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From: orwant@athena.mit.edu (Jonathan L Orwant)
Newsgroups: sci.bio
Subject: Evolution
Keywords: evolution
Message-ID: <5944@bloom-beacon.MIT.EDU>
Date: 28 Jun 88 05:03:32 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: orwant@athena.mit.edu (Jonathan L Orwant)
Distribution: sci.bio
Organization: Massachusetts Institute of Technology
Lines: 15

I'm a bit confused about how special-purpose anatomical parts can evolve, e.g.
the evolution of a bird's wings from an unwinged predecessor.

If it happens gradually, then why isn't the 2% of a wing along the way an
evolutionary detriment?  I've heard that it acts as a heat insulator; maybe 
so, but I would think that there would be much more efficient ways of 
retaining heat that would give competing organisms an advantage in the 
meantime.

Another explanation I have heard is that specialized master-genes turn on
entire sequences of genes so that once a mutation triggers the proper master
gene, an entire wing appears.  If this is the case, where is the information
of how to grow a wing stored in an animal whose ancestors were wingless?

-Jon Orwant (orwant@wheaties.ai.mit.edu)
Pity me.  I'm a computer scientist.