What is the Mechanism of Natural Selection for Evolution?

Discussion in 'Biology & Genetics' started by matthew809, Feb 22, 2014.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Yes. That is what the land creatures that became whales did. I said "thick layer" and did not even imply it did not come from steady increases of existing thin ones. That is some what possible just by adaptation, like getting callouses on workman' hands but evolutionary selection is what gives the new born whale its thick layer of blubber.
     
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  3. matthew809 Registered Senior Member

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    To clear the air.... I am not religious. I don't believe in God. I want to know the truth which is why I'm here. Lets move on.

    Traits which hinder reproduction are not selected for because their genes are not passed on to the next generation. That aspect of natural selection is obvious. It's selection by exclusion and I understand that's it's a powerful force for the shaping of species. But no new animals are created via this process; creation by exclusion doesn't exist.

    So I am interested in the process which does create new animals. Selection by inclusion... the inclusion of novel traits(genes) into the gene pool. There's two processes specifically that I have a problem with:

    1) Do "beneficial" mutations really have an effect on survival and reproduction as often as they would need to in order to explain the existence of such diverse and complex lifeforms that exist today? Not everything beneficial is a matter of life or death(in fact I would think most are not).

    2) Even if mutations are passed on to future generations, wouldn't they eventually be diluted out of the gene pool?
     
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  5. billvon Valued Senior Member

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    Literally true, as long as you consider a flatworm to be the same basic animal as a human. Most people don't.

    No, it's pretty rare. Changes caused by mutation that are both 1) phenotypically significant and 2) beneficial come along only in a great while - once every ten million reproduction events, for example. Due to the complexity of most organism's genome, most mutations are either benign or harmful. That's why, in most cases, it takes millions of years to see significant changes in species.

    If the evolutionary pressure is high then changes happen faster. The breeding of a gray wolf to a chihuahua is one example. Cichlid radiation in Lake Victoria is another. This does not happen because mutation happens faster, but because natural (or in the case of the gray wolf artificial) selection pressures become much stronger. If the existing phenotype is not well suited for survival, many more mutations have the chance to be beneficial.

    No more so than any other gene would be "diluted" out of the gene pool. Mutations become part of your genome, as permanent as any other part of it.
     
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  7. matthew809 Registered Senior Member

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    How many mutations would you estimate it took for the human to evolve to it's current state?
     
  8. Aqueous Id flat Earth skeptic Valued Senior Member

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    Does that mean you disbelieve the catastrophism and special creation? If so, what in the world do think accounts for life? Alien terraforming?

    That goal is inconsistent with discounting first principles of science.

    I think a lot of effort could be saved by dwelling on this. If you would simply state what motivates your disbelief in evolution we might be able to nip the issue in the bud.

    This was one of the ideas well known to Darwin, who studied and understood artificial selection. It was also the basis for Gregor Mendel's discoveries and the founding of genetics.

    That's either false and incorrect or hopelessly vague and speculative. I guess you would have to explain what's bothering you.

    "Creation" is generally used in the religious context, at least in modern vernacular. I think you mean "speciation". Yes, speciation by natural selection does occur. It's the central tenet of the Theory and well enough demonstrated through artificial selection.

    Why only animals? That kind of focus is suspiciously religious in nature. Wasn't evolution covered in your schooling?

    The "process" is evolution, generally through mutation under natural selection. However that's only the broad view. Other factors (genetic drift, migration/radiation/gene flow, co-evolution, niche building and collapse) are also in play.

    That's silly. The process is the same. Selection is selection. I think you're struggling with the difference between selection and other factors like genetic drift. But they can't be isolated. It's all happening concurrently. You might have a case for targeting a specific result, such as in artificial selection or some particular population being studied, but there's no point to this as far as the generalities of evolution are concerned.

    By definition.

    It's a matter of statistics. The best adapted traits thrive; and/or some unusual combination of well- and ill-adapted traits work in tandem. Horses for example are adapted for sleeping while standing which gives them the advantage of bolting when threatened. This works in tandem with the requirement that they need time to ruminate, which works in tandem with the large body mass needed to extract nutrients from forage, etc., etc. Put it all together and you have the success of a large ungulate against the unlikely odds of attracting predators with so much flesh to offer per kill.

    What difference does it make how complex and diverse organisms are? That sounds purely subjective. If all that existed on Earth were all of the grasses, you could equally complain that they are too diverse and complex to suit your taste. You could say the same about insects, bacteria or just about any other taxon. What difference does this make? Organisms are what they are because their traits have been shaped by countless prior speciation events. Besides, "diversity and complexity" is wholly the result of the "diversity and complexity" of the niches.

    What else are you looking for? Magic? Why else would anyone discount the abundance of evidence that all species arrived through evolution? This gets back to dwelling on what it is that's really bugging you.

    Keep in mind that more human embryos are naturally aborted to causes that are also selective. The same idea applies to all species that ever existed, that is, the rate of extinction is estimated to be in the high 90 percentile range.

    Of course not. Look at the Darwin's finches and note how the mutations carried by the progenitor species (feathers, beaks, etc.) led to just the opposite - they became the foundation of entire new species. Every organism is the product of mutation, so of course the mutations are handed down. In H. sapiens sapiens the entire species is founded on the mutations for erect posture. From there the liberation of the hands afforded the opportunity to exploit the innate intelligence of the protohumans (now not only able to create a tool, but to wield it as a weapon). And from there the mutation for a larger brain ensured a strong foothold in a brand new niche.

    This is kind of like asking "what is a genome?". There's no framework from which to make any estimate. It would be sheer speculation. Certainly there is some merit to commenting on the maximum number of permutations. How many ways can you arrange 3 billion base pairs? That gives a far upper limit. Considering there are 20,000 genes that code for proteins, you could still dig for how many mutations each of those can carry. Any way you look at it, the numbers are huge. But none of that even matters since there is no way to convert this into meaningful information.
     
  9. wellwisher Banned Banned

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    If you look at the DNA, not all aspects of the DNA change with the same likelihood. There are highly conservative aspects of the DNA and there are transient aspect of the DNA. Somehow, some of the DNA dice are loaded (conserved) so they always fall a certain way. Maybe a better analogy for evolution is counting cards. The first hands dealt to life (way back when) used the entire deck. But as life evolved milestones, some cards were missing from subsequent hands (conserved or counted cards), so the next hands will not use the entire deck. How does the cell know the difference? There is something more than selection at work, since as shown below, this also occurs with noncoding DNA that is not even needed.

     
  10. matthew809 Registered Senior Member

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    I don't know about that. I can tell you that I believe the physical world is an illusion, created by a "universal" consciousness.... this consciousness being all that there is. But that belief is just an idea I feel strongly about. I would never say that I am sure of it. It just makes the most sense to me because the existence of my consciousness is the only thing which I can be 100% certain of. Also, let's face it...consciousness emerging from physics makes no sense, but physics emerging in the mind of consciousness does make sense to me. And I understand that evolution could still be true as anything can be in such a world, albeit an illusion of consciousness.

    I've already stated the issues that I have with evolution. I love a good theory, especially one dealing with such a profound subject, but it needs to make sense to me. People are as stupid as they are smart, and I've learned that I can't just believe something because everyone else does. I can't suspend my own critical thinking just because I'm told it's already been done for me.

    More complexity requires more successful mutations... and there's a time constraint. Four billion is a large number, but it would take a lot more than 400 mutations to create a human for example.
     
  11. Grumpy Curmudgeon of Lucidity Valued Senior Member

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    matthew809

    Yet the main features of your argument come straight from Creationist thought, if it can be called that.

    The simpler the organism, the more this aspect of evolution becomes important. Sponges, for example, emit millions of sexual gametes, most of which are destined to be eaten. They have taken the production of offspring to an extreme. But all it takes is a genetic modification that makes some gametes just a few percent less buoyant than salt water and they drift down to the floor of the ocean while their siblings are eaten by fish, crabs, shrimp and jellyfish. It will not take many generations before the "fallers" outnumber the "floaters" in the sponge population. It really is just that simple.

    There you go with that religiously based non-sense again. Were you home schooled or go to a religious school? The word "creation" is not one that applies to the natural process, it is Christian based pseudo-scientific drivel. Life was not created, it is the result of complex chemistry through it's normal physical behavior. In fact, it was almost inevitable given the conditions on Earth, and likely Mars, Ganymede and possibly elsewhere in just our own solar system. Once a single self replicating molecule exists, everything that it produces is, by definition, life. In fact, the only real life that exists is the DNA molecules in our genome. All other traits are there to support the reproduction of that genome(individually and collectively as a species). Mankind and all he does is machinery to reproduce the DNA in our cells. It is the competition with other sets of DNA for limited resources(niches)that drives the changes in that DNA by adding advantageous traits(caused by mutation)by the simple process of survival to reproduce them. Disadvantageous traits are eliminated(or tend to be), neutral traits may or may not survive and advantageous traits accumulate. That is Evolution. We still have the same skeleton as the frog, everything descended from the first amphibians do. We share an unbroken strand of descent with those first land dwelling, air breathing creatures, we inherited our skeletal structure from it, it was our many times great, great grandfather. If it had had 6 legs and 11 fingers, it is likely we would too.

    I get the idea you think there is some genetic "norm" that mutations attach to or change. That is a false paradigm. The mutations are the genome, the ones that are tested by the survival to reproduce and win are the genome(as an accumulation of advantageous traits)that is reproduced. Our brains, for example, are the main thing that distinguishes mankind from it's 98.7% identical cousin, the Bonobo. Those brains are what built our technological civilization, the Bonobo sits in trees and scratches fleas. The mutation that joined two of our chromosomes is probably the only reason we could not interbreed. I think brains would be selected for, the clever and the sneaky always get ahead. We did.

    No, they will accumulate and as long as they are advantageous they will continue to survive. If conditions in the niche change so that they are a disadvantage they will be eliminated. If they are neutral they become part of what we used to call "Junk DNA", but that we now know to be storage of traits we once found advantageous. There's code for gills and tails and such in there.

    From what starting point? From the first self replicating molecules? Trillions. From our last common ancestor with a living ape, not so many, but probably tens of thousands, altogether. It's complicated.

    Grumpy

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  12. Grumpy Curmudgeon of Lucidity Valued Senior Member

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  13. Write4U Valued Senior Member

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    Look around you, people in the east who have a different diet tend to be smaller than Europeans who like their meat and potatoes.
    http://www.answerbag.com/q_view/786800

    Must be that rich Dutch milk.

    My guess, it took about 300,000 years, which oddly translates into about 6000 generations (@50 yr average lifespan). Close enough?
     
  14. billvon Valued Senior Member

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    Hundreds of thousands at the very least; most likely millions.
     
  15. Write4U Valued Senior Member

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    Today there are about 6 billion slightly different versions of modern man, give or take. From hair down to fingerprints.

    Only cloning can produce identical offspring. The Silvery Salamander is an example. http://arborwiki.org/Silvery_Salamander
     
  16. Aqueous Id flat Earth skeptic Valued Senior Member

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    Is that God or not? And does that mean you believe God "created the Heavens and the Earth"? So far your reluctance over evolution seems to ring of Creationism. What Darwin realized from his observations at Galapagos was that he had seen hard evidence that special creation was impossible. It would help clarify your position if you would speak to whether or not you agree with Darwin on that issue.

    The next question which I think would help further the discussion is whether you believe in catastrophism (the abrupt appearance of our world
    out of thin air).

    Why? All the evidence suggests the opposite.

    It seems rather odd that a person would feel rather strongly that the world is an illusion.

    Not to burst your bubble, but suppose that's the only illusion going on here.

    It baffles me that people who post about consciousness typically refer it to physical sciences rather than life sciences.

    The conscious mind is a biological phenomenon, not a physical one.

    I gather you would prefer a theory centered around the evolution of the conscious mind. You can actually get quite a bit of that studying biology.

    You can be cured of this quite readily by deciding how else the finches of Galapagos came to exist.

    When did you first decide that science is based on belief rather than knowledge? I suppose if you suffered a severe disability, such as blindness, you would have to rely on what people tell you the world looks like. But if you have reasonable visual acuity, you should have had ample opportunity to experience the evidence first hand.

    Who told you that? And how about applying some of that critical thinking by putting yourself in Darwin's shoes. Suppose it had been you who arrived at Galapagos only to make the same astounding discoveries. What next? Do you opine that the finches confirm special creation or nor? How does actual evidence enter into your critical thinking and how do these other things floating around in your head cause you to toss the evidence out? (You seem to have decided that there is no evidence of speciation.)

    How does pessimism influence your judgment about the evidence? Is that where you really want to be -- throwing out evidence -- or do you want to look at it more closely and not overlook the salient facts leading to the truth of the matter?

    What does that mean? I can't make sense of it. How about this: start from the position that there are 3 billion base pairs in each strand of DNA contributed by each parent. What are the odds a perfect copy will emerge every time?

    And that leads to the next question. If perfect copies are the norm, what accounts for the fact that siblings (other than identical twins) are remarkably different? (It has nothing to with mutation but it may help you start thinking in terms of the actual complexities of evolution.)
     
  17. wellwisher Banned Banned

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    Like I discussed above, there are highly conserved areas on the DNA. This conserved areas of the DNA raises the question, how is possible for the mutation process to be limited on certain areas of the DNA, even though the entire DNA is replicated with the same apparatus subject to random errors? If the cell can be that selective against mutations through many levels of species, one might also expect "mutation is being allowed", in places that help with environmental stress, milestone goals, etc..

    What I also showed was an exception to the theory of natural selection. Experiments have demonstrated that conserved areas of the DNA, 100% common to mice and men, were not even needed. When these were removed from mice, it made little difference between these mice and those who retained this conserved DNA. Selection assumes there should be an advantage, for persistence, yet something without any perceived advantage was being conserved. This suggest, these were selected for reasons only known to the cell, and not the external environment/mating logic of Darwin.

    I was not even aware of this data, until I did a search for conserved genes, yesterday, but I have always contented this and was called a creationist to silence the truth in favor of traditions. The concept of intelligent design means using intelligence to define life, which I try to do.
     
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    No. If there is truly no use of the "junk DNA" even once in many generations, then there is little if any advantage in eliminating it, and some risk that doing so as that may eliminate some needed part of the DNA too.

    For example most animals do have DNA for making vitamin C, but doing that manufacture is more costly biologically that just ingesting vitamin C. So Fruit eaters, of the primate line, whose DNA was "defective" - could not make vitamin C had a slight selection advantage and that part of the DNA eventually dropped out of their gene pool (or is now inactivated and called "junk DNA") but elimination of junk DNA that truly does nothing is not worth the risk elimination of it makes.

    I. e. Mother nature is following the rule: "If it ain't broke, don't fix it."
     
  19. Write4U Valued Senior Member

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    Why do we still have a tail bone? Hair over out entire body but thicker in certain places? We don't really need them anymore. They are vestiges which do no harm the organism and sometimes in certain ways have morphed and adapted for other purposes.

    The whole point of "natural selection" is NOT necessarily "survival of the fittest". We are not perfect, nothing is, but we are constantly evolving by adapting, and now by unlocking the secrets of cellular chemistry.
     
  20. matthew809 Registered Senior Member

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    I can't say whether special creation really happened or not, because that idea trumps any evidence which would show otherwise... isn't that the whole point? I don't believe that special creation happened, but I do believe that disproving it is impossible. I would question the judgment of anyone who would say otherwise.

    I don't disagree with evolutionists on how the finches came to be so varied.

    There is some evidence supporting the idea of speciation, or macroevolution. But evolutionary theory does not have exclusive rights to this evidence. That's not how science works. For example, this same evidence can also support the idea that the same building blocks of life were used to create the different "kinds", and that each kind was given considerable ability to change over time. I'm not saying I do or don't believe this(although it's pretty obvious isn't it) because it's irrelevant to the discussion and will only serve to derail the thread.

    I don't think perfect copies are the norm, but I do think variation is the norm... without the assistance of mutation. In other words, if mutations suddenly ceased happening, species would still continue to adapt and change just as they always do, and just as Darwin's finches did.
     
  21. Grumpy Curmudgeon of Lucidity Valued Senior Member

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    matthew809

    Then you believe in god. You can believe anything you like as long as you realize that what you believe does not trump what we know about reality.

    To you, maybe. I realize that the programs running on my computer are nowhere to be found inside of the computer case. Just as the consciousness you seem so sure of are nowhere to be found inside your head. We call these types of things "Emergent properties". The whole is greater than the accumulated parts considered separately.

    But your mind is prejudiced against accepting reality, so what makes sense to you is already invalid as a standard for reality. That is not a fault of reality.

    You should learn to accept reality without flavoring it with whatever you want to believe. Until you do you have no critical thinking going on at all. It's the old garbage in garbage out conundrum. We're actually asking you to apply critical thinking to your own errors. DON'T accept what anyone tells you, investigate the facts for yourself. Any reasonable person will come to the same conclusion Darwin did as long as their beliefs don't derail their train of thought. Evolution is an observed fact, Evolutionary theories try to explain that observed fact and are subject to improvement and change as we learn more about the facts of evolution. Your resistance to the facts is most of your problem.

    No, there is plenty of time for successful mutations to accumulate. You have an idea what decades mean, one hundred years is within your ability to understand, a thousand years are really just an abstract conception and ten thousand years takes you back to the first human civilizations. 100,000 years and above are meaningless in any real way to you(you think "Long time" but you understand 100 years). It was about 8 million years since we had a common ancestor with the great apes, about 400 million years since the first multicellular life and 3.5 BILLION years since the first lifeform. That was plenty of time when we have observed new species forming in only decades. The truth will set you free from that enormous blind spot you have regarding your incredulity about deep time.

    There are more than 200 new mutations passed on with each reproductive event in humans. Most are harmless, some are fatal(and eliminated)and a very few are advantageous and become the genome. Put evolutionary pressure on(IE let the weak die)and the pace of change can be very rapid indeed. As it stands right now, we allow the weak to reproduce, Nature would cause them to die before reproducing. So we are actually interfering with the natural evolution of humans, just like we did with wolves and cattle. But we use the same mechanisms of natural evolution to do so, substituting our own selection criteria for nature's survival to reproduce.

    Grumpy

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  22. matthew809 Registered Senior Member

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    Exactly.

    In order for evolution to be true, something much more purposeful and consistent must be operating other than natural selection. Natural selection via random mutations/environmental change just doesn't explain how extraneously complex creatures could come to be; it only explains variation of complex creatures which already exist... a fact which I do not dispute in the least.
     
  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Do you thing God or something made all the tiny variations between different stages of fossils found that show the transformation of a large land creature into whales with no gaps in the record?

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    The front leg bones did not fossilize in this example - why is not known, They are present in other samples of this stage of development. Perhaps this animal, just a new born baby, bleed to death after shark attack to forelegs it may have used in self defense? Or it could have been a "birth defect" without forelegs?

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    Note the still exiting, total useless unconnected residual leg bones in side the modern whale. Come back in 10,000 or so years with your whale catching boat and even these useless calcium deposits will probable be gone.

    Yes there are some gaps between these three fossil stages, but about a 100 other fossils fill them all.

    The article (conclusion below) also has some drawings of how the jaw and teeth changed. I.e. as article states, nine different structural aspects in the fossil records show how thousand of "micro-evolution" step made a huge macro-evolution change. Change a large land into a large sea creature but still an air breather and one giving live births, not an egg layer like most fish. The whale is still a mammal, not a fish, for reason I discussed in post 23. ("Trapped by prior history" as evolution can not make a viable one generation change from lungs to gills. etc.)
     
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