Jump to content


Photo

Whale Evolution


  • This topic is locked This topic is locked
15 replies to this topic

#1 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 25 October 2005 - 08:56 AM

I'm having a tough time with whale evolution. I know evolutionists will say this is all a result of my incredulity, but please give me some answers!
Evolution requires gradual functional intermediates, each of which would have a survival advantage sufficient for every mutational step to penetrate and replace the existing population. My challenge is this: Explain how cetaceans (whales) could have evolved from a quadruped land mammal, as commonly supposed. Specifically, since all proposed precursors had a side to side tail movement, what intermediate step(s) are possible that would have had survival advantages and would gradually accomplish an up and down movement to out-survive the side to side motion, while simultaneously sacrificing the hind limbs? In envisioning the transformation, the land ancestor of the whale would have to gradually eliminate its pelvis and its function of supporting the hindlimbs which would have been used for propulsion, replacing it with a very different skeletal structure and associated musculature that would support a massive, flat tail (with flukes). Simultaneously, micromutations would have produced these horizontal tail flukes independently. All this was accomplished in around 8 million years.
Additional Questions:
Some of the proposed whale precursors were hippo-like animals.
1. How many favorable mutations do you suppose would be required to go the tail of a hippo to the flukes of a bottle nosed dolphin. What survival advantage would a hippo have today if a mutation produced a slightly more robust tail?
2. What about the gradual evolution of echolocation?

#2 Stile

Stile

    Newcomer

  • Member
  • Pip
  • 4 posts
  • Age: 27
  • no affiliation
  • Atheist
  • Ontario, Canada

Posted 26 October 2005 - 09:59 AM

..but please give me some answers!

I doubt I know enough to satisfy even the simplest of questions. But I'll put what knowledge I do have out, and you can do with it as you please.


Evolution requires gradual functional intermediates, each of which would have a survival advantage sufficient for every mutational step to penetrate and replace the existing population.

I'm not sure Evolution "requires" anything like this. "Replacing the existing population" is not required. As long as any new survival advantage allows a species to remain alive long enough to reproduce, evolution has occured. Whether or not the existing population dies out has no bearing.


My challenge is this: Explain how cetaceans (whales) could have evolved from a quadruped land mammal, as commonly supposed.

I cannot possibly accept this challenge. My knowledge is too limited. I did find one news story about the whale's ear evolution, and a picture showing some of the ancestors, if you'd like to take a look.


what intermediate step(s) are possible that would have had survival advantages and would gradually accomplish an up and down movement to out-survive the side to side motion, while simultaneously sacrificing the hind limbs?

I do not see where the side-to-side motion was ever used to swim. In fact, I do not see any mention of side-to-side motion at all, although I don't see why it wouldn't go side to side, or up and down. I think that when the mammal was land-based, the tail could either go in pretty much any direction. I don't think side-to-side was ever used to propel these creatures through the water.

Evolution does not aim for a whale. There is no positive force to create an aquatic whale from a land-mammal. It's just that today we have whales.. in the past, we've had all these creatures who almost look like whales but are missing a few of the features that whales have. The "whale evolution" is nothing more than the logical connection of the dots we have. It's possible that it could be wrong, and if some data comes around which does not fit in the current thought.. something which makes it impossible, like say.. we find a new species of whale today that has gills and does not breathe air. Then the current dot-connections will have to be re-thought, and when a new logical connection better explains the old data and the new data.. it then replaces the old way of thinking how it happened. That's how this works. We take what data we have and create a plausible, logical description for it. There's no right or wrong, only "this seems good for what we have".

#3 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 26 October 2005 - 10:26 AM

I'm not sure Evolution "requires" anything like this. "Replacing the existing population" is not required. As long as any new survival advantage allows a species to remain alive long enough to reproduce, evolution has occured. Whether or not the existing population dies out has no bearing.

Evolution does require replacement of the species by the new adaptation, If that did not occur, the probability of going on to more micromutations would be inconceivably low. You need large numbers of affected members of a population to have even a remote chance of another change.

I do not see where the side-to-side motion was ever used to swim. In fact, I do not see any mention of side-to-side motion at all, although I don't see why it wouldn't go side to side, or up and down. I think that when the mammal was land-based, the tail could either go in pretty much any direction. I don't think side-to-side was ever used to propel these creatures through the water.


All proposed whale precursors had side to side motion. Have you ever seen a dog wag its tail up and down? Any proposed whale evolution needs to explain how each step could have been enough of a survival advantage to replace the species.

#4 Guest_Aristarchus_*

Guest_Aristarchus_*
  • Guests

Posted 26 October 2005 - 10:26 AM

If you want to see some of the current ideas, there is a decent quicktime video at the following site. Although, you would need to get into some of the scientific papers to address all your questions.

http://www.pbs.org/w...4/l_034_05.html

#5 chance

chance

    Veteran Member

  • Banned
  • PipPipPipPip
  • 2029 posts
  • Age: 51
  • no affiliation
  • Atheist
  • Australia

Posted 26 October 2005 - 01:19 PM

I'm having a tough time with whale evolution. I know evolutionists will say this is all a result of my incredulity, but please give me some answers!
Evolution requires gradual functional intermediates, each of which would have a survival advantage sufficient for every mutational step to penetrate and replace the existing population.


Yes.

My challenge is this: Explain how cetaceans (whales) could have evolved from a quadruped land mammal, as commonly supposed. Specifically, since all proposed precursors had a side to side tail movement, what intermediate step(s) are possible that would have had survival advantages and would gradually accomplish an up and down movement to out-survive the side to side motion, while simultaneously sacrificing the hind limbs? <moved> Simultaneously, micromutations would have produced these horizontal tail flukes independently. All this was accomplished in around 8 million years.


The whale precursors is thought to be a land mammal. Mammals have an up down moving spine, not a sideways spine as you state (this is to accommodate legs that are mounted beneath the body, not sticking out the sides like a lizard). So the simplest solution is us up down for propulsion as that’s where the flexibility is.



In envisioning the transformation, the land ancestor of the whale would have to gradually eliminate its pelvis and its function of supporting the hindlimbs which would have been used for propulsion, replacing it with a very different skeletal structure and associated musculature that would support a massive, flat tail (with flukes).


Yes it could have passed through a stage something like a seal, or walrus.

#6 Stile

Stile

    Newcomer

  • Member
  • Pip
  • 4 posts
  • Age: 27
  • no affiliation
  • Atheist
  • Ontario, Canada

Posted 26 October 2005 - 01:20 PM

You need large numbers of affected members of a population to have even a remote chance of another change.

I don't understand. Why would one set of creatures need to die off for another set of creatures to be affected by some sort of other selection pressure? The two ideas seem seperate to me.

Sometimes creatures obtain an advantage in acquiring a needed resource. When this happens then yes, the old creatures would generally tend to die out, no longer being able to acquire the vital resource. But this is not a requirement. Merely a possible result, a potential by product.


All proposed whale precursors had side to side motion.

They did? How do you know this? My knowledge of whale precursors is sketchy at best. Out of the 10 whale precursors shown in the picture I provided, only the initial 2 are not obviously known to use an up-down motion. I see no reason to believe they could not move their tails up and down. I do believe that these 2 whale precursors had the ability to move thier tails side to side as well, but I definitely do not know this. As I said, my knowledge of these creatures is limited.


Have you ever seen a dog wag its tail up and down?

I'm not sure what you're getting at by mentioning this either. Are you trying to say that a dog is a precursor to the whale? Dogs are quite capable of moving their tails up and down, but I don't see how my point or yours is relevant.


Any proposed whale evolution needs to explain how each step could have been enough of a survival advantage to replace the species.

Why would it need to explain every step? And even if it did, what constitutes a "step"? As far as I know, this is how the proposed whale evolution came about:

1. We have whales today, by observing them they appear to be mammals.
2. The modern whale skeletal structure somewhat resembles certain modern land-based mammal structures.
3. The theory of evolution would predict that if whales did evolve, they must have come from land based mammals at some point. Therefore, in the past there must have existed:
A. Creatures that are more whale-like and less land-based-mammal-like. These creatures would be more recent.
B. Creatures that are less whale-like and more land-based-mammal-like. These creatures would be more distant in the past.


The fact that fossils and remains have been found for predictions A and B, and in the right order, is evidence that this theory is valid. The fact that evidence of the existance of every "step" has not been found is not evidence against the theory. Evidence against the theory would be, as I stated before, a whale-like creature being found that has absolutely non-whale-like features (like suddenly having gills instead of lungs).

#7 Stile

Stile

    Newcomer

  • Member
  • Pip
  • 4 posts
  • Age: 27
  • no affiliation
  • Atheist
  • Ontario, Canada

Posted 26 October 2005 - 01:39 PM

..Evolution requires gradual functional intermediates, each of which would have a survival advantage sufficient for every mutational step to penetrate and replace the existing population.


Yes.



I don't think this is true.. if Evolution required every intermediate to penetrate and replace the existing population.. we would have an evolutionary line, not a tree (or bush, which more accurately describes it).

When a population evolves, it breaks off. Where there was once 1 population, there is now 2. What happens to each becomes independant. It is certainly possible for one to penetrate and replace the other, but definitely not required. If it were required, we would begin with 1 population and end up with 1.

#8 chance

chance

    Veteran Member

  • Banned
  • PipPipPipPip
  • 2029 posts
  • Age: 51
  • no affiliation
  • Atheist
  • Australia

Posted 26 October 2005 - 03:01 PM

I don't think this is true.. if Evolution required every intermediate to penetrate and replace the existing population.. we would have an evolutionary line, not a tree (or bush, which more accurately describes it).

When a population evolves, it breaks off.  Where there was once 1 population, there is now 2.  What happens to each becomes independant.  It is certainly possible for one to penetrate and replace the other, but definitely not required.  If it were required, we would begin with 1 population and end up with 1.

View Post


Correct, I was generalising.

#9 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 26 October 2005 - 03:08 PM

Yes.
The whale precursors is thought to be a land mammal.  Mammals have an up down moving spine, not a sideways spine as you state (this is to accommodate legs that are mounted beneath the body, not sticking out the sides like a lizard).  So the simplest solution is us up down for propulsion as that’s where the flexibility is.
Yes it could have passed through a stage something like a seal, or walrus.

View Post

The spine moves up and down, but the tail (distal to the pelvis), is side to side.
A seal or walrus uses its hind quarters for propulsion, so that is in no way qualifies as transitional to a whale.

#10 chance

chance

    Veteran Member

  • Banned
  • PipPipPipPip
  • 2029 posts
  • Age: 51
  • no affiliation
  • Atheist
  • Australia

Posted 26 October 2005 - 06:52 PM

The spine moves up and down, but the tail (distal to the pelvis), is side to side.


As the strength of the tail is dependant upon the attachment points, it seem logical to me that a long animal will use the propulsion originating from that strength, and in a whale, and it’s precursors that must come from the spine, thus vertical motion. A dog wagging it’s tale is a very poor analogy, as the tail serves no purpose for locomotion and has evolved into a signalling device, by becoming (in comparison) disarticulated, the strength needed is miniscule in comparison.

However I’m intrigued about this notion that you have that the mammals must have has a predominantly lateral motion in the tail. Even if there is some ability for lateral movement in the tail, swinging the tail from side to side would (I think) induce considerable pain in the spine (for a whale), the natural movement is vertical.

A seal or walrus uses its hind quarters for propulsion, so that is in no way qualifies as transitional to a whale.


I did say ‘something like’, not ‘is’.

P.S. just been doing some reading on whales, apparently there are no bones in the flukes.

#11 ratrat

ratrat

    Junior Member

  • Member
  • PipPip
  • 38 posts
  • Age: 21
  • no affiliation
  • Atheist
  • Edmonton, Alberta, Canada

Posted 27 October 2005 - 10:57 PM

Springer
In your first post you seemed rather incredulous as to the ability of an animal to evolve from land mammal (hippo-like) to a modern cetacean in 8 million years. I will admit, I agreed. However, I was doing some reading in my Evo textbook and the land ancestor you're refering too lived about 50 million years ago and the whale family is beleived to have been evolved for complete aquatic life about 15 million years after that. This too seem short though, just thought it might relieve a little of your incredulence. Anyways...the likely reason for the fact that whales move their flukes in an up-down manner is that the sacral vertebrae (these are between your lumbar and caudal (tail) vertebrae) have been removed as they are associated with the pelvis which was lost when the legs were lost. Also, the caudal (tail) vertebrae of the whale are dorsoventrally flattened (ie they are not as deep from top to bottom as they used to be but are far wider). This would cause the side to side movement of the fluke to become next to impossible. Also, it is not true that all the ancestors demonstrated side to side tail movement. The protocetids, which lived between 49 and 39 million years ago, have reduced fusion in the sacral vertebrae and the caudal vertebrae are already becoming dorso-ventrally compressed. The pelvis of this animal was not strong enough to support its weight which suggests a nearly complete aquatic lifestyle. The basilosaurids (about 35 mya) have a detached pelvis and hind leg and the caudal vertebrae are fully dorso-ventrally compressed. This animal was completely aquatic.

#12 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 28 October 2005 - 07:46 AM

  Also, it is not true that all the ancestors demonstrated side to side tail movement.  The protocetids, which lived between 49 and 39 million years ago, have reduced fusion in the sacral vertebrae and the caudal vertebrae are already becoming dorso-ventrally compressed.  The pelvis of this animal was not strong enough to support its weight which suggests a nearly complete aquatic lifestyle.  The basilosaurids (about 35 mya) have a detached pelvis and hind leg and the caudal vertebrae are fully dorso-ventrally compressed.  This animal was completely aquatic.

View Post

This is typical highly speculative and subjective interpretation biased by the paradigm of evolution. It's very easy to see "reduced fusion" in a "supposedly" 50 million year old fossil if you look hard enough. These proposed models still fail to explain in specific terms how natural selection would force an animal to sacrifice its hindlimbs for an evolving tail, and how the musculature simultaneously could rearrange itself for an up and down movement.

#13 ratrat

ratrat

    Junior Member

  • Member
  • PipPip
  • 38 posts
  • Age: 21
  • no affiliation
  • Atheist
  • Edmonton, Alberta, Canada

Posted 28 October 2005 - 02:44 PM

This is typical highly speculative and subjective interpretation biased by the paradigm of evolution. It's very easy to see "reduced fusion" in a "supposedly" 50 million year old fossil if you look hard enough.


Their is no speculation involved here at all. All that "reduced fusion" of the sacral vertebrae means is that they are no longer fused together and are separate (where there was 1 or 2 big ones before now there are 2 or 4 smaller ones). You do not have to "look hard enough" to see this.

These proposed models still fail to explain in specific terms how natural selection would force an animal to sacrifice its hindlimbs for an evolving tail, and how the musculature simultaneously could rearrange itself for an up and down movement.


Remember that the protocetis lived a fully aquatic lifestyle and was a quadruped. It's pelvis was not strong enough to support it on land and therefore, any adaptation that would allow it to propel itself through the water more effectively would have been beneficial. The use of the tail as a means of propulsion would have helped (look at an alligator swimming vs a dog). Also, it wouldn't have lost its hind limbs in favor of its new tail. The dorudon, which lived more than 10 million years later than the protocetids, still has a pelvis and hindlimbs, but they are separate from the vertebral column.

As for the up-down motion of the fluke, you must remember that this structure is simply a continuation of the spine, which flexes dorsoventrally. The whale does not hold its upper body rigid and use its caudal vertebrae to swim, it uses its entire body to propel itself. As well, the up-down movement of the tail was already possible (but not exclussive) in the protocetids.

#14 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 28 October 2005 - 03:38 PM

Their is no speculation involved here at all.  All that "reduced fusion" of the sacral vertebrae means is that they are no longer fused together and are separate (where there was 1 or 2 big ones before now there are 2 or 4 smaller ones).  You do not have to "look hard enough" to see this.

Please give me a link to the photos (not drawings)


As for the up-down motion of the fluke, you must remember that this structure is simply a continuation of the spine, which flexes dorsoventrally.  The whale does not hold its upper body rigid and use its caudal vertebrae to swim, it uses its entire body to propel itself.  As well, the up-down movement of the tail was already possible (but not exclussive) in the protocetids.

The up and down movement of a whale's tail IS its tail. Just look at the position of the vestigial pelvis. Are you suggesting that the precursor's tail gradually disappeared and the spine gradually lengthened caudal to the pelvis?! There's no question that anatomically a whale's tail is a tail if you're going to suppose it evolved. The question is, how could it make a gradual change from side to side to up and down. This is inconceivable, when you start imagining details and what selective pressure would have to have been in affect. Also, I need some halfway reasonable explanation as to why natural selection would favor a tail lengthing and legs regressing simultaneously. Specifically, why would a mutated offspring with shorter less functional legs have a survival advantage in early whale evolution, when he would obviously be using those legs for either propulsion or walking, depending on the stage of evolution?

#15 ratrat

ratrat

    Junior Member

  • Member
  • PipPip
  • 38 posts
  • Age: 21
  • no affiliation
  • Atheist
  • Edmonton, Alberta, Canada

Posted 28 October 2005 - 10:10 PM

Please give me a link to the photos (not drawings)


Sorry I don't have a link as all this information came from my textbook. However, this link http://members.cox.n...ies/lie030.html shows the remains of Ambulocetus, one of the whale's terrestrial ancestors. Look at the large rectangular bone which is in between the two hind legs. This is the sacrum. It is composed of many fused sacral vertebrae. Now look at this link http://www.cdp1802.o...hen/CetRes.html . If you scroll down to the photos of the Natchitochia jonesi sacral vertebrae, you can clearly see that there is only one distinct individual vertebrae. This photo is from the remains of the protocetids which were fully aquatic.


The up and down movement of a whale's tail IS its tail. Just look at the position of the vestigial pelvis. Are you suggesting that the precursor's tail gradually disappeared and the spine gradually lengthened caudal to the pelvis?! There's no question that anatomically a whale's tail is a tail if you're going to suppose it evolved. The question is, how could it make a gradual change from side to side to up and down. This is inconceivable, when you start imagining details and what selective pressure would have to have been in affect.


It doesn't have a tail like a dog or a cat. It's tail is like that of a fish. The only thing that separates its tail from the rest of its body is that it has a different type of vertebrae in it, just like the lumbar vertebrae in your lower back are different from the thoracic vertebrae in your upper back. The shape of the caudal vertebrae (these are the same vertebrae that make up the tail of any other mammal) has been modified so that it simply does not allow for side to side motion. Therefore, the formation of the fluke by elimination of the pelvis would have gradually changed the motion of the tail from side to side (which the hippo doesn't have anyways) to the up-down motion seen in modern whales.


Also, I need some halfway reasonable explanation as to why natural selection would favor a tail lengthing and legs regressing simultaneously. Specifically, why would a mutated offspring with shorter less functional legs have a survival advantage in early whale evolution, when he would obviously be using those legs for either propulsion or walking, depending on the stage of evolution?


The legs didn't regress at the same time as the tail lengthened. The protocetids looked essentially like a modern whale with legs (at least that is my interpretation). It would make sense that the whales would have had their pelvis separate from the spinal column, hence (eventually) forming the fluke, while the legs were still intact. The protecitids still had a pelvis and very small hind limbs while at the same time possessing the fluke of a modern whale. This means that the legs would not have been used for walking or swimming, but would have had little purpose (they may have played a small roll in mating but this is only speculation on my part).

#16 Springer

Springer

    Member

  • Veteran Member
  • PipPipPip
  • 961 posts
  • Age: 53
  • no affiliation
  • Creationist
  • Kalamazoo, MI

Posted 30 October 2005 - 05:40 PM

Sorry I don't have a link as all this information came from my textbook.  However, this link http://members.cox.n...ies/lie030.html shows the remains of Ambulocetus, one of the whale's terrestrial ancestors.  Look at the large rectangular bone which is in between the two hind legs.  This is the sacrum.  It is composed of many fused sacral vertebrae.  Now look at this link http://www.cdp1802.o...hen/CetRes.html .  If you scroll down to the photos of the Natchitochia jonesi sacral vertebrae, you can clearly see that there is only one distinct individual vertebrae.  This photo is from the remains of the protocetids which were fully aquatic.

I looked at both sites and all the interpretations are highly subjective.

It doesn't have a tail like a dog or a cat.  It's tail is like that of a fish.  The only thing that separates its tail from the rest of its body is that it has a different type of vertebrae in it, just like the lumbar vertebrae in your lower back are different from the thoracic vertebrae in your upper back.  The shape of the caudal vertebrae (these are the same vertebrae that make up the tail of any other mammal) has been modified so that it simply does not allow for side to side motion.  Therefore, the formation of the fluke by elimination of the pelvis would have gradually changed the motion of the tail from side to side (which the hippo doesn't have anyways) to the up-down motion seen in modern whales.

You claim that it is a modified tail, and you're still glossing over the critical issue... How does a tail gradually change from side to side to vertical? All you say is that it gradually happened, without justifying how it could have happened, ie., show the continuum and show how each step could have had a selective advantage. You can't just say it gradually changed, because such a change would require a rearrangement of anatomy. By the way, how do flukes form by elimination of the pelvis?

The legs didn't regress at the same time as the tail lengthened.  The protocetids looked essentially like a modern whale with legs (at least that is my interpretation).  It would make sense that the whales would have had their pelvis separate from the spinal column, hence (eventually) forming the fluke, while the legs were still intact.  The protecitids still had a pelvis and very small hind limbs while at the same time possessing the fluke of a modern whale.  This means that the legs would not have been used for walking or swimming, but would have had little purpose (they may have played a small roll in mating but this is only speculation on my part).

100% speculation




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users