Re: Group selected altruism - (was: Hamilton's rule)
- From: "Jim McGinn" <jimmcginn@xxxxxxxxx>
- Date: Fri, 25 Nov 2005 13:13:37 -0500 (EST)
Perplexed in Peoria wrote:
> "Jim McGinn" <jimmcginn@xxxxxxxxx> wrote in message news:dm2s1k$2cci$1@xxxxxxxxxxxxxxxxxxxxxx
> > Perplexed in Peoria wrote:
> > > "Jim McGinn" <jimmcginn@xxxxxxxxx> wrote in message news:dlvnf0$mco$1@xxxxxxxxxxxxxxxxxxxxxx
> > > > JMcG:-
> > > > All that is necessary for group selection is that there situational
> > > > factors that prevent or reduce gene flow between groups, as Catherine
> > > > described, and situational factors that cause differential
> > > > survival/reproduction between the groups, as Catherine also described.
> > > [snip]
> > > PiP:-
> > > I would claim that the 'reduced gene flow' actually works against you
> > > (even though it is usually assumed as an ingredient in classical group
> > > selection). The usual argument is that the reduced gene flow keeps
> > > the altruistic group from being diluted by non-altruistic migrants.
> >
> > JMcG:-
> > Without reduced gene flow, or relatively reduced gene flow, you don't
> > have groups.
>
> Well, that may be the case for classical group selection
This is the case for *all* group selection. There is no such thing as,
"classical" group selection. There's just group selection. But there
are any number of strategies that can be more or less group selective
oriented.
> , but it is
> definitely not the case for 'trait group selection'.
There is no such thing as, 'trait group selection'.
> You appear to be making the assumption that to have a real 'group',
> the group has to have a lifetime longer than a typical individual and
> it has to reproduce by fission (or something like that). And that
> is definitely true in a large and important class of group selection
> models.
You lost me. I'm not making any such assumptions and I'm having a hard
time figuring out what your point is here.
>
> However, starting around 1970, people like George Price and D. S. Wilson
> came up with some very different group selection models. In these models,
> the first essential feature of a 'group' is that it be a collection of
> organisms. But it can be a temporary collection (the people on a bus
> can constitute a group), and the birth of a group does not necessarily
> involve a parent group. Groups can form by some process of coalescence
> among the individuals of the lower-level population. And they can dissolve
> without 'dieing', thus releasing the group members back into the general
> population of individuals.
>
> The second essential feature of a group, in these models, is that the
> fate of the individuals in the group is in some sense tied up with the
> fate of the group - at least for the portion of the individual's lifetime
> that it spends in the group. Group selection leads to bus passengers
> who do not distract the bus driver.
Jim
.
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