Evolving the Musculoskeletal System

Right. This selects against individuals being born half-formed, which is what we've been telling you consistently for more than 130 posts.The challenge before you is to imagine how an organism could be fully-formed even at the same time that it has more primitive systems. Hint - a worm is born "fully-formed" even though it completely lacks a skeletal system. By evolving through reduced or more primitive function, to make a long story short. In human beings, our complex skeletal system has a lot of complex functions - biophysical functions like providing lever-arms and fulcrums to magnify muscle force, immune system and blood function, etc. In its evolutionary precursors, the skeletal system had less functions, or simpler functions.In it's absolute most primitive, earliest forms - among the simplest organisms where endoskeletons appear - the skeleton does little of what it does in humans. It has no joints at all. It may have done nothing but provide bony protection for crucial organs. It certainly didn't house marrow. Every single one of us has addressed this problem in every post, IC. We're struggling to address it in a way that makes sense to you.

I think where the debate continues to be fruitless is in ICDESIGN's notion of evolutionary history, which he doesn't seem to understand as a history where organisms inherit traits from their species ancestors, have them modified by random mutation, and then are selected for or against by their environments in ways that either extinguish or preserve these new, mutant characteristics.I think, and perhaps he'll be kind enough to tell me how stupid I am and call me names if I'm wrong, that ICDESIGN has the notion of evolutionary history commonly depicted in cartoons:and not only that, I think ICDESIGN interprets that happening for every extant organism, independently.In other words, when he tries to think about the evolutionary origin of organisms, I think he imagines:a bacterium, which then divides and becomes multicellular, and becomes something like a misshappen fish made of Play-Doh, and then over millions of years becomes less blob-like and more fish-like, and then grows scales, and then bones, and then fins, and then gills, and finally it's a modern fish,and then there's another bacterium, which divides and becomes multicellular, and then becomes something like a misshapen cat made of Play-Doh, and then over millions of years becomes less blob-like and more cat-like, and then grows fur, grows bones, grows teeth, grows wiskers and claws, and then finally it's a modern cat,and then there's yet another bacterium, which divides and becomes multicellular, and then becomes something like a misshapen person made out of Play-Doh, and then over millions of years becomes less blob-like and more human-like, and then grows bones, grows nerves, grows blood and vessels for blood, grows a brain, finally crawls out of the water, does this:and then it's finally a modern human being.Is that about right, IC? Are you of the notion that the evolution of the human skeleton is an entirely separate process from the evolution of, say, the skeleton of a fish; two processes that have never been the same process since humans and fish evolved from two different bacteria?If you could correct any of my inaccuracies about your notion of evolutionary history, I'd really appreciate it. We'll explain to you how the above notion is a highly flawed view in a bit.

No, you're talking about skeletons. This topic is about the evolution of skeletons.That evolution does not begin in the human species; humans inherited the traits of their skeletons from their ancestors, which were then changed by random mutation and natural selection. Skeletons are present in all vertebrate life, so to find out how skeletons evolved we have to look to the evolutionary origin of Craniata, the clade of chordate organisms that have bony parts (skulls, specifically.)Organisms like the hagfish have skulls but no skeleton. They have no joints and their bones do not house marrow. MKodern hagfish are, of course, as evolved as everything else but the "oldest bony organism" (which is where we would find the first skeleton in evolutionary history) would look a lot like a hagfish. The descendants of those early hagfish would have also had bony skulls, which they would have modified by mutation until those skulls had a jointed mandible, and then those organisms would have passed on a jointed skull to their descendants, and so on. Ultimately you would come to the first hominid to evolve, which would have had a fully jointed and articulated skeleton from birth. Not by magic, but by inheriting it from its non-hominid ancestors. By evolution - descent with modification of something else that was fully formed. (Earthworms - segmented worms - evolved from fully-formed roundworms.)Every organism that lives is fully-formed, as are it's evolutionary descendants. Half-formed organisms do not survive. Therefore there is substantial evolutionary pressure against organisms being born half-formed.

The Last Universal Common Ancestor, or LUCA, may have been more primitive than any living thing since, but it was an entirely fully-formed LUCA.Evolution isn't about organisms going from no-form, to half-formed blobs, to fully-formed organisms. It's about species of fully-formed organisms giving rise to fully-formed, differently-formed descendant organisms. But they're fully-formed all along the way. Fully-formed fish giving eventual rise to fully-formed lizards, by means of fully-formed intermediate forms like Tiktaalik.It's like, you get on the highway in Peoria and drive to Chicago. The highway doesn't lead from Peoria to Chi, which is like Chicago only it's only the north 20% of the city, and then 20 miles later you come to Chica, which is like Chicago only it's the entire north half of the city, then you come to Chicag, which is just like Chicago except missing Soldier's Field, and then you finally come to fully-formed Chicago.No, you get on the highway in Peoria and drive to Chicago, and on the way you pass through a town like Bloomington, which is a fully-formed Bloomington but is a lot like Peoria except with some Chicago features (better deep-dish and taller buildings), and then you pass through Joilet, which is a fully-formed Joilet but a lot like Chicago but with some features of Peoria (country music, jack-off cops.)Fully-formed towns all along the way - not snapshots of Chicago's construction history. Evolution is the same way, it's fully-formed organisms all along the way, even when those organisms are transitional forms between their ancestors and their descendants.

Like Jar said, no, it's called "birth."

This is really such an obviously true thing that the scientific proof of it predates the notion of academic peer review. Chemical reactions have long been known to be stoichiometric, that is to say that their outcomes are statistical and not deterministic, which means that the mechanism of DNA replication is necessarily one in which changes - mutations - must occur.They're not allowed to occur by something - it's impossible to prevent them from occurring. The fidelity of the replication process can be increased or decreased, and in most cells the fidelity is very high, but just as in any process of information transfer, there's a level of entropy that introduces changes. In a radio signal those changes are called "static." In a DNA sequence those changes are mutations. And unlike in a radio signal, where there can be so much static that the signal itself is lost, any mutation to a DNA sequence is still a DNA sequence, which the cell is going to try to interpret as a protein. No, you're wrong about this. Precisely backwards. 70% of protein changes will have no effect at all; only 30% or less will have any effect, harmful or beneficial, on protein function.The vast bulk of a protein is structural, only generally involved in protein configuration, and any individual amino acid residue's contribution to protein structure is necessarily going to be very small. Proteins can have hundreds or even thousands of residues. The largest monomer protein (titin, a muscle protein) is comprised of over 34,000 amino acid residues, but only about a hundred or so are critical to the function of the protein (and are thus highly conserved.) Coelacanths didn't become "the first land creatures."A much better example of a water-to-land transitional is Tiktaalik.As for the rest, you're quite wrong. Today's horseshoe crabs are substantially different than their fossil ancestors. Today's cockroaches have substantial biochemical adaptations that their ancestors lacked (a big problem for your local Orkin man, trust me.) And, of course, the modern Coelacanth is about a fifth of the size of any of its evolutionary precursors.And where are the mutated horseshoe crabs? Mutated so much, they're nothing like horseshoe crabs anymore. Where are the mutated cockroaches? Mutated so much, they're called "termites" now. Punctuated Equilibria

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PE is not mutually exclusive of phyletic gradualism. Gould and Eldredge take pains to explicitly point out that PE is an expansive theory, not an exclusive one (1977).

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PE sometimes is claimed to be a theory resting upon the lack of evidence rather than upon evidence. This is a curious, but false claim, since Eldredge and Gould spent a significant portion of their original work examining two separate lines of evidence (one involving pulmonate gastropods, the other one involving Phacopsid trilobites) demonstrating the issues behind PE (1972). Similarly, discussion of actual paleontological evidence consumes a significant proportion of pages in Gould and Eldredge 1977. This also answers those who claimed that E&G said that PE was unverifiable.

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What "reads pressure"? You'll have to ask that in a clearer way if we're to understand what you could possibly mean by that.One of the consequences of your open refusal to learn any biological science is that the way in which you speak about biology, and concepts in biology, is all but unintelligible to people who are actually trained in it.Selection pressure is natural selection - the tendency of organisms well-adapted to their environments to survive, prosper, and reproduce, and the tendency of organisms not so well-adapted to be extinguished and leave no descendants.When an environment appears to reward a certain adaptation - say, longer necks on grazing creatures in an environment where foliage is lean except at the treetops - we call that a selection pressure that drives that adaptation. Giraffes evolved from short-necked precursors because they lived in an environment that put a selection pressure on having long necks, because shorter-necked individuals starved to death.Natural selection. Surely you can't be unclear on the notion? The evolution of bony skeletons predates the invention of photography by several million years. Could you be more specific about what you'd like to see a picture of?

But there's no such law.The notion that species are "kinds", that a dog (for instance) has some kind of innate dog "essence" that is fundamentally different from (say) a wolf's essence is "species essentialism", a notion that has been discredited for over a hundred years.There just aren't any observable barriers between species like that. There's literally no inherent barrier to species change. Creationists have never been able to tell one kind from another. Every time they think they have two "kinds", we've been able to find examples of interbreeding between species supposedly in those two different "kinds."The reasonable conclusion is that there is no such thing as "kinds."

Can you at least address the possibility that having imperfect or incomplete knowledge leads to imperfect or incomplete conclusions?How could it not?

There's no need to attack my intelligence; just attack my arguments. Where is there such a law? What is your source for laws about biology?

Why do you think "family" means "kinds"?Why do you think lions not breeding with donkeys disproves evolution? Be specific. Evolution doesn't claim that interbreeding is universal, just proximal.

Living things blur the line. The theory of evolution is simply a description of what living things do.

The skeletal system didn't evolve "bone by bone", though. You have this notion of how a skeleton is assembled - say, by medical supply houses assembling one of those "house of horrors" hanging skeletons, or according to that old song "the ankle bone's connected to the, knee bone" - built up bone by bone, each joint connected to the next, and the finally you have a complete skeleton. The notion here is one of teleology; the doctor is putting each bone in a specific place because he's working towards an ultimate end - a complete reconstructed human skeleton.That's how doctors put skeletons together, like puzzle pieces, but that's not how skeletons grow or evolve; a developing fetus isn't assembled bone by bone and then skinned and filled with blood. All that stuff develops simultaneously, each bone developing from a single stem osteoblast cell that migrates, divides, replicates, grows out to a "bone-shape", and then begins to calcify (this process is not complete by the time the infant is born), all according to a genetic program.Skeletons evolved from simple bony plates to highly-shaped mechanical structures by random genetic mutation of this program, and natural selection of organisms whose skeletal-related adaptations gave them a survival advantage in the environments in which they lived. Not selected for adaptations that made them more like humans, but for adaptations that were useful to them at the time. Primitive hagfish didn't evolve skulls because humans would need them millions of years later, they evolved them because there was a benefit to doing so for the hagfish. There's no teleology in evolution. Hey, me too! Unfortunately the evolution of skeletons happened millions of years before humans even existed so there was nobody around to get all the details for us. There's a lot we can discern from developmentology - morphological adaptations like skeletal structure happen by changes to the prenatal development program, so studying that program can provide clues to evolution, that field is "evo-devo" - and a lot we can discern from comparative zoology, though there aren't any "primitive" organisms any more, all living things have been subject to millions of years of evolution by now.You want to see the complete evolution of skeletons in pictures, but the evolution of skeletons happened millions of years before photography even existed. And even if we could show you, what would be the point? You'd simply abandon skeletons as a fruitful avenue for creationist attack, and move on to nerves, or blood vessels, or some other system with exactly the same origin as skeletons - random mutation and natural selection. And you'd be just as hampered by your complete ignorance of biology in that thread as you've been in this one, as you ridiculously continue to insist that "common sense" is just as good as a doctorate in the life sciences. Have you ever heard people say "geologic time" to refer to time periods of millions of years or more? The reason we say that is that environments change, for the most part, very slowly, so no - "everything" usually doesn't "drastically change". Environments usually impose the same pressures for hundreds of thousands of years or more. When drastic change does occur - say, the conversion of the fertile Sahara area into desert over a period of about 10,000 years - then extinctions are inevitable, just as you suggest.99% of all species that have ever lived are extinct. The organisms we observe today, therefore, are necessarily the descendants of organisms who did not experience drastic, sudden environmental change. So what's wrong with genomic evidence? Ultimately this is the same game creationists always play: "you have no evidence." "Well, we have this genomic evidence." "Ok, but besides the genomic evidence, you've got nothing!" "Well, there's this evidence from stratigraphic comparison." "Well, besides the genomic and stratigraphic evidence, you've got nothing!" Call it the fallacy of the looming caveat, or maybe just creationists assembling their invincible wall of ignorance. After all, you never have to explain away the evidence if you refuse to even listen to it. Ok, but you're the one retreating.

Most atmospheric oxygen is produced by sea life (which makes sense, since the ocean is 3/4 of the surface of the Earth.) Especially in the absence of significant respirating land life, yes, it's more than enough to oxygenate the atmosphere.

Right, like "what was the first actually bony organism, and what characteristics did its skeleton have." I notice you don't ask that, though.Is that because you continue to assume that, according to evolution, humans evolved from ape precursors that had no skeletons at all? Boneless apes? If you continue to lack the background in biology that would allow you to understand a deeper response, you're necessarily going to be limited to shallow responses because those are the only responses we can expect you to understand. Which paper, specifically? I see a citation mark in your quoted text ("[2]"), do you think you could provide the citation, so we could find the paper? You have a tendancy not to actually read materials you cite, or to consider summaries more authoritative than the actual primary source (the Lederbergs' paper, for instance) so we'd like to find this paper and actually read it. You should, too. I just did a PubMed search and Eugene Koonin has about 9 papers published in May of 2007, none of them in a journal called "Biology Today." Did you mean Biology Direct? Much greater than what? I think there's a lot of context you've omitted, perhaps dishonestly, and a "replication/translation system" is more complicated and complex than the proposed first life form. Replication/translation refers to protein synthesis, but the RNA World hypothesizes forms of life that perform chemistry with RNA-based enzymes, not protein enzymes. Yes, ICDESIGN, we know how to read scientific notation of large numbers. Almost certainly you're the only one here for whom "1e1018" is an unfamiliar notation.The question is - 1 times ten to the 1018 power what? Universes? Planets? Discreet chemical interactions? Be more specific. Repeated trials turn improbabilities into inevitabilities.