Why is natural selection not random?

Discussion in 'Biology & Genetics' started by darryl, Jun 1, 2012.

  1. RJBeery Natural Philosopher Valued Senior Member

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    There may or may not be a mind involved in the selection process, but the idea is that the deaths of the victims occur due to some trait of theirs which then has a lesser chance of being carried on to the next generation. The net effect is that the species is now more suited for survivability in that environment. The bird does not eat the green bug so that green bugs are less prevalent and bugs are therefore more survivable in general, it eats the green bug because it is easier to see...
     
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  3. RJBeery Natural Philosopher Valued Senior Member

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    No, the "directed process" is simply evolutionary pressure. The bird is not applying direction to anything, he's just eating the bugs that he can find most easily. Please refer to my "harsh winter" point a few posts ago and you will see that natural selection occurs without minds being involved.
     
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  5. spidergoat Valued Senior Member

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    The bird only knows that it can see the light colored moth on the dark colored bark and eats it. It does not know that it's part of a trend that is causing the proliferation of dark colored moths. The bird doesn't have a plan with regard to evolution, so evolution is still undirected.
     
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  7. darryl Banned Banned

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    Ok thats a nice example but looks directed in my opinion.
     
  8. darryl Banned Banned

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    Yes I agree with that.
     
  9. iceaura Valued Senior Member

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    The bird is not mindfully or intentionally selecting for camouflaged bugs.

    Neither does the weather intentionally select for furry animals, ants that build hills, or trees with compound leaves. Neither does a parasite select for dietary preferences in its host.
     
  10. Neverfly Banned Banned

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    Semantics. You are picking and choosing which words to focus on, while not paying attention to how they are used.
    This is not a matter of opinion. You don't get to reject whatever you don't understand.

    Learn it to understand it, instead.
     
  11. Grumpy Curmudgeon of Lucidity Valued Senior Member

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    We're not talking about the evolution of the bird. Intelligent or not it is still a test of the fitness of the color of the bug. Birds eat bugs, bright bugs get eaten more often(simply because they are easier for the bird to see), bright colors will become less common in the bug(simply because bright bugs get eaten before they reproduce more often than bugs less visible). The bug evolves toward less visible coloring.

    But let's get even simpler...

    There is a population of one celled creatures floating in the ocean. Something happens to the ozone layer and those individuals exposed to too much light die. Within this population are some individuals who have a sensor that, when too much light hits it, causes the cell to swim upward, another cell has the same sensor that, when too much light hit it, causes the cell to move downward. Very quickly all the cells that did not have that sensor and those who swam upward are dead and the only population of cells you will find are downward swimmers. Natural forces(UV rays)killed all the other cells(because they failed the test of survival in current conditions)and selected the downward swimmers(because they survived to reproduce). Natural Selection took the variations(which are random)and tested them against the environment, driving the Evolution of the cell in the direction of the downward swimmers in a non-random but mindless way.

    Grumpy

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  12. DaveC426913 Valued Senior Member

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    Guys, evolution applies to populations, not to individuals.

    Whether a bird eats a brightly coloured bug, or a fox dies because its brown fur stand out against the white snow, the evolution of the population is not directed.

    Those things are causes and effects, yes, but the evolution of the species is an emergent property that is not directed by anyone or anything.

    Analogously, SiO4 tetrahedra will combine preferentially to other SiO4 tetrahedra, ultimately building up a large quartz crystal, but you wouldn't claim that the construction of the quartz crystal was "directed" in any meaningful sense would you? Each SiO4 tetrahedron is simply doing its own little thing.
     
    Last edited: Jun 5, 2012
  13. Aqueous Id flat Earth skeptic Valued Senior Member

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    No, you've got it backwards. It has no sense of selection. It can't see the brown bugs. It only sees and eats green ones. It's not "aware" that it's choosing green over brown. It sees green and snaps it up instinctively.

    Do you understand the difference between "eating a green bug" and "selection of the brown bug" which will alter the gene pool, causing the green variety to die out?

    What is so hard about this? I fail to understand your complaints.

    Let me suggest something: why don't you try to repeat back to me how a population of bugs, brown and green, evolves into a brown variety only, after the habitat - a green and woody area- loses all of its green plants and is left with brown brush.
     
  14. Grumpy Curmudgeon of Lucidity Valued Senior Member

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    DaveC426913

    Yes, Evolution occurs within populations of individuals.

    Yes, it is. It is directed away from bright colors on bugs and toward white fur on the fox by the simple fact that those individuals with the wrong color are eaten or seen before they can capture prey. Natural Selection is different from Evolution. NS tests the individual's reproductive success, driving(directing)the evolution of the population they are in as their genes become more prevalent or less prevalent in the gene pool. Evolution is the change in the species, Natural Selection of individuals determines the direction that the evolution of the population goes in.

    It is driven by survival to reproduce, it is directed in the direction of better survival to reproduce. Every trait any lifeform has has been preserved in the genome because that trait gives reproductive advantage or, like eye color, is largely neutral.

    Grumpy

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  15. DaveC426913 Valued Senior Member

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    I'm trying to disabuse darryl of this notion that a bird deliberately eating a bug is what we mean by "directed" change.
     
  16. Aqueous Id flat Earth skeptic Valued Senior Member

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    You are right for trying to do so. Darryl is playing word games and pretending not to understand the most basic of concepts. Then, when one of us tries to respond like you would to a child, through gross oversimplification, our answers are left with the flaws that oversimplification produces.

    For example, I felt forced to say "brown bug" instead of "brown trait" (3 posts above) as if I were talking to a child who hasn't learned the concept of traits.

    But clearly selection acts on traits within populations. Action on populations is the important point you are making, DaveC. Here we begin to differentiate between phenotype and genotype, but even that is X-rated language in front of darryl.

    And Grumpy, another word for "directed" (or direction) is determinism, or more commonly, just selection. Those are all concepts darryl also pretends not to understand. I understood you clearly.

    Instead darryl is playing word games, as a tactic for arguing ID covertly. By focusing on "directed" and "nonrandom" he inches closer to "design". Or so he thinks.

    Add to this all the manufactured controversy, and the pretense that "no one can define evolution", and pretty soon the reality of what evolution is - what nature is actually doing - has been buried under a rock.

    Along the way great contributors like Darwin get bashed, without any regard for their place in history. One thing Darwin left the world, which leaves his antagonists in the dust, is an impressive set of books, journals, notes, sketches and letters that demonstrate his fascination with nature and his many projects to unravel it. I am particularly impressed with his fascination over coral reefs, and his methodic practice of stopping the ship to take soundings and collect specimens. If I recall, one of the reasons the Beagle was gone so long was due to Darwin's insistence on cataloguing the reefs, and he probably realized he was the first to do so. Apparently he took the crew wandering over many out of the way places just to examine and document more specimens.

    That's just a snippet of the man's work, but compare what I've already said about him to these pundits darryl is offering, who have no rep to stand up to the trailblazing, rolled-up shirtsleeved, world-trotting achievements of the likes of Darwin, or of countless other scientists who merely address nature on its own terms, not these invented ones.

    If only the naysayers would take off the blinders, put away their prejudices and actually try to learn something, they could disabuse themselves of their errors without all the drama.
     
  17. Neverfly Banned Banned

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    A.I.,

    Talk about nailing something on the head!
     
  18. sigurdV Registered Senior Member

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    352
    Hi all!
    Darwinism is often misunderstood, and is still under attack from ppl with religious back ground.
    Even respected scientists have had silly objections (Gould and Popper comes to mind).

    The topic of this thread is of no particular interest to me, but its alive ...

    So I ask: Whats going on, and where in the forum is Darwinism seriously discussed?
    Shouldnt there be topics better suited for serious participators?

    Id be off topic if I were to open a discussion in here about extensions of darwinism ,say: Dawkins Theory of Memes.
    I could open a new thread but what worth is a thread lacking support?
    Maybe first a short discussion in here on how Darwinism should be "topificated"?
     
    Last edited: Jun 5, 2012
  19. DaveC426913 Valued Senior Member

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    It's also a little outdated. Darwin didn't have access to some of the knowledge we do now, and we have greatly refined his theory (though everything he did still serves as the foundation for modern evolutionary theory). But to properly discuss it, we'd need to bring in developments since his time.

    This forum is pretty tolerant of off-topic discussions. There are other fora where the rules are more strict. That swings both ways, but it would keep a thread on-topic and discourage trollers.
     

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