: > * "Much of evolution's novelty arises from the
: > actualization of such latent potentials, not from the
: > slow and explicit improvement of an unchanged function
: > by natural selection."
: > - Steven J. Gould; Discover Magazine - 1996
:
: Gould's theory of exaptation is not uncontroversial.
: Dennett does a fair job of tearing it apart in
: "Darwin's Dangerous Idea".
All theories have a controversial phase.
But exaptation has been found to exist, and have advantages
over other types of evolution. [See "Artificial Life",
Vol 2, No 2, "Preadaptaions in populations of Neural Networks"]
: > * Experiements in artifical evolution show that selecting
: > "less fit" individuals is often useful. One such method is
: > called "Tournament Selection", there are several others. In
: > fact, to make selection work as Dawkin's explains it one
: > must use a special type of selection known as "Elitism".
: > This type of selection often keeps the same individuals alive
: > one generation after another, a process that is not and cannot
: > be duplicated in nature.
:
: Actually elitism does exist in nature. It is called cloning.
: There even exists a species of fresh-water snail that uses
: cloning in good times, and sexual reproduction in tough times.
That's the exception that proves the rule David. And I doubt
that it's an exception. Is it _impossible_ for a clone to have
mutations from its original? If the answer is 'no' then it's
possible for the clone to be less fit than the original. And
since the clone must duplicate the original's DNA, it seems
that mutation is possible.
: > * Dawkin's "Blind Watchmaker" program is obsolete. For
: > example, it does not use parasites, a decade-old (ten years!)
: > concept known to quickly and dramatically increase the
: > efficency of such programs. Nor does it take advantage of
: > new techniqes such as multiple fitness functions.
:
: Perhaps you forgot that the program uses a human evaluation
: function, the user has to pick which biomorph in a particular
: generation will breed to create the next generation. Parasites
: and multiple fitness functions make no sense in this particular
: context.
It seems to me that the limitations Dawkins see in the "Blind
Watchmaker" arise again as he describe limitations in Evolution,
that this obsolete program which he describes so lovingly and
which has produced patterns which decorate his house, has colored
his view of Evolution.
However, that's an opinion not a fact, so I agree to take it
off the list.
: > * From the chapter "Getting Off The Ground"
: > Dawkin's implies that the Flounder fish is at a non-optimal
: > peak in evolution, giving the fact that its eye are on one
: > side of its body as proof.
: >
: > * Dawkin's provides no reason _why_ such an arrangement is
: > non-optimal.
: The arrangement is non-optimal because the flounder starts
: out like a regular fish with its eyes on either side of its
: head. Over the course of its lifetime one eye gradually
: moves over to the other side of the head and as it adopts
: a horizontal posture. Other flat fish species like rays
: are not similarly disadvantaged.
Why is this a disadvantage? The Flounder seems to do just
fine with eyes on the side of its head. Yes, it looks a
little strange, but "Not looking strange to humans" is not
a survival requirement.
: > * From the chapter "Getting Off The Ground"
: > Dawkins states that his theory that evolution can't "go
: > back" is based on neo-Darwinism.
: >
: > * Neo-Darwinism is a discredited theory from the 1920's
: > (seventy-five years ago! (three-quarters of a century!)).
:
: Neo-Darwinism refers to the marriage of Darwin's theory
: of natural selection with genetics. What makes you think
: it has been discredited?
It also implies the old "survival of the fittest" mentality.
If you look at Dawkins description of evolution, you'll
see that's exactly what he does. Less fit beasts are not
allowed, even if they're 0.000001% less fit.
Today we know that "Survival of the Fittest" is not how
evolution works. General purpose solutions often are more
useful than "perfect" specific-purpose solutions. Less-fit,
less adapted beasts are allowed and often enhance the
species chance of survival in the long run. Pure luck also
plays a large role in the modern view of evolution.
: > * The basic premise of Dawkins book assumes that creatures
: > are at a single location on the fitness landscape.
: >
: > * Creatures occupy _many_ locations on the fitness
: > landscape simultaniously. For example, a given creature
: > has a fitnes X at movement, a fitness Y at survival rate
: > of offspring, and a fitness Z at intellect. Deficientcies
: > in one area of often best made up for by strengths in
: > another area. For example, humans naturally have a
: > fitness of zero at flying, but rather than evolve wings,
: > they use their strong fitness at intelligence to build
: > airplanes.
:
: The fitness landscape is multi-dimensional and includes
: such attributes as movement and intellect, whatever is
: included in fitness. Each organism occupies a single point
: on the fitness landscape.
The fitness landscapes in Dawkins' book are two-dimentional.
For example, the X-axis may be sight and the Y-axis a measure
of fitness. Under such an arangement, each organism has many
locations, one on each landscape.
More importantly, each capability has but one phenotype
applied to it, but in real life phenotypes are often multi-
functional and can apply to more than one landscape and a
given capabilty can be supported by various phenotypes.
None of this is present in the book, yet Dawkins uses these
charts to draw conclusions about how evolution works.
-- David Leeper dleeper@gte.net Homo Deus http://home1.gte.net/dleeper/index.htm 1 + 1 != 2 http://home1.gte.net/dleeper/CMath.html