Date: Mon, 27 May 1996 20:26:49 +0000
Subject: Re: Pigs could flya - Reply 


C'mon, Rahul, I doubt I was that categorical about group selection.  I'd 
just like those who invoke it to first betray some understanding of the 
conditions that must be met in order for it to be plausible. 

And Paul, what determines a species "longevity" ?  Does not the 
persistence of a species require the survival and reproduction of many 
of its [individual] members?  I'd like to be clear on exactly what the 
issue is, expecially if I'm to be indicted.

Thanks,
Lisa


Paul Gallagher wrote:
> 
> > The key word in what I said was intrinsic. I would agree that most of the
> > time that one can find a simple physico-chemical reason for certain
> > features, it would probably be the case that they did not arise adaptively.
> > I see no reason, however, why that should be a hard and fast rule.
> 
> I see what you mean.  I wasn't proposing it as a hard and fast rule.
> It's a question of balancing the contributions of various factors that
> constrain evolutionary change.  Why invoke adaptation if a simpler
> explanation exists?  Why invoke adaptation if there's no way to falsify
> your assertion that the feature is an adaptation?  And a characteristic
> can't be selected for or against if it doesn't exist, or can't exist.
> 
> >
> > I also think these ideas are very important, and are probably given less
> > attention than they deserve. Please give us your definition/explanation of
> > species selection. Lisa has categorically stated that there is no such
> > thing as group selection of any kind.
> 
> I should have stopped by
> the library before answering this, but on the other hand the problem here -
> certainly with Lisa Rogers - isn't a lack of access to the literature,
> but a disagreement with it.  If I remember correctly, species selection
> is the theory that the differential survival of species sometimes depends
> not on the fitness of individuals, but on characteristics of the species
> as a whole: for example, the longevity of the species, or its distribution,
> or the rate at which it gives rise to daughter species.  It's unrelated
> to the fitness of individuals.  It isn't a form of group selection, as far
> as I know.
> 
> Paul
> 
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