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Barbarian, please give us your absolute best evidence for evolution.
THE BARBARIAN
Best evidence for evolution?
Hard to say, but directly observed macroevolutionary events would have to be at the top.
There's quite a number of speciations in that category now.
Of course, we could point to the fossil record, which clearly shows evolutionary progressions, and to modern genetics and biochemical data like that for cytochrome c which independently verify the phylogenies obtained by anatomical and fossil data.
We also have the acknowledgement by the Institute for Creation Research that new species, genera, and families evolve from old ones.
We have the remarkable genetic evidence for a common ancestor between man and apes in the remains of a former chimpanzee telemere in human DNA. We also have psuedogenes and other noncoding DNA in common, which make no sense at all, except in terms of evolution. We have a remarkable sequence of tetrapods from lobed fin fishes to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on. All with consistant anatomical transitions which can be explained no other way.
There's lots more. But we'll stop here.
CHET
You said, "Its hard to say".
Its hard because there are not evidences. Just wrong conclusions from the observations. Which is to be expected if you have an already assumed idea that evolution took place.
You said, “directly observed macroevolutionary events would have to be at the top.”
Am I understanding you correctly? Are you saying that macro-evolution is observable? Where is this observed please. Tell me where one observation has been found in one kind turning into another kind. Like a cat turning into a dog.
You said “Of course, we could point to the fossil record, which clearly shows evolutionary progressions,”
I am amazed. O.K. tell me where there are any transitional fossils were we can see one kind turn into another. Specifically an ape into man. In the fossil record. By the way, how do fossils form?
You said, “and to modern genetics and biochemical data”
So a reproduction proves evolution?
You said, “We also have the acknowledgment by the Institute for Creation Research that new species, genera, and families evolve from old ones”
Please point me to an article. I did a search on ICR and could not find such statements. Could you please tell me what a “species” is?
You said, “We have the remarkable genetic evidence for a common ancestor between man and apes in the remains of a former chimpanzee telemere in human DNA. We also have psuedogenes and other noncoding DNA in common”
O.K. your observation leads you to believe in a common ancestor. My observation leads me to believe in a common designer. I can take the lug nuts off a chevy and use them on a buick. Does this mean that automobiles evolved from an airplane 2.5 million years ago? And where does the common ancestor originate? What was the first living thing?
You said, “to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on”
Huh? Was this the latest Disney cartoon?
You said, “which can be explained no other way.”
Let me give you an analogy. This is a picture of how evolutionary scientist are.
In scientific study they took a frog and wanted to measure how far it could jump. They said, “jump frog jump!” It jumped 5 feet. They cut off a leg, and wanted to measure how far it could now jump. “jump frog jump!” they said. It jumped only 3 feet. They cut yet another and said, "jump frog jump" it could only jump 1 foot. They cut the last leg, and yelled, “JUMP frog JUMP!” The frog jumped 0 inches. Therefore these highly educated scientist concluded that with no legs, the frog goes deaf.
THE BARBARIAN
You said, "Its hard to say".
Its hard because there are not evidences.
Rather, because there are so many.
Remember, evolution was discovered by creationists. How could they have assumed something contrary to what they believe?
That [one kind turning into another, such as a cat into a dog] is not macroevolution. Macroevolution is the evolution of new species. Microevolution is variation within species. Presently, scientific creationists, such as the ICR consider the evolution of new species, genera, and families to be a fact.
One could check out the talk.origins archives for a list of observed speciations. Or one could read John Woodmorrap's "Ark Feasibility Study" to learn what sorts of evolution are accepted by creationists. Woodmorrape believes that all cats, for example, evolved from a single kind on the Ark. This would amount to the evolution of new families, at least. Generally, they don't tell this to their followers, however.
Maybe the best example is the transition from therapsid reptiles to mammals. There are numerous examples, with all sorts of intermediate levels. Sometimes, the animals are so precisely intermediate (e.g. Diarthrognathus) that it's impossible to say to which class it belongs.
[Regarding the ‘ape to man’ request for evidence] You've been misled. Apes and men are too specialized for one to have evolved into the other. However, we do have evidence that chimps and humans very recently had a common ancestor.
By the way, how do fossils form?
The most common way is mineral replacement of tissues. But there are things like casts and fossil foot prints, and insects in amber, and so on.
So a reproduction proves evolution?
I don't know what you mean. What I was talking about was that (for example) cytochrome c variation will give you the same phylogenies that early biologists prepared based on anatomical data. So will genetic comparisons. In science, confirmation from several independent sources is considered compelling.
You said, “We also have the acknowledgment by the Institute for Creation Research that new species, genera, and families evolve from old ones”. Please point me to an article. I did a search on ICR and could not find such statements. Could you please tell me what a “species” is?
Sure. John Woodmorappe's "Ark Feasibility Study". In a personal email, he confirmed to me that he thought the limit of variation is the family.
A species is an interbreeding population of organisms.
O.K. your observation leads you to believe in a common ancestor. My observation leads me to believe in a common designer.
Won't work. Psuedogenes are "glitches" in the DNA. A telomere inside a chromosome is evidence of chromosome fusion, which explains why humans and chimps have different numbers of chromosomes. Why would a designer build the same goofs into both species? Makes no sense. And why would the remains of that telomere be sitting right where it would have to be to indicate evolutionary change?
What was the first living thing?
Earliest living things we know about were cyanobacteria. We have very ancient remains in the form of stromatolites. These are still forming today, in the same way as those ancient ones.
You said, “to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on”
Huh? Was this the latest Disney cartoon?
Nope. We have fossils of just those fish. Acanthostega, for example.
http://www.personal.u-net.com/~paleomod/p97/aca.htm
You can find more details on the subject in the excellent book "At the Water's Edge".
CHET
For lack of time I will only comment on a couple of things:
The most common way is mineral replacement of tissues. But there are things like casts and fossil foot prints, and insects in amber, and so on http://www.icr.org/pubs/btg-a/btg-143a.htm http://www.icr.org/pubs/btg-b/btg-081b.htm http://www.icr.org/pubs/btg-b/btg-010b.htm http://www.icr.org/pubs/btg-b/btg-037b.htm
Sure. John Woodmorappe's "Ark Feasibility Study". In a personal email, he confirmed to me that he thought the limit of variation is the family.
This man is not part of ICR. So he does not represent ICR. You have your terms backwards, Macro is the evolution from one kind to another, i.e. Chimp to Man. Micro evolution (even though I don't use the term because it is deceptive) is a variation, like the 250 types of dogs. But you still have a dog. A dog will not turn into a cow. There are limits on the variations. Natural selection can't produce a different kind of animal, only make that animal good. The limits, and the variations are encoded in the DNA the God has designed. And God don't produce "goofed" DNA. But through years of reproduction something could go wrong. For example, if you copy a computer program over and over and over and over eventually a file may get lost or corrupt. God in His greatness has designed a "program" that has been reproducing itself for 6 thousand years.
THE BARBARIAN
This man is not part of ICR. So he does not represent ICR.
The ICR promotes his book, in which he admits to the evolution of these taxa. I think you will find most other members of the ICR will at least concede that new species and genera evolve.
You have your terms backwards, Macro is the evolution from one kind to another, i.e. Chimp to Man.
No. The term means the evolution of new species. Initially, creationists denied that new species evolved, and they agreed with the scientific definition of "macroevolution". But as it became apparent that new species do evolve, they made their own definition, first at the level of genera, and then back to families. I expect that will change in the near future to include even higher taxa.
Microevolution is variation within a species. Macroevolution is variation that produces new species.
…But you still have a dog. A dog will not turn into a cow.
Is that what you think macroevolution is about? If I believed that, I wouldn't like it, either.
There are limits on the variations.
Problem is, no one can say what those limits are. We can't find even one organism on Earth that is anywhere near the supposed limits. There's no evidence for them.
Natural selection can't produce a different kind of animal
No, that's wrong. For example, we have very good evidence for the transition from reptiles to mammals.
"Design" is the activity of a limited creature who must figure things out, I find the attribution of "design" to God to be somewhat blasphemous. God had no need to design anything. He created without any consideration at all, perfect in His understanding of His will and His creation.
The problem is explaining how we and chimps ended up with precisely the same goofs. That makes no sense, except in terms of common descent.
JOHN WELLS
Here is a cut-n-paste from Barbarian's link:
Acanthostega possessed fishlike gill bars. These bones inside the rear of the head support the gill filaments of fish. The presence of gills shows that Acanthostega lived in water, not on land. But why then did it have legs? Perhaps these legs were inherited from a terrestrial ancestor. The presence of gill bars strongly suggest that this was not the case, as internal fishlike gills would have been lost quickly by any terrestrial ancestor. Aquatic amphibians whose ancestors were terrestrial all have external gills outside the head, not internal ones like Acanthostega. Thus, the presence of internal gills in the head of Acanthostega, suggests that legs originally evolved in an aquatic creature, for some aquatic purpose, not for locomotion on land.
The ribs of Acanthostega are thin, possibly too thin to support the weight of the soft tissue of the body, the stomach and other organs. The spine is very flexible, which is great for swimming, but bad news for a terrestrial tetrapod, because a more rigid spine is needed to support the body on land. This indicates that Acanthostega was well adapted for life in the water, but incapable of excursions onto dry land. Thus, legs probably evolved initially for an aquatic use, not for locomotion on land, though evolution later adapted them for that purpose.
[Much of what is written there is] subjective opinion injected as truth. Every evolution related article I've ever read is full of this brainwashing!
THE BARBARIAN
Scientists always treat evidence like this. Notice that they build a case by carefully considering what is, not what they'd like it to be.
Notice that it points out that the creature could not be evolved from a terrestrial creature since it has internal gills which would collapse and suffocate the animal out of water. It also points out that the animal could not walk on land because the spine would not have been able to support it.
The other evidence, while suggestive is not as conclusive. But the whole presents an animal with legs that could not have walked on land, or be descended from such an animal.
Because we have a fish with limbs, yet unable to walk on land, we can conclude that it used limbs to get around under water. Because we see fish doing that today, it's not much of a surprise.
But since we first find the femur, and tibia and fibula, and phalanges of tetrapods on a fish that clearly is not a land dweller, it's pretty obvious what happened when we find later examples with strong limbs and spine, and the lateral line system lost, and the otic notch of amphibians.
Such transitional animals make no sense at all, except in light of evolution. Creationism can merely shrug and say "it's a mystery". But Evolution explains why we see such animals.
“living fossils” are just animals that existed for a very long time without evolving very much. They are important to evolutionary theory, since they validate one of its major predictions.
Fitness has meaning only in terms of the environment. Evolutionary theory says that natural selection will tend to improve fitness in organisms. If an organism is well-adapted to the environment, and selective pressures do not change much for a very long time, then the theory predicts that natural selection will prevent evolution from occurring. And that is what we see. Are there many of these cases? No, it is rare for conditions to stay the same for so long. But it happens now and again, and when it does, we see just what evolutionary theory predicts.
"Polystrate fossils" haven't been a problem for science for a long time. Here's a link to the work of a Christian geologist who solved the "problem" over 100 years ago. Suffice to say, it's not what the ICR presents it to be. http://www.talkorigins.org/faqs/polystrate/trees.html
The major problem with the fossil record, from a creationist point of view, is how to reconcile the sorting of fossils with a sudden, one-time flood. It's impossible to do so.
First, the fossils are sorted according to age, with oldest at the bottom of the geologic column, and the youngest at the top. Various independent dating methods have confirmed this to be true.
Once creationists supposed "differential escape" could explain the results, with the fast mammals outrunning the flood waters more rapidly than slow reptiles. But this could not explain how sloths could outrun velociraptors, or oak trees could outrun pine and ferns.
Another attempt was "hydrologic sorting", in which the shape of the organism determined where it settled in the column. But streamlined icthyosaurs and bulky ammonites ended up in the same strata, below streamlined whales and bulky nautilids. So that didn't work.
Where are all the human fossils? Seems like a great question.
Turns out fossilization is very rare. Most organisms on land decay and disappear, or are scavenged and their fragments scattered.
Let's put this into perspective by thinking about the many millions of people who lived in Europe since history began. Where are all their bodies? Mostly decayed and gone to the dust from which they came. Bodies normally don't last very long after death. We might ask why the soil of woods are not choked with the remains of animal bodies.
Subduction is not a possible answer. For a continent to be subducted in a few centuries, it would produce such heat that the seas would boil. There is friction, and the heat it produces must be accounted for.
[ January 21, 2002: Message edited by: Administrator ]
Barbarian, please give us your absolute best evidence for evolution.
THE BARBARIAN
Best evidence for evolution?
Hard to say, but directly observed macroevolutionary events would have to be at the top.
There's quite a number of speciations in that category now.
Of course, we could point to the fossil record, which clearly shows evolutionary progressions, and to modern genetics and biochemical data like that for cytochrome c which independently verify the phylogenies obtained by anatomical and fossil data.
We also have the acknowledgement by the Institute for Creation Research that new species, genera, and families evolve from old ones.
We have the remarkable genetic evidence for a common ancestor between man and apes in the remains of a former chimpanzee telemere in human DNA. We also have psuedogenes and other noncoding DNA in common, which make no sense at all, except in terms of evolution. We have a remarkable sequence of tetrapods from lobed fin fishes to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on. All with consistant anatomical transitions which can be explained no other way.
There's lots more. But we'll stop here.
CHET
You said, "Its hard to say".
Its hard because there are not evidences. Just wrong conclusions from the observations. Which is to be expected if you have an already assumed idea that evolution took place.
You said, “directly observed macroevolutionary events would have to be at the top.”
Am I understanding you correctly? Are you saying that macro-evolution is observable? Where is this observed please. Tell me where one observation has been found in one kind turning into another kind. Like a cat turning into a dog.
You said “Of course, we could point to the fossil record, which clearly shows evolutionary progressions,”
I am amazed. O.K. tell me where there are any transitional fossils were we can see one kind turn into another. Specifically an ape into man. In the fossil record. By the way, how do fossils form?
You said, “and to modern genetics and biochemical data”
So a reproduction proves evolution?
You said, “We also have the acknowledgment by the Institute for Creation Research that new species, genera, and families evolve from old ones”
Please point me to an article. I did a search on ICR and could not find such statements. Could you please tell me what a “species” is?
You said, “We have the remarkable genetic evidence for a common ancestor between man and apes in the remains of a former chimpanzee telemere in human DNA. We also have psuedogenes and other noncoding DNA in common”
O.K. your observation leads you to believe in a common ancestor. My observation leads me to believe in a common designer. I can take the lug nuts off a chevy and use them on a buick. Does this mean that automobiles evolved from an airplane 2.5 million years ago? And where does the common ancestor originate? What was the first living thing?
You said, “to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on”
Huh? Was this the latest Disney cartoon?
You said, “which can be explained no other way.”
Let me give you an analogy. This is a picture of how evolutionary scientist are.
In scientific study they took a frog and wanted to measure how far it could jump. They said, “jump frog jump!” It jumped 5 feet. They cut off a leg, and wanted to measure how far it could now jump. “jump frog jump!” they said. It jumped only 3 feet. They cut yet another and said, "jump frog jump" it could only jump 1 foot. They cut the last leg, and yelled, “JUMP frog JUMP!” The frog jumped 0 inches. Therefore these highly educated scientist concluded that with no legs, the frog goes deaf.
THE BARBARIAN
You said, "Its hard to say".
Its hard because there are not evidences.
Rather, because there are so many.
Remember, evolution was discovered by creationists. How could they have assumed something contrary to what they believe?
That [one kind turning into another, such as a cat into a dog] is not macroevolution. Macroevolution is the evolution of new species. Microevolution is variation within species. Presently, scientific creationists, such as the ICR consider the evolution of new species, genera, and families to be a fact.
One could check out the talk.origins archives for a list of observed speciations. Or one could read John Woodmorrap's "Ark Feasibility Study" to learn what sorts of evolution are accepted by creationists. Woodmorrape believes that all cats, for example, evolved from a single kind on the Ark. This would amount to the evolution of new families, at least. Generally, they don't tell this to their followers, however.
Maybe the best example is the transition from therapsid reptiles to mammals. There are numerous examples, with all sorts of intermediate levels. Sometimes, the animals are so precisely intermediate (e.g. Diarthrognathus) that it's impossible to say to which class it belongs.
[Regarding the ‘ape to man’ request for evidence] You've been misled. Apes and men are too specialized for one to have evolved into the other. However, we do have evidence that chimps and humans very recently had a common ancestor.
By the way, how do fossils form?
The most common way is mineral replacement of tissues. But there are things like casts and fossil foot prints, and insects in amber, and so on.
So a reproduction proves evolution?
I don't know what you mean. What I was talking about was that (for example) cytochrome c variation will give you the same phylogenies that early biologists prepared based on anatomical data. So will genetic comparisons. In science, confirmation from several independent sources is considered compelling.
You said, “We also have the acknowledgment by the Institute for Creation Research that new species, genera, and families evolve from old ones”. Please point me to an article. I did a search on ICR and could not find such statements. Could you please tell me what a “species” is?
Sure. John Woodmorappe's "Ark Feasibility Study". In a personal email, he confirmed to me that he thought the limit of variation is the family.
A species is an interbreeding population of organisms.
O.K. your observation leads you to believe in a common ancestor. My observation leads me to believe in a common designer.
Won't work. Psuedogenes are "glitches" in the DNA. A telomere inside a chromosome is evidence of chromosome fusion, which explains why humans and chimps have different numbers of chromosomes. Why would a designer build the same goofs into both species? Makes no sense. And why would the remains of that telomere be sitting right where it would have to be to indicate evolutionary change?
What was the first living thing?
Earliest living things we know about were cyanobacteria. We have very ancient remains in the form of stromatolites. These are still forming today, in the same way as those ancient ones.
You said, “to fish with limbs unable to walk on land, to fish that could, to amphibians, and so on”
Huh? Was this the latest Disney cartoon?
Nope. We have fossils of just those fish. Acanthostega, for example.
http://www.personal.u-net.com/~paleomod/p97/aca.htm
You can find more details on the subject in the excellent book "At the Water's Edge".
CHET
For lack of time I will only comment on a couple of things:
The most common way is mineral replacement of tissues. But there are things like casts and fossil foot prints, and insects in amber, and so on http://www.icr.org/pubs/btg-a/btg-143a.htm http://www.icr.org/pubs/btg-b/btg-081b.htm http://www.icr.org/pubs/btg-b/btg-010b.htm http://www.icr.org/pubs/btg-b/btg-037b.htm
Sure. John Woodmorappe's "Ark Feasibility Study". In a personal email, he confirmed to me that he thought the limit of variation is the family.
This man is not part of ICR. So he does not represent ICR. You have your terms backwards, Macro is the evolution from one kind to another, i.e. Chimp to Man. Micro evolution (even though I don't use the term because it is deceptive) is a variation, like the 250 types of dogs. But you still have a dog. A dog will not turn into a cow. There are limits on the variations. Natural selection can't produce a different kind of animal, only make that animal good. The limits, and the variations are encoded in the DNA the God has designed. And God don't produce "goofed" DNA. But through years of reproduction something could go wrong. For example, if you copy a computer program over and over and over and over eventually a file may get lost or corrupt. God in His greatness has designed a "program" that has been reproducing itself for 6 thousand years.
THE BARBARIAN
This man is not part of ICR. So he does not represent ICR.
The ICR promotes his book, in which he admits to the evolution of these taxa. I think you will find most other members of the ICR will at least concede that new species and genera evolve.
You have your terms backwards, Macro is the evolution from one kind to another, i.e. Chimp to Man.
No. The term means the evolution of new species. Initially, creationists denied that new species evolved, and they agreed with the scientific definition of "macroevolution". But as it became apparent that new species do evolve, they made their own definition, first at the level of genera, and then back to families. I expect that will change in the near future to include even higher taxa.
Microevolution is variation within a species. Macroevolution is variation that produces new species.
…But you still have a dog. A dog will not turn into a cow.
Is that what you think macroevolution is about? If I believed that, I wouldn't like it, either.
There are limits on the variations.
Problem is, no one can say what those limits are. We can't find even one organism on Earth that is anywhere near the supposed limits. There's no evidence for them.
Natural selection can't produce a different kind of animal
No, that's wrong. For example, we have very good evidence for the transition from reptiles to mammals.
"Design" is the activity of a limited creature who must figure things out, I find the attribution of "design" to God to be somewhat blasphemous. God had no need to design anything. He created without any consideration at all, perfect in His understanding of His will and His creation.
The problem is explaining how we and chimps ended up with precisely the same goofs. That makes no sense, except in terms of common descent.
JOHN WELLS
Here is a cut-n-paste from Barbarian's link:
Acanthostega possessed fishlike gill bars. These bones inside the rear of the head support the gill filaments of fish. The presence of gills shows that Acanthostega lived in water, not on land. But why then did it have legs? Perhaps these legs were inherited from a terrestrial ancestor. The presence of gill bars strongly suggest that this was not the case, as internal fishlike gills would have been lost quickly by any terrestrial ancestor. Aquatic amphibians whose ancestors were terrestrial all have external gills outside the head, not internal ones like Acanthostega. Thus, the presence of internal gills in the head of Acanthostega, suggests that legs originally evolved in an aquatic creature, for some aquatic purpose, not for locomotion on land.
The ribs of Acanthostega are thin, possibly too thin to support the weight of the soft tissue of the body, the stomach and other organs. The spine is very flexible, which is great for swimming, but bad news for a terrestrial tetrapod, because a more rigid spine is needed to support the body on land. This indicates that Acanthostega was well adapted for life in the water, but incapable of excursions onto dry land. Thus, legs probably evolved initially for an aquatic use, not for locomotion on land, though evolution later adapted them for that purpose.
[Much of what is written there is] subjective opinion injected as truth. Every evolution related article I've ever read is full of this brainwashing!
THE BARBARIAN
Scientists always treat evidence like this. Notice that they build a case by carefully considering what is, not what they'd like it to be.
Notice that it points out that the creature could not be evolved from a terrestrial creature since it has internal gills which would collapse and suffocate the animal out of water. It also points out that the animal could not walk on land because the spine would not have been able to support it.
The other evidence, while suggestive is not as conclusive. But the whole presents an animal with legs that could not have walked on land, or be descended from such an animal.
Because we have a fish with limbs, yet unable to walk on land, we can conclude that it used limbs to get around under water. Because we see fish doing that today, it's not much of a surprise.
But since we first find the femur, and tibia and fibula, and phalanges of tetrapods on a fish that clearly is not a land dweller, it's pretty obvious what happened when we find later examples with strong limbs and spine, and the lateral line system lost, and the otic notch of amphibians.
Such transitional animals make no sense at all, except in light of evolution. Creationism can merely shrug and say "it's a mystery". But Evolution explains why we see such animals.
“living fossils” are just animals that existed for a very long time without evolving very much. They are important to evolutionary theory, since they validate one of its major predictions.
Fitness has meaning only in terms of the environment. Evolutionary theory says that natural selection will tend to improve fitness in organisms. If an organism is well-adapted to the environment, and selective pressures do not change much for a very long time, then the theory predicts that natural selection will prevent evolution from occurring. And that is what we see. Are there many of these cases? No, it is rare for conditions to stay the same for so long. But it happens now and again, and when it does, we see just what evolutionary theory predicts.
"Polystrate fossils" haven't been a problem for science for a long time. Here's a link to the work of a Christian geologist who solved the "problem" over 100 years ago. Suffice to say, it's not what the ICR presents it to be. http://www.talkorigins.org/faqs/polystrate/trees.html
The major problem with the fossil record, from a creationist point of view, is how to reconcile the sorting of fossils with a sudden, one-time flood. It's impossible to do so.
First, the fossils are sorted according to age, with oldest at the bottom of the geologic column, and the youngest at the top. Various independent dating methods have confirmed this to be true.
Once creationists supposed "differential escape" could explain the results, with the fast mammals outrunning the flood waters more rapidly than slow reptiles. But this could not explain how sloths could outrun velociraptors, or oak trees could outrun pine and ferns.
Another attempt was "hydrologic sorting", in which the shape of the organism determined where it settled in the column. But streamlined icthyosaurs and bulky ammonites ended up in the same strata, below streamlined whales and bulky nautilids. So that didn't work.
Where are all the human fossils? Seems like a great question.
Turns out fossilization is very rare. Most organisms on land decay and disappear, or are scavenged and their fragments scattered.
Let's put this into perspective by thinking about the many millions of people who lived in Europe since history began. Where are all their bodies? Mostly decayed and gone to the dust from which they came. Bodies normally don't last very long after death. We might ask why the soil of woods are not choked with the remains of animal bodies.
Subduction is not a possible answer. For a continent to be subducted in a few centuries, it would produce such heat that the seas would boil. There is friction, and the heat it produces must be accounted for.
[ January 21, 2002: Message edited by: Administrator ]