This sounds suspiciously similar to other topics you started.
As an example, I'll focus on the evolution of vertebrate limbs (a subject about which I admit I am not an expert). Let me start with this image:
Although these organisms are not thought to be direct ancestors and descendants of one another, they show an important trend.
On the far left (earlier in time), we see Glyptolepis, a more or less traditional fish. Notice there there is very little variety and specialization among the joints in the fin.
Then, moving right (later in time) across the image, we see a smattering of what I consider to be awkward conglomerations of joints and branches, with increasing specialization of various joints into differing patterns and configurations, with Tiktaalik showing an interesting middle-ground state between the semi-chaotic branches of the second, third and fourth pictures, and the more linear branches of the two amphibian limbs on the right.
It seems pretty straightforward to me to suggest gradualistic, accumulative evolution via mutation and natural selection as the cause here:
Many types of ancient animals secreted minerals as spicules (little chunks), shells or protective crusts.
The ancestors of vertebrates localize this secretion to specific regions inside the body, producing structures we call "bones." Muscles (which also already existed) can attach to bones through developmental mutations, making it easier to produce high-energy motion (i.e. swimming).
Then, irregularities and variations in the genes controlling where bones are formed can explain the diversity of limb-branching we see in the fossil limb drawings above, and natural selection can account for the gradual convergence of these branching patterns on a pattern that is conducive to movement on land.
I see no reason to think this is particularly farfetched.
Edited by Bluejay, : Added "...moving right (later in time) across the image..."
Well, as long as we're just repeating what we said in our earlier posts:
quote:Hi, ICDESIGN.
This sounds suspiciously similar to other topics you started.
As an example, I'll focus on the evolution of vertebrate limbs (a subject about which I admit I am not an expert). Let me start with this image:
Although these organisms are not thought to be direct ancestors and descendants of one another, they show an important trend.
On the far left (earlier in time), we see Glyptolepis, a more or less traditional fish. Notice there there is very little variety and specialization among the joints in the fin.
Then, moving right (later in time) across the image, we see a smattering of what I consider to be awkward conglomerations of joints and branches, with increasing specialization of various joints into differing patterns and configurations, with Tiktaalik showing an interesting middle-ground state between the semi-chaotic branches of the second, third and fourth pictures, and the more linear branches of the two amphibian limbs on the right.
It seems pretty straightforward to me to suggest gradualistic, accumulative evolution via mutation and natural selection as the cause here:
Many types of ancient animals secreted minerals as spicules (little chunks), shells or protective crusts.
The ancestors of vertebrates localize this secretion to specific regions inside the body, producing structures we call "bones." Muscles (which also already existed) can attach to bones through developmental mutations, making it easier to produce high-energy motion (i.e. swimming).
Then, irregularities and variations in the genes controlling where bones are formed can explain the diversity of limb-branching we see in the fossil limb drawings above, and natural selection can account for the gradual convergence of these branching patterns on a pattern that is conducive to movement on land.
I see no reason to think this is particularly farfetched.
I think your drawings are extremely underfetched in explaining any of my posed questions.
Do you want to continue the discussion? If so, it would be in your interest to contribute to it.
The way you carry on a conversation is like a talent show in which you are the judge: you ask for us to present things, then pass judgment on them and say, "Next!"
This is not very enjoyable for us, and it isn't what we thought we were signing up for.
I would personally like to at least get some feedback.
You asked what the evolutionary explanation for the arrangement of the skeleton is. I told you what the evolutionary explanation is, and provided what I thought was a decent visual aid to help explain it better.
Then you told me that it doesn't answer your question, and asked for the next contestant, repeating your original call for entries, without saying why my answer was inappropriate.
Why doesn't it answer the question? I showed you a set of animals with a clear spectrum of characteristics with multiple different organizations of the limb bones. This indicates that the "specialness" of limb and joint organization isn't as great as you think it is.
The broken lock IS the evidence and no inference is necessary.
Think of this formula:
Evidence --> Conclusion
Now, insert the relevant pieces from Percy’s example:
Broken lock --> Burglary
Note that the entity that you put in the evidence slot is not the same thing as the entity you put in the conclusion slot.
Whenever the entities in the two slots are not the same, inference has occurred.
If you didn’t actually see the burglar burglarizing your home, then your conclusion is at least partly derived from inference.
Inference is not really a bad thing or a shady or questionable thing: it’s perfectly normal and perfectly reasonable. There is no reason for you to be slandering the good name of inference.
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ICDESIGN writes:
That eye article is nothing more than pointing to eyes on previous creatures then inferring that is how we ended up with our current eye.
Showing a sequence of eyes (or limbs) that can be arranged by their complexity shows you that there are intermediate steps between the extreme values. Thus, if human limbs and joints are perfect, then we have an entire fossil record and living animal kingdom of evolutionary failures that you claim don’t exist, because no other animal has the same limb positions as us.
Furthermore, if intermediate forms between two extreme forms of an organ can and do exist, they delineate a pathway that very feasibly represents the pathway that evolution might have taken to transition between the first and the last form in the line.
This is the first step any good evolutionist will take in explaining how evolution accounts for any given thing. Once we’ve shown what the pathway is, we can discuss with you the mechanics of getting from one form to the next in more detail.
I, unfortunately, will not be going there right now, because I have already wasted too much of my valuable study time on EvC this weekend.
Thank you for reestablishing my point. What does 26 bones, 31 joints and 20 muscles in the foot have to do with survival?
Bluejay writes:
For humans who live with other people who can protect them and care for them?
Or for fish that have to survive on their own in the wild?
...cute
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.
But how could all the necessary orders be given to create that great potential of variation?
There are two things here:
First, do you really think DNA needs to be given orders to mutate?
And, second, you missed a subtle grammatical point there: I didn’t say that there is great potential for variation (although there is), I said that variation has a great potential to affect fitness.
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ICANT writes:
What mechanism would cause the mutations to mutate (mess up the DNA enough times) to get the proper changes to create the foot?
There are always mutations happening. They are a normal part of the background chemistry of life. They happen because chemical reactions are messy and subject a large number of environmental gradients that will impact the products that the reaction produces.
And, there is also always selection happening. Selection fluctuates over time: it favors one thing, then another, then another. And, each change unlocks new physiological, ecological and behavioral possibilities that can also impact how selection is manifested. The end result is that what constitutes a proper change is entirely subjective: what is proper is determined by which of the current options are most successful.
Ancient organisms developed movement capacity by the gradual accumulation of traits the made movement more efficient than it previously was. Ancient organisms thus developed tissues that could contract and contort the body. Ancient organisms that accidentally secreted minerals into various locations in the body also had a degree of protection from predators, and a useful anchor point to help the contracting tissues perform their functions.
The result was organisms with lots of knobs of mineralized bones and lots of lobes of contractile muscles, and all that was required was for natural selection to amplify those organisms whose bones were arranged in such a way that muscle action was more efficient.
Concurrently, organisms also began using limbs in different ways, thus modifying how selection acted on them. Limbs could be used first only for thrashing about in the water to induce movement or for angling to help steer movement into useful directions. Natural selection amplified the most efficient forms of thrashing until it became the graceful, coordinated motion we see today.
Another success came when thrashing a limb about struck the limb against a solid surface, which gives the organism an added boost due to Newtonian action/reaction. Then, behaviors for increasing the amount of pushing off of solid objects were amplified, and selection favored more coordinated and more efficient forms of pushing off, which caused specific configurations of bones, joints and muscles in the limbs to be amplified in the population. The ability to do the same thing out of the water, where the body’s weight had be born by the limb, was another step forward.
It really isn’t that difficult to envision this process. Just remember that, at every step, there is variation in anatomy and behavior; and that this variation is different from the variation that existed at the last step, because messy chemistry is continually causing changes; and that the most successful, most efficient and most reliable features and behaviors tend to be amplified in the next generations due to the advantages they bestow on their owners.
I think Taq and Crash are better qualified to discuss with you the biochemistry of mutations and their place in evolution, so I’ll yield the floor to them on that topic.
But, I do want to weigh in on a couple of things:
ICANT writes:
I thought an accident was required for the DNA to mutate.
If you thought accidental mutations were required, why did you ask this:
ICANT writes:
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?
On listing random points about mutation? Meh. I defer to Taq and Crash to pass judgment.
On staying on topic? Not too well, I’m afraid.
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ICANT writes:
The Coelacanth that was supposed to have lived in shallow water and finally walked up on land and became the first living land creature has remained basically the same for the past 410 million years. Where is the mutations?
The Horseshoe crab has been around for 425 million years and remains the same today. Where is the mutations?
The cockroach is the oldest winged insect in the world and appears some 350 million years ago, and remains the same today. Where is the mutations?
I swear we’ve been through these exact points before. You can’t seriously tell me that you don’t know the answers to these already.
Since the topic is about the musculoskeletal system of vertebrates, we should focus on fish and tetrapods, but, since neither Taq nor Crash really responded in-depth to the cockroach, I would like to do so.
There were no cockroaches 350 million years ago. In the Carboniferous period, there were Blattopterans (sometimes called ‘roachoids’). They look a lot like cockroaches, but they have ovipositors (egg-laying tubes), and didn’t have the organs for creating oothecae (egg-cases). Furthermore, these Blattopterans are also the ancestors of termites and mantids. I also invite you to peruse this page, which displays pictures of different families of cockroaches, and this picture, which depicts a mantis that looks a whole lot like a cockroach.
But, I digress. Let’s get back to the fish:
I know for a fact that you have argued this line about coelacanths before, and that you have been told that it is inaccurate. Coelacanths are not the ancestors of tetrapods, probably never came out on land, and have not existed unchanged for millions of years in the fossil record. They are not a good example of stasis in the fossil record.
Coelacanths are lobe-finned fish, like modern lungfish, and the ancient ancestors of tetrapods. Earlier on this thread, I showed a diagram of the limbs of various lobe-finned fish:
It is clear from this diagram that there were all kinds of little bones in the limb of the fish that went through a number of experimental configurations (see Sauripterus), culminating in the configuration used by Tiktaalik (which already shows a lot of similarities with tetrapod limbs), before shifting into the configuration used by the earliest tetrapods. In both the case of Tiktaalik and the earliest tetrapods, it is straightforward to pick out which bones would gradually become the radius, ulna, carpals, metacarpals and phalanges (the individual arm bones of humans and other tetrapods).
This is the sequence I pointed out to you, that you thought was difficult to envision outside of a fantasy world: (1) scattered bits of bone in the limb; (2) organization of the bits of bone; (3) modification of the pattern to match modern-day tetrapod patterns.
It seems pretty obvious to me that the same thing explains the emergence of the original pattern of bones. It has been pointed out on this thread that primitive fish only have bones in some parts of their body, and that some fossilized proto-fish have even less bone or none at all. The tendency to form bones would increase as fish evolved, until they had complex skeletons full of unique bones, which could then be altered to form tetrapod limbs.
I am very unclear how changes show up in each off spring.
How does a new bone show up as it is in the process of development?
Bones are produced by a number of different genes acting together.
There are some genes that cause minerals to be collected and deposited, creating bones.
And, there are some genes that direct where and when the minerals are to be deposited.
This second group of genes is important, because they produce the patterns that define how the skeleton forms during the development of the embryo.
When these genes are mutated, they often result in different patterns of bone deposition. Sometimes they cause an extra finger (as has been shown in previous posts), or maybe just an extra bone somewhere. Sometimes they cause a bone to not develop fully, or to develop an unusual shape. Sometimes they cause some bones to be longer or shorter than they would be without the mutation.
Several of these types of mutations in gradual succession, with the help of natural selection, could very easily account for the shift from a fish with one configuration of bones in its fin to a fish with a configuration of bones that is similar to Tiktaalik’s, to a tetrapod with a configuration of bones that is similar to ours.
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ICDESIGN writes:
I am also very unclear about selection pressure.
It’s just like any other pressure: what doesn’t kill you makes you stronger.
In the case of evolution, it’s mostly just about what kills you, and the makes you stronger is actually only about making the population stronger by favoring the better-adapted and killing or otherwise repressing the lesser-adapted.
Examples of selection pressures can be environmental factors: water supply, climate, food supply, etc., things that organisms have to adapt to in order to survive and flourish.
Also, selection pressures can be antagonists (i.e. predators, parasites, diseases or competitors) that may kill organisms from the population or otherwise interfere with their ability to survive and flourish.
Also, selection pressures can be the preferences of potential mates, which the organism may have to impress in order to get the opportunity to pass its genes on the following generations.
None of this is about what an organism wants or knows it has to do in order to survive and continue its lineage: rather, it’s simply that the organisms that successfully meet these selection pressures will survive and will continue their lineage.
So, selection pressure is just a catch-all phrase for things that cause some organisms to survive and reproduce better than others.
Lions and tigers are still within the same kind which is the cat family. Horses and donkeys are of the same family as well. Lets see you breed a lion with a donkey. That is the line! That is the law I am talking about!!
Where is the line? You gave an example of two things that can't interbreed, and claimed that it was a line, but you didn't actually say where the line is.
Let's examine it a little more closely.
You can breed a lion with a lion, or a tiger with a tiger, or a leopard with a leopard, or a cougar with a cougar. If you breed a tiger with a lion, some offspring are fertile, and some are not. If you breed a tiger with a leopard, offspring are stillborn. If you breed a tiger with a cougar, you get no offspring.
I don't see a line at all: I see gradually diminishing success in interbreeding as species get less and less similar. I see a blurry, fuzzy pattern.
You complain that ToE just blurs lines. Well, this is not so: ToE just calls a line blurry when it actually is blurry. Baraminology, on the other hand, just pretends the blur doesn’t exist, and calls it a line.
One of the things that strikes me is that changes that would result from these "pressures" happen at such a slow rate, by the time the thousands of years (or more) transpire into the resulting changes everything has drastically changed making the reasons the changes happened void.
How do you know that the environment is going to change faster than species can evolve under random mutation and natural selection?
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ICDESIGN writes:
You 'claim' it happened but it is sooo slow we can't show it to you.
Nobody actually said this, IC.
Several of us claimed that it happened sooo long ago that we never got to see it, and can thus only put together a few slides in the slideshow.
It’s like that famous sequence of photos from the Mt St Helen’s eruption in 1980.
This is a YouTube video of the photo sequence that was actually taken:
And, with a little application of logic (and some nice computer technology), someone filled in the gaps to make this reasonable recreation of the event as it actually happened:
That’s what we’re doing with evolution, IC: we have found a series of snapshots (fossils, in this case), and have put the pieces together using what evidence we have, using the principles of the world’s operation that we have learned from our study of the world around us to fill in the gaps.
It’s not a perfect system, and nobody claims that it is. But, you have to admit that it makes sense to do things this way! For the life of me, I can't understand why this is such a hard thing for creationists to realize!
P.S. I never learned how to embed videos, and don't have the time to try to learn it now, so if an admin wants to edit this for me to make it easier on everybody, go right ahead.
Edited by Bluejay, : "to fill in the gaps"
Edited by Bluejay, : Embed videos. Thanks, Huntard
I already told you what aspects of the process led me to call it inferior, and nothing you've said changes my mind.
While I favor the "traditional" peer review system, I'm kind of leaning towards WK's position on this.
The Journal of Biogeography ("traditional" review system, impact factor > 3.5 over the last three years) published a Schwartz paper claiming that humans are more closely related to orangutans than chimpanzees. It was explicitly based on the assertion that molecular phylogenetics is less robust than morphological phylogenetics.
Incidentally, the journal published a disclaimer (actually called an "editorial") stating that the paper didn't really convince the reviewers, but that the editorial staff felt it was still worth putting out there for scientific scrutiny, at least in part because of the publicity it would probably receive.
I think it would need a much more in-depth analysis than I think you've actually done to say whether Biology Direct's review process results in inferior science getting through.
You've already got some responses to your post, but I'd like to add a simple side comment. Don't feel like you need to respond: it's more of an aside.
ICdesign writes:
Natural selection has to have intentionality to determine if a mutation is beneficial or not and choose the best for survival.
No doubt this "natural selection" of which you speak wears black robes and carries a scythe, with which it kills off those that it deems unfit for survival?
When we speak of natural selection killing off the weak and preserving the fit, we aren't actually envisioning a real force of nature, to which we ascribe the name "natural selection," that is analyzing information and making decisions about who survives and who dies.
Rather, we are using what is called "teleonomic language." This is a metaphoric language that pretends there is intentionality where we know there isn't. It's usually done for efficiency or for ease of explanation. "Natural selection" is just a pattern of observations that the organisms that survive and reproduce well tend to be organisms that have characteristics that are appropriate for their environment, or characteristics that are conducive to successful reproduction.
That's not too complicated, is it? In fact, it seems kind of a no-brainer, doesn't it? 'Those that have the tools to survive have a better chance of surviving.' Obviously.
Teleonomic language is used when the results of non-intentional processes turn out to look like something that is intentional. For example, in ecology and animal behavior, there is a theory called "optimal foraging theory," which seeks to model animal foraging (food-finding) behavior. The basic model essentially treats animals as if they are making informed, economical decisions by analyzing information about their environment and their prey.
The trouble is, we know that the information the animals are meant to be analyzing is not actually available to them, so they clearly aren't making decisions based on that information. Yet, amazingly enough, optimal foraging theory does a fairly decent job of modeling the foraging behavior of animals anyway. Why? Because the results of natural selection mimic the results of decision-making processes.
So, just because a certain phraseology of a scientific idea seems as if it is referring to intentionality, it doesn't mean intentionality is required or implied.
I hope this helped a little.
Note: "Teleonomy" is not the same thing as "teleology," which is an argument that actually proposes design as an explanation, and not just a metaphor.
Now giving him any amount of time you choose, would he EVER be able to assemble the Rolls Royce?
First, why does he have to build a Rolls Royce? Why can't he build roller skates or a hot dog cooker instead? Why must the end-product be specified beforehand? In evolution, the end-product is not specified beforehand, so this isn't a good analogy for how evolution works.
Now, from where we stand in time, we have to explain how evolution produced, e.g., humans, so it looks like we have to have a process that works toward the "goal" of producing humans.
But, in actuality, the end-product of "human" was not specified when evolution started: it was just the end-product that came about, and our job is to retell the story of how it went down.
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But, even if this were the way evolution works, you're analogy has left out one of the principle characters! In this analogy, Mr Selection is the supervisor, who shakes his head every time Mr Chance puts a part in the wrong place, and removes the offending part.
What do you think Mr Chance's chances of making a Rolls Royce in a billion years would be then?
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