Number: 241 (Read 0 times)              Date: 21 Feb 94  19:07:04
   From: Wayne Throop
     To: All
Subject: Test for evolution

From: throopw%sheol@concert.net (Wayne Throop)
Organization: Alcatel Network Systems (Raleigh, NC)

::: Can "altruistic" traits be passed onto progeny ? There's the
::: Wynne-Edwards observation where in highly populated flocking birds,
::: some birds forego their reproductive capacity and only a few birds
::: reproduce.  How do the net.evolutionist explain this?
:: Of course.  See, for example, "The Evolution of Cooperation" by Robert
:: Axelrod.  Dawkins talks about such things too.

: From: muttiah@thistle.ecn.purdue.edu (Ranjan S Muttiah)
: Could you say a word or two about what they have to say ? How do they
: distinguish this condition from the more familiar evolutionary
: examples ? Sounds like they are deviating quite a bit from
: Neo-Darwinism.

Axelrod studied populations where the "payoff" of progeny was defined by
the "Prisoner's Dilemma" payoff matrix.  That is, it is always to
immediate advantage to "defect", but when everyone follows that
strategy, the payoff isn't optimal.

In particular, by adding some specific more-real-world-like properties
to the game, but retaining the payoff matrix that "encourages"
non-cooperation, Axelrod showed how small initial populations of
cooperators could arise, and eventually penetrate and overcome an
existing population of non-cooperators.

This forms the basis for how mutually altruistic behaviors could arise
by evolutionary processes in the usual way: that is, altruistic
strategies outperform non-altruistic strategies, when a population
interacts with itself.

Dawkins, in _The_Selfish_Gene_ (and quite apropos to the title) shows
how behavior that is altruistic on the level of the organism is,
nevertheless, selfish when considered from the viewpoint of the gene.
In such cases, the altruism is performed towards organisms which are
"known" to contain copies of the altruistic organisms's genes.  Parents
caring for their children is a simple case of this, as is bees caring
for the queen, naked mole rats caring for the reproducing female, and so
on.

Let's take an interesting example of this that is right in front of
everyone's noses, and yet very often overlooked.  Look at things from
the viewpoints of cells.  The vast majority of cells in your body are
"altruistic", in that they service the needs of other cells and the
community at large, while only the gametes actually get to reproduce.
However did multicellular organisms ever evolve then, if Ranjan's
objection is valid? The answer is simple.  If a given single cell line
doesn't reproduce, yet provides resources to "sibling" cells that *do*
reproduce, copies of that cell's genes are propogated.

In general, the altruistic behaviors of cells make people think that
evolution "act"s to the advantage of species, and the altruistic
behaviors of parent, bees, NMRs and so on make people th ink that
evolution "acts" to the advantage of groups or species.  Dawkins' thesis
is that this is exactly backwards, and that *all* such behaviors are
*selfish* (or self-beneficial, and not altruistic) when viewed from the
standpoint of genes, instead of higher-level entities.

There is no special deviation at all from Darwinism, neo or otherwise,
in either of these two models (mutualism or gene-selfishness).  Yet both
result in altruistic behaviors, and in fact the mathematical model of
eusociality was used to *predict* the existance of the NMR.
All perfectly Darwinian.

How all this might be relevant to the bird behavior that Ranjan used
to bring up the subject is obscure, since no specific behavior was
advanced as an example.  In fact, "only a few birds reproduce" and
the rest "forego t heir reproductive capacity" may be simple selection.
That is, all have some *chance* to reproduce (unlike bees, where workers
have zero chance to reproduce.  But even then, there's nothing odd
from an evolutionary perspective there.

--
Wayne Throop   throopw%sheol@concert.net
               throop@aur.alcatel.com

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