Evolving the Musculoskeletal System

I really hate to do this because so many people are so into this discussion, but this site *does* have standards. Perfect compliance with the Forum Guidelines is neither demanded nor expected, but there are limits. I am regretfully suspending Jar, Crashfrog and ICDESIGN for 24 hours. See you all soon. If I failed to suspend someone who deserved it then it is my error, no bias was intended.If you're not sure what is expected of you at EvC Forum then err on the side of caution and do the following:

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--	Percy
	EvC Forum Director

Hi, ICDESIGN. It took me this long to figure out why you didn't want to provide a thorough response to this. I made a mistake, obviously: I meant to write "animals" instead of "fish."For an animal that has to run down prey or climb trees to survive, I think the configuration of the joints, bones and muscles of the feet is not trivial.There is great potential for variation in the foot configuration to alter an animal's ability to run or climb, so there is every reason to think that natural selection is involved in optimizing the joints for their particular function.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi jay,I was catching up on my reading and ran across your statement: Wouldn't it require the DNA to give the order to make a little change in the structor of the foot?Now if the DNA had the informtion stored in it there would be no problem.But how could all the necessary orders be given to create that great potential of variation?What mechanism would cause the mutations to mutate (mess up the DNA enough times) to get the proper changes to create the foot?Just some of my wild thinking.God Bless,

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"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

But there are organisms which have blood and nerves but not bones. I need bones, but then I'm not a basal chordate.As the skeletal system developed, what was once optional became essential. Take the skull, for example. First chordates with no skulls. Then skulls developed apparently as a form of armor, originally as a set of independent plates of dermal bone --- a defense mechanism that assisted survival but was not anatomically essential. To us, it having a skull is essential. I don't know exactly what would happen to us if we didn't have skulls, but for one thing we wouldn't have jaws and so couldn't eat --- unlike basal chordates, which could eat without jaws.An analogy: if you took away electricity now, it would wreck our civilization, we'd all starve within weeks (except the Amish, I guess). But there was civilization before electricity; and then there was a time when it was useful but not essential to Western civilization; and now we're in a situation where we couldn't get by without it, as it has taken on a role which is not merely useful but essential to our way of life.It's a very loose analogy, but hopefully you see the point.

The mechanism which causes mutations is called "mutation".I'm glad I could clear that up for you.

Hi ICDESIGN,I know you don't accept the answers you've been provided, but before you can legitimately repeat your question you have to explain why you reject those answers. We honestly believe we're giving you the correct answers, and until you help us understand why those answers are wrong we'll continue to believe that they're the correct answers.Evolution is a slow process of gradually accumulating change. Whatever mutations get selected to pass on to the next generation must be due to their conferring a greater survival advantage than mutations that were not selected. Concerning skeletal joints, a couple of adjacent bones (perhaps for defense) of an organism must have been more advantageous when additional structures like proto-cartilege or proto-ligaments or proto-lubricant appeared between them through random mutation, and they would have been selected for. Anything that helped the joint confer a survival advantage would have been selected for.In the past you've rejected explanations like this with expressions of incredulity. We clearly understand that you believe evolutionary processes to be woefully insufficient to produce things like skeletal joints, but to convince others of this you need to move beyond expressions of incredulity to precisely explain what makes it so wildly impossible.--Percy

Well, here's one reason for some incredulity; you say random mutations could have caused lubricant forming between joints, or proto-cartilage could have randomly appeared that would have caused some reproductive advantage. But we never see examples of these things happening occasionally in modern species.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. So if we can never see this happening occasionally why do we just have to take your word that it did?But more importantly, why are you constantly shifting the burden on the skeptics to just accept what you say without proof, rather than putting the burden on the one's making the extraordinary claims to provide some extraordinary evidence. Or any evidence for that matter.You are making baseless claims that you can't verify, and asking others to just accept it.

We do see that the differences between species is due to a difference in DNA. We also observe that mutations change DNA, causing it to be different both from the previous generatoin and different from other species. We also observe that advantageous differences are usually kept and amplified in a population. On top of all of that, we observe that this process results in a nested hierarchy.So what do we see in the comparison of genomes, the comparison of morphology of livings species, and the fossil record? The exact pattern we would expect to see if this process were active in the past. We see simpler organisms earlier in history, modifications of those simpler organisms over time, and then the final modifications in modern organisms. All of these modifications fall into a nested hierarchy, both in the present and in the fossil record. We see the modifications of the lobe finned fish morphology into a basal tetrapod. We see the modifications of this basal tetrapod into a reptile. We see the modification of this reptile morphology into a mammalian morphology. We see the modification of this basal mammal into a primate, an ape, and into us. At the same time numerous other lineages are branching out and doing the same thing. Are you to say that we are just dreaming up all of this, that we have absolutely no reason to state that morphology is changed in a step by step process resulting in a branching tree? Are you sure of this? Although I don't know of any examples off hand, I am quite confident that such individuals do exist at least for the ligaments and cartilage. That is something I have wanted to ask the ID crowd for quite some time now.

Excess cartilage: osteochondroma, chondosarcoma, acromegaly
Excess joint fluid: pigmented villonodular synovitis (pvns), arthrocentesis, rheumatoid arthritis
Excess ligaments: Madelung's deformity, scoliosis

We, of course, can't survive without these things. But they didn't evolve in us, or anything like us. Bones first emerged in fish, probably initially as a means of storing valuable minerals which was only later co-opted as a means of additionally strengthening cartilage. Blood evolved earlier, probably in a worm-like organism. Nerves in some of the most basal animals, but in nothing like the organisation or complexity seen in us.

When we have evidence that something has happened, the burden of proof is very much on the person who claims that it can't have happened. Because in the light of the evidence that is an extraordinary claim.If your only argument to back up your claim is personal incredulity, then you are hardly meeting the burden of proof.

Perhaps I wasn't clear enough, maybe that's my mistake, but I thought the implication was obvious enough.Mutations which could possibly, with even the greatest stretch of imagination, actually BENEFIT an individual in the right circumstances.Mutations which could actually cause a different mechanical functioning. A unique physical function. I don't think a tumor counts as a unique physical ability. I am pretty sure arthritis, or pituitary abnormalities are not the origin for any new limbs-now or in the past. Or a congenital deformity that doesn't even effect the victim until later in their life.Besides the fact that I don't believe even one of the things that you mentioned are the type of point mutations that could be carried on to offspring at a specific location.But still, it does say a lot when your side thinks these are the examples that shows that Darwinian evolution could be true. Extraordinary really. And you still believe in your theory?

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.You have evidence of what you feel is common relations, you have absolutely no evidence for the mechanisms that caused complex functioning systems.So when you lie, like you are doing right now, Dr. A, it makes one wonder what your real motive is.

What are you pretending that I am lying about, and whom do you hope to deceive by so doing?

Why Tibetans breathe so easy up high

Residents of the Tibetan Plateau show heritable adaptations to extreme altitude. We sequenced 50 exomes of ethnic Tibetans, encompassing coding sequences of 92% of human genes, with an average coverage of 18x per individual. Genes showing population-specific allele frequency changes, which represent strong candidates for altitude adaptation, were identified. The strongest signal of natural selection came from endothelial Per-Arnt-Sim (PAS) domain protein 1 (EPAS1), a transcription factor involved in response to hypoxia. One single-nucleotide polymorphism (SNP) at EPAS1 shows a 78% frequency difference between Tibetan and Han samples, representing the fastest allele frequency change observed at any human gene to date. This SNP’s association with erythrocyte abundance supports the role of EPAS1 in adaptation to hypoxia. Thus, a population genomic survey has revealed a functionally important locus in genetic adaptation to high altitude.

It is interesting to note that the high altitude adaptations found in residents of the Andes Mountains employ an entirely different mutation.That's evolution in action. And you might consider how quickly this mutation/adaptation occurred in the Andes, as those mountains were populated in the relatively recent past (5,000+ years ago if I remember correctly).

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Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.