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   Creationism vs Evolution Debates
     Natural Selection Analogies
       Analogies for describing mechanism for evolution

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karm

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If anyone knows a good analogy to describe the mechanisms that cause evolution, then I request that it be posted here so that we may discuss it.  Those readers who possess a particularly high degree of certainty in evolution theory as generally formulated today, I request that you share with us your present understanding of these mechanisms.  Please do not be too technical so that more individuals may appreciate the message.


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karm
 


Posts: 2 | Posted: 01:13 AM on August 24, 2003 | IP
imjustsayin

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I know that natural selection suggests that the animal/organism better adapted for its environment will fare better than those who are not as well suited....ie. giraffes with longer necks eat better, survive, and mate in areas without a lot of grass, but lots of trees. The only problem is that, at the end of this selection, the giraffe is still a giraffe. Nothing has changed, except maybe the length of it's neck. Even that can go back in future generations, because the allele (gene copies) that code for shorter necks are still in the gene pool of the given population of breeding individuals.  


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imjustsayin
 


Posts: 6 | Posted: 04:28 AM on August 24, 2003 | IP
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An analogy is tricky, it's a pretty unique situation. I can't think of anything apart from life that replicates itself.

Natural Selection is best explained by the  tired out example of the peppered moth:

The peppered moth lives in england and originally had light wings. This gave it great camoflage against the light bark of trees.
But once the industrial revolution occured pollution levels rose, soot made the trees darker.
This made it easy for preditors to see the light colored moths.
Since then most peppered moths now have dark wings which allows them to camoflage on dark trees.
In fact you can work out how polluted an area is by observing how dark the moths that live there are.

Do how did the moths become dark? It's all down to melanin, a chemical that is responsible for pigmentation. People who have dark skin or dark hair have more melanin than people with lighter.
The amount of melanin is determined genetically.
What happened is that the characteristic for melanin was naturally selected for. Moths that had light wings were picked off by preditors, moths with dark wings survived to reproduce and pass on their gift.

So Natural selection is one mechanism responsible for guiding evolution. For this reason it is wrong to claim evolution is a random process, it isn't. Dark moths didn't survive from random luck but because they were better adapted.
Of course natural selection needs variation to work with. If there was only light moths then natural selection cannot create dark moths - it can only select what is already there.

Mutations when passing down genes are one mechanism that adds variation. If everyone's children were clones of them then nothing would change.

 


Posts: 66 | Posted: 2:39 PM on August 24, 2003 | IP
karm

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I was hoping more for an analogy rather than an example.  The analogy presented by Richard Dawkins in The Blind Watchmaker involving the typing monkey is frequently cited.  However, there are several problems with that analogy and I was hoping that there is a better one out there.  The problem with most of the analogies or examples that I've seen is that no tenable mechanism for the generation of new functional genes is addressed.  I suppose that I am presenting another "information quandary" problem.  


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Posts: 2 | Posted: 12:03 AM on August 25, 2003 | IP
Loudmouth

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Since evolution relies on random mutation and natural selection a good analogy would have to include both.  

Analogy:

Rocks can be broken into certain sizes by a random event, such as with a pick axe or a rock crusher.  This would represent random mutation.  The rock chips are then passed over a seive and those rock chips that are small enough to fit through the seive and collect in a pile.  This pile can even be passed over other seives to separate out the sizes even more.  

Therefore we see a seemingly ordered system that does not look random but was created by random events.  Rock chipping is random while the seive is selective.
 


Posts: 1 | Posted: 8:20 PM on August 25, 2003 | IP
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The example of rocks in a seive is a good one.
Finding and analogy for natural selection is particulary difficult.  I am a science professor and I am actually studying analogies generated by students to help understand natural selection.  Most analogies fail to incorperate vareity and probability.  Most are "need based" or "driven by the organism itself."  Students tend to try and find anologies related to their daily lives - learning, physical fitness, changing things based on desire.  Of course, these daily motivations are not part of natural selection, so the use of such faul;ty analgical thinking leads to more problems for the students.  

This is why I think the rock shifting analogiy is a good one.  It is easy to understand and incorporate variation and selection well.  I wish I had come up with that one.
 
 


Posts: 0 | Posted: 3:00 PM on November 4, 2003 | IP
    
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