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#21
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Re: Selling Evolution
Fred - You keep referring to "top down" natural selection. I can't imagine what that means - unless maybe you're trying to slip some ID in under the door.
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For someone who complains about rigor in others' arguments, you should understand that your saying that something is true is not enough to establish its validity. You need to have some logical connection in the equation to get from one to the other. Or, is that too rigorous for you? Margaret Last edited by Margaret McGhee; August 2nd, 2006 at 06:02 PM.. |
#22
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Re: Selling Evolution
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Stop and think for a second . . . if the environment changed randomly, then how could a population evolve to tolerate it? Say, for example, that suddenly a random number generator were used to determine the temperature each day in the range of 0 to 100 Degrees Celsius. One day, it would be, say, 75 degrees, which is well beyond the temperature at which most proteins dissociate. At best, a few bacterial species adapted to life around thermal vents would survive. Then, the next day, the temperature drops to 1 degree, and the only remaining organisms (i.e. the ones adapted to very high temperatures), now have trouble getting on . . . within a few days or weeks, at most, there would be very little or nothing left of life on earth if the environment were "random". Why do you think that it was only AFTER the earth's atmosphere stabilized that life first got going on this planet? The features of the environment to which life adapts are the regularities, which exert consistent selection pressures that aren't so powerful that they eliminate every member of the population, rather than just some of them. The more extreme and unpredictable an environmental factor, the more likely it is to wipe out species that were previously adapted to a specific set of environmental conditions. Environmental regularity, not randomness, allows evolution to proceed. The very term "environment" in biology only makes sense with reference to a particular set of conditions and patterns that recur from day to day and year to year. There may be stochastic elements of an environment (e.g. food is randomly distributed in habitat A), but they are generally part of a larger regularity (there is food to be found in habitat A) to which populations can adapt. The greater the degree random facotrs play in a population's evolution, generally, the more likely that population is to crash. Two extreme illustrative examples: 1) A cactus plant can live in the desert because it possesses a large suite of desert-specific adaptations, including: water storage structures, deep root systems, thick waxy outer skin, and highly altered, water-efficient photosynthetic biochemical mechanisms. These adaptations are costly and would not be favored if the annual rainfall changed randomly from year to year . . . 2) Consider the meteor that hit this planet and prompted the end-Cretaceous extinction event (the one that killed the dinosaurs, except for birds). This was a highly irregular, extreme environmental event, and it annihilated a large fraction of metazoan life on earth. Adaptive evolution proceeds because natural selection non-randomly preserves elements of the variation generated by random mutation. Without environmental regularity, natural selection would be so immensely strong that populations would not be able to respond to it, biological evolution would halt, and life would cease to exist. The point on which Margaret was heading in the right direction is that the variation generated by random mutation is definitely what gives a population its "evolvability" . . . without varitation from which to select, natural selection cannot mold a population in a changing (or static) environment. Last edited by Carey N; August 5th, 2006 at 09:38 PM.. |
#23
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Re: Selling Evolution
Carey, Thanks for the clarification. As I was writing that I thought it seemed a bit squishy. I said,
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Margaret Last edited by Margaret McGhee; August 2nd, 2006 at 10:04 PM.. |
#24
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Re: Selling Evolution
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However, I suspect that most Darwinians would consider the fact that there’s an Earth at all with the requisite “Environmental REGULARITY,†to be the result, ultimately, of random or “effectively random†things. So that while you may decree that “natural selection is a NON-random force,†this so-called “force†seems to require, in addition to effectively random mutations to select from, an “Environmental REGULARITY†that is itself the result of “effectively random†things that have occurred over the last 14 billion years—ultimately, eventually, your so-called “NON-random force†of Darwinian “natural selection†ends up being the result of random or effectively random things. Be that as it may, let me repeat the more interesting point made in my last post to you regarding your misunderstanding/misinterpretation regarding Penrose. As you, Carey, have acknowledged at http://www.behavior.net/bolforums/s...990&postcount=4 — “Mutation is the ultimate source of all variation present within a population . . . without mutation, there would eventually be nothing for natural selection to select, and evolution would halt.†IOW, whether selection be top down, bottom up, “natural,†“artificial,†blind, mindless, whatever, it can only select from what is already available; from, in a sense, what already has blindly, directionlessly, “effectively randomly,†changed/mutated/evolved; at least according to current Darwinian dogma. So I doubt Penrose is saying, as you opine, that he "can't possibly believe that natural selection, lacking any foresight, produced biological complexity." Rather I think he’s saying exactly what he said: "To my way of thinking, there is still something mysterious about evolution, with its apparent 'groping' towards some future purpose. Things at least seem to organize themselves somewhat better than they 'ought' to, just on the basis of blind-chance evolution and natural selection." And I’d add that while Penrose indicates that he himself is a strong believer in “natural selection,†I suspect that he, like I, fully realizes that “natural selection,†whether it be a top down or bottom up selection, is ultimately little more than a circular account that really doesn’t explain or predict all that much. |
#25
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Re: Selling Evolution
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"If you atheists think that the universe wasn't made by a Designer, then it must have been made randomly [this is false], which means that everything in the universe is also random [also false]". Seriously, Fred, that's what you sound like. Quote:
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Last edited by Carey N; August 3rd, 2006 at 08:16 AM.. |
#26
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Re: Selling Evolution
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Speaking of selection from only what’s available, I’m reminded of one of my old 4/2002 posts regarding what LeDoux had to say concerning selection vs. instruction as it relates to human “learningâ€: Quote:
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#27
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Re: Selling Evolution
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#28
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Re: Selling Evolution
You built a straw man of evolutionary biology, I knocked it down, and now you're saying that I agree with you indirectly? Your argument tactics are child's play, Fred. Grow up.
Last edited by Carey N; August 3rd, 2006 at 09:54 AM.. |
#29
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Re: Selling Evolution
Removed by user.
Last edited by Carey N; August 3rd, 2006 at 03:15 PM.. |
#30
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Re: Selling Evolution
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Those fluctuations caused energy to clump due to gravity; those clumps cooled to stars; those stars pressed the energy into the different elements; those elements were spread by novae; those elements made your DNA. We've been living off those fluctuations. |
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