"dkomo"  wrote in message
news:cdnfmf$9ae$1{at}darwin.ediacara.org...
> Jim Menegay wrote:
>
> > dkomo  wrote in message
news:...
> >
> >>"Wilson argued that the trait group is a unit of selection.  Trait
> >>groups composed of altruistic animals can outcompete trait groups of
> >>selfish animals.  This can be true even if if within every trait group
> >>the selfish animals are outcompeting the altruistic individuals."
> >
> >
> > Yes, but for this to continue to work, generation after generation,
> > there has to be some way of creating new trait groups that are
> > predominantly altruistic.  Notice that in the logic of what has been
> > presented so far, the trait groups that start predominantly altruistic
> > become less so over time.
> >
>
> Only if trait groups are permanent.  They are not.

Regardless of how long they last.  Though if they last only a short time,
then they become only a little less altruistic.  By definition, altruism
means adverse within-group selection.

> > If these new predominantly altruistic trait groups have to be created
> > by sampling error, then trait group selection has to be seen as a very
> > weak force in evolution.
> >
>
> Trait groups with predominantly selfish individuals go extinct because
> of the low overall average fitness.  Trait groups with predominantly
> altruistic individuals have high overall fitness so they will pump more
> such individuals into the general population.  New trait groups will
> form consisting of mostly altruistic individuals, and these groups will
> recolonize the territory vacated by the extinct selfish groups.
>
> Here's how Sterelny and Griffiths explain it:
>
> "Under Wilson's trait group model, group selection also exerts its
> effects through the greater productivity of altruist groups. Trait
> groups sooner or later merge into the general population, and the next
> generation of groups re-forms from that population.  If groups that form
> from the general population tend to be differentiatied, with altruists
> associating with altruists and freeloaders with freeloaders, then group
> selection acts through altruistic groups pumping more individuals into
> the general population from which new groups form, not just through the
> differential extinction of groups."
>
> _Sex and Death_, Kim Sterelny and Paul Griffiths, p. 165
>

Right.  Trait group selection plus $3.50 will get you a cup of mocha.
But trait group selection plus assortive trait group formation may
get you polite service and other forms of altruism.
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