Guy Hoelzer  wrote in
news:bn9pg3$2tvk$1{at}darwin.ediacara.org: 

> in article bn7cci$28l9$1{at}darwin.ediacara.org, William Morse at
> wdmorse{at}twcny.rr.com wrote on 10/22/03 6:54 PM:
>> I had envisioned the group (wolf pack, macaque ?troop?) as having to
>> reproduce  through individuals because otherwise everyone in the
>> group would have to split in two. So what I was really talking about
>> was replacement of the group (which is one form of reproduction) by
>> reproduction of individuals. You are thinking, at the group level of
>> selection,  of a group growing by accumulation of individuals and
>> then splitting, without creating a "copy" of the old group.
>> Interesting. 
> 
> Right.  Selection and evolution can't occur if reproduction always
> results in perfect copies.  Reproduction requires heritability, which
> is a continuous variable, and offspring groups in this context do tend
> to resemble the parental group, relative to the average group in the
> population of groups, due to both cultural and genetic modes of
> inheritance. 
>

One of my later objections was to the likelihood of sufficient 
heritability of groups. Both the above influences certainly  help 
overcome this objection. One would like to see actual numbers. I am aware 
of documented cultural influence in macaques, and would guess that it 
also occurs in wolves.  An interesting question is how far down the scale 
of intelligence we can go and still find significant cultural influence. 
Imitation has been shown to occur in guppies, so this influence should 
probably not be underestimated.
 
> I would actually push this issue further on theoretical grounds. 
> Group identity need not depend upon the identities of group members. 
> Like anyTHING in nature, group identity depends on structural and
> process coherence over time.  You, for example, are composed of a set
> of cells that is almost entirely non-overlapping with the set of cells
> you had when you were born.  This does not, IMHO, make you a different
> person than the one who was born.  The continuity of functional
> coherence in your existence has been sustained despite the turnover in
> the membership of your components. Similarly, functional social
> organizations, like a church congregation, also experience turnover in
> membership.  In fact, individuals can switch congregational
> affiliations, but this does not entirely disrupt the continuity of
> coherent function sustaining the identities of different 
> congregations.  The same logic is easily applied to social groups in 
> non-human societies.
> 
> The point here is that we should be no more concerned with the
> identities of individuals within groups, or their reproductive
> successes and patterns, in thinking about group selection than we are
> with the identities of cells in the bodies of multicellular organisms
> in thinking about individual selection.  These concerns represent
> overly reductionistic views that obfuscate putative higher order
> processes by assumption. 

OK, but remember my original argument on this was that the replicator was  
at a different level than the selectee. 


 
> Actually, I would say you hit the nail on the head in pointing to the
> empirical evidence for heritability at the group level.  Of course,
> questions like this only enter the empirical realm when someone (or
> enough someones) think that there is a reasonable chance that
> heritability at the group level might be real and significant.  I
> think it is high time this empirical question be taken seriously.
> 

There may well have been an over-reaction to arguments based on "the good 
of the species". There is also the problem that many of these effects 
(group selection, symbiosis) are not easily modeled. Because of the 
pervasive influence of "physics envy", phenomena that are not easily 
modelled are sometimes dismissed. Note that I am not against modelling, 
(but I do have a problem with "physics envy" - as a civil engineer I find 
that my most complex calculations have to do with politics, which is 
decidedly non-reductionist)


> It is very interesting that you raise the issue of "ostracizing",
> which is a particular form of "policing."  The evolution of policing
> (a form of individual spite manifested as a coherent process at the
> group level) has received some significant attention over the past
> couple of years. 


And policing represents some of the best evidence for group selection. 
There was a recent finding about capuchin monkeys rejecting an "unfair" 
reward that received much attention. I also remember a very interesting 
article in Scientific American last year discussing research on policing, 
in which one person could determine the split of a pot of money between 
the two subjects and the second person could accept the split (with both 
receiving the split share) or reject the split (with both receiving 
nothing). It was made clear that this was a one time interaction, so 
there was no incentive for the second subject to reject based on a future 
negotiation with the first subject. Under game theory the first subject 
should propose a lopsided split in their favor, and the second subject 
should accept such a split (also note that the amount of money was enough 
to represent a significant windfall for many of the participants). In 
fact the first subjects typically proposed splits close to 50:50 and the 
second subjects rejected splits that were significantly lower than that. 
The only reasonable explanation for this behavior has to be based on 
group selection.
 
>> Packs composed of such members will on average do better than other
>> packs, which will in turn enhance the reproductive success of the
>> pack members, which will in turn create more "good" pack
members that
>> will reproduce better packs. But the traits that are useful in a pack
>> will be useless in the absence of a pack. So is this not group
>> selection at the level of the pack? 
> 
> If I read you correctly, part of your scenario is that groups composed
> of individuals behaving in synergistic ways (i.e., ways that are
> reciprocally beneficial among group members) grow in group size and
> split (group reproduction) more frequently (have higher group level
> fitness).  If this is right, than I would say YES; this would be group
> selection at the level of the pack.  If your scenario does not include
> reproduction at the level of the pack, then I would say this is NOT
> group selection. 


Initially I would not have included the splitting of groups, but the 
alternative is growth in group size, which will obviously run into limits 
in animal systems. Some of my thinking has been influenced by thoughts 
about human economic groups, simply because I am more familiar with them, 
and in human economic groups there are fewer limits on the size of a 
group.

 
> I think that there may be some confusion here introduced by the
> assumption that natural selection is the only process that can result
> in adaptive evolution of a complex dynamical entity, like a social
> group.  IMHO this is not the case, although it is certainly the
> current conventional wisdom in the evolutionary biology community.  In
> my view, natural selection is a subset of self-organizing processes,
> all of which lead to adaptive evolution.  Self-organizing processes,
> in general, don't require variable populations of entities passing
> through selective filters.  Adaptive change can be driven by the
> internal dynamics of single entities, such as we conventionally
> recognize as adaptive phenotypic plasticity (or GAIA, to be more
> controversial). 

But why would such change be adaptive? Note that I am attracted by GAIA, 
perhaps because I am an optimist and think that stable patterns will 
outcompete unstable ones. But this may be different from adaptive, which 
in my mind is a sharper term than simply successful, even though adaptive 
is only a result of successful.

Yours,

Bill Morse
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