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fellfire
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PostPosted: Tue Jan 15, 2008 4:29 pm    Post subject: Reply with quote
Your play on words are cute, Trespasser.

TrespassersW wrote:

What's not fine; what doesn't make sense to me is this: at some point that limb was useful for walking, or climbing, or clinging to things; it's form at that time was useful. Fast forward to today and it's current form is useful, albeit in a new way. BUT consider the midpoint in the physical evolution of that limb into that wing; at some point, evolution-wise, we had something that was not-limb and not-wing. It was probably not as useful as it had been for walking, or climbing, or clinging to things, but neither was it yet useful for flying.


Why have you not considered the transistion from gliding to flying? There are several species in existence today that glide and there are several species that glide almost exclusively using their wings for initial altitude and adjustments.

TrespassersW wrote:
The theory of evolution tells us that nature favors more useful forms, but in order to get from one useful form to another, that wing had to--for a significant period of time--evolve into a LESS useful form. Why would it do so? The theory of evolution suggests it wouldn't.


Your assumption here is that the wing, being used for climbing and gliding becames something that could not be used for flying. Look at todays bats - their wings are perfectly capable of flying and as limbs for climbing and walking. One would certainly state that bats are not the best flyers in the world - one could say they are not specialized for flight, but generalized for flying and climbing.

It does not take a leap of faith to see the interim state between gliding and flying right now among modern species. It does not take a leap of faith to see the fossil record and find transitional forms that have similar capabilites as these modern forms.

These modern forms may never evolve beyond gliding or lose their ability to climb as they seem to be well evolved to their ecological niches.

TrespassersW wrote:
Again, this is not so much an argument against the theory of evolution as an example of what we don't yet understand about that theory. We don't understand quite a lot about how it happens, yet so many people accept it as absolute fact. Surely that is a kind of faith.


It is no more "faith", then studying string theory. It is no more "faith" then seeking the Unified theory. We actually understand quite alot about the mechanisms of evolution. We certainly have questions about abiogenisis and cosmology and several other sciences. That isn't "faith" as the typical use of the word.

This is what I beleive we are talking about when we speak of faith:

Websters Dictionary wrote:
2 a (1): belief and trust in and loyalty to God (2): belief in the traditional doctrines of a religion.
b (1): firm belief in something for which there is no proof (2): complete trust


2 b.(1) above, a firm believe in something for which there is no proof. This is certainly not what is required for evolution but is the requisite for religion beleif; there is tremendous proof to support the Theory of Evolution.
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TrespassersW
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PostPosted: Wed Jan 16, 2008 4:35 am    Post subject: Reply with quote
I suspect that evolution works more by leaps than by tiny steps as you seem to believe. Just my opinion.
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exton
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PostPosted: Wed Jan 16, 2008 9:07 am    Post subject: Reply with quote
TrespassersW wrote:

Let me start out by saying that I believe evolution occurred, though I don't think we understand how it occurred sufficiently to claim that believing evolution doesn't require some level of faith (as you put it). I'd rather call it something like blind acceptance or a leap of faith. Oops, there's that word again.


But in order to think that, you have to be unaware of the evidence at hand, or unwilling to be aware of it.

Evidence unequivically points to changing phenotypes over long periods of time in the life that has existed on earth; this is a fact that exists separately from ideas on how or why such a thing would happen (such as natural selection). There hasn't been any true debate on that matter for centuries; it was known even before darwin came up with natural selection.

Quote:

The theory of evolution tells us that nature favors more useful forms,


That's too general of a statement. Natural selection doesn't favor "usefulness" in general; it favors utility in reproducing (where life is concerned, anyway). It doesn't matter how smart or fast you are - or whatever - if it doesn't get you to reproduce better.

Quote:

but in order to get from one useful form to another, that wing had to--for a significant period of time--evolve into a LESS useful form. Why would it do so? The theory of evolution suggests it wouldn't.
(Of course, it's quite possible someone else here knows more than I on the subject and can explain this in such a way that it need not be taken on faith. If so, I look forward to learning more.)


I'll try....

First, you've got to keep in mind exactly what evolution does, and why it happens in the first place.

Considered purely in the sense of a mathematical algorithm, what natural selection does is it finds the local high point of a function, for a given starting point.

Here's a graph:


Imagine that the blue line is a graph of a function that represents an organism's likelihood of reproducing. The y-axis is the likelihood of reproducing, and the x-axis is some value of some trait of the organism's - eyeball diameter, skin roughness, whatever - that helps determine its likelihood of reproducing.
Disclaimer: The actual function representing an organism's likelihood of reproducing involves millions of variables, and those variables all represent genes, in one way or another. I can't graph more than two variables in a 3 dimensional graph, though, and it's easiest to do just one variable, so you're going to have to deal with that for the sake of illustration. And if you want a detailed treatise on how these variables affect one-another, i can do that later.

The shape of this graph (ie, the function that it represents) is determined by the environment that the organism lives in. And by "environment", i mean more than just the nature of their geographical location - but not much more. Again, further explanation on that can come later.

Suppose a group of organisms with trait X starts out at point A on the graph. Natural selection will cause, as each generation passes, and providing that the environment doesn't change, this group of organisms to move closer and closer (on the graph, meaning trait X will change in the negative direction) to point B on the graph - that's what is meant by a local peak.

If the environment stays the same, the group of organisms will never reach point C - whenever an individual pops up with a value for trait X that is less than trait X at point B, that individual will - on average - have less offspring than the ones closer to point B. So, the group will continue to hover around B. It will never totally stay exactly at B, because random mutation will always move it a little from side to side. But natural selection will always move it back towards B.

If the environment stays the same, the organism group will stay at point B forever. It will, we would say, "stop evolving".
Evolution only happens when a group of organisms is not close to the local maximum. And that happens when environments change.

Does that...make anytihng more clear?

As for your flying example...like fellfire said, there IS something in between walking and flying: gliding. And in between walking and gliding? Falling gracefully, or jumping between branches.

A good example of a creature in between flying and wlaking is a flying squirrel. Flying squirrels, despite their name, do not fly - they glide.

And there are plenty of things, like some monkeys, that don't glide, but whom jump and fall gracefully. And if you watch them, they shape their movements in order to use air resistance to help them on their way.
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TrespassersW
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PostPosted: Wed Jan 16, 2008 10:28 pm    Post subject: Reply with quote
exton - Perhaps--just perhaps--if everyone understood this stuff as well as you appear to, everyone would agree on it. Wink

Excellent response! If you can recommend a book that goes into more depth on the concept(s) you've touched upon, I'd be interested.

==

BTW, this points out quite nicely one of the problems we sometimes run into in these discussions: Sometimes we disagree because one of us has less information on the issue than (a) he believes he has and/or (b) he needs to have in order to reach an informed opinion.

And the solution: That person (in this case, me) has to be open to recognizing that fact, be ready to acknowledge it, and be willing to learn so that he can become better informed and move towards forming a more meaningful opinion on the topic. Cool
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exton
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PostPosted: Fri Jan 18, 2008 8:39 am    Post subject: Reply with quote
TrespassersW wrote:

Excellent response! If you can recommend a book that goes into more depth on the concept(s) you've touched upon, I'd be interested.


The best thing you can do is read a good biology textbook. That's where you can get the matter treated at the proper level of detail.

The second best thing you can do is read books about biology written by richard dawkins. He does a good job of writing about it in a way that is both interesting and informative.

Particularly, i've heard good things about a book of his called "The Blind Watchmaker".

If you want to read about evolution in a more distilled, mathematical sense, you might try looking up "evolutionary algorithms". Those are techniques for designing computer programs that use evolution.
I can't guarantee how clear that will make things for you, though, so i'd go with dawkins or textbooks when in doubt.
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TrespassersW
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PostPosted: Fri Jan 18, 2008 6:50 pm    Post subject: Reply with quote
I'm Googling "The Blind Watchmaker" now. Sure I can get it on Amazon or somewhere. Thanks.

Local Barnes & Noble has it. I'll be running over there later today. Cool
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Lester
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PostPosted: Mon Jan 21, 2008 11:26 am    Post subject: Reply with quote
Oh books, how I adore thee.
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shankarsingam
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PostPosted: Mon Jan 21, 2008 5:15 pm    Post subject: Reply with quote
The difference between evolutionists and creationists, is that evolutionists accept their notion as THEORY, where as creationist assume their notion as FACT.

How do you honestly have a logical rational discussion with someone who beleives the world is 6000 years old?!
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TrespassersW
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PostPosted: Mon Jan 21, 2008 6:12 pm    Post subject: Reply with quote
shankarsingam wrote:
How do you honestly have a logical rational discussion with someone who beleives the world is 6000 years old?!

You use logic and reason, and set your expectations for the other side of the discussion fairly low. Wink
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Lester
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PostPosted: Tue Jan 22, 2008 9:01 am    Post subject: Reply with quote
I just fall back on the old, "don't wrestle with a pig, cause you'll both get dirty, and the pig will like it."
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