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Author Topic:   Evolving the Musculoskeletal System
scarab
Junior Member (Idle past 4753 days)
Posts: 5
Joined: 06-24-2010


Message 117 of 527 (578046)
08-31-2010 3:47 PM
Reply to: Message 103 by Bolder-dash
08-31-2010 1:50 PM


I have asked repeatedly for you to produce the evidence, any evidence, that a random mutation caused the beginning of a new functioning limb or system.
You can't do that. Mobiogirl it seems just tried, and I don't think anyone could call that a success.
She demonstrated that you were talking nonsense when you said, "We don't see sporadic examples of people born with excess cartilages in random areas, or lubricant forming between some peoples finger joints, or extra ligaments appearing in some individuals which causes some difference of their physical capabilities."
Here is an example of a woman with two patellas: 403 Forbidden There is cartilage and ligaments attached to both patellas and there are joints between the two patellas and between the extra patella and the femur. She had an extra bone with associated cartilage, ligaments and joints so your statement that we don't see these things is wrong.
Here is an example of a known change to a known gene that suppresses limb development on the abdominal segments of insects: How insects lose their limbs | Nature Here is a quote:
The work of Galant and Carroll1, and Ronshaugen et al.2, is a striking demonstration of the importance of protein evolution in the diversification of arthropod limbs. The analysis2 of the crustacean Ubx protein provides a particularly rigorous standard for future evo—devo studies, in that these authors identified the exact amino-acid substitutions that are responsible for the suppression of insect limbs.
So we see that mutations can make radical changes to limb development.
As a direct response to your question
I have asked repeatedly for you to produce the evidence, any evidence, that a random mutation caused the beginning of a new functioning limb or system.
Well there is always bithorax, a hox gene. Mutation of genes in the bithorax complex have resulted in flies growing an extra pair of functioning wings. The International Journal of Developmental Biology

This message is a reply to:
 Message 103 by Bolder-dash, posted 08-31-2010 1:50 PM Bolder-dash has not replied

  
scarab
Junior Member (Idle past 4753 days)
Posts: 5
Joined: 06-24-2010


(1)
Message 120 of 527 (578103)
08-31-2010 6:29 PM
Reply to: Message 1 by ICdesign
08-28-2010 2:32 PM


Lets start out here by asking the simplest of questions.
How did Evolution create the more than 1200 bones,
joints and muscles and manage to put them all in just
the right position performing the exact needed functions?
That's an easy one: it did it gradually, starting from simple beginnings and progressing from there. The Human skeleton is an example of the current mammalian state of the art.
Here is an oldish paper (1938) that addresses the knee. Domain Names, Web Hosting and Online Marketing Services | Network Solutions
It gives examples of simpler knees than those found in mammals and we see examples of possible intermediate stages from the simplest knees to the more complex.
Note: I am not saying that any of the example animals used were our ancestors; I am saying that these are living animals with fully functional knees that nevertheless range from the simple to the more complex. So we know from them that simpler knees can function, that knees do not have to be complex to function and that our ancestors' knees could have been similar to those we see in living animals today.
How did Evolution create the more than 1200 bones,
joints and muscles and manage to put them all in just
the right position performing the exact needed functions?
The incidence of joint and skeletal injury show that our joints and skeltons do NOT perform the exact needed functions. I'm not talking about dramatic assaults, say those caused by car crashes. I'm talking about sports injuries, cruciate tendon injuries from soccer, or back injuries from lifting moderate weights. We have moderately functional joints, they are certainly not up to the strains that our leisure or work activities require yet they are good enough for our species to reproduce itself. That is all that evolution requires.
Our current skeletons are the result of large numbers of trial and error experiments. Every embryo conceived is a genetic crap shoot. Every one has random genetic changes, differences from its parents. These differences could be disastrous to the embryo, neutral, or beneficial. The one thing that every embryo had in its favor was that it was a, usually minor, recombination of the genes from fully functioning parents (parents that were functional enough to breed and rear children). Every one was the offspring of a long line of winners.
Every animal born is an experiment, we are all different from our parents. Some people are born with disabilities, some people are gifted athletes. The details of my skeleton and joints are different from the details of those of either of my parents. And I'm not just talking about changes due to sexual dimorphism; my sisters differ from my mother. Yet we all have functional skeletons. There is not one perfect skeleton that we must not deviate from. If there was only a small set of viable solutions for skeletal conformations then either all people would be uniform or we would see large numbers of disabled people. We see neither so we know that skeletons don't have to be conform to an exact specification in order to function. We can also guess this because our skeletons change as we grow. Young children have large parts of their skeleton comprised of cartilage instead of bone, even well after their first decade. Our limb proportions, the curvature of our spines, the fusion of various bones change from child to adult to old adults.
So we know that there is room for variety in skeletons, room for experiments. We know that animals have reasonably different skeletal arrangements from what humans have so we know that there is not one true form that must be hit first time.
We also know that human skeletons vary even inside a single generation. We know that skeletons change between generations (my parents were thick set, I am not), we know that these changes are viable (I am reasonably athletic though I do suffer from occasional, mild backache). So why can't change happen over time? Viable offspring subtly different from their viable parents.
There are 5 basic types of joints: ball-in-socket, hinge, gliding, pivoting, and fixed.
Each type is specifically appropriate for its particular motions.
How did Evolution manage to put the correct joint in the appropriate position?
These specializations can develop over time from simpler joints and these types of joints merely refer to different types of movement of the joints. This movement is influenced by shape and the conformation of ligaments that connect the joints, tendons that cross them and the orientation of fibers in their joint capsules. The paper that I linked to above shows various plausible intermediate configurations of joint capsules, tendons, ligaments and the acquisition of the patella.
The collateral ligaments of the knee are localized thickenings of the joint capsule so its easy to see how they may have evolved. The patella is just a bone that developed inside a tendon. The synovial fluid in joints is just an excretory product of some cells that line the joint cavity. There is nothing here that seems impossible to evolve.
Edited by scarab, : The original could have been taken to mean that we evolved from knees. That wasn't what I meant :-)

This message is a reply to:
 Message 1 by ICdesign, posted 08-28-2010 2:32 PM ICdesign has replied

Replies to this message:
 Message 124 by ICdesign, posted 09-01-2010 4:06 AM scarab has not replied

  
scarab
Junior Member (Idle past 4753 days)
Posts: 5
Joined: 06-24-2010


(2)
Message 153 of 527 (578493)
09-01-2010 8:36 PM
Reply to: Message 71 by ICdesign
08-30-2010 6:02 PM


Thanks for your welcoming words in your other post. I wont be able to respond to that post tonight.
The FACT is my friend, every system within our bodies is dependent on each other for survival.
I think that this is true. They are dependent on each other now but our ancestors would not have needed many of the systems that we rely on today.
For a start, if you are small and live in water then you don't need a heart, or lungs, or gills, or a circulatory system, or even a gut. You can exchange all waste products and gases, and intake all nutrients directly through your integument. Simple diffusion is sufficient because all cells are close to the environment. Its only when an organism gets bigger that it needs anything more sophisticated. This is because its surface area increases as the square of its length whilst its volume increases as the cube of its length. (So the surface area / volume ratio drops as the organism gets bigger. And that is a problem if you are relying on your skin to exchange substances with your environment.)
This is basic, beginners biology. I don't mean this in a cheeky way but you really should read some basic biology text books, some simple undergraduate level texts, they all explain the stuff that I'm going to mention here and they will do a better job of it. The reason that you don't make much traction with these arguments is that they have all been answered long before you made them and, probably, long before you even thought of them.
Which order did the systems evolve and how would they survive the development process when they have to be complete to survive?
If you want me to address the other part of your question then I will do it in another post. Its a fun topic, well its interesting but its not nearly as important as the second part of your question because that goes straight to heart of the mistakes that you are making, the conceptual hurdles that you will have to overcome to understand how evolution could work. I can see three flawed assumptions, 3 mistakes that are holding you back.
1) You assume that because something is needed now then it must always have been needed. This simply isn't true as I explained above. Small animals need very little in the way of complex systems. Our early ancestors would have been small, marine, organisms.
2) You assume that a feature must be fully developed before it can be of use to an organism. (Though I'm not sure about this. Is it one of your assumptions?)
3) You assume that an organism that has never had a feature could not survive without this feature. We know that this is nonsense because there are animals alive today that lack many of the complex systems that mammals have and yet they live just fine. :-) Our early ancestors would not have had hearts and lungs but that's OK, they didn't need them. They were small marine organisms; they weren't humans without hearts.
So why did you make those mistakes?
I think that you make the first mistake because you are fixated on the final product. You think that every human ancestor had to have the same requirements as humans do. They wouldn't have had the systems necessary to meet those requirements therefore they couldn't have lived. You need to realize that our ancestors go far back into deep time. They were nothing like us. (In the sense that a layman would not recognize them.) They had vastly reduced needs and could meet those needs with whatever systems they had at the time. In the earliest days those systems would have been: 'skin' ;-)
I'm not sure that you make assumption 2) but I'd like to address it just in case.
Its not necessary to have a fully evolved organ system in order to benefit from a partial implementation.
We see this in nematodes where they have a fluid filled internal body cavity where the fluid bathes the organs and muscular contractions of the body mix the fluid. This is a simple way to transport wastes and nutrients around the body pseudocoel | anatomy | Britannica . See here for an explanation of the insect circulatory system Color Diagrams of Insect Organs and Internal Structures . This isn't a fully developed closed vessel circulatory system like vertebrates have but it does let them grow very much larger than nematodes.
I gave those two examples above to demonstrate that 'partially developed' systems are of benefit to the organisms that have them but there is a second point to be learned from those examples. The point is that although large organisms depend on having good circulatory systems: small ones don't. They can get by with less but once they develop even rudimentary systems then they are able to grow in size. Once they do this they start to become dependent on those systems and will die without them. Its a seductive trap but its not a bad trade-off, I'd much rather be a human than a nematode.
Your 3rd assumption is rather strange. Have I understood you correctly? Did you really think that our earliest ancestors would have died without our two pressure circulatory systems or without advanced brains and a central nervous system? Maybe the thing that I have identified as assumption 3) is really just a rephrasing of assumption 1) What do you think? Have I understood your points? Have I misrepresented them? What would you say that your assumptions were?

This message is a reply to:
 Message 71 by ICdesign, posted 08-30-2010 6:02 PM ICdesign has not replied

  
scarab
Junior Member (Idle past 4753 days)
Posts: 5
Joined: 06-24-2010


(1)
Message 195 of 527 (579139)
09-03-2010 5:50 PM
Reply to: Message 187 by ICdesign
09-03-2010 1:07 PM


Re: Seeking to understand basis for incredulity
I was taught that bees give birth to bees and birds give birth to birds.
The ToE violates this simple law over and over and over again which is all the proof I need that this theory is 100% impossible.
This is a very important point. It appears to be a key issue that prevents you from accepting the theory of evolution. I imagine that it is a real problem for many people who can not accept the theory of evolution.
You are wrong when you say that the ToE violates your law. Of course you wont believe me if I simply tell you that you are wrong. I bet that you believe that birds are completely different animals from bees. You are wrong about that too but you just don't know it yet. :-)
You think that because birds are completely different things from bees then any common ancestor would have been neither a bird nor a bee. Or, at best, it could have been only one of the two kinds (either a bird or a bee). So even in the friendliest scenario for evolution, a hypothetical ancestor would have had to have changed from one kind into a completely different kind.
That's the only position you could take if you think in terms of completely separate kinds. That is your block, the thing that prevents you from learning how the world works. Your early teaching has blinded you to deeper understanding.
But how could your teaching be wrong? How is that even possible? Kinds don't change into completely separate kinds. That's a fact. How can a fact be wrong? :-) Any theory that says otherwise has got to be wrong. That's obvious.
Lets look at this because its pretty essential and if we don't address it then we are just talking past each other or we are just talking at each other and not to each other.
So how can the fact that kinds don't change into completely different kinds be wrong?
The short answer is that it is not wrong; kinds do not change into completely different kinds. Creationists and evolutionists are in agreement on this point
This is an important point and I don't think that it should be glossed over or ignored. Also, if you disagree with me, if you think that evolutionists do think that kinds change into completely separate kinds then please say so. Let me know if you disagree.
Or if you agree then please say so and we can move on and make more progress.

This message is a reply to:
 Message 187 by ICdesign, posted 09-03-2010 1:07 PM ICdesign has not replied

Replies to this message:
 Message 196 by Percy, posted 09-03-2010 5:57 PM scarab has replied

  
scarab
Junior Member (Idle past 4753 days)
Posts: 5
Joined: 06-24-2010


Message 197 of 527 (579179)
09-03-2010 7:20 PM
Reply to: Message 196 by Percy
09-03-2010 5:57 PM


Re: Seeking to understand basis for incredulity
Do you think the problem is that ICDESIGN thinks evolution teaches that one kind can give birth to a different kind?
That's the one. Its such a fundamental blocker. If you don't grok nested sets or if you just don't know enough biology to see how birds and bees are related then you'll never 'get it'.
This is drifting far from the specific topic: 'Evolving the Musculoskeletal System' but I thought if we could get past the blocker and then establish how new varieties come into being by the addition of features to existing varieties then maybe we could then move on and maybe enumerate some of the necessary additions/acquired features that would lead to the development of a musculoskeletal system.
I think that to answer his original question we need to explain general developmental processes, how any organ in the body gets its form, cell fates and how they are determined, explain extracellular matrix, how bone is a tissue comprised of cells and ECM, early unicellular examples of ECM, unicellular examples of cell signaling therefore leading on to how multicellular organisms could have developed from unicellular forms, how our genome 'specifies' form, establish that changes in the genome cause changes in form, how NS can act on this and therefore generate the complex musculoskeletal systems that we see today.
His original question is a good one and is a good opportunity to explain developmental processes and evolution. I just find the task of explaining all that stuff rather daunting. To avoid writing a textbook on developmental and evolutionary biology (which I'm not really qualified to do even if the forum had the space for it) I thought that if I could establish a dialog with ICDESIGN then maybe we could go at his pace, find out what he knows and just concentrate on the stuff that he doesn't understand. I thought that a dialog with ICDESIGN would give any explanation more structure and keep it briefer (I wouldn't have to cover every possible question that he might have, just the ones that he asks.)
Edited by scarab, : Why is it that you can preview something twenty times, hit submit, then see silly extraneous words? Where do they come from? How did they hide?
Edited by scarab, : better definition of bone

This message is a reply to:
 Message 196 by Percy, posted 09-03-2010 5:57 PM Percy has seen this message but not replied

  
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