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Author Topic:   How do we know about natural selection? (Igor and Lithodid-Man only)
igor_the_hero
Inactive Member


Message 1 of 43 (298150)
03-25-2006 10:00 PM


A Great Discussion between Igor and Lithodid-Man

How can we know about natural selection? All I understand it to be is nature itself deciding who is supreme and who is not. It all sounds like God but without a brain or any idea what it is doing. Everytime it seems like it is doing good work through its mechanism, evolution. We can not prove it because it is a force nobody can tell you a thing about. Nobody has ever seen natural selection. They have no idea WHAT is natural selection. Yes we may have a definition for it, but can somebody explain what it is? If we never see it than how do we know it exists. I know this sounds like a God argument but there are reasons to believe in Him. People have talked to God but nobody has talked to natural selection. I do realize this is badly written but this is the best way I could think of to write it and help people understand my confusion. Also this is a flawed understanding of natural selection but it is all that I understand that it is. Clairification is very neccessary.

This message has been edited by igor_the_hero, 03-25-2006 10:58 PM

This message has been edited by AdminJar, 03-26-2006 04:41 PM

{Edited topic title to add the "(Igor and Lithodid-Man only)" part. - Adminnemooseus}

This message has been edited by Adminnemooseus, 03-30-2006 04:19 PM


Replies to this message:
 Message 2 by AdminJar, posted 03-25-2006 10:14 PM igor_the_hero has responded
 Message 11 by crashfrog, posted 03-26-2006 5:32 PM igor_the_hero has not yet responded

  
AdminJar
Inactive Member


Message 2 of 43 (298153)
03-25-2006 10:14 PM
Reply to: Message 1 by igor_the_hero
03-25-2006 10:00 PM


Needs lots of work.
Your post sounds like you really don't have a clue what Natural Selection is. Could you edit your original message and outline what you think Natural Selection is? After that just reply to this message and I'll take another look.


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  • This message is a reply to:
     Message 1 by igor_the_hero, posted 03-25-2006 10:00 PM igor_the_hero has responded

    Replies to this message:
     Message 3 by igor_the_hero, posted 03-25-2006 10:59 PM AdminJar has responded

      
    igor_the_hero
    Inactive Member


    Message 3 of 43 (298172)
    03-25-2006 10:59 PM
    Reply to: Message 2 by AdminJar
    03-25-2006 10:14 PM


    Re: Needs lots of work.
    Does this help any? I am sorry. This is just a very confusing subject for me.
    This message is a reply to:
     Message 2 by AdminJar, posted 03-25-2006 10:14 PM AdminJar has responded

    Replies to this message:
     Message 4 by AdminJar, posted 03-25-2006 11:06 PM igor_the_hero has responded

      
    AdminJar
    Inactive Member


    Message 4 of 43 (298176)
    03-25-2006 11:06 PM
    Reply to: Message 3 by igor_the_hero
    03-25-2006 10:59 PM


    Re: Needs lots of work.
    Igor, your changes show you don't really have a clue what Natural Selection is or the Theory of Evolution. If I promote this as is, all that will happen is a million folk will jump all over you.

    Here is what I suggest. I will set this up as a Great Discussion, just you and one other poster. Maybe that way it can be a learning experience for you.

    Would you agree to a Great Discussion?


    This message is a reply to:
     Message 3 by igor_the_hero, posted 03-25-2006 10:59 PM igor_the_hero has responded

    Replies to this message:
     Message 5 by igor_the_hero, posted 03-25-2006 11:10 PM AdminJar has responded

      
    igor_the_hero
    Inactive Member


    Message 5 of 43 (298178)
    03-25-2006 11:10 PM
    Reply to: Message 4 by AdminJar
    03-25-2006 11:06 PM


    Re: Needs lots of work.
    Absolutely. Nobody has ever explained it to me and when I ask they avoid the question.
    This message is a reply to:
     Message 4 by AdminJar, posted 03-25-2006 11:06 PM AdminJar has responded

    Replies to this message:
     Message 6 by AdminJar, posted 03-25-2006 11:12 PM igor_the_hero has responded

      
    AdminJar
    Inactive Member


    Message 6 of 43 (298183)
    03-25-2006 11:12 PM
    Reply to: Message 5 by igor_the_hero
    03-25-2006 11:10 PM


    Re: Needs lots of work.
    Okay. Give me a day or so to set it up.
    This message is a reply to:
     Message 5 by igor_the_hero, posted 03-25-2006 11:10 PM igor_the_hero has responded

    Replies to this message:
     Message 7 by igor_the_hero, posted 03-25-2006 11:15 PM AdminJar has responded

      
    igor_the_hero
    Inactive Member


    Message 7 of 43 (298185)
    03-25-2006 11:15 PM
    Reply to: Message 6 by AdminJar
    03-25-2006 11:12 PM


    Re: Needs lots of work.
    Done.
    This message is a reply to:
     Message 6 by AdminJar, posted 03-25-2006 11:12 PM AdminJar has responded

    Replies to this message:
     Message 8 by AdminJar, posted 03-26-2006 4:48 PM igor_the_hero has not yet responded

      
    AdminJar
    Inactive Member


    Message 8 of 43 (298374)
    03-26-2006 4:48 PM
    Reply to: Message 7 by igor_the_hero
    03-25-2006 11:15 PM


    Here's the set up for you.
    This will be moved to the Great Debates forum. The person you'll be discussing this with is Lithodid-Man, a biologist and mentor/teacher.

    I hope you enjoy this.

    This message has been edited by AdminJar, 03-26-2006 03:55 PM


    This message is a reply to:
     Message 7 by igor_the_hero, posted 03-25-2006 11:15 PM igor_the_hero has not yet responded

      
    AdminJar
    Inactive Member


    Message 9 of 43 (298376)
    03-26-2006 4:48 PM


    Thread moved here from the Proposed New Topics forum.
      
    Lithodid-Man
    Member (Idle past 315 days)
    Posts: 504
    From: Juneau, Alaska, USA
    Joined: 03-22-2004


    Message 10 of 43 (298379)
    03-26-2006 5:23 PM


    Igor,

    I hope that I can answer some of your questions regarding natural selection. From what I have read in your other posts you have a lot of questions and a willingness to listen.

    First of all I want to define natural selection. In biology we often refer to natural selection in terms of "forces" but it is important to recognize that these are not forces as are discussed in physics (gravity, etc). Selection is a mechanism rather than a persuasive invisible force.

    Natural selection is based upon several observable characteristics of living organisms.

    1) Most individuals in a population are different. With the exception of clones and identical twins (even these can vary) individuals have different genetic characteristics. Some of these are mutations, some just different combinations of traits.

    2) Not all members of a population will reproduce as successfully. Some will die before reproducing. Some will mate less often or be able to raise fewer offspring.

    Numbers 1 & 2 are tied together because #2 is non-random. Some of the differences in #1 may lead to differential reproductive success. If this happens then the difference may be weeded out OR may spread. This is the elegance and beauty of natural selection.

    Darwin relied heavily on the concept of artificial selection in formulating natural selection. A farmer or breeder will select only certain individuals to reproduce. The wooliest sheep, the fattest pig, the most obedient dog, etc. What Darwin saw was that in nature it wasn't human choice limiting reproduction but competition for resources, for mates, etc.

    I look forward to this discussion and will try to answer any questions you might have. -LM


    Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
    Elim Garak: "My dear Doctor, they're all true"
    Doctor Bashir: "Even the lies?"
    Elim Garak: "Especially the lies"
    Replies to this message:
     Message 13 by igor_the_hero, posted 03-26-2006 9:32 PM Lithodid-Man has responded

        
    crashfrog
    Inactive Member


    Message 11 of 43 (298382)
    03-26-2006 5:32 PM
    Reply to: Message 1 by igor_the_hero
    03-25-2006 10:00 PM


    How can we know about natural selection? All I understand it to be is nature itself deciding who is supreme and who is not.

    We can know all about natural selection, because it isn't some abstract force of nature; it's merely the observation that an individual's unique traits have a considerable influence on the likelyhood that that individual will survive long enough to mate.

    Imagine two populations of foxes and rabbits in a snowy wilderness. Some of the rabbits are white and some are brown. The foxes are hungry and eat rabbits, but you can't eat what you can't see. After a round of predation, we find that a lot more brown rabbits have been eaten than white ones, and those white rabbits mate and produce more white rabbits. A few more rounds of this and the brown rabbits might be all but extinct.

    It isn't nature that does the selection; in this case it's the environment and the foxes.

    Yes we may have a definition for it, but can somebody explain what it is?

    It's merely the simple fact that not every organism in a population succeeds in passing on offspring, and that this pre-reproductive mortality is not typically random, but determined by the interactions between an individual's traits and the environment in which it lives.

    People have talked to God but nobody has talked to natural selection.

    Nobody has ever talked to God, but it's easy to observe natural selection.

    This message has been edited by AdminJar, 03-26-2006 04:38 PM


    This message is a reply to:
     Message 1 by igor_the_hero, posted 03-25-2006 10:00 PM igor_the_hero has not yet responded

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    AdminJar
    Inactive Member


    Message 12 of 43 (298383)
    03-26-2006 5:35 PM
    Reply to: Message 11 by crashfrog
    03-26-2006 5:32 PM


    Crash, this is a Great Debate.
    Sorry but I need to hide your content.


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  • This message is a reply to:
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    igor_the_hero
    Inactive Member


    Message 13 of 43 (298440)
    03-26-2006 9:32 PM
    Reply to: Message 10 by Lithodid-Man
    03-26-2006 5:23 PM


    Yes, but what IS it? You told me what it is referrd to, but what kind of force is it?
    This message is a reply to:
     Message 10 by Lithodid-Man, posted 03-26-2006 5:23 PM Lithodid-Man has responded

    Replies to this message:
     Message 14 by Lithodid-Man, posted 03-27-2006 2:50 AM igor_the_hero has responded

      
    Lithodid-Man
    Member (Idle past 315 days)
    Posts: 504
    From: Juneau, Alaska, USA
    Joined: 03-22-2004


    Message 14 of 43 (298512)
    03-27-2006 2:50 AM
    Reply to: Message 13 by igor_the_hero
    03-26-2006 9:32 PM


    Great question!
    Igor,

    Great question! I will do my best to answer what natural selection is.

    First, what is selection? This might sound simple (selection is, well, selecting) but it really isn't. In a biological sense it is selecting those characteristics that are best able to survive given the current circumstances. I apologize for the lengthy example but I hope it illustrates my point. Please bear with me on this!

    Here is a real world example. Dandelions are common weeds in lawns. If you look at a field of dandelions you can see that they are not all the same. Some are very tall, some are short. Some have leaves that stick up, some have leaves that are flat against the ground. This is natural variability that exists in the dandelion population. If you look at alot of dandelions you may find actual mutations, some with curly leaves, etc.

    If you then examine dandelions in a regularlly mowed lawn you find only those that are flat leaved (leaves are level with the ground) and the flowers are on tiny, short stalks. As a scientist you might wonder why are the dandelions this way in the lawn when the ones near the fence or outside the lawn are different (as in normal tall, short, a mixed population).

    In science when we observe something we don't understand we form hypotheses. These are ideas that may explain what we see. What makes a hypothesis unique is that it is framed in a way that we can test. Usually a scientist will try to think of all possible explanations that would lead to what is observed. For our dandelion example you might think of these:

    1) Dandelions have a means of recognizing a mowed lawn and only produce short offspring in this situation (they only grow as tall as the surrounding vegetation)

    2) Dandelions that have been mowed down change their breeding strategy so that future offspring are short (they can adapt to environmental changes)

    3) Tall dandelions and their genes became extinct in the lawn because only short ones survived the mowing

    After outlining these ideas as a scientist you would then think of experiments to test them. You are not trying to prove them, you are trying to disprove them.

    So for #1 you might transplant dandelions (or plant seeds) from the lawn to an unmowed habitat. If the plants or offspring grow tall then you didn't PROVE #1 but you did fail to disprove it. As it turns out the offspring are just as short as their parents in the lawn, so you now reject #1.

    For #2 you might do a repeat experiment. Plant your mowed dandelions in an unmowed field and see their height. You also might take an tall dandelion crop and mow it to see if the next crop are short. As it turns out the mowed dandelions produce short offspring and the tall ones continue to produce tall offspring, no matter how many generations you mow them.

    For #3 you could take seeds from your lawn samples and seeds from your unmowed samples and grow them in an experimental plot. If they both grow tall (or short), then you disprove #3. If the tall seeds grow tall and your lawn seeds are short, then you again failed to disprove #3. As it turns out this is the result that is seen.

    Now in your dandelion experiment you have the following results:
    #1 - unlikely
    #2 - unlikely
    #3 - not disproven

    Because #3 is not disproven you might think of other experiments to test it further. But in this case let's pretend this is the end and you go with number 3 as the answer to the big question, "why are dandelions in mowed lawns short?".

    Your experiment demonstrates selection. Only those dandelions that carried the genes for flat leaves and short flowers survived to reproduce. Out of the millions of dandelion seeds that blew into the lawn, only the shortest were able to have offspring in that environment (remember, the ones nearby were tall and normal). If someday the house went unsold and no one took care of the lawn anymore this could change. The grass could grow and shade the short dandelions. Only those mutants in the 'short' gene pool that were slightly taller could survive to reproduce. Eventually their descendents would look very much like the original types, tall and with upright leaves.

    This is natural selection, even though it is a human-caused environment. In place of dandelions think of deer with thick and thin coats living in a valley. If the climate changes to cooler those with thicker coats may have an advantage. They have more offspring and soon the whole population carries the gene for thick coats.

    The important point to keep in mind is that selection is ONLY for the current environmental conditions. And several different traits may be selected for at the same time, sometimes in different directions. This is why we see variation in selected traits.

    I again apologize for the length of this post, please feel free to ask questions. -LM


    This message is a reply to:
     Message 13 by igor_the_hero, posted 03-26-2006 9:32 PM igor_the_hero has responded

    Replies to this message:
     Message 15 by igor_the_hero, posted 03-27-2006 5:04 PM Lithodid-Man has responded
     Message 43 by westernjoe, posted 01-09-2007 5:04 PM Lithodid-Man has not yet responded

        
    igor_the_hero
    Inactive Member


    Message 15 of 43 (298782)
    03-27-2006 5:04 PM
    Reply to: Message 14 by Lithodid-Man
    03-27-2006 2:50 AM


    Re: Great question!
    Ok, I understand you. I think. But how would you prove it? Also, when you are selecting, you have to have a selector, correct? I think I may be misinterpreting what you are saying about selecting not being selecting.
    This message is a reply to:
     Message 14 by Lithodid-Man, posted 03-27-2006 2:50 AM Lithodid-Man has responded

    Replies to this message:
     Message 16 by Lithodid-Man, posted 03-29-2006 1:41 PM igor_the_hero has responded

      
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