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Re: Feathers, insulators, reasons for both



At 09:52 PM 10/8/96 -0400, George Olshevsky wrote:

>What's so sacred about Occam's Razor? The minimal hypothesis is seldom if
>ever the one that ultimately proves best.

                Your theories get bogged down in trying to synthesize
conflicting evidence, often relying heavily on assumptions which have not
been tested, and for which thre is no corroborating evidence other than the
theory in question.   True, they tend to fit the data (being inherently
flexible theories).
        We are looking for the theory which fits the data best, BUT which
includes the fewest untestable or untested assumptions, not necessarily the
simplest.  This is a rational and scientific way of going about things.  No
theory which has survived to this day intact does not hold up to these
standards.  If one choosse not to subject your work to these criteria, I
suspect one will have a great deal of difficulty convincing people that it's
scientific.

>The data, such as they are, fit BCF far better than they do BADD. And as far

        See above about untested and untestable assumptions.

>The quick-fix cladogram.

        Others have already addressed this point.  I would rather not bring
it up yet again...

>Whose voodoo evolution? BCF or BADD? When we can't make an argument, let's go
>for _ad hominem_...

        BCF
        Now George, there was no ad hominem intended, and you know it.  I
apologize if it seemed that way.  I was trying to tie up my responses as
neatly as you tie up your theories.  Be flattered!  :)
        By "voodoo evolution" I meant that, in both of your theories, you
base a large portion of your argument on untested or untestable assumptions,
and you seek to tie up all conflicting evidence into one package, as if by
magic.  Granted, voodoo does involve snakes and chickens...  ;)
        And I think I made a darned good argment, thankyouverymuch....

>Yes, dinosaurs could have needed insulation.

        Then don't argue that they a priori didn't need insulation, so
therefore feathers evolved for flight.

>question is >not< whether they >needed< insulation, but why--IF THEY NEEDED
>INSULATION--did they SPECIFICALLY acquire FEATHERS for insulation rather than
>hair, fat, asbestos linings, fiberglass, etc.

        Like I said:  evolution does not always answer a problem in the same
manner.  Perhaps it was a shorter adaptive path to develop feathers.  You
are assuming a lot of things about the first feathers.  You assume that they
weere more difficult to develop than hair.  Proof?
        Turn it around.  Ask yourself what it is that is so special about
feathers that you deny that they could have developed for insulation.
        As for your serious alternatives:
        Hair is a mammalian trait (let's leave pterosaurs out of this, ok?).
To ask why they didn't develop hair is as good as asking why they didn't
develop mammary glands rather than regurgitate food for their young (or
whatever they did).  It could happen, but it is *not* necessarily Mother
Nature's first recourse in insulating her creatures.
        Fat is heavy.  I don't expect fast little critters to always be
running around putting on fat for insulation.  Ever noticed that many
animals who use fat as insulation are aquatic?

>Nobody has explained why feathers are BETTER insulators than hair, for
example, or what it even means to be a better insulator [snip]
>Why a rachis, why barbs and barbules, why all that architecture, even in the
>contour feathers, if we're going for insulation?

        I just offered a hypothesis in my last two postings on this subject.
I crave the indulgence of the innocent bystanders to reiterate:
        1) Rachi may be explained as simply part of the structure of the
insulation.  How else would you build a feather?  As a mass of hairs
radiating from a single root?  The rachis provides a stiff structure to hold
the feathers against the body (or not, as the case may be), and is a
continuation of the branching pattern of the feather (see below).  I simply
cannot accept the a priori assumtion that this structure is a result of
flight and not a precursor (snicker) to flight.
        2) Barbs and barbules increases the area and the insulative
abilities of the feather.  While they are not necessary for *any* insulative
structure, I'm still betting that it takes fewer feathers to cover the same
area as mammalian hair.

        To turn around one of your points:  you say Feduccia says contour
feathers evolved from flight feathers.  Well, if your rachis is so important
for flight, well then maybe it developed *after birds learned how to fly*,
but wasn't on the early, insulating feathers.  And maybe (although I doubt
it) a lot of the barbs and barbules developed later too....
        this is the sort of thing evolution does when it goes exapting
things...

>All these features appear in fossil feathers 150 million years old. Where did
>they come from?

        Since the earliest known feathers are flight feathers, or feathers
on unquestionably flying animals, you're engaging in circular reasoning.

        Wagner

+--------------------------------------------------------------------------+
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |
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