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Posts posted by Pete

  1. most people find the idea of creating a new life form to be an idiotic idea but i believe otherwise i mean from one strand of dna we could grow a sheep or a human (even if it is illegal) so why couldn't we mix a a hamster and a fish to make a hamfish or something similar any ideas welcome
    Mixing DNA seems to fail when the species are even a little different.


    "can we play God" if other than a technical question, a moral issue, is a moral one.


    But I don't think we should make a hamfish. It'd taste aweful! :D

  2. Okay. I think I pretty much have what I came to ask.


    Here is the gist of what I got from all this:


    Mayr used the term gill to refer to the structure that will become the gill if the embryo is a fish. These same structure become other things in other species.


    Analogy - The term eye could be used to refer to the structure that will become the eye.

  3. The pharyngeal pouches are indeed common across vertebrates. The difference is that only in gilled animals do they perforate and become gill slits.

    Why is that anyway? Do you think' date=' perhaps, that ist an evolution thing like I've read about?


    Eyes become eyes, heads become heads, but pharyngeal pouches become various things. From what little I know of evolution it seems like its related to the idea that, loosely speaking, animals evolved from fish. So perhaps those structures originally all became gills. And perhaps that's what Mayr was arguing.

    I should also note that this is precisely why books are considered inferior to scientific articles - books aren't peer-reviewed, so mistakes can slip through.

    What kind of mistake could he have made? Do you believe Mayr made an mistake in his reasoning or his or was the mistake in his knowledge of embrology? I don't mean to be difficult but Mayr was one of the greatest scientists of his time and a very proliphic writer. His books for the layman aren't exactly easy reading so its not as if he dumbed them down. I just find it a hard to accept that Mayr made a bogus arguement on what must have been to him an obvious falsehood. For this reason I'd prefer to find out why he wrote what he did rather than to dismiss it as a mistake.


    I know of no example of a physics book where the author used such a horribly weak arguement.

  4. Probably. In technical literature, such a glossing-over of differences would be impossible, but in popular literature, it's practically a necessity (otherwise it winds up as unreadable as the technical literature). It may even have been insisted upon by the editor or publisher of his book.



    I read that book and recall that chapter. If that was his intent then it was a very serious mistake. I.e. the purpose of that portion of the book was to argue that early embryonic stages have features in common across certain species. If he didn't really means gills then it would appear as if he was intentionally trying to mislead the reader. I don't know how else to interpret it otherwise.
  5. Because he's an ornithologist, ...


    Its my understanding that he started out as an ornithologist and ended up as an evolutionary biologist. The Harvard University Press refers to Mayr as a ..giant among evolutionary biologists


    Widely considered the world's most eminent evolutionary biologist and even one of the 100 greatest scientists of all time, ...

    Pretty impressive credentials!!


    Nature refers to him as The evolutionary biologist... They write (http://www.nature.com/news/2005/050131/full/news050131-19.html)

    The evolutionary biologist Ernst Mayr died on 3 February at the age of 100, after a short illness. A hugely prolific writer and researcher, he was instrumental in developing modern ideas in evolutionary theory.

    FYI - See also



    ...I'm a world expert in snake locomotion..

    :eek: I suffer from ophidiophobia so I'm not responsible for my actions if your "little friends" get near me. :D

    The "gill slits" story is pretty prevalent, and I only know it to be false after having some embryology eduction.

    Perhaps its a matter of interpretation and semantics. E.g. if the embryo is at a stage where the structures that become the eyes are present then it may be legitimate to refer to them as the eyes even though they aren't fully formed. Perhaps when Mayr refers to the pharyngeal pouches as gills that he's doing something analogous.

  6. They're not the same thing, and the examples above are either sloppy writing, or simplifications for a lay audience.

    Thanks. That answers my question. Much appreciated. :)

    Now, as for recapitulation theory, ...

    I only saw the term "gill slits" from that page on which recapitulation theory was menioned. And I only came across that page when I did a search on that term. I looked through a book by Richard Dawkins and found recapitulation theory in it. He referred to recapitulation theory as unfashionable.


    The only assumption I made was what I learned in that biology text, i.e. that in some species those things become gills which in other species they become other things. From what I read, in humans the first gill pouch forms the middle ear and the Eustachian tube, the second becomes the tonsils, the third and fourth become the thymus and parathyroid and the fitfh pouch disappears.

    Merged post follows:

    Consecutive posts merged
    They're not the same thing, and the examples above are either sloppy writing, or simplifications for a lay audience.

    Why would Mayr refer to pharyngeal pouches as gills?


    Also, Mayr implies that there is an structure in fetal embryos which become tails in monkeys and disappears in humans. Is there a name for that structure?

  7. Please don't do this again.

    Perhaps you're unaware of it but that kind of response is irritatating. Please don't do it again.

    I was referring to your telling me I didn't understand your purpose and therefore tried to define your purpose.

    Let me get this right. I said that you didn't understand me. You're response is to that assertion is to chastise me, your reason being that I didn't understand you? :eek:


    Sorry dude but that seems quite hypocritical to me.

  8. Please don't do this again.

    (sigh!) Please don't start making accusations like this, i.e. as if I'm doing somthing wrong "again".


    You wrote I also think the opening post was loaded by suggesting ...


    That reads as if you thought the OP was loaded and that you suggested that it meant something else. And I hold that you thought wrong. I you disagree with that then simlpy say so.

  9. I also think the opening post was loaded by suggesting there is something psychologically wrong with people who get angry with a label like evolutionist.

    That's because you didn't understand how the term psychological basis (i.e. psychological reason) was used in this context. Since only I can say what the purpose of the opening post was then only I can tell you that if anyone did make such an assumption then they be wrong. My question in the opening post was phrased as follows

    What I don't understand is the psychological basis for this. Can someone, perhaps somone well versed in psychology, shed some light on why some people get so pissed off by such a universally used term like "evolutionist"?

    It was a Why do some people ...? kind of question and as such it was a question on psychology since it addresses mind set. If I thought there was something wrong with people who got pissed off for that reason then I'd have called it a question on pathology rather than psychology.


    My question is similar in nature to the questions at The Psychology of Atheism (http://www.columbia.edu/cu/augustine/arch/vitz.txt)

    Next, Dr. Vitz moved on to the deeper psychological reasons some

    people do not believe in God.

    Dr. Vitz didn't imply that there is something psychologically wrong with atheists.

    I tried to steer clear of that but putting this thread in this section may have doomed it from the start.

    If I placed this in the Evolution forum then people might have thought I wanted to talk about whether the term evolutionist was derogatory, well-defined, meaningful etc. That wasn't what I wanted to know. As sugh this is the correct place to ask this question.

  10. Basically, what human and all vertebrate embryos have are properly called Pharyngeal Pouches.

    Thank you. I didn't mention that since I looked that term up before I started this thread and came across sources which implied that it was just a synonym for gill slits. E.g. see


    For example, Haeckel believed that the human embryo with gill slits (pharyngeal arches) in the neck not only signified a fishlike ancestor, but represented an adult "fishlike" developmental stage.

    This page seems to indicate that gill slit is a synonym of pharyngeal arche. I also learned about this in Biology, by Sylvia S. Mader, page 607

    The diagram illustrates that the embryonic chordates have a notochord and a dorsal hollow nerve cord. Another characteristic of all vertebrate embryos is the presence of gill pouches or slits (fig. 27.9). Only the lower vertebrates (fishes and amphibian larvae) use the gill slits as functioning structures. The fact that higher forms go through this embryonic stage indicates that the higher forms are related to lower forms. The phrase “ontogeny (development) recapitulates (repeats) phylogeny (evolutionary history)” was coined some years ago as a dramatic way to suggest that animals share the same embryonic stages.

    and from B]What Evolution Is, by Ernst Mayr (http://home.honolulu.hawaii.edu/~pine/book1qts/embryo-compare.html)

    ...why should the embryos of birds and mammals develop gill slits, like fish embryos?

    All this seems to imply that Pharyngeal Pouches is just a formal/scientific name for gill slits. These are simply more reasons why I asked Is this an issue of semantics?

  11. Note - Pmb = Pete

    Well, I don't really know for sure. Maybe the gill slits on the embryos aren't connected to the circulatory system, so they don't actually work despite being 'real' gills.


    Perhaps the genes for gill creation are still encoded in the DNA, and expressed during embryonic pre-development, but are suppressed or overwritten by lung genes being dominant when the lung genes start to become expressed in later embryonic development. Or I could be talking rubbish. *shrug*


    Anyway... aren't fish vertebrates? They have spines, don't they?


    I think that the problem lies in the fact that I came to think about this because a theist claimed that human embryos don't have gills. So the real problem is that I started discussing science with a theist (even though I am one). :D

  12. Maybe it means the form of gills, but not the function?


    As in, the embryo couldn't use them to "breathe" with, it has to rely on the mother's blood for oxygen?

    Doesn't that imply that comment? Gill slits on fish embyros are not actual gills? What use is such a comment? Its like saying fetal legs are not actual legs because the fetus can't use them to walk. :confused:


    If that's all there is to it then this was a dumb question. Lol!

  13. I'm confused about something. Its probably a mere problem of semantics but I figured I'd ask to make sure.


    The following site defines Gill slit (http://en.wikipedia.org/wiki/Gill_slit) as follows

    Gill slits are gills with individual openings rather than an outer cover.

    So gill slits are a type of gill. But at the bottom it says

    In the 19th century, gill slits of vertebrate embryos were erroneously thought to be actual gills, and thus evidence for the recapitulation theory.

    Those two statements taken together are confusing to me.


    gill slits of vertebrate embryos -Are they are or are they not gill slits?


    Is this an issue of semantics?

  14. ... but i can see that it's not so simple to swap time and space coordinates as though they are the same.
    Absolutely not. Only in a mathematical sense are they treated on the same footing, not in a physical sense. Even mathematically there is a bit of a difference due to a negative sign in front of only one diagonal term in the Minkowski metric.
  15. Actually I'm not even clear on what this about anymore since I can't imagine what "matter bent in time" could possibly mean.


    When defining new terms one starts with an idea and then forms a term around it. This is different. We are trying to start with a term and define an idea around it.


    Does this sound accurate?

  16. I thought we were talking about non-vacuum solutions, i.e. the bending of matter!
    Who said that? They were talking about gravitational time dilation, right? For the sake of arguement consider a black hole. Everywhere outside the event horizon the spacetime is curved and there is no matter present. The Ricci tensor vanishes. I believe that the question about bending time applies to outside the event horizon.
  17. That is not the reply I was hoping for etc.

    And I was hoping that you'd be able to let go of your combative attitude. Its undesirable to all.


    Olkay. Fine. I see you're one of those people who just have to have the last word or jibe in. So post another one and get it over and let it die after that for cripes sake!

    In that case, shouldn't an evolutionist only be one that studies evolution just like a physicist studies physics? Hence, only evolutionary biologists are "true" evolutionists, according to this.



    To be precise you're correct. The analogy is nor 100% perfect. An evolutionist is an adherent to evolution be it a layman or an expert.

  18. 4) Mokele suggested that we use the label creationist but refuse the label evolutionist' date=' to marginalize the creationists (see post 32). This seems wrong to me, but is probably another reason people object to using the word evolutionist.


    :confused: Does that imply that someone will be telling me what words I use in the future, i.e. that someone can tell me if I can use the term evolution or not? I hope not. I had to leave that other forum because of this. I don't want to leave this one for the same reason. Then again I don't talk about evolution that much ... yet.

  19. Alright, how 'bout we concentrate on how to bring this discussion back on track rather than dwell in past mistakes?


    We should debate the definitions and not the person making a claim about the definitions.




    I originally created this thread to learn more about the negative emotions associated with its usage. It took a bit of a turn to its definition but I guess that was to be expected. But I don't think that there is really much arguement on what it means. When I saw the term in Ernst Mayr's book there was no ambiguity to what it meant: Think of it like this


    "Study of physics" is to physicist as "Study of evolution" is to evolutionist

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