Russ,
Yes. I agree. However, the problem with the chicken experiment is that the
chickens in the cages were SISTERS. Not a problem, obviously, for the purposes
of egg production, but for peace and quiet of group selection theorists, not so
great.
You could double the readership my paper on this subject by going to
http://www.behavior.org/journals_bp/index.cfm?page=http%3A//www.behavior.org/journals_bp/BP_welcome.cfm.
Behavior and Philosophy, 28, 83-101 (2000). © 2000 Cambridge Center for
Behavioral Studies
Take care,
Nick Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology,
Clark University ([EMAIL PROTECTED])
----- Original Message -----
From: Russ Abbott
To: [EMAIL PROTECTED];The Friday Morning Applied Complexity Coffee Group
Sent: 10/13/2008 3:14:43 PM
Subject: Re: [FRIAM] Selection, Reproductive rate, and Karrying Kapacity.
One of my favorite books of the year is David Sloan Wilson's Evolution for
Everyone. Wilson has been arguing for multi-level selection for quite a while
-- and as far as I'm concerned he makes very good points.
The fundamental insight is that everything is both a group and an individual.
And hence virtually anything can evolve at the individual level -- even if it's
a group.
Wilson likes talking about religions (or religious groups united by religious
practices) as an example of a group that competes evolutionarily. He argues
that religious that promote hard work, support of fellow members of one's
religious community, etc. tend to succeed.
He also tells the story of the experient in which groups of hens were allowed
to evolve. It was done in two ways.
1. Start with (say) a dozen cages, each with a certain number of hens. At the
end of a given time, the best egg-layer in each cage were bred to create a
second generaation of cages. Continue for a certain number of generations.
2. Start the same way, but after each generation, breed the best cage,
regardless of how its individual members performed. Continue for a certain
number of generations.
The result: breeding cages was much more successful than breeding individuals.
In this case it turns out that breeding individuals produced macho hens who
pecked each other to death. Breeding cages produced cooperative hens who lived
happily with each other and produced lots of eggs.
The larger lesson is that groups often embody structures that support the
group's success. To enable those structures the group needs members who play
various roles. Simply selecting the most productive members of a group and
rewarding them breaks down the group structure.
-- Russ
On Mon, Oct 13, 2008 at 11:18 AM, Nicholas Thompson <[EMAIL PROTECTED]> wrote:
All,
Here are some comments on various comments. I succumb, reluctantly, to the
community norm about caps.
[grumble, grumble]
Glen Said ====>
The idea of expansion and contraction is
interesting: rapid expansion of populations
(when selection is relaxed) vs. rapid contraction
of populations (when selection is intensified).
The human population went indeed through a
phase of rapid expansion in the last decades while
natural selection was released through cultural
and technological progress.
Seed Magazine has an article about human
evolution and relaxed selection, too
http://www.seedmagazine.com/news/2008/10/how_we_evolve_1.php <===
Nick Replies ===>
I think this is a confusion between carrying capacity and selection. When, for
some reason, carrying capacity is increased, the whole population can expand,
but this does not stop selection. It may change the nature of selection from
tracking how well individuals can make use of limited resources to how fast
they can reproduce when times are flush, but there is no reason to think that
raising the carrying capacity should "relax" selection.
Russell Wrote ===>
Any extinction event is a collapse of the food web. And selection only
proceeds by means of extinction. So I'm not really quite sure what
you're trying to nuance here.
Nick Replies ===>
OK. Here is where we disagree, I think. Let's worry this a bit, before we
talk about anything else, because it seems absolutely central: When talking
about selection, at what level of organization are we speaking? Gene,
individual, small group, "deme", species, ecosystem? etc. I grew up under the
influence of George Williams who argued that no entity above the individual
could serve as a level of selection and of Richard Dawkins, who argued that no
entity above the level of the gene could serve as a level of selection. So, in
my world, species level selection is not a powerful cause of evolution.
Indeed, on some definitions, species, by definition, cannot compete. Now, in
the last decade, I have thrown off Williams' shackles and started to talk about
selection at the level of the small group. And, indeed, I do know that some
others have started talking about species-level selection. But species level
selection has not become the received view, has it???? If not, the statement
above must be EXTREMELY [whoops, _extremely_] controversial.
Let's pause here and see what others say.
Nick
Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology,
Clark University ([EMAIL PROTECTED])
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