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Evolution Proven

  1. Mar 17, 2003 #1

    Another God

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    Evolution not proven? here is its logical proof:

    1. The current theory of evolution states that any system where there is hereditary information, slight alterations of that information, and a selection pressure for the best system of hereditary information, evolution will occur.

    2. DNA is the hereditary code, passed down from generation to generation in an essentially static form.

    3. Mutations occur irregularly in all forms of DNA, in a myriad of different ways.

    4. In nature, at every level, more organisms are given birth to/replicated/produced, than are able to surive to sexual/replicable age.

    Conclusion
    5. Therefore, Evolution occurs.



    While I believe this proof is unquestionable (prove me wrong), it doesn't address whether or not evolution explains the variety of life we can see. It just proves that Evolution is an unquestionable fact of life.
     
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  3. Mar 17, 2003 #2
    You know, this is a very important point (kudos, AG). Evolution has been proven to occur. I also really appreciate the mention (at the bottom of your post) of the fact that it does not account for the variety of life that we see around us.

    In short: Evolution is an observable fact, but we can only formulate hypotheses (some even become theories) as to the variety of life that is currently to be found in the Earth.
     
  4. Mar 17, 2003 #3

    Monique

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    Isn't the fact that we are able to make children genetically composed of two people proof enough of evolution? Or say, the fact that we are able to breed certain strains of organisms in order to get new phenotypical characteristics?

    And euhh, AG? Since when is DNA passed down from generation to generation in an essentially static form?? There are on average 40 cross-overs in our genome per meiosis. The process of meiosis essentially requires cross-overs to occur. I am not sure about the selection process after these 40 meiosis, how many can actually form a zygote..
     
  5. Mar 17, 2003 #4
    Are there records of different variations throughout relatively recent human history that imply evolution occuring?
     
  6. Mar 17, 2003 #5

    FZ+

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    Well, I guess you can take the variation in skin colour or lung capacity etc across the human race as evidence for a drive towards diversity. The increased size of US people over past years, or earlier appearance of puberty is also evidence, though I don't think it is entirely genetic.
     
  7. Mar 17, 2003 #6
    I'm beginning to doubt genetics is the first thing that "causes"(so to speak) evolution.
     
  8. Mar 17, 2003 #7

    Another God

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    Huh? Whats to doubt? Evolution occurs through genetic mutations. Observable, testable, obvious fact.

    That is an essential part of the proof above.

    And:
    The member formerly known as theOwl :

    Perhaps essentially static sounds too strong, but I just couldn't think of a better adjective at the time.

    Still, the idea remains I think, because even though there is so much crossing over in meiosis, the DNA which is crossing over is so damn similar (almost identical considering the bulk size of it) the change is negligable.

    Besides, meisis is only a fraction of the evolutionary chain. A recent fraction.
     
  9. Mar 18, 2003 #8
    Bacterial sex is particularly interesting. It's as though those bacteria are throwing around code and using it to build entirely new bacteria. Oh wait, that's exactly what it is. Even crosses species bariers completely.
     
  10. Mar 18, 2003 #9

    Another God

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    Well, I wouldn't say that exactly.

    I asked a question just last week to one of my Microbial Genetics lecturers about that actually. One question we were asked in a test was about whether DNA could jump from species to species etc. And its not as obvious as it may seem.

    Firstly, of course DNA is just DNA. Its the same in all species, so if it gets into any species genome, then its in there and it will be copied.

    What needs to be considered though, is
    1. How it gets in there
    2. Whether it will do anything once it gets in there

    For 1, naked DNA can get into Bacteria, but certain conditions need to be present for that to happen, so it is not frequent. Plus, once it gets into the bacteria, it still needs to get into the Chromosome. This is even harder, and not something which usually 'Just happens'.

    The other way DNA can get into other bacteria is through Conjugation (this is probably the type of DNA u are refering to when u talk of Bacterial Sex). COnjugation occurs when a bacteria contains a series of genes which encode for this thing caleld 'The Sex Pilus'. When they have these genes (usually on a plasmid), a short lived bridge forms between it and a neighbouring bacteria, and a plasmid can pass from one to the other.

    ..

    I could go into a lot of detail, but well, I don't think anyone is really that interested. Actually, you might be. If anyone is interested, raise your hands, and I will start a whole new topic.

    But to get to the point of it, bacterial 'sex' as such, doesn't occur between different species very much at all. For the Sex Pilus to form, there are the usual sorts of recognition things which need to happen. If there are two different species, then they won't recognise each other.
     
  11. Mar 18, 2003 #10
    I raise my hand.

    Anyway, no, I wasn't implying that it happens often, even though it sounds that way. But it is one of the big parts of bacterial evolution, is it not? Every once in a while a bacterium can pick up a stray plasmid. Am I right? I could just be having bad memory again.
     
  12. Mar 18, 2003 #11

    Another God

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    Well..um..i guess it could be.

    I'm not really sure what has more influence on evolution, but I can tell you that plasmids are definately an obvious phenomenon. They have a quick recognizable phenotypic effect when present, and are very convenient when it comes to genetic engineering stuff.

    We are currently doing a lab in Microbial Genetics which is using a plasmid to mutate a E Coli bacteria (A very normal experiment really), and the plasmid which we are using has been almost completely engineered to do exactly what we want it to do. Its all so damn clever when u understand it.


    For plasmids to have any sort of permanent effect on evolution though, they need to have a transposon on them, or some method of integrating themselves into the chromosome permanently.

    So yeah, when this happens, i guess it could very easily be beneficial to the evolution of bacteria.
     
  13. Mar 18, 2003 #12
    g'day!

    that is an interesting proof of evolution, however it doesn't consider other reasons for evolution, i am thinking of the non biological ones. evolution is always assiociated with natural selection, the fitter have more babies etc. but there are other forces promting evolution that have nothing to do with the 'selection pressure for the best system of hereditary information' as you rightly put it. physical forces like thermodynamics also have an effect on evolution.

    The universe 'prefers' systems that turn collected energy into difuse energy, in this way systems like individual species or ecosystems will tend towards greater energy consumption for no aparent survival reason. the only evidence i've heard for this argument is that systems that have more time to evolve are the biggest energy wasters, just look at humanity!

    cheers!
     
  14. Mar 18, 2003 #13

    Another God

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    I know it is related, but I can't manage to get my head around exactly how this affect evolution.

    Sure, laws of thermodynamics affect everything, but, what explicitly are u getting at which can't be assumed as 'Evolution works as explained in the proof, under the laws present in our universe.'?
     
  15. Mar 18, 2003 #14
    because your proof is based on the importance of the transmission of genetic information, ie the ability of a species to live long, prosper and reproduce. the difference with the thermodynamic theroy is the cause of this transmission, both theories admit the ability of a trait to be passed on to the next generation (this is the 'how'), but with 'classical' evolution the reason for evolution (the 'why') is this exact ability to pass on traits as much as possible, where as with this 'other' evolution the 'why' has nothing to do with the 'how'.

    at least that's how i understand it... crazy huh?

    trust the physicists to complicate things! :wink:
     
  16. Mar 18, 2003 #15

    Another God

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    oh yeah.... I'm confused.
     
  17. Mar 18, 2003 #16

    russ_watters

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    Heh. I'll join you. We'll start a club.

    I'm not seeing that. Like mitosis, or nuclear fission, evolution is a geometric progresson. If mutations occur enough that you have ANY new species evolving, your world should quickly fill up with MILLIONS of different species. That appears to be exactly what happened.
     
  18. Mar 18, 2003 #17
    I'm afraid I didn't see where this apparent confusion started. What is it that confused everyone?
     
  19. Mar 18, 2003 #18
    This proof explains evolution in terms of a particular ecological niche or adapative landscape. Given there are a miriad of ecological niches and that adaptive lanscapes are constantly changing, an similar number of species will result.
     
  20. Mar 18, 2003 #19

    Monique

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    I think the big issue in this type of discussion is to separate evolution from creationalism.. evolution is proven, but the fuzzy part is how an a photoreceptor evolved into an eye, not how how a gliding squirrel got to its skin flaps to glide (probably the route by which birds evolved wings).

    Mutations happen, ever seen the deformeties that are encountered in fetuses/embryo's? Mutations happen, diseases are genetic, aggregation of mutations in a certain direction will lead to evolution. The major factor influencing evolution is environmental pressure. The squirrel with the larger skin flaps is able to make it to the next tree without crashing into the ground, if selective pressure is high enough, the trait will be passed down.

    How about comparing genomes? Only 1% of the genes in the mouse have no homologues in humans..

    To address MajinVegeta's original question about human evolution.. how about Africans being long and lean and Eskimo's being short and chubby? How about sickel cell anemia being prevalent in Malaria-infested regions? Skin color? All these things have evolved for a reason.
     
  21. Mar 18, 2003 #20

    russ_watters

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    Steppenwolf's posts. They don't make any sense.
     
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