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Any thoughts?

Here is an entire journal issue on this very topic Enjoy the rest of the day.

I don't understand why a non-functioning composition couldn't have originally been a neutral mutation, neither benefiting nor hurting the eye, until at some point in time, another mutation caused this positive mutation to form. As far as I know, nothing in evolution says that, if a function is neither beneficial or detrimental, it will be evolved out. There's no reason for it to be lost if it's not affecting the organism negatively.

Note: I did not read GH's article, so this may have been already covered in more detail. I just think that a majority of people won't read through the entire article, so they may want a more succinct answer.

Originally posted by MrManNo1

I don't understand why a non-functioning composition couldn't have originally been a neutral mutation, neither benefiting nor hurting the eye, until at some point in time, another mutation caused this positive mutation to form. As far as I know, nothing in evolution says that, if a function is neither beneficial or detrimental, it will be evolved out. There's no reason for it to be lost if it's not affecting the organism negatively.

Note: I did not read GH's article, so this may have been already covered in more detail. I just think that a majority of people won't read through the entire article, so they may want a more succinct answer.

Well it seems that either the strap or loop came first. And then down the road, quite randomly, either the strap came and threaded itself through the loop or the loop formed around the strap. Both then becoming necessary to hold the eye in place, something that was not necessary before. And it had to happen with both eyes.

Originally posted by seer

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Any thoughts?

It may be a result of what we often find in evolutionary development when it is forced to make-do with what’s available. This “poor engineering” is evident in the circuitous routing of the cord that carries the sperm from the testes to the penis in human males.

As the spermatic cord goes up toward the waist, it loops over the pelvis and then through it before finally reaching the penis, which causes a weak spot in the body wall where the cord attaches that never quite repairs itself. This makes the spot prone to both direct and indirect inguinal hernias. The former is caused when a portion of our intestine tears through the weak point when we are contracting our abdominal muscles, while the latter is congenital as is ultimately caused when a piece of the gut descends with the testes and there is a failure of embryonic closure of the internal inguinal ring.

The reason that the spermatic cord loops around like this and causing a weakness where we are prone to get hernias is because like our ancestors the fish our gonads still form up near the heart and liver in the embryo. But since male mammals reproduce better when their sperm is kept a bit cooler than body temperature, during gestation, human testicles descend down through the body cavity to the scrotum where the temperature can be better regulated. Neil Shubin does an superb job of dealing with all of this in much better detail on pages 193-196 of his book "Your Inner Fish."

So through evolution you end up with this torturous routing that at first glance seemingly can’t be explained. I wouldn’t be surprised if this “problem” isn’t also a result of something similar.

Originally posted by rogue06

So through evolution you end up with this torturous routing that at first glance seemingly can’t be explained. I wouldn’t be surprised if this “problem” isn’t also a result of something similar.

I don't know rogue. This eye thing seems really strange. Even if the strap and the loop had different previous functions, which seems unlikely, the fact that they were both there to to serve this new and necessary function - well it looks like anticipation. And look how the strap narrows as it goes through the loop. The loop is just big enough to accept the strap, but only when narrowed. And sure enough the strap narrows at that point (but not before). If the loop came after the strap then it formed just right, not to big or to small.

Originally posted by seer

I don't know rogue. This eye thing seems really strange. Even if the strap and the loop had different previous functions, which seems unlikely, the fact that they were both there to to serve this new and necessary function - well it looks like anticipation. And look how the strap narrows as it goes through the loop. The loop is just big enough to accept the strap, but only when narrowed. And sure enough the strap narrows at that point (but not before). If the loop came after the strap then it formed just right, not to big or to small.

Not sure what you're trying to say here. Why is it weird that the strap and the loop fit? Why is it any more different than any pulley-like structure in the body?

If the "strap" is the problem, then think of it as a simple band of fibrous tissue inserted between muscle fibers. As the orientation of the eye changed, the band became more and more like a pulley, to facilitate the function of the muscle. Of course it's "just big enough" for the narrow point of the muscle; they evolved together.

If it's the orientation of the muscle that's the issue, bear in mind that the superior oblique has that specific insertion only in Gnathostomata (a group that includes all jawed vertebrates). In organisms like lampreys, the muscle (called caudal oblique) has a different insertion and a less peculiar orientation. Still works, though.

On the other hand: What is the point of the superior oblique under a design perspective? A simple medial origin and anterolateral insertion of the muscle would do the same job, without thre Rube Goldberg design. The inferior oblique does the same job just as well that way.

Originally posted by Faid

Not sure what you're trying to say here. Why is it weird that the strap and the loop fit? Why is it any more different than any pulley-like structure in the body?

If the "strap" is the problem, then think of it as a simple band of fibrous tissue inserted between muscle fibers. As the orientation of the eye changed, the band became more and more like a pulley, to facilitate the function of the muscle. Of course it's "just big enough" for the narrow point of the muscle; they evolved together.

If it's the orientation of the muscle that's the issue, bear in mind that the superior oblique has that specific insertion only in Gnathostomata (a group that includes all jawed vertebrates). In organisms like lampreys, the muscle (called caudal oblique) has a different insertion and a less peculiar orientation. Still works, though.

On the other hand: What is the point of the superior oblique under a design perspective? A simple medial origin and anterolateral insertion of the muscle would do the same job, without thre Rube Goldberg design. The inferior oblique does the same job just as well that way.

So the strap just happend to form through the loop, or the loop just happen to form around the strap and then both suddenly became absolutely necessary to support the eye? Not only this, unless one can show that the loops (on both eyes) and straps (on both eyes) and the future orientation of the eye (on both eyes) are controlled by the same gene(s) then this had to happen independently for both eyes.

And I'm not sure what you mean by evolved together? Why would the strap be thin enough to fit the loop or the loop be small enough to hold the strap in place? If the loop was much bigger the eye would flop back into the socket.

Originally posted by seer

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Yes, one thought : prepare yourself for two things -- a wild stampede for the
EXIT or tap-dancing / hand-waving like you've never seen before in your life.

Jorge

Originally posted by seer

So the strap just happend to form through the loop, or the loop just happen to form around the strap and then both suddenly became absolutely necessary to support the eye? Not only this, unless one can show that the loops (on both eyes) and straps (on both eyes) and the future orientation of the eye (on both eyes) are controlled by the same gene(s) then this had to happen independently for both eyes.

And I'm not sure what you mean by evolved together? Why would the strap be thin enough to fit the loop or the loop be small enough to hold the strap in place? If the loop was much bigger the eye would flop back into the socket.

Um, let me try to explain this. The strap and the loop did not "happen" to fit, any more than the eye "happened" to fit in the eye socket. The two elements evolved together; and by that I mean that they modified their structure one in relation to the other.

Imagine a fairly straight muscle, originating and insetring close to the inner surface of the cavity. One or more fibrous bands can form to keep it in place close to the bone, as we see in many other muscles. Now, if the insertion of the muscle changed to a more lateral position in the eye (as it happened in all Gnathostomata), an angle forms, and the fibrous band begins to act like a pulley. If the modified function of the muscle is an advantageous one, the angle is preserved, and further modifications to strenghthen and facilitate it are also favored. The band can get stronger to provide more stability, or narrower to minimize the friction surface. The muscle becomes more round and gets a bursa at the friction point, then the angle might get bigger with the insertion of the muscle moving further laterally... All these modifications are used to enhance and assist the new improved function of the muscle. It's not much different from the pulleys we have in our fingers; The angle is the only difference, but then again it's the angle that provides the different function.

And like I said, what's the point of all that from a design perspective? Why couldn't we have a superior oblique muscle functioning just like the inferior oblique one? It would be way more simple, and just as effective.

(My guess is that 'Goddidit' to annoy the heck out of medical students studying Anatomy. Hey, he did set up the Greatest Prank of all Time, making the world seem really ancient when it's only 6000 years old, so what's another little joke? )

Originally posted by Jorge

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Yes, one thought : prepare yourself for two things -- a wild stampede for the
EXIT or tap-dancing / hand-waving like you've never seen before in your life.

Jorge

But most of all, prepare for more content-free ironic posts like this one, from our resident spoiled little kid. That is, as you'll soon see, all his poor wit has to offer.

Originally posted by Faid

Um, let me try to explain this. The strap and the loop did not "happen" to fit, any more than the eye "happened" to fit in the eye socket. The two elements evolved together; and by that I mean that they modified their structure one in relation to the other.

Why would they do that?

Imagine a fairly straight muscle, originating and insetring close to the inner surface of the cavity. One or more fibrous bands can form to keep it in place close to the bone, as we see in many other muscles. Now, if the insertion of the muscle changed to a more lateral position in the eye (as it happened in all Gnathostomata), an angle forms, and the fibrous band begins to act like a pulley. If the modified function of the muscle is an advantageous one, the angle is preserved, and further modifications to strenghthen and facilitate it are also favored. The band can get stronger to provide more stability, or narrower to minimize the friction surface. The muscle becomes more round and gets a bursa at the friction point, then the angle might get bigger with the insertion of the muscle moving further laterally... All these modifications are used to enhance and assist the new improved function of the muscle. It's not much different from the pulleys we have in our fingers; The angle is the only difference, but then again it's the angle that provides the different function.

Ok so the loop and strap were in place just waiting for the eye orientation to change. BTW - do you know if the strap was controlled by the same gene for both eyes? The loop? Or did the loop and strap develop independently for both eyes?

And like I said, what's the point of all that from a design perspective? Why couldn't we have a superior oblique muscle functioning just like the inferior oblique one? It would be way more simple, and just as effective.

Who knows, though efficiency would only be necessary for beings with limited resources or time. Neither of which would apply to God.

(My guess is that 'Goddidit' to annoy the heck out of medical students studying Anatomy. Hey, he did set up the Greatest Prank of all Time, making the world seem really ancient when it's only 6000 years old, so what's another little joke? :wink

Well saying that "nature did it" may be more unbelievable. And I did not say anything about the age of the earth. One thought though, if we were able to examine a cup of wine from the miracle at Cana, it would have displayed all the markers of age. Not that God intended to deceive with the apperance of age, but that the apperance of age was inherent to the process and result.

Originally posted by seer

Not that God intended to deceive with the apperance of age, but that the apperance of age was inherent to the process and result.

Are you saying that God is incapable of creating the universe to look like it's the age it actually is? That's quite a restriction to put on God.

Originally posted by seer

Well it seems that either the strap or loop came first. And then down the road, quite randomly, either the strap came and threaded itself through the loop or the loop formed around the strap. Both then becoming necessary to hold the eye in place, something that was not necessary before. And it had to happen with both eyes.

Why did you say that? Do you think that the two eyes evolved separately and independently? Or is this a comment about the development of these structures?

Originally posted by seer

Why would they do that?

Why would the eye and the eye socket do that? Why does our tongue fit in our mouth? Why do our top teeth fit on our bottom teeth? Why does the tibia match the femoral condyles, and why do all the cartillages fit in there too? :)
Like I explained, both are features that develop simultaneously, as a new variation in function emerges and becomes an adaptive trait. It's not like the muscle had to have that form from the start, or the fibrous band had to be like a pulley from the beginning.

Ok so the loop and strap were in place just waiting for the eye orientation to change.

They did not start as "loops" and "straps" more likely, and did not have the same size, shape or orientation. But the basis for their forming was there. That's what we find in other muscles, and that's what we find specifically in the case of the superior oblique: Like I said, a similar muscle but with different position and insertion exists in animals outside the Gnathostome group.

BTW - do you know if the strap was controlled by the same gene for both eyes? The loop? Or did the loop and strap develop independently for both eyes?

I don't know which genes are responsible, but since we are talking about parts of the genome that deal with phenotypical characteristics, my guess would be that it's a single gene for both sides in both the "loop" and the "strap". Think of it as the single gene that controls blue eye colour, or pointy ears if you like.

Who knows, though efficiency would only be necessary for beings with limited resources or time. Neither of which would apply to God.

I'm not sure I understand that. God supposedly is both omnipotent and eternal, but here he designs a mortal creature. He knows the most simple mechanism, since he uses it in the inferior oblique. Why take take this weird designing choice with the superior oblique? Come to think of it, why use a unique cranial nerve for the muscle, when all others are efficiently nerved by the occulomotor?

Well saying that "nature did it" may be more unbelievable.

Only we see evidence that "nature did it", including the existence of previous homologous muscle in organisms outside the Gnathostoma group.

And I did not say anything about the age of the earth. One thought though, if we were able to examine a cup of wine from the miracle at Cana, it would have displayed all the markers of age. Not that God intended to deceive with the apperance of age, but that the apperance of age was inherent to the process and result.

Well, that's the Omphalos Hypothesis, an opinion long abandoned by philosophers and theologians alike. Philosophers simply applied Occam's razor, while Theologians argued that making something appear old, when it is, in fact, not, either assumes that God is not omnipotent (since even his creative power has to comply to what is essentially a need for an appearance of age), or that he could make it look young, but chose not to- which yes, it would make him deceptive.
But all that is for another forum, I think.

Originally posted by ck11

Why did you say that? Do you think that the two eyes evolved separately and independently? Or is this a comment about the development of these structures?

I think seer believes there is one different gene for every feature in each side of the body. But I'm not sure.