Dolphins' are back on Earth

[Gman]

Read what you just deleted. I don't understand why you're spending much of your post pointing out perceived contradictions in my statements?
Read more carefully and it is obvious that you are simply misunderstanding. I implore you to stick to the subject and try to maintain an academic discussion.

I implore you to stick to the subject as well.. Are you implying that you are maintaining the academic discussion? I deleted that to show the contradictions in your first statements..

Saying that a particular article is not convincing evidence for the terrestrial origin of dolphins is not tantamount to stating that I do not think there is any evidence for the terrestrial origins of dolphins.

There has been no change in position.

Only your position...

I don't follow your logic.

Good, I don't follow your logic either..

The two statements are not in opposition.

A conclusion is on the right side of the equation.
Homology --> similar function in the past.

Use in determination is on the left side of the equation.
Similar Function --> Homology
There is no conflict so simply

Don't forget about analogous organs... They are organs that have the same function. The fins of fishes and the flippers of dolphins and penguins are analogous organs because they are all used for swimming. The wings of birds, bats, and insects are analogous organs that make flying possible. Their form was determined by their function.

There is no conflict so simply
"Now you are saying it is a poor choice to determine homology.... Well which one is it?" The answer is both.

Thanks for agreeing with me...

Function cannot be used to determine homology, however homology can be used to determine that at one time the functions were the same (they shared a common ancestor).

The statement remains function is a poor determinent.

Tell that to the scientists who were saying that these dolphin fins were once used for walking on land..

Exactly,there is no term functional homology. However your insistence in using functions to show that a common ancestor could not have existed can only be termed functional homology. Which is my point, your argument is flawed, you cannot argue that differing functions are proof against common descent. see below your dolphin quote
Analogy cannot be used to argue for or against common descent.

Like saying that the functions of these extra dolphin fins were once used for walking? Again, tell that to those scientists...

Function follows structure. So functional analogy can come into the discussion but only after structural homology has been determined.

That is why the scientists were saying that these extra fins were once used to WALK on the earth...

"Japanese fishers have found an unusual bottlenose dolphin with an extra set of fins that could be an evolutionary throwback to the time when the marine mammals' ancient ancestors walked on land."

Source: //news.nationalgeographic.com/news/2006/11/061106-dolphin-legs.html

The lets take out all the references to function in your quote. We are left with the following.
What we have left are sesamoid bones varying in size in a population and perhaps a mutation which can cause joints to become imobile. Do you see any of these posing a challenge to evolutionary theory? In other words is it possible that a dog can be born with a fused elbow joint? What about a human born with a sesamoid on the end of their thumb? Of course it's possible. If this population happened to be living in the ocean would nature select against it?
In the case of the elbow joint I would expect this trait to become fairly common in the population. Would you disagree?

Yes I do disagree... Try replacing the elbow joint of a land mammal with one from a dolphin.. See how long it would survive..

1. The bones are fused together so that they form a paddle with the skin. They work perfectly in the ocean, not on land.
2. Dolphins' bones are softer than the ones that land animals have. They are filled with fat and oil. This makes the bones more flexible.
3. The phalanges of the dolphin is longer than that of the land mammals. The dolphin has many bones that make up the “fingers” (fin rays) rather than the typical sequence of three bones seen in the digits of humans and many other mammals. This serves to greatly lengthen the fin.
4. Dolphins do not have a movable elbow joint and hold their pectoral fins rather rigidly out from the body. Their only mobile joint is at the shoulder.
5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..


An anatomical analysis of the forelimb of the mammals suggests that they are homologous structures.

If you agree that dolphins were land animals then perhaps then you would agree with angel that the "common designer" approach would be a lazy and unimaginative one. Maybe God in your view was stupid too...

[BGoodForGoodSake]

Interesting, before you stated, "The function of once walking is concluded from structural homology." Now you are saying it is a poor choice to determine homology.... Well which one is it? If it can bring it to an end and conclude it, then how can it suddenly be a poor choice now?

There is no conflict so simply
"Now you are saying it is a poor choice to determine homology.... Well which one is it?" The answer is both.The statement remains function is a poor determinent.

Thanks for agreeing with me...

I am not agreeing with you. I am stating that structure determines function, you are stating the reverse. The similarity of structure leads one to surmise a common function in the past. Current function is immaterial. Chopping up my statements and misrepresenting them is not good form.

Function cannot be used to determine homology, however homology can be used to determine that at one time the functions were the same (they shared a common ancestor).

The statement remains function is a poor determinent.

Tell that to the scientists who were saying that these dolphin fins were once used for walking on land..

This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

Exactly,there is no term functional homology. However your insistence in using functions to show that a common ancestor could not have existed can only be termed functional homology. Which is my point, your argument is flawed, you cannot argue that differing functions are proof against common descent. see below your dolphin quote
Analogy cannot be used to argue for or against common descent.

Like saying that the functions of these extra dolphin fins were once used for walking? Again, tell that to those scientists...

That is not even an example of analogy, at this point it seems as if you are just posting random comments. When a dolphin develops in the uterus there is a point at which rear limb buds develop.

But the limbs do not continue to develop as in other mammals but gets reabsorbed. The scientist believed that for this particular individual these buds continued to develop into the rear flippers. Because the limb buds may have continued to develop into limbs, they surmise that the homology of the dolphins limb buds is now stronger. Meaning at some point all dolphins had four flippers but selective pressures were not strong enough to keep them. (I.E. dolphins born without back flippers suffered no consequences.)

Function follows structure. So functional analogy can come into the discussion but only after structural homology has been determined.

That is why the scientists were saying that these extra fins were once used to WALK on the earth...

No, scientists are saying that dolphins ancestors once walked on earth.

"Japanese fishers have found an unusual bottlenose dolphin with an extra set of fins that could be an evolutionary throwback to the time when the marine mammals' ancient ancestors walked on land."

Source: //news.nationalgeographic.com/news/2006/11/061106-dolphin-legs.html

See no mention of fins being used to walk.

The lets take out all the references to function in your quote. We are left with the following.
What we have left are sesamoid bones varying in size in a population and perhaps a mutation which can cause joints to become imobile. Do you see any of these posing a challenge to evolutionary theory? In other words is it possible that a dog can be born with a fused elbow joint? What about a human born with a sesamoid on the end of their thumb? Of course it's possible. If this population happened to be living in the ocean would nature select against it?
In the case of the elbow joint I would expect this trait to become fairly common in the population. Would you disagree?

Yes I do disagree... Try replacing the elbow joint of a land mammal with one from a dolphin.. See how long it would survive..

That's not the point, I think you need to do a little more research on evolution, it would seem that you have a poor understanding of it. The point I was making was that small modifications over time can indeed lead to these features. If a population of mammals (the dolphins ancestors) lived in a marine environment, certain features would be beneficial. In your example you stated "try replacing the elbow joint of a land mammal with one from a dolphin". But here the mammals were marine, what would happen if a mutation lead to a fused joint? The animal would prosper not suffer, they are marine. the point is that the environment in which a population exists determines which features found within a population are favorable.

1. The bones are fused together so that they form a paddle with the skin. They work perfectly in the ocean, not on land.

Are all fins the same? Do all dolphins swim equally well?

2. Dolphins' bones are softer than the ones that land animals have. They are filled with fat and oil. This makes the bones more flexible.

Are changes to bone chemistry outside of the bounds of mutation?

3. The phalanges of the dolphin is longer than that of the land mammals. The dolphin has many bones that make up the “fingers” (fin rays) rather than the typical sequence of three bones seen in the digits of humans and many other mammals. This serves to greatly lengthen the fin.

Refer to an earlier post. Sesamoid bones can be coopted to to create additional phalangial bones, also duplications can lead to this as well. Is this outside of the realm of possible features which can be introduced by mutations?

4. Dolphins do not have a movable elbow joint and hold their pectoral fins rather rigidly out from the body. Their only mobile joint is at the shoulder.

See above.

5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..

This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg? In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air? Why form back limb buds when it would just get readsorbed? Why have a propultion system which seems to be modified running rather than the side to side sweeping found in fish?

An anatomical analysis of the forelimb of the mammals suggests that they are homologous structures.

If you agree that dolphins were land animals then perhaps then you would agree with angel that the "common designer" approach would be a lazy and unimaginative one. Maybe God in your view was stupid too...

No, I don't agree with angel on this point. One does not lead to another. Whoever told you evolution was in disagreement with God really has you fooled.

I don't think God would create in the same clumsy and inefficient laughable manor as people make things. You think you're creating when you make a house with wood. You're only rearanging things, in a pre instructed way. The people who "created" died many generations ago, you're just copying them.

[Gman]

I am not agreeing with you. I am stating that structure determines function, you are stating the reverse. The similarity of structure leads one to surmise a common function in the past. Current function is immaterial. Chopping up my statements and misrepresenting them is not good form.

In your dreams Bgood... YOU are the one chopping up statements... I was saying that function can be used to CONTRAST structure. Not stand alone.. Also I see that you deleted my post about analogous organs... They are organs that have the same function.

This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

Yeah, but you omitted that part that they associated these fins to legs..

That is not even an example of analogy, at this point it seems as if you are just posting random comments.

LOL.. I have to keep posting what you seem to be misreading..

When a dolphin develops in the uterus there is a point at which rear limb buds develop. But the limbs do not continue to develop as in other mammals but gets reabsorbed. The scientist believed that for this particular individual these buds continued to develop into the rear flippers. Because the limb buds may have continued to develop into limbs, they surmise that the homology of the dolphins limb buds is now stronger. Meaning at some point all dolphins had four flippers but selective pressures were not strong enough to keep them. (I.E. dolphins born without back flippers suffered no consequences.)

Interesting... Because evolution is looking for NEW structures not reabsorbed structures.. All dolphins could have once had two rear fins, and lost the information? Even if dolphins lost their hind limbs, loss of information is not what is required for progressive evolution to occur. Loss of information has been well documented in nature. Rather, a gain of information is the chief problem Darwinists need to solve to support their theory. That is hardly good science what you posted there for the case for evolution...

No, scientists are saying that dolphins ancestors once walked on earth.

And who is the dolphin's ancestor Bgood? Are you going to get your model silly puddy clay out for us again?

See no mention of fins being used to walk.

Re-read the post again Bgood... What do you think they are equating these fins too? What function? Jumping or swimming? Maybe the dolphin was four wheeling with a beer...

That's not the point, I think you need to do a little more research on evolution, it would seem that you have a poor understanding of it.

It seems that you have the poor understanding of it.. Evolution is looking for a GAIN of new information.. Not the loss of information...

The point I was making was that small modifications over time can indeed lead to these features. If a population of mammals (the dolphins ancestors) lived in a marine environment, certain features would be beneficial. In your example you stated "try replacing the elbow joint of a land mammal with one from a dolphin". But here the mammals were marine, what would happen if a mutation lead to a fused joint? The animal would prosper not suffer, they are marine. the point is that the environment in which a population exists determines which features found within a population are favorable.

That's all you have... A lot of time and a lot of chance... Land animals morphing into marine animals... Marine animals morphing into land animals... Dreamland... No God either...

Are all fins the same? Do all dolphins swim equally well?

Fins have different shapes sizes and functions.. But they are used for one thing... SWIMMING not walking... Not for tap dancing or jumping ropes...

Are changes to bone chemistry outside of the bounds of mutation?

Are all mutations beneficial? Are mutations your only answer?

Refer to an earlier post. Sesamoid bones can be coopted to to create additional phalangial bones, also duplications can lead to this as well. Is this outside of the realm of possible features which can be introduced by mutations?

Show me the bones of some earlier dolphins with lesser phalangial bones in their fins than the modern ones then...

See above.

See above...

This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg?In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?

Why don't dolphins' fins resemble land mammals' legs? Why are the fins webbed? Why is the dolphin's air hole in their back then? Ever seen a land mammal with blow holes on their back?

Why form back limb buds when it would just get readsorbed?

You mean a loss of information again?

Why have a propultion system which seems to be modified running rather than the side to side sweeping found in fish?

Maybe that's why they called it a dolphin?

No, I don't agree with angel on this point. One does not lead to another. Whoever told you evolution was in disagreement with God really has you fooled.

What are you talking about Bgood? Theistic evolution? I've been reading your other posts... You are not a defender of any God... Not even your own God. Not at least from what I've seen. But you will defend mutations.. And then you will defend someone who laughs at God... Go figure.

I don't think God would create in the same clumsy and inefficient laughable manor as people make things. You think you're creating when you make a house with wood. You're only rearanging things, in a pre instructed way. The people who "created" died many generations ago, you're just copying them.

LOL.. Oh, that's real funny Bgood... The only one that can rearrange things is God.. Not man... So you rearrange things created with your own evolution theory and your mutations and then call yourself God it seems...

[BGoodForGoodSake]

Also I see that you deleted my post about analogous organs... They are organs that have the same function.

This statement had no relevance to the discussion, we both agree on what analogous organs are.

This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

Yeah, but you omitted that part that they associated these fins to legs..

That goes without saying, structural homology connotes just that.

When a dolphin develops in the uterus there is a point at which rear limb buds develop. But the limbs do not continue to develop as in other mammals but gets reabsorbed. The scientist believed that for this particular individual these buds continued to develop into the rear flippers. Because the limb buds may have continued to develop into limbs, they surmise that the homology of the dolphins limb buds is now stronger. Meaning at some point all dolphins had four flippers but selective pressures were not strong enough to keep them. (I.E. dolphins born without back flippers suffered no consequences.)

Interesting... Because evolution is looking for NEW structures not reabsorbed structures.. All dolphins could have once had two rear fins, and lost the information?

So are you conceding that dolphin ancestors originally had hindlimbs?
Not all the information is necessarily lost. The only thing which needs to have happened is that the signaling molecule for rear limb development aquire a defect.

Even if dolphins lost their hind limbs, loss of information is not what is required for progressive evolution to occur. Loss of information has been well documented in nature. Rather, a gain of information is the chief problem Darwinists need to solve to support their theory.

This is rather subjective. Since we are talking about homologies, we are talking about modification of information, most of the changes don't require loss or gain of any information.

No, scientists are saying that dolphins ancestors once walked on earth.

And who is the dolphin's ancestor Bgood? Are you going to get your model silly puddy clay out for us again?

It is enough to say that life begets life, and continue to look for clues to the dolphins origin.

Are all fins the same? Do all dolphins swim equally well?

Fins have different shapes sizes and functions.. But they are used for one thing... SWIMMING not walking... Not for tap dancing or jumping ropes...

The point being that variety exists within a population. Some dolphins swim better than others. As must have been the case in ancient populations. It is not too difficult to understand that the poorer performers over time will be removed from the gene pool.
Here's an experiment for you.
Equipment
2 Packs of M&M's 55g
A Coin with a head and tail side.
A bowl
A non-transparent bag.

Step 1. Take out 2 M&M's of each color.

Step2. Place one at a time into the bowl. As you do so do the following for each M&M.
Flip the coin.
If it's tails add one additional M&M of the same color.
If it's heads add two.

The bowl should now contain between 20 and 30 M&M's.
Now physically remove 3 M&M's which are not (Red Orange or Yellow).

Place all the M&M's in the bag.
Randomly remove 12 M&M's.

Repeat the whole process from step 2.
After repeating this process several times you should start to see a trend.

Are changes to bone chemistry outside of the bounds of mutation?

Are all mutations beneficial? Are mutations your only answer?

These types of mutation are well documented and do occur. Are you denying that they exist? Does variation in bone chemistry exist within a population? Yes.

Refer to an earlier post. Sesamoid bones can be coopted to to create additional phalangial bones, also duplications can lead to this as well. Is this outside of the realm of possible features which can be introduced by mutations?

Show me the bones of some earlier dolphins with lesser phalangial bones in their fins than the modern ones then...

The point here however is that it is possible that sesamoid bones can be copted to grow longer. There is no gain in information just a change in developmental signaling. If the case were gene duplication then this too is not outside of the range of posibilities.

This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg?In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?

Why don't dolphins' fins resemble land mammals' legs?

They do, in fact they resemble forelimbs more than fins. They appear to be modified forelimbs.

Why are the fins webbed?

Webbing between the fingers is found in most vertebrate embryos, in humans a chemical signal causes the webbing to kill itself during development. This is known as Apoptosis.

Why is the dolphin's air hole in their back then? Ever seen a land mammal with blow holes on their back?

No, but it is possible that this adaptation came from selecting among a variation within a population, just as beak sizes on Galapagos island, which you assure us is only microevolution.

Why form back limb buds when it would just get readsorbed?

You mean a loss of information again?

You assume a loss of information, developmental signaling is all that is needed to prevent the limb from developing, it's not neceassarily a loss of information just a change in the order of development.

Why have a propultion system which seems to be modified running rather than the side to side sweeping found in fish?

Maybe that's why they called it a dolphin?

The name follows the organism, it is not the reasoning behind its method of locomotion.

No, I don't agree with angel on this point. One does not lead to another. Whoever told you evolution was in disagreement with God really has you fooled.

What are you talking about Bgood? Theistic evolution? I've been reading your other posts... You are not a defender of any God... Not even your own God. Not at least from what I've seen. But you will defend mutations.. And then you will defend someone who laughs at God... Go figure.

I am not defending Angel, I am only here to keep the facts straight.

[godslanguage]

If evolution is defined as anything but random then it is illustrating the point that it is based on goal directed intelligent processes that require some type of intelligence. The proper term for this would be external intelligent agency or external intelligent causation. What do you think of this Bgood?

Could the process of evolution produced a different outcome, could it have been different? If the external natural forces or external natural environment are playing a role in producing the complexity of function based on input processes then how do we define these (in terms of producing an output), in terms of producing a function based on no goal (in ND'st terms)? You would probably define these goal directed processes as part of natural selection, I would define them as external intelligent forces that are yet to be defined by real hard science.

[BGoodForGoodSake]

If evolution is defined as anything but random then it is illustrating the point that it is based on goal directed intelligent processes that require some type of intelligence. The proper term for this would be external intelligent agency or external intelligent causation. What do you think of this Bgood?

Intelligence is required in understanding, however in a system where a set of rules exist, it is possible for an optimized state to be reached, if duplication and modification are allowed, without understanding. Like peanuts and crackerjacks the peanuts settle to the bottom. Why? We can quantify and rationalize forever, but fundamentally we do not know why.

Could the process of evolution produced a different outcome, could it have been different?

Current theories say yes and no. The details may be different yes, but the numbers of species, the relationships predator and prey etc, can be calculated and predicted.

If the external natural forces or external natural environment are playing a role in producing the complexity of function based on input processes then how do we define these (in terms of producing an output), in terms of producing a function based on no goal (in ND'st terms)? You would probably define these goal directed processes as part of natural selection, I would define them as external intelligent forces that are yet to be defined by real hard science.

Good point, and I agree at some level.

[Gman]

Where was I again... Oh yah...

This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

That goes without saying, structural homology connotes just that.

I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals. Again the fins of fishes and the flippers of dolphins and penguins are analogous organs because they are all used for swimming not walking on land...

So are you conceding that dolphin ancestors originally had hindlimbs?

No.. That was posed as a question to you... Read it again...

Not all the information is necessarily lost. The only thing which needs to have happened is that the signaling molecule for rear limb development aquire a defect.

And defects are not usually good...

This is rather subjective. Since we are talking about homologies, we are talking about modification of information, most of the changes don't require loss or gain of any information.

Rather subjective?? Since we are talking about homologies we are talking about a common ancestor.. Are you suggesting that there is only a small modification of information for structural homology to achieve it's goal? Where did the original ancestor come from then? It didn't require much loss or gain of any information to get where it is today? What is your natural selection going to select then to get started? If anything your statement connotes creationism...

It is enough to say that life begets life, and continue to look for clues to the dolphins origin.

In other words the evidence is there but we need more time and more money... It is NOT all factual then if you still need clues to the dolphins origin... Is it..

Are all fins the same? Do all dolphins swim equally well?

No they probably don't all swim equally well... But they are still dolphins...

The point being that variety exists within a population. Some dolphins swim better than others. As must have been the case in ancient populations. It is not too difficult to understand that the poorer performers over time will be removed from the gene pool.
Here's an experiment for you.
Equipment
2 Packs of M&M's 55g
A Coin with a head and tail side.
A bowl
A non-transparent bag.

Step 1. Take out 2 M&M's of each color.

Step2. Place one at a time into the bowl. As you do so do the following for each M&M.
Flip the coin.
If it's tails add one additional M&M of the same color.
If it's heads add two.

The bowl should now contain between 20 and 30 M&M's.
Now physically remove 3 M&M's which are not (Red Orange or Yellow).

Place all the M&M's in the bag.
Randomly remove 12 M&M's.

Repeat the whole process from step 2.
After repeating this process several times you should start to see a trend.

Yes your experiment is starting to take shape...

These types of mutation are well documented and do occur. Are you denying that they exist?

I didn't say that... Quit twisting my words...

Does variation in bone chemistry exist within a population? Yes.

No you didn't answer the question.. Are all changes to bone chemistry good? What about deformed bones? Why are dolphins' bones are softer than the ones that land animals have? Why are they filled with fat and oil?

Refer to an earlier post. Sesamoid bones can be coopted to to create additional phalangial bones, also duplications can lead to this as well. Is this outside of the realm of possible features which can be introduced by mutations?

The point here however is that it is possible that sesamoid bones can be copted to grow longer. There is no gain in information just a change in developmental signaling. If the case were gene duplication then this too is not outside of the range of posibilities.

Nice picture of some whales bones... Looks like you got that here. You're suppose to be going from smaller to larger not larger to smaller. A 63 ton whale shrinking to a 175 pound dolphin? This is hardly good evidence. Just shrinking evidence... If you were reading before, the evidence for the common ancestor is having a hard time in the fossil record. That is why most evolutionists are turning to genetics... Their last stand..

This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg?In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?

All mammals need air... Are you saying they don't need to breath air at the embryonic stage?

They do, in fact they resemble forelimbs more than fins. They appear to be modified forelimbs.

Are you kidding me? Hardly.. And heavy on the modification...

What would you suggest to God to make the differences more pronounced? Stick rocket boosters on the side of the dolphin so that he could skip his way to another part of the ocean?

Look at the forelimbs of a dog..



Now the fins of the dolphin..



But if you drink enough beers anything is possible with your homology theory...

Webbing between the fingers is found in most vertebrate embryos, in humans a chemical signal causes the webbing to kill itself during development. This is known as Apoptosis.

This is hardly a case for a common ancestor.. At that early part of the stage the embryo's fingers could resemble fatty tissue or anything.. Like also having gill slits, yolk sac, and a tail.. Also the surface layer or epidermis of a dolphin's skin is ten times thicker than any land mammal, and serves as protection against the elements.

Also apoptosis is a loss of information again..

No, but it is possible that this adaptation came from selecting among a variation within a population, just as beak sizes on Galapagos island, which you assure us is only microevolution.

Some variations but not that drastic.. If you had a bird with a beak on it's back you may have a case...

You assume a loss of information, developmental signaling is all that is needed to prevent the limb from developing, it's not neceassarily a loss of information just a change in the order of development.

Well if you get any more developmental signaling you probably won't have enough to signal out left...

The name follows the organism, it is not the reasoning behind its method of locomotion.

That is locomotion in water not land...

I am not defending Angel, I am only here to keep the facts straight.

And what facts are those? Evolution is a THEORY not a fact... Ask any real scientist...

EDIT: to correct picture.

[BGoodForGoodSake]

Where was I again... Oh yah...

This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

That goes without saying, structural homology connotes just that.

I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.

How is this analogous? They have different functions.

So are you conceding that dolphin ancestors originally had hindlimbs?

No.. That was posed as a question to you... Read it again...

So then where did the hindlimbs in the original article come from?

Not all the information is necessarily lost. The only thing which needs to have happened is that the signaling molecule for rear limb development aquire a defect.

And defects are not usually good...

The defect is in the signaling molecule. This translated hypothetically to a modification in the adult form.

Would you agree that if the dolphins once had hind limbs that they certainly do not need it to survive? Then is this modification itself a defect?

Does variation in bone chemistry exist within a population? Yes.

No you didn't answer the question.. Are all changes to bone chemistry good? What about deformed bones? Why are dolphins' bones are softer than the ones that land animals have? Why are they filled with fat and oil?

Perhaps this "defect" (if it were to occur to terrestrial mammals) is not so much a defect for aquatic species thanks to the bouyancy that water provides. In other words being aquatic allows a freedom of development otherwise closed to the dolphins ancestors.

Nice picture of some whales bones... Looks like you got that here. You're suppose to be going from smaller to larger not larger to smaller. A 63 ton whale shrinking to a 175 pound dolphin? This is hardly good evidence. Just shrinking evidence...

???
Cetartiodactyla is a super order which includes whales and dolphins. Modern Cetaceans have more finger bones, whales and dolphins.

All mammals need air... Are you saying they don't need to breath air at the embryonic stage?

No, they do not breath during the embryonic stage.

They do, in fact they resemble forelimbs more than fins. They appear to be modified forelimbs.

Are you kidding me? Hardly.. And heavy on the modification...

5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..

An anatomical analysis of the forelimb of the mammals suggests that they are homologous structures.

I am only echoing your sentiments. My statement was that the fin of a dolphin more closely resembles the forelimb of terrestrial mammals than that of the fins of fish. Do you disagree?

Also apoptosis is a loss of information again..

Not necessarily, apoptosis can be a duplication of a singnaling segment. A loss of tissue can be the result of an addition or modification to the signaling mechanism. For example lets say we have instructions to cut string.

Measure out 10 feet of string.
Cut it.
Tie one end to a stick.
Let the other end fall lose.

Now we modify these instructions.
Measure out 10 feet of string.
Cut it.
Cut it in half.
Tie one end to a stick.
Let the other end fall lose.

As you can see an added instruction resulted in a loss of half the length of string. Subtraction by addition.

No, but it is possible that this adaptation came from selecting among a variation within a population, just as beak sizes on Galapagos island, which you assure us is only microevolution.

Some variations but not that drastic.. If you had a bird with a beak on it's back you may have a case...

Is the location of the blow hole variable within a population?

And what facts are those? Evolution is a THEORY not a fact... Ask any real scientist...

I am clarifying the definition of homology and analogy. It should be pretty straight forward

[Gman]

How is this analogous? They have different functions.

And why are those functions different? Also I thought you said that functionality is insignificant to homology..

So then where did the hindlimbs in the original article come from?

You are still not answering my question.. Why did the the dolphins once have two rear fins and then lost the information? Why is it always a loss of information or a duplication of information. Where's the NEW information? Where did that come from? Natural selection? What is natural selection going to select to get started?

The defect is in the signaling molecule. This translated hypothetically to a modification in the adult form.

Would you agree that if the dolphins once had hind limbs that they certainly do not need it to survive? Then is this modification itself a defect?

They were never on land... Ok? A defect in the signaling molecule? Why is it called a defect then? Are dolphins simply remnants of defective mutations and signaling molecules then?

To build a building you have to carefully place the bricks in the right place. If not your structure will fall. Throwing your bricks around like a helpless child will not construct a building and will damage the bricks...

Perhaps this "defect" (if it were to occur to terrestrial mammals) is not so much a defect for aquatic species thanks to the bouyancy that water provides. In other words being aquatic allows a freedom of development otherwise closed to the dolphins ancestors.

See above about defects... Also water is mainly a dissolver of structure..

???
Cetartiodactyla is a super order which includes whales and dolphins. Modern Cetaceans have more finger bones, whales and dolphins.

?? You are jumping to a super order? Cetartiodactyla is a superorder to which whales dolphins and even-toed ungulates (land animals such as cattle, pigs, goats, and sheep) belong to. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word called "Cetartiodactyla." Try going from smaller bones to larger bones in the dolphin family called delphinidae..

No, they do not breath during the embryonic stage.

No.. The point is that they need oxygen to survive.. The oxygen is supplied by the mother until the embryo can survive on it's own.

I am only echoing your sentiments. My statement was that the fin of a dolphin more closely resembles the forelimb of terrestrial mammals than that of the fins of fish. Do you disagree?

Let's see.. A dolphin was found with 4 fins on it.. Two in the front and two in the back. You stated "fin of a dolphin more closely resembles the forelimb of terrestrial mammals." LOL.. In other words you have a dolphin that is walking on 4 forelimbs with no hind legs... I'm surprised you fell for that one...

Not necessarily, apoptosis can be a duplication of a singnaling segment. A loss of tissue can be the result of an addition or modification to the signaling mechanism. For example lets say we have instructions to cut string.

Measure out 10 feet of string.
Cut it.
Tie one end to a stick.
Let the other end fall lose.

Now we modify these instructions.
Measure out 10 feet of string.
Cut it.
Cut it in half.
Tie one end to a stick.
Let the other end fall lose. As you can see an added instruction resulted in a loss of half the length of string. Subtraction by addition.

And where did the string come from? Did it subtract itself to become a string first? Do you have a magic show for us too?

Is the location of the blow hole variable within a population?

Only if you want to add ones' rear end as a blow hole..

And what facts are those? Evolution is a THEORY not a fact... Ask any real scientist...

I am clarifying the definition of homology and analogy. It should be pretty straight forward

Straight as a curved road... And what does homology state? Do you think it has something to do about a common ancestor? And what do you think a common ancestor theory comes from? Do you think it has anything to do with evolution?

[BGoodForGoodSake]

How is this analogous? They have different functions.

And why are those functions different? Also I thought you said that functionality is insignificant to homology..

It is, we are talking about analogy. Look what you wrote below
Gman wrote - I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.

So then where did the hindlimbs in the original article come from?

You are still not answering my question.. Why did the the dolphins once have two rear fins and then lost the information?

It would appear that their ancestors had rear fins because they were descended from quadrapedal mammals. In the case of dolphins I might surmise that they first developed four fins and then lost the rear two, but there is not enough evidence to make this conclusive. Certainly if the new case can be shown to represent a hind limb which resulted from a failure of apoptosis, then the idea can be given more merit. However the actual path of development could never be completely recovered.

Why is it always a loss of information or a duplication of information. Where's the NEW information?

New information comes from modification. For instance a mutation which causes the fusion of the elbow joint is a modification to the current joint. Mutations which duplicate phalangial bones can then later become modified to better form the fins.

Where did that come from? Natural selection? What is natural selection going to select to get started?

Variations within a population. It is also possible that some of the variety which exists within a population was previously selected against, but having moved to a marine environment they are now actively selected for. Such as bones which contain more fat and oil. Webbed footing is another good example.

The defect is in the signaling molecule. This translated hypothetically to a modification in the adult form.

Would you agree that if the dolphins once had hind limbs that they certainly do not need it to survive? Then is this modification itself a defect?

They were never on land... Ok? A defect in the signaling molecule? Why is it called a defect then?

In terms of the preexisting develepmental pathway it is a defect. A defect can lead to an improvement. We can term this as a modification if you like.

Are dolphins simply remnants of defective mutations and signaling molecules then?

Yes dolphins and all animals appear to be more a result of modifications to developmental pathways than to actual changes in protein structure.

To build a building you have to carefully place the bricks in the right place. If not your structure will fall. Throwing your bricks around like a helpless child will not construct a building and will damage the bricks...

Biological reproduction is nothing like a helpless child throwing bricks around. A better analogy would be skilled craftsmen who have passed on their skills from generation to generation. Each craftsman has their own unique idiosyncracy which they might pass down to their own student(s).

???
Cetartiodactyla is a super order which includes whales and dolphins. Modern Cetaceans have more finger bones, whales and dolphins.

?? You are jumping to a super order? Cetartiodactyla is a superorder to which whales dolphins and even-toed ungulates (land animals such as cattle, pigs, goats, and sheep) belong to. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word called "Cetartiodactyla."

This is correct in a way. Whales and dolphins are believed to have evolved from a common ancestor. I don't think you would have any problems using a whale fossil ancestral to both whales and dolphins to show that at one time these creatures had less phalangial bones.

No, they do not breath during the embryonic stage.

No.. The point is that they need oxygen to survive.. The oxygen is supplied by the mother until the embryo can survive on it's own.

No the point is that fish who live in the ocean derive their oxygen from the water through their gills. Why would dolphins have to get theirs from the air?

See below the whole conversation
Gman said - 5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..
I said - This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg? In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?
Gman said - All mammals need air... Are you saying they don't need to breath air at the embryonic stage?
I said - No, they do not breath during the embryonic stage.
Gman said - No.. The point is that they need oxygen to survive.. The oxygen is supplied by the mother until the embryo can survive on it's own.

And where did the string come from? Did it subtract itself to become a string first? Do you have a magic show for us too?

It's a given, in this example we are trying to demonstrate that an additional instruction can lead to loss of material. This is exactly what can occur in the development process of an embryo.

Is the location of the blow hole variable within a population?

Only if you want to add ones' rear end as a blow hole..

The location of the nostril is variable within a population, it is not out of the question that variations within the population favored the development of the blowhole in the dolphin/whale ancestors. A chance mutation which gave the nostril a more superior/dorsal orientation is not out of the realm of possibilities.
Lets examine a cow skull.

And a dolphin skull.

Notice the nasal cavity in the dolphis is pushed back and over the eyes. The blow hole is then located superior to the cavity on top of the dolphins head.

Straight as a curved road... And what does homology state? Do you think it has something to do about a common ancestor? And what do you think a common ancestor theory comes from? Do you think it has anything to do with evolution?

Of course it does, but however much you disagree with evolution we need to agree on what it means, don't you think? It's similar to a Muslim comming into a Baptist church and having a different definition for the trinity. You're use of analogy and homology are wrong. And we have spent three whole pages trying to correct you.

[Gman]

It is, we are talking about analogy. Look what you wrote below
Gman wrote - I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.

No you missed my point... It is not insignificant to homology.. Analogy is different from homology but not insignificant to it. Again as I have stated many times before "the concept of analogy is contrasted with that of homology, which refers to two structures that share a common ancestor and share basic structure." It is not a worthless study as you seem to be implying..

http://www.answers.com/topic/analogy-biology

It would appear that their ancestors had rear fins because they were descended from quadrapedal mammals. In the case of dolphins I might surmise that they first developed four fins and then lost the rear two, but there is not enough evidence to make this conclusive. Certainly if the new case can be shown to represent a hind limb which resulted from a failure of apoptosis, then the idea can be given more merit. However the actual path of development could never be completely recovered.

You surmise? Finally you are starting to sound reasonable...

New information comes from modification. For instance a mutation which causes the fusion of the elbow joint is a modification to the current joint. Mutations which duplicate phalangial bones can then later become modified to better form the fins.

No... The problem is that you have to start from "scratch." At this point there isn't any living matter to even modify. There is no elbow joint to modify, no bones, no skin, no duplication...

Variations within a population. It is also possible that some of the variety which exists within a population was previously selected against, but having moved to a marine environment they are now actively selected for. Such as bones which contain more fat and oil. Webbed footing is another good example.

Again there is no population to select from... You are simply making things up as needed..

Biological reproduction is nothing like a helpless child throwing bricks around. A better analogy would be skilled craftsmen who have passed on their skills from generation to generation. Each craftsman has their own unique idiosyncracy which they might pass down to their own student(s).

A skilled craftsman? LOL.. You mean an intelligent designer? Do forget you are advocating the case for Darwinian evolution..

In terms of the preexisting develepmental pathway it is a defect. A defect can lead to an improvement. We can term this as a modification if you like.

Again there is no new information... Rather, a mutation mainly results in already preexisting information being switched on in the wrong place. That is why it is a defect...

See below the whole conversation
Gman said - 5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..
I said - This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg?

I'm glad you brought this up because you totally missed my point here.. My statement "The dolphin fin resembles an arm better than a leg" was put there to show the absurdity of the argument.. Why? Because you can't have an ancestor walking on 4 forelimbs with no hind limbs. And then you agreed with me that the fins of the dolphins resembled forelimbs.

In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?
Gman said - All mammals need air... Are you saying they don't need to breath air at the embryonic stage?
I said - No, they do not breath during the embryonic stage.
Gman said - No.. The point is that they need oxygen to survive.. The oxygen is supplied by the mother until the embryo can survive on it's own.

At this point the only thing I was addressing here was the forcing of oxygen.. It is needed by the embryo to develop.. Both fish and dolphins need oxygen.. This is not a mystery.

This is correct in a way. Whales and dolphins are believed to have evolved from a common ancestor. I don't think you would have any problems using a whale fossil ancestral to both whales and dolphins to show that at one time these creatures had less phalangial bones.

I do have a problem using whale bones because they are larger than dolphins... Again try going from smaller bones to larger bones in the dolphin family called "delphinidae.."

The location of the nostril is variable within a population, it is not out of the question that variations within the population favored the development of the blowhole in the dolphin/whale ancestors. A chance mutation which gave the nostril a more superior/dorsal orientation is not out of the realm of possibilities.
Lets examine a cow skull and a dolphin skull.

Are you joking? Do you know the difference between a cow and a dolphin? Do you?

Of course it does, but however much you disagree with evolution we need to agree on what it means, don't you think?
It's similar to a Muslim comming into a Baptist church and having a different definition for the trinity.

Oh my God Bgood... You really haven't studied other religions have you? The Trinity it totally DESPISED by Muslims.. If a Muslim ever admitted he had a different definition for the Trinity he would probably be killed by his peers..

You're use of analogy and homology are wrong. And we have spent three whole pages trying to correct you.

Excuse me? You didn't even know that analogy even existed before I pointed it out to you.. And then you kept on saying that there was a "functional homology." Since we are using previous statements, remember this statement? Quote Bgood: "Making conclusions on functional homology alone doesn't make any sence."

[BGoodForGoodSake]

Since this topic has broken down into several series of conversations I have separated out each thread to avoid any further confusions.

It is, we are talking about analogy. Look what you wrote below
Gman wrote - I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.

No you missed my point... It is not insignificant to homology.. Analogy is different from homology but not insignificant to it. Again as I have stated many times before "the concept of analogy is contrasted with that of homology, which refers to two structures that share a common ancestor and share basic structure." It is not a worthless study as you seem to be implying..

http://www.answers.com/topic/analogy-biology

I did not say it was a worthless study, how does your statement above even follow?
Here's our conversation.
Me - This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.
GMan - Yeah, but you omitted that part that they associated these fins to legs..
Me - That goes without saying, structural homology connotes just that.
GMan - I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.
Me - How is this analogous? They have different functions.
GMan - And why are those functions different? Also I thought you said that functionality is insignificant to homology..
It is, we are talking about analogy. Look what you wrote below

As you can see you stated that the back fins of dolphins are analogous to the hind legs of terrestrial mammals, I was correcting you. They are homologous.

They have different functions but similar structure.

From your link.
"Homologous structures may retain the function they served in the common ancestor or they may evolve to fulfill different functions for example, the wings of birds versus the forelimbs of mammals."

[BGoodForGoodSake]

New information comes from modification. For instance a mutation which causes the fusion of the elbow joint is a modification to the current joint. Mutations which duplicate phalangial bones can then later become modified to better form the fins.

No... The problem is that you have to start from "scratch." At this point there isn't any living matter to even modify. There is no elbow joint to modify, no bones, no skin, no duplication...

No we start with a population ancestral to dolphins and related to the population ancestral to hippos, or cows. Animals reproduce.

Variations within a population. It is also possible that some of the variety which exists within a population was previously selected against, but having moved to a marine environment they are now actively selected for. Such as bones which contain more fat and oil. Webbed footing is another good example.

Again there is no population to select from... You are simply making things up as needed..

Why do you surmise that there was no population to work with? Where does this conclusion come from?

Biological reproduction is nothing like a helpless child throwing bricks around. A better analogy would be skilled craftsmen who have passed on their skills from generation to generation. Each craftsman has their own unique idiosyncracy which they might pass down to their own student(s).

A skilled craftsman? LOL.. You mean an intelligent designer? Do forget you are advocating the case for Darwinian evolution..

Reproduction itself handles the modification passing on of information.
Would you disagree?

In terms of the preexisting develepmental pathway it is a defect. A defect can lead to an improvement. We can term this as a modification if you like.

Again there is no new information... Rather, a mutation mainly results in already preexisting information being switched on in the wrong place. That is why it is a defect...

So if a dolphin ancestor is born with fused elbow joints which allows it to steer with less effort is this a defect? A modification is new information.

See below the whole conversation
Gman said - 5. The dolphin fin resembles an arm better than a leg. See example of a whale fin..
I said - This is an excelent aexample of homology. Why would a dolphin and fish have such different structures? Why does the structure of a dophins fins resemble a foreleg?

I'm glad you brought this up because you totally missed my point here.. My statement "The dolphin fin resembles an arm better than a leg" was put there to show the absurdity of the argument.. Why? Because you can't have an ancestor walking on 4 forelimbs with no hind limbs. And then you agreed with me that the fins of the dolphins resembled forelimbs.

The front flippers found in modern dolphins resemble the forelimbs of terrestrial mammals. We are not talking about the rear fins of which we have no data for. I would venture to guess that they would resemble hindlimbs, but that would just be an educated guess. Your juxtaposition of the two statements and the resulting logical inconsistency is a non-sequitor. In other words it's an absurd conclusion to say that I meant that dolphin ancestors walked on four front limbs. Would you disagree?

In the development of a dolphin the forlimb in the embryo develops intot the flippers of a dolphin, it makes perfect sense. Why would a created dolphin be forced to breathe air?
Gman said - All mammals need air... Are you saying they don't need to breath air at the embryonic stage?
I said - No, they do not breath during the embryonic stage.
Gman said - No.. The point is that they need oxygen to survive.. The oxygen is supplied by the mother until the embryo can survive on it's own.

At this point the only thing I was addressing here was the forcing of oxygen.. It is needed by the embryo to develop.. Both fish and dolphins need oxygen.. This is not a mystery.

You have yet to address the original intent of the exchange. Why would dolphins, which are aquatic be created with the need to breath air(once out of the womb).

This is correct in a way. Whales and dolphins are believed to have evolved from a common ancestor. I don't think you would have any problems using a whale fossil ancestral to both whales and dolphins to show that at one time these creatures had less phalangial bones.

I do have a problem using whale bones because they are larger than dolphins... Again try going from smaller bones to larger bones in the dolphin family called "delphinidae.."

This restriction makes absolutely no sence within the paradigm of evolution. Dolphins are beleived to have evolved from non-dolphin whale like creatures. Thus the theory that modern whales and dolphins share a common ancestor.

The location of the nostril is variable within a population, it is not out of the question that variations within the population favored the development of the blowhole in the dolphin/whale ancestors. A chance mutation which gave the nostril a more superior/dorsal orientation is not out of the realm of possibilities.
Lets examine a cow skull and a dolphin skull.

Are you joking? Do you know the difference between a cow and a dolphin? Do you?

The point here is that one can see that a possible evolutionary pathway exists. The telescoping of the dolphin skull and the modification in the orientation of the dolphin nasal cavity could lead to the migration of the breathing aparatus back and up over the head.

Of course it does, but however much you disagree with evolution we need to agree on what it means, don't you think?
It's similar to a Muslim comming into a Baptist church and having a different definition for the trinity.

Oh my God Bgood... You really haven't studied other religions have you? The Trinity it totally DESPISED by Muslims.. If a Muslim ever admitted he had a different definition for the Trinity he would probably be killed by his peers..

The point is that a muslim who is studying Christianity needs to understand the Christian definition of trinity in order to discuss it's merits. And similarily you need to understand what homology and analogy represent within the paradigm of evolution.

[BGoodForGoodSake]

You're use of analogy and homology are wrong. And we have spent three whole pages trying to correct you.

Excuse me? You didn't even know that analogy even existed before I pointed it out to you..

This is categorically false.

And then you kept on saying that there was a "functional homology." Since we are using previous statements, remember this statement? Quote Bgood: "Making conclusions on functional homology alone doesn't make any sence."

This was a term you and angel was tossing about. See the first page of this thread.

Can you show me the reference where evolution is mainly concerned with homology of structures and very little with functional homology?

And I already explained that this term was "coined" to describe your misuse of the term analogy.

Angel stated - The discussion started on homologies in evolution.
You posted a quotation (from answers in genesis).
I just pointed out that in THAT quotation they mixed functional homologies and structural homologies. It is my opinion that functional homologies are very misleading.
Gman said - Then why were scientists claiming that dolphins had once WALKED on earth with legs as once the land mammals did? Isn't walking a FUNCTION?
I replied - The function of once walking is concluded from structural homology. What use would functional homology be to any discussion?
Gman said - Oh, so you do agree that there can be a functional homology?
To which I replied NO
Then Gman said - Let me ask you this.. What use would structural homology be to any discussion without functional homology? What good are legs if they are not used to walk? Do you suppose they are used simply for looks or pantyhose??
I replied - Function follows structure. So functional analogy can come into the discussion but only after structural homology has been determined.

As you can see whole conversation stems from when you posted that quote from Answers in genesis. That quote confuses readers by introducing function to try to discredit homology. This makes absolutely no sence, because it is the similarity of the basic structures, which leads one to conclude common ancestry despite differences in function.

We begin the conversation with functional differences and structural similarity.

The reason the homology argument is so strong is simply as follows. There are many solutions to a problem, why would the solution to the dolphins flipper be so similar to that of a cows forelimbs? It certainly does not need to be.

Introducing functionality to the equation after estabilishing homology is simply muddying the waters. The question is despite the difference in functionality why is there a shared basic structure. Function being different is already a given.

[Gman]

I did not say it was a worthless study, how does your statement above even follow?
Here's our conversation.

Excuse me? Let's roll back the tape...

Me: And why are those functions different? Also I thought you said that functionality is insignificant to homology..
BGood: It is, we are talking about analogy.

Analogy is not insignificant...

Do you know what the word insignificant means? Please look it up in the dictionary if you are confused on what it means.. It means "unimportant, trifling, or petty..."

Me - This is exactly what the scientists did. They surmised that dolphins once walked on land because of structural homologies. And to clarify the dolphins ancestors once walked on land, not walked on fins.

No... Again they are were associating this fins to the remains of back legs.

Quote: "Japanese researchers said Sunday that a bottlenose dolphin captured last month has an extra set of fins that could be the remains of back legs, a discovery that may provide further evidence that ocean-dwelling mammals once lived on land."

GMan - Yeah, but you omitted that part that they associated these fins to legs..
Me - That goes without saying, structural homology connotes just that.
GMan - I hope you understand that now because when it comes to function, the back fins found on the dolphin appear to be analogous to the hind legs of terrestrial mammals.
Me - How is this analogous? They have different functions.
GMan - And why are those functions different? Also I thought you said that functionality is insignificant to homology..
It is, we are talking about analogy. Look what you wrote below.

As you can see you stated that the back fins of dolphins are analogous to the hind legs of terrestrial mammals, I was correcting you. They are homologous.

Correcting me? And why aren't the back fins of dolphins analogous to the hind legs of terrestrial mammals?

They have different functions but similar structure.

From your link.
"Homologous structures may retain the function they served in the common ancestor or they may evolve to fulfill different functions for example, the wings of birds versus the forelimbs of mammals."

But you said that functionality is insignificant to homology...

And then you kept on saying that there was a "functional homology." Since we are using previous statements, remember this statement? Quote Bgood: "Making conclusions on functional homology alone doesn't make any sence."

This was a term you and angel was tossing about. See the first page of this thread.

Can you show me the reference where evolution is mainly concerned with homology of structures and very little with functional homology?

And I already explained that this term was "coined" to describe your misuse of the term analogy.

You didn't think I saw that before? That is why I posted it as a question to angel... Because it was an upsurd question... Nice try.. By the way your time is wrong..

Angel stated - The discussion started on homologies in evolution.
You posted a quotation (from answers in genesis).
I just pointed out that in THAT quotation they mixed functional homologies and structural homologies. It is my opinion that functional homologies are very misleading.
Gman said - Then why were scientists claiming that dolphins had once WALKED on earth with legs as once the land mammals did? Isn't walking a FUNCTION?
I replied - The function of once walking is concluded from structural homology. What use would functional homology be to any discussion?
Gman said - Oh, so you do agree that there can be a functional homology?

Hold it right there... You are taking things out of context...

Before I stated that last post of mine you stated this...

Bgood said: The function of once walking is concluded from structural homology. What use would functional homology be to any discussion?

After that I stated this..

Gman said - Oh, so you do agree that there can be a functional homology?

So you agreed at this point that there was a functional homology.. Don't blame Angel or me...

To which I replied NO
Then Gman said - Let me ask you this.. What use would structural homology be to any discussion without functional homology? What good are legs if they are not used to walk? Do you suppose they are used simply for looks or pantyhose??
I replied - Function follows structure. So functional analogy can come into the discussion but only after structural homology has been determined.

As you can see whole conversation stems from when you posted that quote from Answers in genesis. That quote confuses readers by introducing function to try to discredit homology. This makes absolutely no sence, because it is the similarity of the basic structures, which leads one to conclude common ancestry despite differences in function.

Who's confused? Why did you state ""Making conclusions on functional homology alone doesn't make any sence." Here you are again stating it again...

We begin the conversation with functional differences and structural similarity.

The reason the homology argument is so strong is simply as follows. There are many solutions to a problem, why would the solution to the dolphins flipper be so similar to that of a cows forelimbs? It certainly does not need to be.

The forelimbs of a cow and the dolphins fin have no resemblance whatsoever.... But again in dreamland anything is possible...

Introducing functionality to the equation after estabilishing homology is simply muddying the waters.

That's right it muddies up the water for your common ancestor theory even more... That's why you despise it..