Gman wrote:Bgood wrote: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...
I did not state that analogy is insignificant, read more carefully what I am agreeing with here.
Functionality is insignificant to
homology. I am agreeing with your statement that FUNCTIONALITY is insignificant to
homology.
Gman wrote: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..."
Bgood wrote: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."
Bgood wrote: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?
Because they have different functions. It will be proposed that the back fins of this particular dolphin and hindlegs of terrestrial mammals are
Homologous.
Also note that analogy does not lead to the conclusion of common descent, so pointing out an analogy does nothing to backup the statement "may provide further evidence that ocean-dwelling mammals once lived on land."
Here's a definition of analogy from your
link.
Analogy - Two structures in biology are said to be analogous if they perform the same or similar function by a similar mechanism.
What function does the back fins of this dolphin serve?
Does it perform the same or similar function by a similar mechanism to hindlimbs of terrestrial mammals?
Are you sure that this dolphins back fins and the hind legs of terrestrial mammals of are analogous?
Gman wrote:Bgood wrote:]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...
"Homologous structures may retain the function they served in the common ancestor
OR they may evolve to fulfill different functions"
If it may or may not retain the same function, using your esteemed judgement how significant is function to homology.
Lets restate this using alternative terms.
The color you choose may be the one I chose, or may be a completely separate color, as long as it's oil based. So tell me is color significant here?
Gman wrote:BGoodForGoodSake wrote:]
Gman wrote: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.
Gman Posted: Wed Nov 15, 2006 2:10 am wrote: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..
In any case we both agree that there is no such a thing as functional homology. And having said that that using functions to argue against homology is absurd. Would you agree? Then as a result the argument you posted from AIG is completely devoid of any persuasive statements. Because AIG basically argued that homology was impossible due to functional differences.
Gman wrote:BGoodForGoodSake wrote:]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...
No again, I explained before, I was using this term to describe the attempt to use function in a discussion of common descent. Read carefully.
"What use would
functional homology be to any discussion?"
Translated - it's a worthless term.
You think I am promoting something by declaring it useless?
For example if I said what use would astrology be in any discussion, am I giving it my full support?
And for those interested here is the full quote.
Bgood wrote:The function of once walking is concluded from structural homology. What use would functional homology be to any discussion?
Would it be helpful to say tigers walk so they must have once walked? Spiders walk too so they must be closely related?
Making conclusions on functional homology alone doesn't make any sence.
Yet that seems to be what you are suggesting.
Gman wrote:BGoodForGoodSake wrote:]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...
BGoodForGoodSake wrote: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...
Your source states otherwise.
AIG wrote:"It should be noted that the pectoral fins or flippers of the dolphin contain bones that are homologous (similar) to those of the human arm and hand (as well as the forelimbs of other mammals). The pectoral fin of the dolphin, for example, contains a short bone similar to the humerus (upper arm bone) of land dwelling mammals which is attached by a ball socket type joint to a scapula (shoulder blade). The humerus in turn articulates with a pair of side-by-side short bones similar to the radius and ulna (lower arm bones) of other mammals. Finally, the fin contains small bones roughly comparable to wrist bones and linear rows of bones that superficially resemble fingers."
In any case it brings us back to one of the earlier observations, dolphins flippers more closely resemble the forelimbs of a cow than it does the fins of a fish. Why?
A dolphin needs to breath air, it seems a handicap for a marine creature, do you see any reason for this?
What about the elbow joint? Why have a joint if it's just fused?
These are but a few of the questions which quickly arise from a cursory study of dolphin anatomy.
Gman wrote:BGoodForGoodSake wrote: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..
No, it muddies up the waters because the impetus for investigation began with "different functions yet similar structure". Then to reintroduce function to question conclusions represents a mental derailing.
See below.
Function is different yet Structure is the same?
Why is the structure the same?
Common Ancestry could be a possible explanation.
But the functions are different!
Yes the functions are different, those doing the investigating knew this all along. Thus the reason for the investigation!
As you can see this is mudding the waters.
If you like detective novels try this one.
The suspect is not a copper miner yet there is copper sulfide ore residue on the murder weapon.
How did it get there?
Wasn't the victims brother a mine worker, perhaps the victim borrowed his brothers coat.
But the suspect is not a copper miner!
Yes the suspect is not a copper miner, those doing the investigating knew this all along. Thus the reason for the investigation!