Evolution: Transitional forms

[hexag1]

Transitional forms are often brought up in debates about the truth of natural selection (it was mentioned in the Ant and the blade of grass thread), so I wanted to start a thread here to work out some of the problems we have in our understanding. Well, I still think I need some clarification.
In my view, transitional forms are just a concept made by theorists so they can better tell an evolutionary story. The classic example is the picture of man evolving from 'lower' apes like this one:

These images are as old as the debate, and do a lot to confuse us. The main problem is that the stages shown here only represent a tiny cross-section of a multidimensional tree (also, nobody thinks that man came from chimps). It doesn't show the whole picture, just a few points selected arbitrarily, that can be arranged to show an easy to follow evolutionary 'just so' story.
Images like this have dominated the average person's view of evolutionary theory (I find it hard to get them out of my head). Creationists often ague that since a single link is missing in this story, the whole picture of evolution must be invalid.

However, these images also have a grain of truth to them. Look at this image: [image]http://www.kgs.ku.edu/Publications/Bulletins/ED15/gifs/fig1.gif [/image]

You can see a succession of ancestors of modern whales. Even though the VAST majority of the picture is missing. The picture shows four creatures. How many individuals would we see if we had a snapshot of all the descendants of the first creature? Millions at the very least. Even if we were just looking at the individuals that lived between the first creature and the second, we would have millions of individuals to consider.

However, with all those creatures missing from our picture of the evolutionary tree, we can still infer ancestry. How? Because of comparative anatomy. We can see the similarities in the bone structures, with slight deformations, that line up quite nicely. Sometimes we can even see these transitional forms in related creatures that are alive simultaneously. The example of Caribbean anoles is a case in point.

Rainforests in Jamaica and Hispaniola are home to little lizards called Anoles. Different species of anoles live in the trees at different altitudes and levels of canopy. They are all specialized for different jobs, and they don't interbreed. Yet a striking similarity can be seen their bones. If you line up the skeletons, starting with the ones that live on the ground and all the way to the top of the trees, you can see a progression not unlike the images above. The differences in skeletal anatomies is slight, but not much less than the evolutionary trees assembled by paleontologists. The ones in the middle could be seen as 'transitional forms'. But what makes these mid-dwelling lizards the transitional forms? Nothing. It is only an artifact created by our linear diorama.

Because these creatures are distinct species, that cant interbreed, the Creationist has to argue that they were made separately. But this view is exploded when we can see the similarity in the anatomy of these lizards. Furthermore, DNA results (see National Geographic Nov. 2004) show that these anoles are all closely related, with a clear common ancestor. These are the same DNA techniques that show who is the babydaddy on Maury Povich.

With all this in mind, why do creationists focus on these transitional forms? Because when we don't have one to show, they can jump on this gap and say “AHA theres a gap in your theory!” But this seems trivial in light of the fact that the fossil record is one gigantic gap, peppered with a random spattering of fossils finds. We can still recognize a friend's face when seen through gauze. So it is with the tree of life. We can still recognize the genealogical tree of life through the gaps in the fossil record, stretching its branches out at us from the roots of the distant past.

Sorry if this seems like a random exercise, I just wanted to rant and try my hand at writing for 1/2 hour.

[kiwidonk]

Thanks for your post, I'm always very interested to read about the fossil record.

From what I've read of creationist theory, I doubt that they would disagree with the 2 examples you raised, as they lizards diversifying into lizards, whales diversifying into whales etc, they do not doubt that this kind of variation occurs within species.

Their main contention is that there is apparently none/scant evidence in the fossil record showing transitional forms between species as we see them today, of which they think would make up a fair portion of the fossil record under an evolution type scenario.

Is this correct/incorrect, or a valid point? I'd love to see discussion on this as I don't know a whole lot about it.

[Sephus]

lizards and whales are not species.

[bluesbassman]

[ QUOTE ]
The example of Caribbean anoles is a case in point.

Rainforests in Jamaica and Hispaniola are home to little lizards called Anoles. Different species of anoles live in the trees at different altitudes and levels of canopy. They are all specialized for different jobs, and they don't interbreed. Yet a striking similarity can be seen their bones. If you line up the skeletons, starting with the ones that live on the ground and all the way to the top of the trees, you can see a progression not unlike the images above. The differences in skeletal anatomies is slight, but not much less than the evolutionary trees assembled by paleontologists. The ones in the middle could be seen as 'transitional forms'. But what makes these mid-dwelling lizards the transitional forms? Nothing. It is only an artifact created by our linear diorama.


[/ QUOTE ]

If different species (such as, perhaps, these anoles) are sufficiently closely related on the tree of life, creationists will arbitrarily label them the same "kind," and declare they differ only via "microevolution," which they typically accept.

Species which are more distantly related beyond a certain arbitrary threshold are declared unrelated, since that would require "macroevolution," which they don't accept.

Interestingly, creationists are often divided about to which "kind" a particular species belongs. For example, some creationists consider the extinct hominid [censored] habilis to be an "ape," while others consider it to be a human. Yet they would all deny it represents a transitional form between other apes and modern humans. (I'm using the word "ape" in a casual sense, I know humans are classified as apes.)

(And lol that I'm censored from naming that hominid species habilis.)

[NotReady]

[ QUOTE ]

And lol that I'm censored from naming that hominid species habilis.)


[/ QUOTE ]

Do it like this h o m o habilis. And the creationist complaint against the evolutionist is they will label anything in the fossil record between 2 fossils as a transitional form. What is needed is a fixed definition of transitional. I don't think it exists and doubt it can, which means the question of evolution will never be settled.

[tpir]

[ QUOTE ]
I don't think it exists and doubt it can, which means the question of evolution will never be settled.

[/ QUOTE ]
Creationism triumphs again?

I ask for the 4th time (and in the 3rd different thread): so anytime we don't know something, creation becomes the true answer by default? Have you re-examined this false dilemma in your thinking?

[NotReady]

[ QUOTE ]

Have you re-examined this false dilemma in your thinking?


[/ QUOTE ]

What false dilemma?

How do you define transitional and what's your authority?

[tpir]

[ QUOTE ]
[ QUOTE ]

Have you re-examined this false dilemma in your thinking?


[/ QUOTE ]

What false dilemma?

[/ QUOTE ]
The one that you keep dodging in all of these threads and asking me to repeat. Namely, that creationism becomes true automatically because evolution is not 100% perfectly proven.

[NotReady]

[ QUOTE ]

Namely, that creationism becomes true automatically because evolution is not 100% perfectly proven.


[/ QUOTE ]

Cite, please.

And what about those transitions? Why do you always evade my questions?

[tpir]

[ QUOTE ]
[ QUOTE ]

Namely, that creationism becomes true automatically because evolution is not 100% perfectly proven.


[/ QUOTE ]
Cite, please.

[/ QUOTE ]
You can't be serious. I have already cited this citation twice now.

http://forumserver.twoplustwo.com/sh...age=0&vc=1
NR said: The reason I attack evolution is because I don't think it's true and if that can be shown the only option left is creationism.


[ QUOTE ]
And what about those transitions?

[/ QUOTE ]
Even if we take it as a given that transitional forms do not exist, that still doesn't make creationism magically correct by default. I concede that I am not an expert or even very knowledgeable about transitional forms. Thankfully, they are irrelevant to the point I am trying to get you to address.


[ QUOTE ]
Why do you always evade my questions?

[/ QUOTE ]
Not sure where you get "always" from. I would be happy to answer your questions, but I feel like you are trying to distract the discussion and avoid giving any answers of your own. Last time you went with "Why not unveil the mystery and let us all know the third way?" A clever attempt, but a dodge nonetheless.

Why do you always ask me to recite questions I have posed multiple times? You forget that I used to be a theist who used these same tactics, so I refuse to bite sometimes. I know that you know that I know you are doing this, so why continue?