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Thread: One-on-One:Questions about Evolution, MrJack and Truppenzwei

  1. #16
    Journeyman Mr Jack's Avatar
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    Hi Truppenzwei,

    Quote Originally Posted by Truppenzwei
    Now using that as the basis for speciation then I could agreee that speciation occurs - however it only seems to occur within what I would previously of thought of as a species ie. Mosquitos I thought of mosquitos as being the species but it is some other word instead.
    Indeed so, and that is exactly what we should expect if evolution is true. Evolution is primarily a gradual process of accumulated small changes. Given the time scale on which we have been able to observe these processes we shouldn't expect to see any radical changes occurring. Your statement is analogous to measuring a tree in the morning, then again in the afternoon and concluding it can't be growing by cell division because it is the same height in the afternoon as it was in the morning.

    Because at the moment I see no reason why given a diverse set of common ancestors at the point of reproduction beginning we wouldn't end up with exactly the situation we have today. And to be honest I see no evidence to disprove the theory either.
    Hmm, I'd like to know your response to the questions I posed in my last proper post. I find the arguments from homology and genetic compelling - what is it about them that you find lacking?

    Please note - I'm making no claims to where these ancestors came from as that is outwith the purview of a discussion on evolution.
    Of course. However, I do need to know something about what it is you are thinking if I am to argue cogently as to why SCA should be considered a more convincing explanation.

    Rather than going straight to establishing a SCA for two distinct and extant groups I'd like to start by looking at the fossil record of evolution for whales, at the evolution from this to this. The full story in some detail can be found here, although that source is rather lacking in actual fossil photos, so you may want to visit here as well.

    I've chosen this example for two reasons: firstly, it's one of the ones for which the fossil record is particularly good and, secondly, because it shows a rather radical change from a wolf-sized, terrestrial tetrapod to a huge, legless, ocean going whale. The important point I wish draw your attention to here is the convergence of separate lines of evidence. If, in fact, Sinonyx is not an ancestor (or close relation of the ancestor of, more precisely) modern cetaceans why is it that these evidential lines converge? Why is it that we can locate such a series of fossils documenting the evolutionary history of whales?

    Now, to bring it back to the question you asked, the fact is that we do not have a nice fossil record like this one for all mammals. I doubt I can locate a neat sequence of fossils tracing both horses and dogs back to their common ancestor in a way that would convince you (horses have a very good record going back about 60 million years, but I couldn't locate a similar record for canidae and even if I had the two evolved from ancestors who had already diverged by that time). However, if you look at the whale evidence you can see a well documented case linking very dissimilar animals so we can know that such changes are possible.

    I have tried throughout this discussion to present multiple sources of evidence for each evolutionary claim. I think this is the key point about evolution. There is no single piece of smoking gun evidence for evolution that should convince you beyond reasonable doubt but rather a large, coherent and consistent body of evidence and confirmed predictions.

    For a sufficiently devious set up of common ancestors there is no possible test we can do that will prove that it didn't happen - this is essentially a re-telling of Descartes's demon doubt - but if we look at the evidence we have and try to construct the most parsimonious (containing the least co-incidences) and plausible explanation we are inevitably drawn to a SCA interpretation for all higher life. Why else would all vertebrates use the same spine design? Have the same crossing of the genital and urinary tracts and the same eye design?

    The fossil record can't prove SCA but it can show convergence in time. The whale ancestor Sinonyx is more similar to ancestral horses than a horse is to a whale, both converge towards earlier mammals, then protomammals and what appear to be reptile-mammal transitionals. This pattern is exactly what we should expect from SCA but has no explanation under MCA. Now you could argue that we're simply looking for similar animals and then lining them up like they're related when, in fact, they're not (which, wouldn't IMO be a fair criticism but I'll let it stand for now) but then you are left with trying to explain why the evidence from genetic sources matches that from the fossil record, and why ontogeny confirms them both.

    I've been talking thus far about SCA among higher animals. Sadly the evidence slips rather as we move away from them. There are no fossil indicating when insects emerged as a separate group, or how. No records proving a link between Archae and Eucaryotes and no records indicating when plants and animals diverged. Here we must rely on homology among basic systems (e.g. DNA) and extrapolation - essentially having satisfied ourselves that all higher animals share a common ancestor it seems most reasonable to assume that, in the absence of other evidence, we share our ancestors. Other explanations must make unreasonable appeals to chance.

    Cheers,

    Mr. Jack.

    (As an aside, in an earlier post you mentioned abiogenesis as being off-topic, I would be quite happy to discuss this with you later on providing it understood that it is a separate subject)

  2. #17
    Supreme Goombah of the Goombahs
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    HI Mr Jack,

    Sorry for the delay - snowed under at work at the moment. I'll try and sit down on Saturday and respond.
    Trupp's Scientific Law:
    God exists

    How to falsify:

    Method 1 - Die, come back and tell me I'm wrong.
    Method 2 - Go back in time and verify whether Adam and Eve existed or not.

  3. #18
    Journeyman Mr Jack's Avatar
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    Hi Truppenzwei,

    I'd rather have a thought out response later than a quick response now so, please, take your time.

    Cheers,

    Mr. Jack.
    If you're really a Goth, where were you when we sacked Rome?

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    Hi Mr. Jack - sorry for the delay but work is frantic at the moment - I am considering your questions and have ordered a couple of books on evolution just to make sure that I've got things right. I will hopefully have a decent response in the next day or so if work calms down a bit.
    Trupp's Scientific Law:
    God exists

    How to falsify:

    Method 1 - Die, come back and tell me I'm wrong.
    Method 2 - Go back in time and verify whether Adam and Eve existed or not.

  5. #20
    Journeyman Mr Jack's Avatar
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    Hey Truppenzwei,

    What's the state of play? Are we to continue with this?
    If you're really a Goth, where were you when we sacked Rome?

  6. #21
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    Hi Mr Jack.

    Yeah I'd like to continue it's just I'm snowed under at work at the moment as my boss is stateside so I'm dealing with his workload as well as mine.

    I am reading through the evolution books that I got and so will be better placed to debate once my work calms down a bit.
    Trupp's Scientific Law:
    God exists

    How to falsify:

    Method 1 - Die, come back and tell me I'm wrong.
    Method 2 - Go back in time and verify whether Adam and Eve existed or not.

  7. #22
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    Mr Jack,

    Knight is wanting to shut this thread down due to inactivity and I've agreed because work is way busy and I honestly can't predict when I'll be free to respond in a decent form. Once I get some free time we can either carry this on by PM or if we are both feeling really brave in a public thread Thanks for your time so far, and rest assured I'm doing my research thoroughly.
    Trupp's Scientific Law:
    God exists

    How to falsify:

    Method 1 - Die, come back and tell me I'm wrong.
    Method 2 - Go back in time and verify whether Adam and Eve existed or not.

  8. #23
    Journeyman Mr Jack's Avatar
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    That's a shame. Oh well. Thanks for listening.
    If you're really a Goth, where were you when we sacked Rome?

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