[from Gary Cziko 931003.1600 GMT]
Bill Powers (931002.1130 MDT):
Lots of interesting stuff relating PCT to evolution. You always seem to
find a new slant when you bring together my two favorite subjects.
Arcs, rings, and nests are effects on human
perceptions created by the actions of the behaving systems: side-
effects. Simply by looking at these side-effects, we can't tell
what's important about them, if anything.
But wasn't Avery Andrews saying, in effect, that there are TWO different
types of side effects? There are the "true side effects" which are neither
controlled by the organism nor do they have any role in contributing to the
organism's evolutionary fitness. But there are also effects which are side
effects in that they are not controlled by the individual organism but
which ARE important in contributing to inclusive fitness of the species
over phylogenetic time. Some aspects of the termites' nest are undoubtedly
true side effects, but others are most likely only partial side effects
(I'm open to suggestions for better names for these two types of effects).
A termites' nest, in some parts of the world, may take the form
of a dirt mound five feet high and two or three feet in diameter.
Does this mean that natural selection has selected for building a
nest with these dimensions, or for the fact that the nest is
built above ground? Not at all; in fact, those aspects of the
nest are probably of no significance to any termite. To
understand why the nest appears as it does, we would have to
discover what the actual survival factors are that are affected
by the actions we call "nest-building" (which are not nest-
building at all, from the termites' point of view). We would have
to get inside a termite and see how it feels to be inside a nest
-- what the temperature is, the humidity, the path length to
various places where critical things happen like the laying of
eggs and feeding of young, and so forth. Natural selection will
operate to preserve just exactly those variables controlled by
the individual termites that bear directly on reproduction. All
other effects of the termites' behavior, however organized or
interesting they may look to us, are irrelevant.
I don't think this "termite's eye view" is always necessary to understand
what is going on. If we see that termite eggs left exposed to the sun
shrivel up in a few hours, can't we assume that the nest provides important
protection from the sun? If we see an archer fish dropping insects into
the water with its built-in squirt gun and then gobbling them up, isn't it
clear that this behavior important for its survival? I suppose that I am
talking here about what Don Campbell calls "puzzles of fit." These are
often quite obvious (e.g, the airfoil shape of a bird's wing). I don't see
why The Test would be always necessary to find these. I do realize,
however, that one can go overboard seeing adaptation in places where it
doesn't exist--Steven J. Gould's warnings about "Panglossian adaptationism"
and his example of the spandrels of St. Mark's in Venice. The spandrels
may look at first to have been designed to contain those neat little
paintings, but in reality they are just the architectural consequences of
intersecting arcs which are then used for paintings.
Suppose we try to set up the CROWD program so it will evolve to
produce arcs and rings. What would we use as the survival
criteria that would lead to this result? If we followed the naive
biological "genetic algorithm" approach, we would make survival
depend on the formation of arcs and rings. Individuals whose
behavior promoted the formation of arcs and rings would survive;
the rest would be weeded out. Eventually we would be left with
only those individuals whose behavior promoted the formation of
arcs and rings.That might eventually work, but does it make organismic sense? We
have imposed from outside the organism a condition that makes
sense in our own perceptions, but has nothing to do with the
perceptions or experiences of the individuals in the program.In fact there is a much more "organism-like" approach thathas
nothing to do with arcs and rings. All we have to do is make food
available to the leader at the destination, provide that the
others get food if they stay close but not too close to the
leader, and provide penalties for collisions. This would
eventually result in the acquisition of the appropriate control
systems by the individuals: destination-seeking, person-seeking,
and collision-avoidance. Those would be the control systems that
actually promote survival by putting each individual into the
position it needs to be in to survive.
Most artificial life programs that I have seen recently do the latter,
starting with Thomas Ray's TIERRA program in which "organisms" inside the
computer compete for processing time and memory.
Getting back to the different types of side effects and evolution, it just
occurred to me that humans are so successful because they can control for
higher-level variables. Let's assume that parasol (leaf-cutting) ants
control for bringing a certain type of leaf into their colony. A fungus
grows on the leaf fragments and they use this for food. Since they are
controlling only for bringing a certain type of leaf into their colonies
and NOT for growing fungus (let's assume this, anyway), they are in big
trouble if this particular leaf is no longer available. They have no way
to vary the reference level for type of leaf in order to continue to grow
fungus since they have no control system for the higher-level variable of
fungus growing in the first place.
But a human farmer is very different since he is controlling for the
higher-level variable of agricultural output. If his cows don't produce
enough manure, he buys fertilizer. If there is a glut of corn, he grows
soybeans or vegetables. And if he can't make a living farming (a
higher-variable still), he may sell the farm and get a job in town. So the
farmer can successfully resist all types of disturbances that the parasol
ant cannot who must rely on the uncontrolled link between leaf and fungus
growth. Stable environments can make control of lower-level variables very
effective. In these environments we find what are called the "living
fossils" like the nautilus and horseshoe crab. But less stable
environments would seem to favor the evolution of organisms who control at
higher levels in order to be able to maintain control despite unstable
environments. Bill Calvin has written about how varying climatic
conditions favored the development of the human brain.
In general, the organized patterns we see in the behavior of
organisms are not very likely to be relevant to that behavior --
either to the behavior that produces the patterns, or to the
evolutionary forces that shaped the organism to produce the
behavior that results in the patterns. We need a Test for the
Evolved Control System just as much as the Test for the
Controlled Variable. Without some systematic way of finding out
just what survival factor is actually involved, we will continue
to think, naively, that all we need to do is to look and we will
see the survival factor that accounts for the behavior.
As I've already said, I think that in many cases the survival factor
involved is quite clear. How do you propose doing the Test of the Evolved
Control System? Let's take a real example. I notice that when flounders
come to rest on the ocean floor, they dig into the sand a bit with only
their eyes protruding above the sand. I don't have a clue as to what
perceptions they are controlling to achieve this effect (The Test could be
used to find out), but knowing something of the kinds of onery critters
that inhabit the deep sea, I would bet sand dollars to sandy doughnuts that
evolution is "selecting" flounders which are well camouflaged against
predators (flounders who flounder are eaten). Do you disagree? How would
your test work here?--Gary
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Gary A.Cziko Telephone: 217-333-8527
Educational Psychology FAX: 217-244-7620
University of Illinois E-mail: g-cziko@uiuc.edu
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