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Re: What is an "active ectotherm"?



In a message dated 96-10-10 14:17:55 EDT, znc14@ttacs1.ttu.edu (Jonathan R.
Wagner) writes (quoting me):

> >What "back-up" does >this< need, for crying out loud? Simply consider the
> >alternative: that a fully endothermic animal developed immediately (within
> >one generation, or a bit more slowly, within, say one speciation) from a
> >fully ectothermic one.
>
>         No.  This is not the only alternative to your hypothesis.  One
> alternative is that the transition to endothermy was fast, in a geological
> sense, and that it is unlikely that we will find transitional fossils at
> all.  You have given no reason why the transition *must* have a priori taken
> place, as I quoted you "surely... in stages" and "over quite a few million
> years".  this is the "back-up" I requested.

The fossil record is irrelevant here. I'm simply addressing the >number< of
speciation events it would take to go from full ectothermy to full
endothermy. I don't care whether all, some, or none of the resultant species
is preserved in the fossil record. There are only two alternatives: either
endothermy arose in 1-10 speciations (just to pick a number), or it took more
than 10 speciations. To claim that full endothermy arose after only a few
speciations is, I again assert, absurd. Like lizards giving rise to gerbils.
To go from full ectothermy to full endothermy involves fine-tuning of
innumerable physiological processes. If you're going to make the
extraordinary claim that this can occur within a few speciations, then it's
up to you to provide the reasons for your claim.
 
> >If you're going to advocate this kind of hog-wild evolution, I think it's
> >time for >you< to provide the "back-up."
>
>         Any modern textbook on evolution will address the possibility I have
> adressed above.  Go to the index and look up "punctuated equilibria".

Sorry, I'm not referring to punctuated equilibria here. The theory of
punctuated equilibria describes the apparent speed with which one species
forms from another; it has little if anything to do with how long a species
lasts or how many speciation events it takes to get from, say, an ectothermic
animal to an endothermic animal. Go back to the textbook and reread the
section yourself.
 
>> Unless, of course, you adopt the BADD viewpoint, which is, "I don't
>> prefer either alternative, but if >you're< going to prefer an
>> alternative, >you< back it up."
>
>         Oh contraire, I certainly would not pin this exclusively on "BADD"
> paleontology.  As far as I can tell, this is a knee jerk habit in most every
> science-related endeavor, including your own, I might add.  It does not do
> to pass the buck, no matter who you are.

You show me the buck I've passed.