: > 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"]
:
: The question is not whether they exist, the question is whether
: they are different than Darwin's adaptations. If so, how? If not,
: then Dawkins is right.
They are different in that they require no mutations. An existing
genotype or phenotype is used for a new purpose. It is only after
this occurs that adaptations begin to occur.
And much more than this must be overcome before Dawkins is right.
: > 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.
:
: No, if it is possible for the clone to be identical to the parent
: (and in reality it often is), then elitism exists in nature.
Not in the context used by Dawkins. _Nothing_ goes back down
the hill.
: > 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.
:
: "Doing just fine" does not mean optimal. It is at a disadvantage
: because considerable resources are necessary to metamorph midway
: through life, resources that could better be spent foraging and
: reproducing.
And non-optimal does not mean it's peaked, as Dawkins claims. I
think your "disadvantage" statement is a subjective opinion. Are
moose at a disadvantage because of their large antlers? The question
is, does the beast get at least as much resources out of what it
"spends". In the case of the Flounder I would answer "Yes". The
metamorposis lets it enter its true niche, the bottom of the water.
This is where it spends its time foraging and reproducing. This is
not a disadvantage, it is an advantage.
Maybe Hakeeb can find us an online reference for Flounder so we can
take a closer look at this.
: OK, I was wrong, but so were you.
Well, that makes us no better than Dawkins. ;->
: Neo-Darwinism has not been discredited. Neither has
: the Synthetic Theory. It is true that Gould, Eldredge
: et al have criticized the Synthetic Theory, advancing
: their own "punctuated equilibrium" theory an an alternative
: model. However defenders of the Synthetic Theory (Dawkins
: and Dennett among them) point out that ST always included
: the idea that evolution can proceed at different rates.
I'm not sure how you're using the word "evolution" here. For
a given gene, mutations occur at a statistically constant rate.
For phenotypes, there is no statistically constant rate. This
situation is called punctuated equilibrium. Here's a graph of
it in action (as always, fixed-width font is best):
M| !
U| ! $
T| !
A| !
T| ! $
I| !
O| ! $
N|!
+-----------------------------------------------------------
0 T I M E N
! = Cumultive mutation of some gene, X
$ = Cumultive mutation of some phenotype, Y, which provides
higher fitness.
Any ! without a corresponding change in phenotype is an example of
non-darwinian evolution.
Each $ that is part of a process of non-darwinian evolution is an
example
of punctuated equilibrium.
Perhaps you'd be kind enough to explain "Synthetic Theory" to me.
> Some writers (incorrectly) use Neo-Darwinism as a
> more general term, to cover all of 20th-century
> biology, including the combination with population
> genetics in the 1930s that produced the Synthetic
> Theory.
> Do you have quote (included
> with enough context to discern Dawkins real intent)?
Please don't make me type all that stuff in. Page 135. Dawkins
refers to Neo-Darwinism as being created in the 1920's and 30's.
Take it from there.
: > 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.
:
: If general purpose solutions are more useful than "perfect"
: specific-purpose solutions, guess which is more fit?
In most situations, the perfect one. :-p In the long run, it's
a crap shoot, though I'd put my money on general pupose. Notice
it's "often", not "always". We don't really know what will happen,
do we.
: You seem to be confusing the graphs in the book with the
: concept of fitness landscape.
That's what they are. Dawkin's says it's natural selection that
moves the beast up the landscape. Sound's like fitness to me.
He goes on to say that beasts cannot go down the hill. This is
wrong. Offspring are not required to be more fit than their parents.
If a less-fit offspring is fit enough to reproduce, that's good
enough.
If it's not fitness, what is it? A graph of mutational change? If
so, Dawkins contradicts himself by saying "You can't go back down the
hill" and saying "Mutations can be reversed".
If its not a graph of fitness and it not a graph of some current
form produced by mutation, what is it?
David, you're a smart guy. I ask that you read the book and subject
it to the same level of skeptisism that you (rightly) apply to this
thread. As you read it, keep this in your mind:
1] The book is self-contradictory.
2] The book is out of step with modern evolutionary thought.
3] Dawkins no longer does research. He's now on the book-tour, and
dinner-party circut.
4] The book is wrong in many of its descriptions of the processes of
Evolution.
5] The short-comings of Dawkins' "Blind Watchman" program resurface
as shortcomings of Dawkin's description of Evolution.
Hell, he doesn't even mention "cross-over" in the index (perhaps he
mentions it in passing in the book, but I don't remember it.). Yet,
"mutation", which is considered less effective than crossover, gets
14 entries. Again, the book does not reflect modern evolutionary
thought.
Can I say anything good about the book? Yes, I liked the "Kaleidoscopic
Embryos" chapter (although it contained nothing new).
BTW, did Dawkins originate the "meme" concept?
-- David Leeper dleeper@gte.net Homo Deus http://home1.gte.net/dleeper/index.htm 1 + 1 != 2 http://home1.gte.net/dleeper/CMath.html