On Thu, 26 Feb 2004 16:44:30 +0000 (UTC), 
Anon.  wrote:
> Larry Moran wrote:
>> On Tue, 24 Feb 2004 20:57:28 +0000 (UTC), Anon. 
>>  wrote:
>>>dkomo wrote:
>>>>Tim Tyler wrote:

[snip]

>>>Of course, drift may also be an explanation, but I believe that we can 
>>>only separate out the contributions of the different causes empirically.
>> 
>> Yes. Until we can actually test the hypotheses it's wise not to *assume*
>> that all morphological features are adaptations, don't you think?
>> 
> As long as we can't exclude non-adaptive explanations, then we can't 
> dismiss them.  But there may be occasions when making that assumption 
> does lead to further enlightenment.  It seems to be a problem of 
> scientific rhetoric.
> 
> Hmm.  I'm not sure whether I answered you or not.

Yes, you've helped me to understand your point of view.   :-)

>> Tim seems to be making the default assumption that most morphological
>> features are due to natural selection. Dawkins certainly makes that 
>> assumption. Is this valid? 
>> 
> Well, it's valid.  Is it correct?  My feeling is that it is, but if 
> someone show me evidence that it isn't, then I'll change my mind.

I can understand your "feeling." Since we don't have very good evidence
one way of the other is it valid science to rely on "feeling"? Why are 
you asking for experimental evidence against your feeling? I could just
as easily state that most features are due to drift and it's up to you 
to prove otherwise. Would that be an example of good science?

Why don't we just say that morphological features can become fixed in
a population by adaptation - and quote some known expamples. We don't
know if *most* morphological features are due to adaptation or whether
they are accidents of evolution. 




Larry Moran
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