You say here that the airsac could have developed initially attached to the
main lung, well I thought I should point out that this would not be very
helpful for the animal. It would mean that the animal would be drawing in
more air, needing a bigger chest cavity, but having the same size lung, and
so much extra effort used in trying to fill an extra sac would be wasted.
Unless the airsac could itself draw in air then it would be a hassle for
the lung, and even if it could, it would be much better off with a bigger
lung. If it then seperated and had a pipe joining it to the lung, then it
would serve no purpose, take up more room, and could only store stale air,
or fresh air, neither of which is of benifit! Much better to simply have a
bigger lung. If it did then have a valve system, there may have been some
benifit, but here we see that it must be the whole system changing at once,
or it won't help.
I think I have said more than enough, I'm sure everyone is sick of this
disscusion so I'll stop now.
Donald
P.S. Surviving is not the issue in evolution, passing on your genes is.
Therefore for something to be an advantage, means you have to be able to
get the ladies to like it.
At 10:20 AM 21/08/98 -0700, you wrote:
>Donald:
><<Now if we look at these two lungs, we can see the differences are vast.>>
>
>Yep. But your argument is that the differences are unsurmountable by
evolution.
>
>
>Donald: <<Here's what I propose, for the bird lung to come from the animal
lung, in
>small steps, certain parts of the lung would have to develope first. Lets
>look at the air sacs on either side of the lung. These sacs would have had
>to be developed, with all the appropriate valves and passageways, before
>they could have the air directed into them.>>
>
>Not at all, the airsac could have developed initially attached to the main
lung. When at a later stage the division was 'punctured' (you seem to like
the term) the increased air capacity allowed the bird to be more efficient
in breathing. Over time the hole between the air sac and the lung could
have developed a 'valve' allowing for more efficient use of the organ.
>You are using the same faulty logic used by Gish that 'half an eye' is 'no
eye'. Yet it is possible to show how intermediate steps in the eye
development could have been advantageous. And the same could be done here.
Whether or not this is how it actually happened we will probably never
know. Few data remain about lungs of fossils and most of it is argued from
what they evolved into many million years since the two diverged. In order
to understand in full detail the development we need more data than we will
likely ever see. Does this disprove evolution ? Of course not.
>
>See, none of these steps involve a lung which would be unusable. Yet you
claim that there is no way imaginable how this could have happened. Don't
get me wrong though, I am not proposing that this is THE way it happened,
just a plausible way. Since you have shown no plausible way that it could
NEVER have happened through small steps, I suggest that you 1) try to
establish this 2) try another argument.
>
>It never worked for Denton, who tried through 'irreducibly complex'
systems to prove that evolution could not have happened. When however,
plausible pathways were provided, this argument lost much of its foundation.
>
>Donald: << If the air went into them before they were ready, the animal
would not be able to breath, as the air wouldn't be passed properly into
the lung.>>
>
>That is an assumption that you need to prove. Perhaps the addition of the
airsac, coupled with muscular structures in the body of the bird allowed
the bird to more efficiently pump air into and out of the lungs.
>
>
>Donald: <<Ok, so that would mean that these sacs would have to develope
first, slowly over many generations, untill finally they were ready to pass
the air into the lungs.>>
>
>That is another method
>
>Donald: << At every step of the way, the animal with the best sac would
obviously get the most mates, as natural selection demands. I'm sure having
a useless organ in your body would be of great advantage in finding
mates......>>
>
>Not at all, the advantage might have been slight or none at all. That does
not mean that the 'sacs' would suddenly disappear. And neither you nor I
know the advantages/disadvantages of such air sacs. Little evidence is
left. Further more finding mates is not the only factor relevant here.
Surviving is.
>
>Donald: <<Anyway, next, just by chance, the animal developes all the pipes
that connect this intricate system together, slowly, one pipe at a time
over many generations, while they still can't be used. If they were used,
the air would be directed away from the lung, and the animal wouldn't be able
>to breath. >>
>
>Explain why the pipes cannot be used ? After all it would merely form an
extension (buffer) to the lung. The increased lung capacity, combined with
the buffer and the muscular structure around the air sacs could perhaps
have increased the bird's ability to breath.
>
>Donald: <<<I think we could see that if at any stage the air was
redirected, before
>the whole system was ready, without the assistance of medical science that
>our one lunged man recieved, death would soon follow.>>
>
>Such has been your argument yet you have failed miserably in showing that
this is the case. All you use is ridicule, strawman, argument ad ignorance...
>
>
>Donald: <<That is my hypothesis, refute it if you will. >>
>
>If that's all then consider it done:
>
>Your hypothesis requires that any imaginable intermediate lung would have
been detrimental for the animal. I have given a plausible though probably
incorrect example that this need not be the case.
>Your argument therefor has been disproven, there are imaginable ways for
the change to have taken place.
>
>Now you only response to this can be that 1) you do not consider it
plausible 2) the lung would still not have worked. But you have no way of
knowing 2) with a 100% certainty and 1) is merely argument from
incredulity. Neither one will solve your problems, although they might hide
them for a bit longer.
>
>
>As I said before and you failed to address this:
>
><< But all we have now is a statement that no way is known for a long to
evolve into a bird type lung. But all that could show is 1) our
understanding of lung evolution is lacking, after all there is little
evolutionary evidence left over 2) your understanding of what is known
about lung evolution is lacking. Neither one would form an unsurmountable
problem for evolution. In many sciences details about certain mechanisms
are lacking, that however doe s not necessarily form a problem for the
validity or invalidity of the science in question. >>
>
>
>
---------------------
Donald Howes
Acting Research Systems Co-ordinator
Research Services
University of New England
Australia
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