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From: dubois@uwmacc.UUCP (Paul DuBois)
Newsgroups: net.origins
Subject: Flying Squirrels
Message-ID: <975@uwmacc.UUCP>
Date: Wed, 24-Apr-85 13:51:02 EST
Article-I.D.: uwmacc.975
Posted: Wed Apr 24 13:51:02 1985
Date-Received: Fri, 26-Apr-85 23:31:45 EST
References: <335@iham1.UUCP> <3570015@csd2.UUCP>
Organization: UW-Madison Primate Center
Lines: 42


>>>>             For example, if a limb were to evolve into a
>>>>             wing,  it  would become a bad limb long before it became a
>>>>             good wing.
>>>
>>>    Try telling that to flying squirrels and see how far it gets you.  
>>
>>[DuBois]
>>Try asking them to really fly and see how far it gets you.  What, do
>>you think they have "wings"?

> [Isaac Dimitrovsky]
> The point of the flying squirrel example is NOT that the squirrel can
> really fly. After all, if it could, you would just say it was an example
> of an animal with a fully developed wing. The point of the example is
> precisely that the squirrel can't fly. In other words, it may be useful
> to an animal to have a limb which is both a bad wing and a reasonably
> good limb. In other other words, at least in the case of wings,
> it is possible to have intermediate forms which are useful for
> gliding and short flights but are not capable of full flight. And, at
> least in this case, I don't think you can dispute that this point has
> been established. Can you?

I will not dispute that they can glide and that they are not capable of
full flight.  That is obvious.  I am of course unconvinced that they
are intermediates (that is, intermediates which developed from a
non-intermediate).  The skin flaps are not wings and there is no
evidence that they ever will be.  There is also (as far as I am aware)
no evidence that they ever were anything but skin flaps.  Perhaps you
will say that there is not evidence that they were *not* something
besides skin flaps.  I think you would be right in this, but that is
not a very strong position to argue from.  This puts us at a standoff,
because we simply do not know whether they were ever any different than
they are now.  If it suits you to be an agnostic in this matter, fine.
That makes two of us.  But if you wish to use this as evidence of an
"intermediate" to press your case, I will object and demand evidence
which, I think, you shall be unable to produce.
-- 
                                                                    |
Paul DuBois	{allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
                                                                    |
"Danger signs, a creeping independence"                             |