Perplexed in Peoria  wrote:

> "Guy Hoelzer"  wrote in message
> news:c9389m$e25$1{at}darwin.ediacara.org...
> > in article c92cvt$3s4$1{at}darwin.ediacara.org, John Wilkins at
> > john_SPAM{at}wilkins.id.au wrote on 5/26/04 8:26 AM:
> > > I have already delivered myself of my dismissal of emergence as a
> > > metaphysically interesting feature of physical systems, so I won't
> > > rehearse it here. Flocking behavior, though, is a property
of individual
> > > birds (or boids) and their genetic and developmental programs, not of
> > > flocks...
> >
> > I'm afraid that I don't understand your objection to my example.  I
> > agree that flocking behavior is a property of individual birds, and not
> > of flocks. Similarly, flocks are a property of a species, not of
> > individual birds. Therefore, a single genetic mutation can lead to
> > heritability of flocking behavior at the individual level, and flocks at
> > the species level; so changes in the frequency of this mutation can
> > potentially be influenced by selection at both the individual and
> > species levels.  Do you agree?
> 
> I have already delivered myself of my middle-ground position
> between Guy and John, but, what the hell, I will repeat it here.
> 
> If a deme of swallows does well because it flocks, then the
> individual swallows also do well.  If the flocking behavior
> is due to individuals heading toward concentrations of
> other birds sighted visually, then individual selection
> seems to be the explanation of choice.
> 
> If a deme of peacocks does poorly because runaway sexual
> selection has caused the males to carry outlandish tails,
> then the individual peacocks also do poorly.  But an
> individual peacock has no opportunity to do well in this
> situation.  If it doesn't grow a tail, it can't reproduce.
> If it does grow a tail, it cannot survive predation.  The
> tail is a deme-level property, and deme-level selection
> is the explanation of choice.
> 
> Notice that this is just the opposite of what intuition
> would say about where the property resides.  A flock
> seems to be collective, whereas a tail seems to be
> individual.  Ignore the guidance of intuition!  Instead,
> pay attention to whether an individual can do better
> than the deme as a whole by bucking the system.  If
> he can, then blame the individuals.  If not, then
> blame the system.
> 
> Another example:  If the swallows flock because of sound
> signals emitted expressly for the purpose of attracting
> birds to the flock, then we have a borderline case.
> An individual has no particular reason to signal, if
> it lives in a deme of birds that ignore the signal.
> 
> Whenever you see frequency-dependent selection at the
> individual level, there is the possibility that the
> trait is maintained by feedback loops at the demic
> level, and demic-level selection may be the best
> explanation for what is happening.

Nicely put. I don't think this is "middle ground" - it summarises my own
views very well.
-- 
John S Wilkins PhD - www.wilkins.id.au
  a little emptier, a little spent
  as always by that quiver in the self,
  subjugated, yes, and obedient.  -- Seamus Heaney
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