Re: Article: Group selection, a theory whose time has come...again

On Dec 4, 11:38 am, "Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx>
wrote:
"chris thompson" <chris.linthomp...@xxxxxxxxx> wrote in message

news:62b0ea23-8296-4c60-93c0-1bc9f4b98e2a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx



On Dec 3, 12:17 pm, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:
chris thompson wrote:

[snip]

Is it unreasonable to think that if a given situation somehow favors
group selection, the most profitable group would be one composed of
relatives? You would seem to get the best of both worlds in that
case. Most groups I can think of in natural populations seem to
consist of kin, unless there are compelling reasons to make it
otherwise- for instance, groups that come together for the sole
purpose of reproduction, like herds of deer. And, actually, even they
have some degree of relatedness if I recall my Big Game Management
course correctly.

Sure. In that case we call it kin selection. You may say that kin
selection is a form of group selection, and it is possible to think of
it that way, yet the best understanding is in terms of individual fitness.

Has anyone done any modeling (this is surely a silly question) on the
difficulty of evolving an altruistic non-kin group when a kin-group is
available?

There has been both simulation modeling and analytical study (looking
at the equations and thinking about them). But there are some important
distinctions that have to be made in thinking about the results.

The original analysis of kin selection (Hamilton's) made the assumption
that the interesting phenomenon is non-discriminatory altruism - treating
everyone you come into contact with the same. And, under this assumption,
Hamilton found that altruism can be favored by NS if (and only if) the
population structure and behavioral habits are such that the individuals
that you normally come into contact with are more closely related than
the individuals with whom you compete for resources. This already
leads to very complex math.

But it was recognized very quickly that parental care can be treated as
just another example of kin selection, and that many parents actually
recognize their own offspring and give them preferential treatment. So
the math had to be made even more complicated by taking into account
the possibility of 'kin recognition' and abolishing the assumption that
everybody you come into contact with is treated with the same level
of altruism. But this, then, opens the possibility of phenomena like
altruism within clans and general hostility to outsiders. The important
distinction here is that you can have 'kin selection' without 'kin recognition'
but that the recognition can enhance the effectiveness of the selection.

But, then, once you have admitted the possibility that individuals
can recognize and remember other individuals, and adjust their behavior
to discriminate, you have opened the door to what Trivers called
'reciprocal' altruism - do unto others as others have done unto you.
And, of course, the study of this phenomenon requires all the machinery
of game theory, and the simulation models can become very complex -
like the famous Tit-for-Tat simulation experiments of Axelrod and Hamilton.

Fnord to all fnordlings:

I've occasionally wondered if altruism was something imposed top-down
by dominant members of a group since it seems to me that the top
of a hierarchy might benefit from the stability altruism might
strengthen.

Just a thought, not sure how to pursue it. Any thoughts?

gregwrld

.

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