pointed out the existence of identical designs of the pentadactyl forelimbs and hindlimbs of terrestrial mammals. Apparently the evolutionists on this forum are unwilling to squarely confront this remarkable evidence of ID. No evolutionist believes that one evolved from the other. Thus, how does one reconcile such a profound “coincidence” in terms of natural selection and laws of probability?

#2 chance

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Posted 22 November 2005 - 09:14 PM

Just to clarify and make sure we are on the same page, is this what you mean by ?homologous structures

#3 Springer

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Posted 23 November 2005 - 07:24 AM

Just to clarify and make sure we are on the same page, is this what you mean by ?homologous structures

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I suppose you could use "analagous", as they're not related. In any event, my question remains: How does evolution arrive at two identical designs by different routes? This finding is far more consistent with ID.

#4 chance

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Posted 28 November 2005 - 02:38 PM

I suppose you could use "analagous", as they're not related. In any event, my question remains: How does evolution arrive at two identical designs by different routes? This finding is far more consistent with ID.


ID doesn’t propose a direction as far as I am aware, it just states it could not have happened by chance because it’s too improbable, so there is no way of comparing the two. As far as similar structures go, I would presume that similar pressures produce similar results. E.g. a Dolphin resembles a fish (superficially) because of the demands to be streamlined.

#5 Angelus-Tenebrae

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Posted 28 November 2005 - 04:41 PM

The idea that a structure in a living organism formed by natural, possibly random and inefficient processes, but is still able to survive is from natural selection. If natural processes are inefficient and somewhat random, it is still possible for a natural process to produce an effective or at least barely functional structure in a living organism that will allow the organism to survive. The reason you see more of those is precisely because of natural selection. The other variations of the same structure in other living organisms of the same species may not allow those organisms to survive because the other variations produce structures that are not even barely able to allow the organism to survive.

#6 Grengor

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Posted 28 November 2005 - 07:12 PM

If there's a certain structure that would greatly aid in survival, why would it not develope?

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Posted 28 November 2005 - 07:28 PM

If there's a certain structure that would greatly aid in survival, why would it not develope?


Because the mutation that's needed to produce it may never occur. The environment needed to take advantage of the mutation if it did occur, may never occur.

It would be a miracle if both events occured to produce one of the structures. To get two of the same structures via seperate processes would be the same miracle happening twice.

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#8 chance

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Posted 28 November 2005 - 07:45 PM

If there's a certain structure that would greatly aid in survival, why would it not develope?

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Because evolution is not guided by what will work the absolute best, but by good enough does the job. E.g. why the quadruped form? Lets presume that 6 limbs is better than 4 (by a small amount), but if 4 limbed creatures evolved first and become established, it will be nigh on impossible to displace the established creatures if 4 is almost as good as 6. Survival solutions only have to work, they don’t have to work very well.

Sight is another example, there are dozens of solutions for seeing, yet why have not all creatures evolved the avian eye?

#9 Springer

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Posted 29 November 2005 - 11:03 AM

ID doesn’t propose a direction as far as I am aware, it just states it could not have happened by chance because it’s too improbable, so there is no way of comparing the two.  As far as similar structures go, I would presume that similar pressures produce similar results.  E.g. a Dolphin resembles a fish (superficially) because of the demands to be streamlined.

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The analagous structures are: femur:humerus
tibia/fibula: radius/ulna
8 carpals/8tarsals
5 metacarpals/5 metatarsals
2 phylanges on thumb/2phylanges on great toe
3 phylanges on 2nd through 5th fingers/
3 phylanges on 2nd through 5th toes.

You're suggesting that chance mutations and natural selection produced these identical structures independent of each other. What selective pressure would be operational that would, for example, demand five digits on the forelimb and not some other number on the hindlimb, if they evolved independently? Why would there need to be the same number of carpal and tarsal bones? How can you ascribe these similarities to chance?

#10 chance

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Posted 29 November 2005 - 01:46 PM

The analagous structures are:  femur:humerus
                                          tibia/fibula:  radius/ulna
                                          8 carpals/8tarsals
                                          5 metacarpals/5 metatarsals
                                          2 phylanges on thumb/2phylanges on great toe
                                          3 phylanges on 2nd through 5th fingers/
                                                      3 phylanges on 2nd through 5th toes.

You're suggesting that chance mutations and natural selection produced these identical structures independent of each other.  What selective pressure would be operational that would, for example, demand five digits on the forelimb and not some other number on the hindlimb, if they evolved independently?  Why would there need to be the same number of carpal and tarsal bones?  How can you ascribe these similarities to chance?

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I must admit that I am confused about the point you are trying to put forward. If you could refer to the link I posted and use the 3 examples of wing, (Bird, Bat, Pterosaur) and explain what exactly you see as problem of these structures.

e.g. Are you stating that as these 3 examples shared a common ancestor, why the 3 differing solutions to flight? WRT your quote of

How can you ascribe these similarities to chance?

, I would answer - the respective animals evolved in a different environment before flight, then acquired flight using the body plan they were stuck with.

Sorry if this is not addressing the point you want, I am trying to second guess the problem.

#11 Springer

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Posted 29 November 2005 - 07:58 PM

quote=chance,Nov 29 2005, 01:46 PM

I must admit that I am confused about the point you are trying to put forward.  If you could refer to the link I posted and use the 3 examples of wing, (Bird, Bat, Pterosaur) and explain what exactly you see as problem of these structures.

My point is that the pentadactyl forelimb
and hindlimb of the [b]same vertebrate, e.g., man,
are virtually identical in design.
No evolutionist will claim that one evolved from another. They supposedly evolved from the pectoral and pelvic fins of a fish. Thus, you have two identical designs which evolved independent of each other. This is mind boggling to explain in terms of fortuitous mutations and natural selection.
If evolution were true, and everything is random and purposeless as has been proclaimed, one would not expect that natural selection would demand identical designs. Why didn't the hind limb end up with four toes instead of five? Why does the great toe have two phylanges, as does the thumb? Why are there eight tarsals and eight carpals? This observation strongly suggests purposeful design, and does not fit with an evolutionary model.

#12 Angelus-Tenebrae

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Posted 29 November 2005 - 09:04 PM

quote=chance,Nov 29 2005, 01:46 PM
My point is that the pentadactyl forelimb
and hindlimb of the [b]same vertebrate, e.g., man,
are virtually identical in design.
No evolutionist will claim that one evolved from another.  They supposedly evolved from the pectoral and pelvic fins of a fish.  Thus, you have two identical designs which evolved independent of each other.  This is mind boggling to explain in terms of fortuitous mutations and natural selection. 
If evolution were true, and everything is random and purposeless as has been proclaimed, one would not expect that natural selection would demand identical designs.  Why didn't the hind limb end up with four toes instead of five?  Why does the great toe have two phylanges, as does the thumb?  Why are there eight tarsals and eight carpals?  This observation strongly suggests purposeful design, and does not fit with an evolutionary model.

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The femur and humerus are not identical--they appear that way morphologically, but their development is not limited to how they look. The femur and humerus are formed from two separate genes for posture and body plan, the bicoid and nanos. Furthermore, development of the femur and humerus are different for each species. In tetrapod animals, the femur is proportionally shorter than it is in bipedal animals, namely humans. That randomness is expected can mean that repetition in structure or function can happen, but that does not mean they are identical. One would have to look at genetics to determine such relationships.

All of our limbs are pentadactyl because they are regulated by one gene. This does fit with an evolutionary model because a mutation in such a gene would cause other abnormalities to happen, including problems with genitals, "foxy feet" and "butterfly fingers", or problems with conception and infertility. If that same gene regulates the number of digits and reproductive function, and reproductive function is only adequate when the number of digits expressed is five, then such a trait will be passed on, and will be naturally selected.

#13 chance

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Posted 30 November 2005 - 01:46 PM

My point is that the pentadactyl forelimb and hindlimb of the same vertebrate, e.g., man, are virtually identical in design.


Ok arms and legs look superficially the same.


No evolutionist will claim that one evolved from another. They supposedly evolved from the pectoral and pelvic fins of a fish. Thus, you have two identical designs which evolved independent of each other. This is mind boggling to explain in terms of fortuitous mutations and natural selection.


As Angelus-Tenebrae they are not exactly identical. IMO front and back legs are homologous, because the evolved from a similar limb, i.e. front and rear fins were more or less the same to start with. To me this suggests a symmetry sort of thing as for the reason the tetrapod has 4 limbs and not 2.



If evolution were true, and everything is random and purposeless as has been proclaimed, one would not expect that natural selection would demand identical designs.

The cause for changes are random but the selection is not, thus the various types of wing.

Why didn't the hind limb end up with four toes instead of five? Why does the great toe have two phylanges, as does the thumb? Why are there eight tarsals and eight carpals? This observation strongly suggests purposeful design, and does not fit with an evolutionary model.

There does not have to be a reason why 5 and not 4 toes is the current form, is 5 better than 4? I would think not, it’s just the reflects the original form.

For your argument to move forward I think you need to show why 5 is a better ‘design’ than any other.

#14 Springer

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Posted 01 December 2005 - 08:24 AM

quote=chance,Nov 30 2005, 01:46 PM

The cause for changes are random but the selection is not, thus the various types of wing.


How can you conclude that natural selection would be that discriminating as to demand that the design be identical?


For your argument to move forward I think you need to show why 5 is a better ‘design’ than any other.


I'm not saying that five is better than four. I'm saying that there's no reason to believe that natural selection would coincidentally select out mutations resulting in exactly the same design by two different pathways. You've agreed that five might not be better than four. This being the case, why did not one limb evolve with five digits and the other four? Why do both the carpus and the tarsus have eight bones? They are identical in overall design but, as you inferred, there is no obvious reason why. You cannot say that natural selection demanded 8 bones in the wrist and for some reason also required the same number in the ankle. If natural selection were making design decisions, the numbers and design would be more random... at least the evolutionary model would predict this. Evolutionists keep stating that there is no direction in nature. If that is true, why do we see identical designs without any sort of ancestral link?

#15 chance

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Posted 01 December 2005 - 01:36 PM

How can you conclude that natural selection would be that discriminating as to demand that the design be identical?


I don’t think they are identical enough, to be a serious argument against evolution, the similarities only reflect the starting theme.



For your argument to move forward I think you need to show why 5 is a better ‘design’ than any other.

I'm not saying that five is better than four. I'm saying that there's no reason to believe that natural selection would coincidentally select out mutations resulting in exactly the same design by two different pathways. You've agreed that five might not be better than four. This being the case, why did not one limb evolve with five digits and the other four? Why do both the carpus and the tarsus have eight bones?


Perhaps there is a controlling segment of DNA that ensures bilateral symmetry, for left and right, or the DNA in that area is very robust (cant think of any animal that is not symmetrical in some fashion)


They are identical in overall design but, as you inferred, there is no obvious reason why. You cannot say that natural selection demanded 8 bones in the wrist and for some reason also required the same number in the ankle. If natural selection were making design decisions, the numbers and design would be more random... at least the evolutionary model would predict this. Evolutionists keep stating that there is no direction in nature. If that is true, why do we see identical designs without any sort of ancestral link?


I agree there is no demand for any feature we see, but I don’t see any requirement either for non-identical features when they originate from a common source. I mean that is the core feature of evolution common ancestry, yes? Is it any wonder then that common ancestry equates to common features.

Perhaps I am missing some crucial point in this discussion, do you have a link to the source of this question?

#16 Angelus-Tenebrae

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Posted 01 December 2005 - 02:55 PM

Porifera is not symmetrical, but it's also rather primitive. In some cases, it looks almost like nothing more than a hollowed out blob.




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