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Genetic Limitations To Evolution Between Kinds


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#21 rico

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Posted 15 October 2011 - 10:03 AM

Interesting line of thought there. I guess we have to wait for the gurus to give us their take on that one. If i were to propose a conspiracy theory (based on the assumption that that question HAS been asked before) i would say no-one would want to answer a question that would put an end to a theory held in such high esteem.

I was wondering, are there any known genetic limitations that would NOT allow for:
a) the creation of new traits in organisms (which would lead to)
B) evolution between kinds.

As a springboard; it would seem to me that sign epistasis would potentially limit mutation of alleles with large epistatic loads. This would restrict mutations that would cause drastic new traits to arise that would be positive enough to select for. This would restrict organisms to primarily mutate alleles with less epistatic load, which would cause slower development of new traits, which would disappear due to further mutation before becoming complex new systems or traits (I am thinking of musculoskeletal systems here, or blood's ability to clot, fight infections, etc). I admit my understanding of sign epistasis is a bit fuzzy.

If we find empirical data for such limitations, it would be one of the biggest stumbling blocks to evolution since abiogenesis. I am just wondering if such limitations have been observed. I have not been able to find an article on this that I could make sense of.

Laughing at myself; I may have found a more specific answer to your question. The claim has been made in regaurd to genetic information, not data, that evolution (mutation, natural selection, etc.) cannot add completely new information to the genome (not referring to copies of information already present). Some examples:
1) nylonaise through natural selection and 2) mutations from chernobyl. I keep thinking of hybrids; wholphins, ligers, zonkeys, and wonder if we could genetically modify dolphins into whales; a dolphin is a whale is a cetacean...

Here is a link to a creation wiki that has examples of no new information and is tentative: http://creationwiki....ic_information?

#22 JayShel

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Posted 15 October 2011 - 12:21 PM

Laughing at myself; I may have found a more specific answer to your question. The claim has been made in regaurd to genetic information, not data, that evolution (mutation, natural selection, etc.) cannot add completely new information to the genome (not referring to copies of information already present). Some examples:
1) nylonaise through natural selection and 2) mutations from chernobyl. I keep thinking of hybrids; wholphins, ligers, zonkeys, and wonder if we could genetically modify dolphins into whales; a dolphin is a whale is a cetacean...

Here is a link to a creation wiki that has examples of no new information and is tentative: http://creationwiki....ic_information?


I don't know about the Chernobyl mutations, but I was under the impression that nylonase was not new information, rather it was a modification of a mechanism that already existed to digest something in the nylonase that is chemically similar to what it was digesting previously.

#23 jason777

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Posted 15 October 2011 - 01:54 PM

I don't know about the Chernobyl mutations, but I was under the impression that nylonase was not new information, rather it was a modification of a mechanism that already existed to digest something in the nylonase that is chemically similar to what it was digesting previously.


Yes. The same gene added two amino acids to a protein chain.

http://www.google.co...KzLCdrOGdYpTghQ


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#24 JayShel

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Posted 15 October 2011 - 07:17 PM

Yes. The same gene added two amino acids to a protein chain.

http://www.google.co...KzLCdrOGdYpTghQ


Enjoy.


That article meant nothing to me :P Your summary of it tells me more, but does this have implications for evolution between kinds?

#25 jason777

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Posted 15 October 2011 - 08:09 PM

That article meant nothing to me :P Your summary of it tells me more, but does this have implications for evolution between kinds?


No. But it does prove (through an empirical method) that no increase of genetic information was involved.

Enjoy.

#26 aelyn

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Posted 16 October 2011 - 06:26 AM

I don't know about the Chernobyl mutations, but I was under the impression that nylonase was not new information, rather it was a modification of a mechanism that already existed to digest something in the nylonase that is chemically similar to what it was digesting previously.

Right. The kind of incremental change the theory of evolution is all about.

#27 JayShel

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Posted 16 October 2011 - 09:41 AM

Right. The kind of incremental change the theory of evolution is all about.


I was under the impression that evolution was about cells/organisms gaining new functions that never existed before, not modifying the functions that already exist. I would consider the modification of functions that already exist to be adaptation. How can we come to the conclusion that evolution gives rise to new and more complex organisms if we do not observe new functions developing?

#28 aelyn

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Posted 16 October 2011 - 09:59 AM

I was under the impression that evolution was about cells/organisms gaining new functions that never existed before, not modifying the functions that already exist. I would consider the modification of functions that already exist to be adaptation. How can we come to the conclusion that evolution gives rise to new and more complex organisms if we do not observe new functions developing?

New functions can develop from the gradual modification of functions that already exist. Digesting nylon is a new function for example. I don't know what definition of "new function" you could use that said it wasn't. Would you call "flying" a new function ? It can arise as a modification of gliding, which can itself be a modification of jumping, which can itself be a modification of running...

#29 JayShel

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Posted 16 October 2011 - 12:35 PM

New functions can develop from the gradual modification of functions that already exist. Digesting nylon is a new function for example. I don't know what definition of "new function" you could use that said it wasn't. Would you call "flying" a new function ? It can arise as a modification of gliding, which can itself be a modification of jumping, which can itself be a modification of running...


The assertion of evolutionists is that new functions can develop from gradual modification of functions that already exist, and that this would eventually lead to completely different organisms that cannot interbreed. It would be great to see some evidence of this.

At the lowest level (after abiogenesis) I would consider prokaryotic cells developing eukaryotic properties (precursors to a nucleus or organelles) the development of new functions that would prove such transitions possible.


It seems clear that plasmids are designed features of bacteria that enable adaptation to new food sources or the degradation of toxins. The details of just how they do this remains to be elucidated. The results so far clearly suggest that these adaptations did not come about by chance mutations, but by some designed mechanism. This mechanism might be analogous to the way that vertebrates rapidly generate novel effective antibodies with hypermutation in B-cell maturation, which does not lend credibility to the grand scheme of neo-Darwinian evolution.11 Further research will, I expect, show that there is a sophisticated, irreducibly complex, molecular system involved in plasmid-based adaptation—the evidence strongly suggests that such a system exists. This system will once again, as the black box becomes illuminated, speak of intelligent creation, not chance. Understanding this adaptation system could well lead to a breakthrough in disease control, because specific inhibitors of the adaptation machinery could protect antibiotics from the development of plasmid-based resistance in the target pathogenic microbes. -Don Batten http://creation.com/...-on-nylon-waste



#30 aelyn

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Posted 16 October 2011 - 01:14 PM

The assertion of evolutionists is that new functions can develop from gradual modification of functions that already exist, and that this would eventually lead to completely different organisms that cannot interbreed. It would be great to see some evidence of this.

Interbreeding and leading to different organisms are two different issues. Populations can change while interbreeding continuously with each other (although two different populations that interbreed routinely usually won't change too much from each other, for the simple reason that there's constant gene flow keeping them "in sync" - but exceptions exist), and two populations can stop being able to interbreed without having dramatic differences in phenotype. Of course once two populations have stopped interbreeding, then there's no more gene flow keeping them similar so over time they can grow arbitrarily different. How different depends on what we're looking at : random drift means that genetically they'll diverge in any case, but how much their functional characters change depends on the selection pressures they're under.

And "completely different organisms" is a relative term - I've seen it said (by bacteriologists, who else) that eukaryotes are all the same, the variety in multicellular organisms is just different arrangements of the same building blocks. And if you read Wonderful Life you'll see Gould lamenting that the Cambrian was full of wondrously weird creatures most of which went extinct so that modern life consisted of many variations off the same few body plans. And then there are those who look at the wide variety in domesticated species and say since they can still interbreed those differences don't count or something.

Anyway, what kind of evidence do you need ? We know traits can change over generations. We know new functions can arise from the modification of previous functions. We know life has changed a lot over geological periods of time (snobby bacteriologists notwithstanding). Unless there is something stopping those differences (that we know happen) from adding up to being big differences there's no reason they shouldn't.

At the lowest level (after abiogenesis) I would consider prokaryotic cells developing eukaryotic properties (precursors to a nucleus or organelles) the development of new functions that would prove such transitions possible.

Do you mean you want experimental evidence of modern prokaryotes evolving into eukaryote-like organisms ? A repeat of the most significant evolutionary event since, well, life itself appeared ? That event that most biologists think must have been massively unlikely, because while life seems to have appeared shortly after conditions were right for it, eukaryotes only appeared a billion or so years later ?
Is that the evidence you need before you'll believe that, say, a jumping squirrel could evolve into a gliding squirrel ?

#31 jason777

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Posted 16 October 2011 - 01:18 PM

Right. The kind of incremental change the theory of evolution is all about.


(Mod hat on)

Rule #6)Equivocation, particularly regarding what "evolution" means. It is intellectually dishonest to claim that micro-evolution (something everyone agrees occurs) proves that all life originates from a common ancestor.

This type of adaptation is not an increment of common descent; There wasn't even a gene duplication involved.

(Mod hat off)

Although it is interesting that organisms can use multiple genes or even a single gene to produce different variants of a pre-existing enzyme, this is essentially the observed limits predicted by creation.



Enjoy.

#32 aelyn

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Posted 16 October 2011 - 01:28 PM

(Mod hat on)

Rule #6)Equivocation, particularly regarding what "evolution" means. It is intellectually dishonest to claim that micro-evolution (something everyone agrees occurs) proves that all life originates from a common ancestor.

I didn't say it did. And it doesn't; the evidence that all life originates from a common ancestor is completely different.
But the theory of evolution isn't just about all life originating from a common ancestor, it's about the mechanisms through which this happened. And those mechanisms are all about incremental change.

#33 JayShel

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Posted 16 October 2011 - 03:40 PM

Interbreeding and leading to different organisms are two different issues. Populations can change while interbreeding continuously with each other (although two different populations that interbreed routinely usually won't change too much from each other, for the simple reason that there's constant gene flow keeping them "in sync" - but exceptions exist), and two populations can stop being able to interbreed without having dramatic differences in phenotype. Of course once two populations have stopped interbreeding, then there's no more gene flow keeping them similar so over time they can grow arbitrarily different. How different depends on what we're looking at : random drift means that genetically they'll diverge in any case, but how much their functional characters change depends on the selection pressures they're under.


One way to tell that organisms are different, is that they can no longer interbreed. One of the predictions of evolution is that if one species was geographically separated into two different habitats, with different demands on the organisms, that eventually, these organisms would no longer be able to interbreed. Have we observed this?

And "completely different organisms" is a relative term - I've seen it said (by bacteriologists, who else) that eukaryotes are all the same, the variety in multicellular organisms is just different arrangements of the same building blocks. And if you read Wonderful Life you'll see Gould lamenting that the Cambrian was full of wondrously weird creatures most of which went extinct so that modern life consisted of many variations off the same few body plans. And then there are those who look at the wide variety in domesticated species and say since they can still interbreed those differences don't count or something.


I believe you are trying to play a word game and confuse concepts which I am communicating clearly. The "completely different organisms" was qualified, in the same sentence, by the phrase "that cannot interbreed". In bacteria, since they do not reproduce s*xually, there should be other ways of distinguishing between kinds. There is no universal distinction for this in the bible, but I would say prokaryotes and eukaryotes are different enough that they would be considered completely different organisms. This is why I used this example.

Anyway, what kind of evidence do you need ? We know traits can change over generations.

Yes.

We know new functions can arise from the modification of previous functions.

We understand that organisms can adapt to their environment, this involves changes in their current functions, which is possibly a part of their original design. We disagree whether or not this can lead to the development of more complexity functions and structures within organisms.

We know life has changed a lot over geological periods of time (snobby bacteriologists notwithstanding).

This statement is not very specific. There are living fossils which, according to evolutionists assessment of the fossil age, have not changed much at all over millions of years. Your statement assumes the accuracy of the "geologic column" dating, which is debatable. Also, there are a wide variety among living organisms, so finding fossils of extinct organisms does not necessarily indicate that genetic mechanisms could explain common descent.

Unless there is something stopping those differences (that we know happen) from adding up to being big differences there's no reason they shouldn't.


That is exactly what this thread is inquiring about. Proof that there is no genetic limitation is not proof of evolution, it just means that evolution remains possible, but then so does creation.


Do you mean you want experimental evidence of modern prokaryotes evolving into eukaryote-like organisms ? A repeat of the most significant evolutionary event since, well, life itself appeared ? That event that most biologists think must have been massively unlikely, because while life seems to have appeared shortly after conditions were right for it, eukaryotes only appeared a billion or so years later ? Is that the evidence you need before you'll believe that, say, a jumping squirrel could evolve into a gliding squirrel? (emphasis added)


I would love some evidence that eukaryotes formed from prokaryotes, but you consider this to be unreasonable. As far as I know, this would be the only sign of evolution in prokaryotes. I am looking for a gain in a new function in organisms, like I said. I believe this last sentence is a straw man. I never said that a gliding squirrel could not come from a jumping squirrel (or vice versa). I would say that plausibility that wings can form in stages is not proof that they did.


I think this topic is in danger of being derailed. The point of this thread was not to rehash the entire creation vs evolution argument, rather to inquire if there are any genetic limitations to evolution between kinds.

#34 aelyn

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Posted 17 October 2011 - 01:31 AM

One way to tell that organisms are different, is that they can no longer interbreed. One of the predictions of evolution is that if one species was geographically separated into two different habitats, with different demands on the organisms, that eventually, these organisms would no longer be able to interbreed. Have we observed this?

We haven't just observed reproductive isolation, we've made it happen in the lab, with flies. Usually associated with behavioral and physical modifications too. In the wild most observed cases involve plant hybrids or polyploidization events, because that's the fastest way speciation can happen. Then there are cases where we know speciation happened very recently (through historical knowledge but also genetic analysis) and involve dramatic changes in behavior and morphology, in cases such as the African cichlid fish or animals that colonized archipelagos. Note that "very recently" can be very recently : house mice were introduced to the island of Madeira just a few hundred years ago, and now over a hundred different reproductively isolated groups exist with different morphologies and different chromosome counts. And then there are groups that speciated so gradually they constitute ring species, where every adjacent population can interbreed with each other one but the two populations at each end can't. In this case we still see every intermediate of the speciation event although the event itself happened already.

The issue with speciation is that genetic incompatibility usually comes about through genetic drift, and that happens at a constant rate that can't be forced (except by increasing the mutation rate, which doesn't happen a lot). So the African cichlid fishes for example are very similar genetically - it's unknown whether they'd be genetically compatible, but as far as reproductive isolation goes it's moot because they have complex mating rituals that mean they never mate outside their own species.

I believe you are trying to play a word game and confuse concepts which I am communicating clearly. The "completely different organisms" was qualified, in the same sentence, by the phrase "that cannot interbreed". In bacteria, since they do not reproduce s*xually, there should be other ways of distinguishing between kinds. There is no universal distinction for this in the bible, but I would say prokaryotes and eukaryotes are different enough that they would be considered completely different organisms. This is why I used this example.

I'm sorry you think I'm playing word games; I sincerely don't know what you mean by "completely different organisms". "That cannot interbreed" doesn't narrow things down because there are plenty of groups that cannot interbreed but that I think are very similar. And using prokaryotes and eukaryotes as an example of "completely different" is more confusing still, because prokaryotes and eukaryotes are more different than any two eukaryotes you could come up with. Yeast are more like humans than they are like bacteria. If we take prokaryotes vs eukaryotes as our template for "completely different" then we've got a scale on which humans and tunicates are substantially similar. I don't think that's the scale either of us is interested in.

This statement is not very specific. There are living fossils which, according to evolutionists assessment of the fossil age, have not changed much at all over millions of years. Your statement assumes the accuracy of the "geologic column" dating, which is debatable. Also, there are a wide variety among living organisms, so finding fossils of extinct organisms does not necessarily indicate that genetic mechanisms could explain common descent.

When we look at fossils, we see that different layers have systematically different fossils. Yes, some fossils span a lot of layers but most don't, and that doesn't change the point that the overall fossil composition is different for each layer. No need for radiometric dating to see that.
And yes, there is a wide variety among living organisms today... But the species makeup of today's biosphere isn't what we see in the fossil record. The highest layers have a species makeup that's very much like today's, and each layer has a species makeup very much like the one above it (with a few exceptions, but even those show a continuity in the kind of species both layers contain), but as we go deeper they get more and more different and fossils that even resemble modern species get more and more rare.

That is exactly what this thread is inquiring about. Proof that there is no genetic limitation is not proof of evolution, it just means that evolution remains possible, but then so does creation.

That is indeed what this thread is inquiring about. And that there is no genetic limitation to species change is indeed not evidence that species actually have changed that much. The evidence for that is the patterns of morphology and genetics we see and what we see in the fossil record.

And creation is always possible. God could have done anything and made it look like anything. If all you're concerned about is that creation be possible then there's no need to look for evidence for or against it.

I would love some evidence that eukaryotes formed from prokaryotes, but you consider this to be unreasonable.

Sorry, I misspoke. I meant that expecting that event to be reproduced in the lab is unreasonable. As for evidence that it happened, there are genetic and metabolic homologies between eukaryotes and some prokaryotes for one, and genetic and morphological evidence that mitochondria and chloroplasts evolved from endosymbiotic prokaryotes.

As far as I know, this would be the only sign of evolution in prokaryotes.

That's your eukaryotic bias speaking. Prokaryotes are much more diverse amongst themselves than eukaryotes are; I'm pretty sure they're also more diverse amongst themselves than they are different from eukaryotes. Yep, checked Wikipedia : archaea are more like eukaryotes than they are like bacteria.
I wasn't joking when I said I'd seen bacteriologists say there had been no evolution in eukaryotes since they'd arisen. Bacteria have much bigger differences in basic things like cellular metabolism than eukaryotes do.

I am looking for a gain in a new function in organisms, like I said. I believe this last sentence is a straw man. I never said that a gliding squirrel could not come from a jumping squirrel (or vice versa). I would say that plausibility that wings can form in stages is not proof that they did.

Sorry, I didn't mean to make a straw-man, I just wanted to point out how completely different what you were asking was from what I assume you're really interested in (evolution among animals). After all some people believe that eukaryotes and prokaryotes were specially created but everything after that came through evolution (mostly because of how unlikely the evolution of eukaryotes appears to have been). They're separate questions, really.

And I'm sorry but I still don't know what kind of gain in a new function you're looking for. You yourself suggested such a new function (digesting nylon) and rejected it because it was the modification of a previously existing function. But the modern theory of evolution requires every new function to be a modification of a previous function. If we ever find evidence of a new function arising with no relation to previous functions, evolutionists would be as baffled as you. It would be evidence against the theory of evolution in its current form. (common descent is about the only aspect of the theory of evolution that wouldn't affected much either way)

So I really don't know what to tell you here.

I think this topic is in danger of being derailed. The point of this thread was not to rehash the entire creation vs evolution argument, rather to inquire if there are any genetic limitations to evolution between kinds.

Sorry; obviously that's something I can't address. But dismissing nylon-digesting bacteria because it's a modification of a previous function is a serious misunderstanding of the theory of evolution so I felt I had to address that.

#35 JayShel

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Posted 18 October 2011 - 01:38 AM

We haven't just observed reproductive isolation, we've made it happen in the lab, with flies. Usually associated with behavioral and physical modifications too. In the wild most observed cases involve plant hybrids or polyploidization events, because that's the fastest way speciation can happen. Then there are cases where we know speciation happened very recently (through historical knowledge but also genetic analysis) and involve dramatic changes in behavior and morphology, in cases such as the African cichlid fish or animals that colonized archipelagos. Note that "very recently" can be very recently : house mice were introduced to the island of Madeira just a few hundred years ago, and now over a hundred different reproductively isolated groups exist with different morphologies and different chromosome counts. And then there are groups that speciated so gradually they constitute ring species, where every adjacent population can interbreed with each other one but the two populations at each end can't. In this case we still see every intermediate of the speciation event although the event itself happened already.

The issue with speciation is that genetic incompatibility usually comes about through genetic drift, and that happens at a constant rate that can't be forced (except by increasing the mutation rate, which doesn't happen a lot). So the African cichlid fishes for example are very similar genetically - it's unknown whether they'd be genetically compatible, but as far as reproductive isolation goes it's moot because they have complex mating rituals that mean they never mate outside their own species.


I'm sorry you think I'm playing word games; I sincerely don't know what you mean by "completely different organisms". "That cannot interbreed" doesn't narrow things down because there are plenty of groups that cannot interbreed but that I think are very similar. And using prokaryotes and eukaryotes as an example of "completely different" is more confusing still, because prokaryotes and eukaryotes are more different than any two eukaryotes you could come up with. Yeast are more like humans than they are like bacteria. If we take prokaryotes vs eukaryotes as our template for "completely different" then we've got a scale on which humans and tunicates are substantially similar. I don't think that's the scale either of us is interested in.


When we look at fossils, we see that different layers have systematically different fossils. Yes, some fossils span a lot of layers but most don't, and that doesn't change the point that the overall fossil composition is different for each layer. No need for radiometric dating to see that.
And yes, there is a wide variety among living organisms today... But the species makeup of today's biosphere isn't what we see in the fossil record. The highest layers have a species makeup that's very much like today's, and each layer has a species makeup very much like the one above it (with a few exceptions, but even those show a continuity in the kind of species both layers contain), but as we go deeper they get more and more different and fossils that even resemble modern species get more and more rare.


That is indeed what this thread is inquiring about. And that there is no genetic limitation to species change is indeed not evidence that species actually have changed that much. The evidence for that is the patterns of morphology and genetics we see and what we see in the fossil record.

And creation is always possible. God could have done anything and made it look like anything. If all you're concerned about is that creation be possible then there's no need to look for evidence for or against it.


Sorry, I misspoke. I meant that expecting that event to be reproduced in the lab is unreasonable. As for evidence that it happened, there are genetic and metabolic homologies between eukaryotes and some prokaryotes for one, and genetic and morphological evidence that mitochondria and chloroplasts evolved from endosymbiotic prokaryotes.


That's your eukaryotic bias speaking. Prokaryotes are much more diverse amongst themselves than eukaryotes are; I'm pretty sure they're also more diverse amongst themselves than they are different from eukaryotes. Yep, checked Wikipedia : archaea are more like eukaryotes than they are like bacteria.
I wasn't joking when I said I'd seen bacteriologists say there had been no evolution in eukaryotes since they'd arisen. Bacteria have much bigger differences in basic things like cellular metabolism than eukaryotes do.


Sorry, I didn't mean to make a straw-man, I just wanted to point out how completely different what you were asking was from what I assume you're really interested in (evolution among animals). After all some people believe that eukaryotes and prokaryotes were specially created but everything after that came through evolution (mostly because of how unlikely the evolution of eukaryotes appears to have been). They're separate questions, really.

And I'm sorry but I still don't know what kind of gain in a new function you're looking for. You yourself suggested such a new function (digesting nylon) and rejected it because it was the modification of a previously existing function. But the modern theory of evolution requires every new function to be a modification of a previous function. If we ever find evidence of a new function arising with no relation to previous functions, evolutionists would be as baffled as you. It would be evidence against the theory of evolution in its current form. (common descent is about the only aspect of the theory of evolution that wouldn't affected much either way)

So I really don't know what to tell you here.


Sorry; obviously that's something I can't address. But dismissing nylon-digesting bacteria because it's a modification of a previous function is a serious misunderstanding of the theory of evolution so I felt I had to address that.


Evolutionists have a similar problem with the fossil record, the organisms within do not seem to be declining in complexity as we go down the layers. I am sure both sides have come up with a satisfactory answer. I will look into this when I get some more time, you have piqued my interest on this.

I don't think that macro-evolution can happen from micro-evolutionary processes. I guess my question would be best stated "Are there genetic barriers to macro evolution.". I stated at the beginning of this thread that I didn't know what I was looking for, but certainly, if a bacteria keeps changing its metabolic processes, it does not make it turn into a eukaryote. It is not an explanation of macro-evolution. Also, homologies go either way, as proof of the same creator, or the same creation process depending on your bias. You cannot prove macro-evolution by working backwards. Mechanisms must be shown, and so far, evolutionists would seem to be content on saying that micro-evolution can cause macro. I guess I was looking for proof for or against such plausibility claims. I am not so sure we have found such proof for or against, so you will have to excuse me if it does not exist yet. Feel free to list other proofs that you may feel fit the criteria.

#36 aelyn

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Posted 18 October 2011 - 03:40 AM

Evolutionists have a similar problem with the fossil record, the organisms within do not seem to be declining in complexity as we go down the layers.

How so ? Organisms are clearly simpler and less diverse the earlier the strata. Compare stromatolites to Precambrian fossils to Cambrian to Silurian to Devonian fossils... How are you defining "complexity" here ? I can see how by some definitions (like, say, "all multicellular organisms are equally complex") you could say that complexity increased at the beginning and has plateaued ever since, but overall that's still an increase.

And note that the theory of evolution doesn't say complexity should always increase. Organisms only evolve to be more complex if complexity is adaptive. As it happens the earliest life forms were rather simple so the upper bound of complexity would have to increase if only by diffusion (as does the upper bound of size for example), and complexity often is adaptive in that it permits more diverse behavior. But it's also energy-intensive and prone to getting lost with genetic drift, so whether an organism evolves to be more complex or simpler depends on its circumstances.

I am sure both sides have come up with a satisfactory answer. I will look into this when I get some more time, you have piqued my interest on this.

Good luck ! As an aside because you made me think of Cambrian fossils, there's this adorable 7-year-old kid who's crazy about fossils and has a blog listing all the seriously old and weird fossils that don't get talked that much about. Obviously he's posting about what he's read so it all assumes evolution and an old Earth, but just as a gloriously jumbled overview of the fossils that are out there it's a fun read. And he's been giving sources for the last few months like a real professional and everything :)
It's "Life before the Dinosaurs".

I don't think that macro-evolution can happen from micro-evolutionary processes. I guess my question would be best stated "Are there genetic barriers to macro evolution.". I stated at the beginning of this thread that I didn't know what I was looking for, but certainly, if a bacteria keeps changing its metabolic processes, it does not make it turn into a eukaryote. It is not an explanation of macro-evolution. Also, homologies go either way, as proof of the same creator, or the same creation process depending on your bias. You cannot prove macro-evolution by working backwards. Mechanisms must be shown, and so far, evolutionists would seem to be content on saying that micro-evolution can cause macro. I guess I was looking for proof for or against such plausibility claims. I am not so sure we have found such proof for or against, so you will have to excuse me if it does not exist yet. Feel free to list other proofs that you may feel fit the criteria.

I'm afraid from what you describe I can't tell if what you call "macro-evolution" is something that's in the actual theory of evolution or not. AFAIK current theories don't propose that Prokaryotes changed into Eukaryotes just from changing their metabolic processes : the current hypothesis is that it happened through endosymbiosis. But as I said in another post... That was a massive, and as far as we know unique event, to the point that some people think God did it. If you use that as a template for what "macro-evolution" is, then every other change would be "micro-evolution" by comparison. And it doesn't sound as if that's what you mean by "macro-evolution".

But either way the question for common descent is separate from the exact mechanism for it. In fact we don't know everything about the exact mechanism - the idea that adaptation results from natural selection and random mutation is well-accepted, but within that people disagree on how much of evolutionary change is adaptive vs how much is neutral, how important random drift is, on the influence of epigenetics and development...
None of those people however disagree that common descent happened, because the evidence for that (morphological, genetic, fossil) exists regardless of the mechanism at play. Unless every proposed mechanism is impossible, but like all negatives that's a very hard proposition to prove.

#37 JayShel

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Posted 18 October 2011 - 04:46 AM

How so ? Organisms are clearly simpler and less diverse the earlier the strata. Compare stromatolites to Precambrian fossils to Cambrian to Silurian to Devonian fossils... How are you defining "complexity" here ? I can see how by some definitions (like, say, "all multicellular organisms are equally complex") you could say that complexity increased at the beginning and has plateaued ever since, but overall that's still an increase.

And note that the theory of evolution doesn't say complexity should always increase. Organisms only evolve to be more complex if complexity is adaptive. As it happens the earliest life forms were rather simple so the upper bound of complexity would have to increase if only by diffusion (as does the upper bound of size for example), and complexity often is adaptive in that it permits more diverse behavior. But it's also energy-intensive and prone to getting lost with genetic drift, so whether an organism evolves to be more complex or simpler depends on its circumstances.


Good luck ! As an aside because you made me think of Cambrian fossils, there's this adorable 7-year-old kid who's crazy about fossils and has a blog listing all the seriously old and weird fossils that don't get talked that much about. Obviously he's posting about what he's read so it all assumes evolution and an old Earth, but just as a gloriously jumbled overview of the fossils that are out there it's a fun read. And he's been giving sources for the last few months like a real professional and everything :)
It's "Life before the Dinosaurs".


I'm afraid from what you describe I can't tell if what you call "macro-evolution" is something that's in the actual theory of evolution or not. AFAIK current theories don't propose that Prokaryotes changed into Eukaryotes just from changing their metabolic processes : the current hypothesis is that it happened through endosymbiosis. But as I said in another post... That was a massive, and as far as we know unique event, to the point that some people think God did it. If you use that as a template for what "macro-evolution" is, then every other change would be "micro-evolution" by comparison. And it doesn't sound as if that's what you mean by "macro-evolution".

But either way the question for common descent is separate from the exact mechanism for it. In fact we don't know everything about the exact mechanism - the idea that adaptation results from natural selection and random mutation is well-accepted, but within that people disagree on how much of evolutionary change is adaptive vs how much is neutral, how important random drift is, on the influence of epigenetics and development...
None of those people however disagree that common descent happened, because the evidence for that (morphological, genetic, fossil) exists regardless of the mechanism at play. Unless every proposed mechanism is impossible, but like all negatives that's a very hard proposition to prove.


If the gradual progression of common descent as you describe it is truly history, then why doesn't it show up in the fossil record so gradually? Why do we see so many diverse species, but so few that would resemble the intermediate stages between species? Where is the proof of non-living matter transitioning to the first living cell, single cells to multicelled creatures (plants, animals, fungi, etc), and invertebrates to vertebrates, wingless creatures to winged creatures, apes to humans? This is the macro-evolutionary evidence I am not seeing in the fossil record that I believe evolution predicts. It is all well to come up with a philosophy based on naturalism and uniformitarianism, but at some point you have to admit that you have to take this whole idea with some faith. I don't have so much faith in it as you do. Besides fossil evidence that there is no macro evolution, I am looking for some genetic limitations to it also in this thread. I suspect we have not gotten that far in understanding genetics to make a clear determination.

#38 aelyn

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Posted 18 October 2011 - 06:49 AM

If the gradual progression of common descent as you describe it is truly history, then why doesn't it show up in the fossil record so gradually?

... but it does. As gradually as we'd expect given how imperfect the fossil record is at least. To give you an idea, these guys came up with a mathematical model of eye evolution that came to the conclusion it could have happened in as little as a few hundred thousand years.
http://www.ncbi.nlm..../pubmed/8008757
Geological periods are usually measured in the millions of years; obviously we don't see the progression with a resolution of a few hundred thousand years.

We don't need such a resolution though; in fact as far as eyes go we don't even really need fossils, we can see practically every transitional step in nature today. Basically, evolution doesn't work like a line : ancestor -> descendant, fish -> amphibian -> amniote. Evolution works like a tree, with each species begetting many different descendants that are more or less like their ancestors. This means at any point in time there may be ONE species that will be ancestral to a later group - but that species belongs to a family of species that are all more or less similar, and will have descendants that may remain very similar to it along with the descendants that become different. And while ONE ancestral species may be short-lived and its fossils unlikely to be found, the family of organism similar to it spans a much longer period and many such fossils can be found. And are. Which gets us to...

Why do we see so many diverse species, but so few that would resemble the intermediate stages between species?

We find plenty that "resemble the intermediate stages between species". You are very right to phrase it a "resemble the intermediate stages", because while many people confuse "transitional" and "ancestral", what a transitional fossil actually is is a specimen that combines traits belonging to the purported ancestral species and traits belonging to the descendent species. Whether it's an actual ancestor or a cousin or side-branch is irrelevant : in either case it's a member of that family of species that shared those characteristics at that time.

I don't know what more to say; I can't exactly list all transitional fossil that have ever been found. But if you want such a list somebody listed the fossils documenting some transitions between major vertebrate groups :
http://www.talkorigi...ansitional.html
I'm afraid it's a bit out of date though : for example in the middle of the fish-amphibian transition it says "GAP: Ideally, of course, we want an entire skeleton from the middle Late Devonian, not just limb fragments. Nobody's found one yet". Tiktaalik, which was found in 2004, is exactly that. Same for the reptile-bird transition : so many fossils have been found in the last decade that one is better off just looking up all the fossils in the group "Maniraptora" on Wikipedia.

Where is the proof of non-living matter transitioning to the first living cell, single cells to multicelled creatures (plants, animals, fungi, etc), and invertebrates to vertebrates, wingless creatures to winged creatures, apes to humans?

There is no proof of the first; abiogenesis research currently consists of various hypotheses, not a theory. For all the rest it's the nested hierarchy and genetics. For non-human apes to humans we have in addition to that tons of of transitional fossils.
Here are a few examples, and how various creationists classify them :
http://www.talkorigi...ms/compare.html

This is the macro-evolutionary evidence I am not seeing in the fossil record that I believe evolution predicts.

If you don't mind, could you explain what you believe evolution predicts, and what you've seen of the fossil record ?
Although I guess that would be going way off-topic for your thread. If you want to discuss it in another thread...

#39 JayShel

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Posted 19 October 2011 - 05:28 AM

This mathematical study would seem to calculate the potentially minimum time it would take through proposed mechanisms of evolution to give rise to an eye. The results must be taken with a grain of salt, since it could just as easily have taken longer, or not be possible due to some currently unknown circumstance. Without reality to give us an idea, we don't know. The mathematical calculation is somewhat of an illustration of what we imagine could have happened given an evolutionary paradigm, but it doesn't do much to further our discussion.

It is also questionable to say that the organisms that we observe today have progressively complex eyes by evolutionary predictions.

The possibility of classifying eyes in living animals from simple to complex—simple types existing in simple animals and complex types in complex animals (which we will show cannot be done)—does not provide evidence for an evolutionary relationship. A primary problem is that this attempt is based only on eye characteristics as they presently exist. Historical eye evolution cannot be proven by listing a series of existing eyes from simple to complex and then arguing that the complex evolved from the simple because evolution requires that all existing eyes have an equally long evolutionary history. http://creation.com/...nian-mechanisms


If I understand what you are saying about :

Geological periods are usually measured in the millions of years; obviously we don't see the progression with a resolution of a few hundred thousand years.

then my response is that different ages of rock are not a measurement of frequency of fossil generation within a particular time period as I believe you made reference to, rather it is a testament to the imprecision of our own dating methods. We cannot pinpoint just when any given organism lived.


I am not sure what you think the attributes of the Tiktaalik are that would make it transitional. They did find footprints near the Tiktaalik, but those were later dated to be 18 million years older than Tiktaalik. Were there other features you believe to be transitional?

The talk origins article suggests that almost all creationists consider certain skulls to be ape and certain others to be human. One or two disagreements among scientists is normal, and I can't say I am surprised. There is likely varying levels of anthropological expertise among creationists and so we would expect to see some disagreement on classification of these skulls. This can happen in any field with any scientific observation.

As for the transitional fossils listed on wikipedia, I don't really have the time to give them an accurate reflection. This article suggests that it is hair that was found on the maniraptora, not feathers among other discrepancies. http://creation.com/...re-the-skeptics

#40 aelyn

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Posted 19 October 2011 - 12:40 PM

This mathematical study would seem to calculate the potentially minimum time it would take through proposed mechanisms of evolution to give rise to an eye. The results must be taken with a grain of salt, since it could just as easily have taken longer, or not be possible due to some currently unknown circumstance. Without reality to give us an idea, we don't know. The mathematical calculation is somewhat of an illustration of what we imagine could have happened given an evolutionary paradigm, but it doesn't do much to further our discussion.

Right. I didn't bring up that study to say how fast the eye evolved; I brought it up to illustrate that it could have happened in a very short period of time, geologically speaking.

It is also questionable to say that the organisms that we observe today have progressively complex eyes by evolutionary predictions.

The paragraph you quoted seems to have the exact same misunderstanding I was trying to address in my previous post as I talked about families of organisms being more or less different from their common ancestor.
Basically, evolution doesn't make non-neutral traits change at a constant rate, quite the opposite. If the environment doesn't change evolution will make a trait stay the same. And different environmental changes might make a same trait change in different ways. So overall the descendants of an organisms will have mosaics of primitive (=like the ancestor) and derived (=unlike the ancestor) traits. All living organisms have a long evolutionary history behind them but not all of their traits have changed in the same way.

If I understand what you are saying about :
...
then my response is that different ages of rock are not a measurement of frequency of fossil generation within a particular time period as I believe you made reference to, rather it is a testament to the imprecision of our own dating methods. We cannot pinpoint just when any given organism lived.

I'm afraid I don't quite understand what you mean. I was just saying that a few hundred thousand years is an extremely short time geologically speaking. We're talking about a few hundred thousand years out of the 80 or so million years between the Ediacaran fauna and the earliest trilobites found. Finding a specific fossil from a specific hundred-thousand-year slice in the two centuries or so we've been looking is just very unlikely.

I am not sure what you think the attributes of the Tiktaalik are that would make it transitional. They did find footprints near the Tiktaalik, but those were later dated to be 18 million years older than Tiktaalik. Were there other features you believe to be transitional?

I'm not an palaeontologist, it isn't about what I believe. According to Wikipedia Tiktaalik has fish-like gills, scales and fins, tetrapod-like limb and wrist bones with fish-like fins on the end, an intermediate ear region, a tetrapod-like neck and pectoral girdle. And lungs.

The talk origins article suggests that almost all creationists consider certain skulls to be ape and certain others to be human. One or two disagreements among scientists is normal, and I can't say I am surprised. There is likely varying levels of anthropological expertise among creationists and so we would expect to see some disagreement on classification of these skulls. This can happen in any field with any scientific observation.

Yes. It's the kind of disagreement we expect to see when something is hard to identify. Like say, if a skull looks like an ape skull in some ways and like a human skull in other ways.

As for the transitional fossils listed on wikipedia, I don't really have the time to give them an accurate reflection. This article suggests that it is hair that was found on the maniraptora, not feathers among other discrepancies. http://creation.com/...re-the-skeptics

Well, proto-feathers would have been hair-like - we can even see that in modern feathers, with feathers being more hair-like the simpler they are. Either way there are maniraporans with clear flight feathers, like Anchiornis (classified in Deinonychosauria) or Protarchaeopteryx (classified in Oviraptosauria).
I see your link mentions the latter, saying that the author didn't see the feathers on the slab where they were indicated. Here are closeups of said location on slab from the paper :
Attached File  protarchaeopteryx.jpg   156.66KB   0 downloads




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